Add more articles from readme sections
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Joshua Suskalo
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18 changed files with 1357 additions and 99 deletions
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<!DOCTYPE html PUBLIC ""
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<html><head><meta charset="UTF-8" /><title>Getting Started</title><link rel="stylesheet" type="text/css" href="css/default.css" /><link rel="stylesheet" type="text/css" href="css/highlight.css" /><script type="text/javascript" src="js/highlight.min.js"></script><script type="text/javascript" src="js/jquery.min.js"></script><script type="text/javascript" src="js/page_effects.js"></script><script>hljs.initHighlightingOnLoad();</script></head><body><div id="header"><h2>Generated by <a href="https://github.com/weavejester/codox">Codox</a></h2><h1><a href="index.html"><span class="project-title"><span class="project-name">coffi</span> <span class="project-version">v1.0.486</span></span></a></h1></div><div class="sidebar primary"><h3 class="no-link"><span class="inner">Project</span></h3><ul class="index-link"><li class="depth-1 "><a href="index.html"><div class="inner">Index</div></a></li></ul><h3 class="no-link"><span class="inner">Topics</span></h3><ul><li class="depth-1 current"><a href="01-Getting-Started.html"><div class="inner"><span>Getting Started</span></div></a></li></ul><h3 class="no-link"><span class="inner">Namespaces</span></h3><ul><li class="depth-1"><div class="no-link"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>coffi</span></div></div></li><li class="depth-2 branch"><a href="coffi.ffi.html"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>ffi</span></div></a></li><li class="depth-2 branch"><a href="coffi.layout.html"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>layout</span></div></a></li><li class="depth-2"><a href="coffi.mem.html"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>mem</span></div></a></li></ul></div><div class="document" id="content"><div class="doc"><div class="markdown"><h1><a href="#getting-started" id="getting-started"></a>Getting Started</h1>
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<html><head><meta charset="UTF-8" /><title>Getting Started</title><link rel="stylesheet" type="text/css" href="css/default.css" /><link rel="stylesheet" type="text/css" href="css/highlight.css" /><script type="text/javascript" src="js/highlight.min.js"></script><script type="text/javascript" src="js/jquery.min.js"></script><script type="text/javascript" src="js/page_effects.js"></script><script>hljs.initHighlightingOnLoad();</script></head><body><div id="header"><h2>Generated by <a href="https://github.com/weavejester/codox">Codox</a></h2><h1><a href="index.html"><span class="project-title"><span class="project-name">coffi</span> <span class="project-version">v1.0.486</span></span></a></h1></div><div class="sidebar primary"><h3 class="no-link"><span class="inner">Project</span></h3><ul class="index-link"><li class="depth-1 "><a href="index.html"><div class="inner">Index</div></a></li></ul><h3 class="no-link"><span class="inner">Topics</span></h3><ul><li class="depth-1 current"><a href="01-Getting-Started.html"><div class="inner"><span>Getting Started</span></div></a></li><li class="depth-1 "><a href="02-Memory-Management.html"><div class="inner"><span>Memory Management</span></div></a></li><li class="depth-1 "><a href="03-Builtin-Types.html"><div class="inner"><span>Built-in Types</span></div></a></li><li class="depth-1 "><a href="04-Custom-Types.html"><div class="inner"><span>Custom Types</span></div></a></li><li class="depth-1 "><a href="05-Low-Level-Wrappers.html"><div class="inner"><span>Low-Level Wrappers</span></div></a></li><li class="depth-1 "><a href="50-Data-Model.html"><div class="inner"><span>Data Model</span></div></a></li><li class="depth-1 "><a href="99-Benchmarks.html"><div class="inner"><span>Benchmarks</span></div></a></li></ul><h3 class="no-link"><span class="inner">Namespaces</span></h3><ul><li class="depth-1"><div class="no-link"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>coffi</span></div></div></li><li class="depth-2 branch"><a href="coffi.ffi.html"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>ffi</span></div></a></li><li class="depth-2 branch"><a href="coffi.layout.html"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>layout</span></div></a></li><li class="depth-2"><a href="coffi.mem.html"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>mem</span></div></a></li></ul></div><div class="document" id="content"><div class="doc"><div class="markdown"><h1><a href="#getting-started" id="getting-started"></a>Getting Started</h1>
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<h2><a href="#installation" id="installation"></a>Installation</h2>
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<p>This library is available on Clojars. Add one of the following entries to the <code>:deps</code> key of your <code>deps.edn</code>:</p>
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<pre><code class="language-clojure">org.suskalo/coffi {:mvn/version "x.y.z"}
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<p>Be aware however that there is no synchronization on these types. The value being read is not read atomically, so you may see an inconsistent state if the value is being mutated on another thread.</p>
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<p>A parallel function <code>fswap!</code> is also provided, but it does not provide any atomic semantics either.</p>
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<p>The memory that backs the static variable can be fetched with the function <code>static-variable-segment</code>, which can be used to pass a pointer to the static variable to native functions that require it.</p>
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<h3><a href="#complex-wrappers" id="complex-wrappers"></a>Complex Wrappers</h3>
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<p>Some functions require more complex code to map nicely to a Clojure function. The <code>defcfn</code> macro provides facilities to wrap the native function with some Clojure code to make this easier.</p>
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<pre><code class="language-clojure">(defcfn takes-array
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"takes_array_with_count" [::mem/pointer ::mem/long] ::mem/void
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native-fn
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[ints]
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(let [arr-len (count ints)
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int-array (mem/serialize ints [::mem/array ::mem/int arr-len])]
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(native-fn int-array arr-len)))
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</code></pre>
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<p>The symbol <code>native-fn</code> can be any unqualified symbol, and names the native function being wrapped. It must be called in the function body below if you want to call the native code.</p>
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<p>This <code>serialize</code> function has a paired <code>deserialize</code>, and allows marshaling Clojure data back and forth to native data structures.</p>
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<p>This can be used to implement out variables often seen in native code.</p>
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<pre><code class="language-clojure">(defcfn out-int
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"out_int" [::mem/pointer] ::mem/void
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native-fn
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[i]
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(let [int-ptr (mem/serialize i [::mem/pointer ::mem/int])]
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(native-fn int-ptr)
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(mem/deserialize int-ptr [::mem/pointer ::mem/int])))
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</code></pre>
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</div></div></div></body></html>
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docs/02-Memory-Management.html
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docs/02-Memory-Management.html
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"">
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<html><head><meta charset="UTF-8" /><title>Memory Management</title><link rel="stylesheet" type="text/css" href="css/default.css" /><link rel="stylesheet" type="text/css" href="css/highlight.css" /><script type="text/javascript" src="js/highlight.min.js"></script><script type="text/javascript" src="js/jquery.min.js"></script><script type="text/javascript" src="js/page_effects.js"></script><script>hljs.initHighlightingOnLoad();</script></head><body><div id="header"><h2>Generated by <a href="https://github.com/weavejester/codox">Codox</a></h2><h1><a href="index.html"><span class="project-title"><span class="project-name">coffi</span> <span class="project-version">v1.0.486</span></span></a></h1></div><div class="sidebar primary"><h3 class="no-link"><span class="inner">Project</span></h3><ul class="index-link"><li class="depth-1 "><a href="index.html"><div class="inner">Index</div></a></li></ul><h3 class="no-link"><span class="inner">Topics</span></h3><ul><li class="depth-1 "><a href="01-Getting-Started.html"><div class="inner"><span>Getting Started</span></div></a></li><li class="depth-1 current"><a href="02-Memory-Management.html"><div class="inner"><span>Memory Management</span></div></a></li><li class="depth-1 "><a href="03-Builtin-Types.html"><div class="inner"><span>Built-in Types</span></div></a></li><li class="depth-1 "><a href="04-Custom-Types.html"><div class="inner"><span>Custom Types</span></div></a></li><li class="depth-1 "><a href="05-Low-Level-Wrappers.html"><div class="inner"><span>Low-Level Wrappers</span></div></a></li><li class="depth-1 "><a href="50-Data-Model.html"><div class="inner"><span>Data Model</span></div></a></li><li class="depth-1 "><a href="99-Benchmarks.html"><div class="inner"><span>Benchmarks</span></div></a></li></ul><h3 class="no-link"><span class="inner">Namespaces</span></h3><ul><li class="depth-1"><div class="no-link"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>coffi</span></div></div></li><li class="depth-2 branch"><a href="coffi.ffi.html"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>ffi</span></div></a></li><li class="depth-2 branch"><a href="coffi.layout.html"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>layout</span></div></a></li><li class="depth-2"><a href="coffi.mem.html"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>mem</span></div></a></li></ul></div><div class="document" id="content"><div class="doc"><div class="markdown"><h1><a href="#memory-management" id="memory-management"></a>Memory Management</h1>
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<p>In order to serialize any non-primitive type, off-heap memory needs to be allocated. When memory is allocated inside the JVM, the memory is associated with an arena. If none is provided, the arena is an implicit arena, and the memory will be freed when the serialized object is garbage collected.</p>
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<p>In many cases this is not desirable, because the memory is not freed in a deterministic manner, causing garbage collection pauses to become longer, as well as changing allocation performance. Instead of an implicit arena, there are other kinds of arenas as well. A <code>confined-arena</code> is a thread-local arena. Confined arenas are <code>Closeable</code>, which means they should usually be used in a <code>with-open</code> form. When a <code>confined-arena</code> is closed, it immediately frees all the memory associated with it. The previous example, <code>out-int</code>, can be implemented with a confined arena.</p>
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<pre><code class="language-clojure">(defcfn out-int
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"out_int" [::mem/pointer] ::mem/void
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native-fn
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[i]
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(with-open [arena (mem/confined-arena)]
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(let [int-ptr (mem/serialize i [::mem/pointer ::mem/int] arena)]
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(native-fn int-ptr)
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(mem/deserialize int-ptr [::mem/pointer ::mem/int]))))
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</code></pre>
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<p>This will free the pointer immediately upon leaving the function.</p>
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<p>When memory needs to be accessible from multiple threads, there’s <code>shared-arena</code>. When a <code>shared-arena</code> is <code>.close</code>d, it will release all its associated memory immediately, and so this should only be done once all other threads are done accessing memory associated with it.</p>
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<p>In addition, two non-<code>Closeable</code> arenas are <code>global-arena</code>, which never frees the resources associated with it, and <code>auto-arena</code>, which is an arena that frees its resources once all of them are unreachable during a garbage collection cycle, like an implicit arena, but potentially for multiple allocations rather than just one.</p>
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</div></div></div></body></html>
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docs/03-Builtin-Types.html
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30
docs/03-Builtin-Types.html
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<!DOCTYPE html PUBLIC ""
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"">
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<html><head><meta charset="UTF-8" /><title>Built-in Types</title><link rel="stylesheet" type="text/css" href="css/default.css" /><link rel="stylesheet" type="text/css" href="css/highlight.css" /><script type="text/javascript" src="js/highlight.min.js"></script><script type="text/javascript" src="js/jquery.min.js"></script><script type="text/javascript" src="js/page_effects.js"></script><script>hljs.initHighlightingOnLoad();</script></head><body><div id="header"><h2>Generated by <a href="https://github.com/weavejester/codox">Codox</a></h2><h1><a href="index.html"><span class="project-title"><span class="project-name">coffi</span> <span class="project-version">v1.0.486</span></span></a></h1></div><div class="sidebar primary"><h3 class="no-link"><span class="inner">Project</span></h3><ul class="index-link"><li class="depth-1 "><a href="index.html"><div class="inner">Index</div></a></li></ul><h3 class="no-link"><span class="inner">Topics</span></h3><ul><li class="depth-1 "><a href="01-Getting-Started.html"><div class="inner"><span>Getting Started</span></div></a></li><li class="depth-1 "><a href="02-Memory-Management.html"><div class="inner"><span>Memory Management</span></div></a></li><li class="depth-1 current"><a href="03-Builtin-Types.html"><div class="inner"><span>Built-in Types</span></div></a></li><li class="depth-1 "><a href="04-Custom-Types.html"><div class="inner"><span>Custom Types</span></div></a></li><li class="depth-1 "><a href="05-Low-Level-Wrappers.html"><div class="inner"><span>Low-Level Wrappers</span></div></a></li><li class="depth-1 "><a href="50-Data-Model.html"><div class="inner"><span>Data Model</span></div></a></li><li class="depth-1 "><a href="99-Benchmarks.html"><div class="inner"><span>Benchmarks</span></div></a></li></ul><h3 class="no-link"><span class="inner">Namespaces</span></h3><ul><li class="depth-1"><div class="no-link"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>coffi</span></div></div></li><li class="depth-2 branch"><a href="coffi.ffi.html"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>ffi</span></div></a></li><li class="depth-2 branch"><a href="coffi.layout.html"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>layout</span></div></a></li><li class="depth-2"><a href="coffi.mem.html"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>mem</span></div></a></li></ul></div><div class="document" id="content"><div class="doc"><div class="markdown"><h1><a href="#built-in-types" id="built-in-types"></a>Built-in Types</h1>
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<h3><a href="#primitives" id="primitives"></a>Primitives</h3>
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<h3><a href="#arrays" id="arrays"></a>Arrays</h3>
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<h3><a href="#pointers" id="pointers"></a>Pointers</h3>
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<h3><a href="#structs" id="structs"></a>Structs</h3>
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<h3><a href="#enums" id="enums"></a>Enums</h3>
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<h3><a href="#flagsets" id="flagsets"></a>Flagsets</h3>
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<h3><a href="#unions" id="unions"></a>Unions</h3>
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<p>Unions in coffi are rather limited. They can be serialized, but not deserialized without external information.</p>
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<pre><code class="language-clojure">[::mem/union
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#{::mem/float ::mem/double}
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:dispatch #(cond
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(float? %) ::mem/float
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(double? %) ::mem/double)]
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</code></pre>
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<p>This is a minimal union in coffi. If the <code>:dispatch</code> keyword argument is not passed, then the union cannot be serialized, as coffi would not know which type to serialize the values as. In the example with a tagged union, a dispatch function was not provided because the type was only used for the native layout.</p>
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<p>In addition to a dispatch function, when serializing a union an extract function may also be provided. In the case of the value in the tagged union from before, it could be represented for serialization purposes like so:</p>
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<pre><code class="language-clojure">[::mem/union
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#{::mem/int ::mem/c-string}
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:dispatch #(case (first %)
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:ok ::mem/int
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:err ::mem/c-string)
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:extract second]
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</code></pre>
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<p>This union however would not include the tag when serialized.</p>
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<p>If a union is deserialized, then all that coffi does is to allocate a new segment of the appropriate size with an implicit arena so that it may later be garbage collected, and copies the data from the source segment into it. It’s up to the user to call <code>deserialize-from</code> on that segment with the appropriate type.</p>
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<h3><a href="#raw-types" id="raw-types"></a>Raw Types</h3>
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</div></div></div></body></html>
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82
docs/04-Custom-Types.html
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82
docs/04-Custom-Types.html
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<!DOCTYPE html PUBLIC ""
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"">
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<html><head><meta charset="UTF-8" /><title>Custom Types</title><link rel="stylesheet" type="text/css" href="css/default.css" /><link rel="stylesheet" type="text/css" href="css/highlight.css" /><script type="text/javascript" src="js/highlight.min.js"></script><script type="text/javascript" src="js/jquery.min.js"></script><script type="text/javascript" src="js/page_effects.js"></script><script>hljs.initHighlightingOnLoad();</script></head><body><div id="header"><h2>Generated by <a href="https://github.com/weavejester/codox">Codox</a></h2><h1><a href="index.html"><span class="project-title"><span class="project-name">coffi</span> <span class="project-version">v1.0.486</span></span></a></h1></div><div class="sidebar primary"><h3 class="no-link"><span class="inner">Project</span></h3><ul class="index-link"><li class="depth-1 "><a href="index.html"><div class="inner">Index</div></a></li></ul><h3 class="no-link"><span class="inner">Topics</span></h3><ul><li class="depth-1 "><a href="01-Getting-Started.html"><div class="inner"><span>Getting Started</span></div></a></li><li class="depth-1 "><a href="02-Memory-Management.html"><div class="inner"><span>Memory Management</span></div></a></li><li class="depth-1 "><a href="03-Builtin-Types.html"><div class="inner"><span>Built-in Types</span></div></a></li><li class="depth-1 current"><a href="04-Custom-Types.html"><div class="inner"><span>Custom Types</span></div></a></li><li class="depth-1 "><a href="05-Low-Level-Wrappers.html"><div class="inner"><span>Low-Level Wrappers</span></div></a></li><li class="depth-1 "><a href="50-Data-Model.html"><div class="inner"><span>Data Model</span></div></a></li><li class="depth-1 "><a href="99-Benchmarks.html"><div class="inner"><span>Benchmarks</span></div></a></li></ul><h3 class="no-link"><span class="inner">Namespaces</span></h3><ul><li class="depth-1"><div class="no-link"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>coffi</span></div></div></li><li class="depth-2 branch"><a href="coffi.ffi.html"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>ffi</span></div></a></li><li class="depth-2 branch"><a href="coffi.layout.html"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>layout</span></div></a></li><li class="depth-2"><a href="coffi.mem.html"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>mem</span></div></a></li></ul></div><div class="document" id="content"><div class="doc"><div class="markdown"><h1><a href="#custom-types" id="custom-types"></a>Custom Types</h1>
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<p>Custom types with serializers and deserializers may be created. This is done using two sets of three multimethods which can be extended by the user. For any given type, only one set need be implemented.</p>
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<p>Two examples of custom types are given here, one is a 3d vector, and the other an example of a tagged union.</p>
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<h3><a href="#vector3" id="vector3"></a>Vector3</h3>
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<p>For the vector type, it will serialize to a pointer to an array of three floats.</p>
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<p>The multimethod <code>primitive-type</code> returns the primitive type that a given type serializes to. For this example, it should be a pointer.</p>
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<pre><code class="language-clojure">(defmethod mem/primitive-type ::vector
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[_type]
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::mem/pointer)
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</code></pre>
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<p>For any type which doesn’t serialize to a primitive, it returns nil, and therefore need not be overriden.</p>
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<p>Next is <code>serialize*</code> and <code>deserialize*</code>, multimethods that work with types that serialize to primitives.</p>
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<pre><code class="language-clojure">(defmethod mem/serialize* ::vector
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[obj _type arena]
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(mem/serialize obj [::mem/array ::mem/float 3] arena))
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(defmethod mem/deserialize* ::vector
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[segment _type]
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(mem/deserialize (mem/reinterpret segment (mem/size-of [::mem/array ::mem/float 3]))
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[::mem/array ::mem/float 3]))
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</code></pre>
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<p>The <code>reinterpret</code> function allows you to take a segment and decorate it with a new size, and possibly associate it with an arena or add cleanup functions on it.</p>
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<p>In cases like this where we don’t know the arena of the pointer, we could use <code>reinterpret</code> to ensure it’s freed. For example if a <code>free-vector!</code> function that takes a pointer exists, we could use this:</p>
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<pre><code class="language-clojure">(defcfn returns-vector
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"returns_vector" [] ::mem/pointer
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native-fn
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[arena]
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(let [ret-ptr (native-fn)]
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(-> (reinterpret ret-ptr (mem/size-of ::vector) arena free-vector!)
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(deserialize ::vector))))
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</code></pre>
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<p>This function takes an arena and returns the deserialized vector, and it will free the pointer when the arena closes.</p>
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<h3><a href="#tagged-union" id="tagged-union"></a>Tagged Union</h3>
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<p>For the tagged union type, we will represent the value as a vector of a keyword naming the tag and the value. The type itself will need to take arguments, similar to <code>struct</code>. For example, if we were to represent a result type like in Rust, we might have the following values:</p>
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<pre><code class="language-clojure">[:ok 5]
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[:err "Invalid number format"]
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</code></pre>
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<p>To represent this, we can have a <code>tagged-union</code> type. For this instance of the result type, it may look like this:</p>
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<pre><code class="language-clojure">[::tagged-union [:ok :err] {:ok ::mem/int :err ::mem/c-string}]
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</code></pre>
|
||||
<p>The native representation of these objects is a struct of the tag and a union of the value. In order to correctly serialize the data and pass it to native code, we need a representation of the native layout of the data. The <code>c-layout</code> multimethod provides that.</p>
|
||||
<pre><code class="language-clojure">(defmethod mem/c-layout ::tagged-union
|
||||
[[_tagged-union tags type-map]]
|
||||
(mem/c-layout [::mem/struct
|
||||
[[:tag ::mem/long]
|
||||
[:value [::mem/union (vals type-map)]]]]))
|
||||
</code></pre>
|
||||
<p>Types with type arguments are represented as vectors of the type name and any additional arguments. The type name is what is dispatched on for the multimethods.</p>
|
||||
<p>Now that we have a native layout, we need to be able to serialize and deserialize the value into and out of memory segments. This is accomplished with <code>serialize-into</code> and <code>deserialize-from</code>.</p>
|
||||
<pre><code class="language-clojure">(defn item-index
|
||||
"Gets the index of the first occurance of `item` in `coll`."
|
||||
[coll item]
|
||||
(first
|
||||
(->> coll
|
||||
(map-indexed vector)
|
||||
(filter (comp #{item} second))
|
||||
(map first))))
|
||||
|
||||
(defmethod mem/serialize-into ::tagged-union
|
||||
[obj [_tagged-union tags type-map] segment arena]
|
||||
(mem/serialize-into
|
||||
{:tag (item-index tags (first obj))
|
||||
:value (second obj)}
|
||||
[::mem/struct
|
||||
[[:tag ::mem/long]
|
||||
[:value (get type-map (first obj))]]]
|
||||
segment
|
||||
arena))
|
||||
</code></pre>
|
||||
<p>This serialization method is rather simple, it just turns the vector value into a map, and serializes it as a struct, choosing the type of the value based on the tag.</p>
|
||||
<pre><code class="language-clojure">(defmethod mem/deserialize-from ::tagged-union
|
||||
[segment [_tagged-union tags type-map]]
|
||||
(let [tag (mem/deserialize-from segment ::mem/long)]
|
||||
[(nth tags tag)
|
||||
(mem/deserialize-from
|
||||
(mem/slice segment (mem/size-of ::mem/long))
|
||||
(get type-map tag))]))
|
||||
</code></pre>
|
||||
<p>Deserialization is a little more complex. First the tag is retrieved from the beginning of the segment, and then the type of the value is decided based on that before it is deserialized.</p>
|
||||
</div></div></div></body></html>
|
||||
51
docs/05-Low-Level-Wrappers.html
Normal file
51
docs/05-Low-Level-Wrappers.html
Normal file
|
|
@ -0,0 +1,51 @@
|
|||
<!DOCTYPE html PUBLIC ""
|
||||
"">
|
||||
<html><head><meta charset="UTF-8" /><title>Low-Level Wrappers</title><link rel="stylesheet" type="text/css" href="css/default.css" /><link rel="stylesheet" type="text/css" href="css/highlight.css" /><script type="text/javascript" src="js/highlight.min.js"></script><script type="text/javascript" src="js/jquery.min.js"></script><script type="text/javascript" src="js/page_effects.js"></script><script>hljs.initHighlightingOnLoad();</script></head><body><div id="header"><h2>Generated by <a href="https://github.com/weavejester/codox">Codox</a></h2><h1><a href="index.html"><span class="project-title"><span class="project-name">coffi</span> <span class="project-version">v1.0.486</span></span></a></h1></div><div class="sidebar primary"><h3 class="no-link"><span class="inner">Project</span></h3><ul class="index-link"><li class="depth-1 "><a href="index.html"><div class="inner">Index</div></a></li></ul><h3 class="no-link"><span class="inner">Topics</span></h3><ul><li class="depth-1 "><a href="01-Getting-Started.html"><div class="inner"><span>Getting Started</span></div></a></li><li class="depth-1 "><a href="02-Memory-Management.html"><div class="inner"><span>Memory Management</span></div></a></li><li class="depth-1 "><a href="03-Builtin-Types.html"><div class="inner"><span>Built-in Types</span></div></a></li><li class="depth-1 "><a href="04-Custom-Types.html"><div class="inner"><span>Custom Types</span></div></a></li><li class="depth-1 current"><a href="05-Low-Level-Wrappers.html"><div class="inner"><span>Low-Level Wrappers</span></div></a></li><li class="depth-1 "><a href="50-Data-Model.html"><div class="inner"><span>Data Model</span></div></a></li><li class="depth-1 "><a href="99-Benchmarks.html"><div class="inner"><span>Benchmarks</span></div></a></li></ul><h3 class="no-link"><span class="inner">Namespaces</span></h3><ul><li class="depth-1"><div class="no-link"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>coffi</span></div></div></li><li class="depth-2 branch"><a href="coffi.ffi.html"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>ffi</span></div></a></li><li class="depth-2 branch"><a href="coffi.layout.html"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>layout</span></div></a></li><li class="depth-2"><a href="coffi.mem.html"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>mem</span></div></a></li></ul></div><div class="document" id="content"><div class="doc"><div class="markdown"><h1><a href="#low-level-wrappers" id="low-level-wrappers"></a>Low-Level Wrappers</h1>
|
||||
<h3><a href="#unwrapped-native-handles" id="unwrapped-native-handles"></a>Unwrapped Native Handles</h3>
|
||||
<p>Some native libraries work with handles to large amounts of data at once, making it undesirable to marshal data back and forth from Clojure, both because it’s not necessary to work with the data in Clojure directly, or also because of the high (de)serialization costs associated with marshaling. In cases like these, unwrapped native handles are desirable.</p>
|
||||
<p>The functions <code>make-downcall</code> and <code>make-varargs-factory</code> are also provided to create raw function handles.</p>
|
||||
<pre><code class="language-clojure">(def raw-strlen (ffi/make-downcall "strlen" [::mem/c-string] ::mem/long))
|
||||
(raw-strlen (mem/serialize "hello" ::mem/c-string))
|
||||
;; => 5
|
||||
</code></pre>
|
||||
<p>With raw handles, the argument types are expected to exactly match the types expected by the native function. For primitive types, those are primitives. For pointers, that is <code>MemorySegment</code>, and for composite types like structs and unions, that is also <code>MemorySegment</code>. <code>MemorySegment</code> comes from the <code>java.lang.foreign</code> package.</p>
|
||||
<p>In addition, when a raw handle returns a composite type represented with a <code>MemorySegment</code>, it requires an additional first argument, a <code>SegmentAllocator</code>, which can be acquired with <code>arena-allocator</code> to get one associated with a specific arena. The returned value will live until that arena is released.</p>
|
||||
<p>In addition, function types can be specified as being raw, in the following manner:</p>
|
||||
<pre><code class="language-clojure">[::ffi/fn [::mem/int] ::mem/int :raw-fn? true]
|
||||
</code></pre>
|
||||
<p>Clojure functions serialized to this type will have their arguments and return value exactly match the types specified and will not perform any serialization or deserialization at their boundaries.</p>
|
||||
<p>One important caveat to consider when writing wrappers for performance-sensitive functions is that the convenience macro <code>defcfn</code> that coffi provides will already perform no serialization or deserialization on primitive arguments and return types, so for functions with only primitive argument and return types there is no performance reason to choose unwrapped native handles over the convenience macro.</p>
|
||||
<h3><a href="#manual-deserialization" id="manual-deserialization"></a>Manual (De)Serialization</h3>
|
||||
<p>Coffi uses multimethods to dispatch to (de)serialization functions to enable code that’s generic over the types it operates on. However, in cases where you know the exact types that you will be (de)serializing and the multimethod dispatch overhead is too high a cost, it may be appropriate to manually handle (de)serializing data. This will often be done paired with <a href="#unwrapped-native-handles">Unwrapped Native Handles</a>.</p>
|
||||
<p>Convenience functions are provided to both read and write all primitive types and addresses, including byte order.</p>
|
||||
<p>As an example, when wrapping a function that returns an array of big-endian floats, the following code might be used.</p>
|
||||
<pre><code class="language-clojure">;; int returns_float_array(float **arr)
|
||||
(def ^:private returns-float-array* (ffi/make-downcall "returns_float_array" [::mem/pointer] ::mem/int))
|
||||
;; void releases_float_array(float *arr)
|
||||
(def ^:private release-floats* (ffi/make-downcall "releases_float_array" [::mem/pointer] ::mem/void))
|
||||
|
||||
(defn returns-float-array
|
||||
[]
|
||||
(with-open [arena (mem/confined-arena)]
|
||||
;; float *out_floats;
|
||||
;; int num_floats = returns_float_array(&out_floats);
|
||||
(let [out-floats (mem/alloc mem/pointer-size arena)
|
||||
num-floats (returns-float-array* out-floats)
|
||||
floats-addr (mem/read-address out-floats)
|
||||
floats-slice (mem/reinterpret floats-addr (unchecked-multiply-int mem/float-size num-floats))]
|
||||
;; Using a try/finally to perform an operation when the stack frame exits,
|
||||
;; but not to try to catch anything.
|
||||
(try
|
||||
(loop [floats (transient [])
|
||||
index 0]
|
||||
(if (>= index num-floats)
|
||||
(persistent! floats)
|
||||
(recur (conj! floats (mem/read-float floats-slice
|
||||
(unchecked-multiply-int index mem/float-size)
|
||||
mem/big-endian))
|
||||
(unchecked-inc-int index))))
|
||||
(finally
|
||||
(release-floats* floats-addr))))))
|
||||
</code></pre>
|
||||
<p>The above code manually performs all memory operations rather than relying on coffi’s dispatch. This will be more performant, but because multimethod overhead is usually relatively low, it’s recommended to use the multimethod variants for convenience in colder functions.</p>
|
||||
</div></div></div></body></html>
|
||||
25
docs/50-Data-Model.html
Normal file
25
docs/50-Data-Model.html
Normal file
|
|
@ -0,0 +1,25 @@
|
|||
<!DOCTYPE html PUBLIC ""
|
||||
"">
|
||||
<html><head><meta charset="UTF-8" /><title>Data Model</title><link rel="stylesheet" type="text/css" href="css/default.css" /><link rel="stylesheet" type="text/css" href="css/highlight.css" /><script type="text/javascript" src="js/highlight.min.js"></script><script type="text/javascript" src="js/jquery.min.js"></script><script type="text/javascript" src="js/page_effects.js"></script><script>hljs.initHighlightingOnLoad();</script></head><body><div id="header"><h2>Generated by <a href="https://github.com/weavejester/codox">Codox</a></h2><h1><a href="index.html"><span class="project-title"><span class="project-name">coffi</span> <span class="project-version">v1.0.486</span></span></a></h1></div><div class="sidebar primary"><h3 class="no-link"><span class="inner">Project</span></h3><ul class="index-link"><li class="depth-1 "><a href="index.html"><div class="inner">Index</div></a></li></ul><h3 class="no-link"><span class="inner">Topics</span></h3><ul><li class="depth-1 "><a href="01-Getting-Started.html"><div class="inner"><span>Getting Started</span></div></a></li><li class="depth-1 "><a href="02-Memory-Management.html"><div class="inner"><span>Memory Management</span></div></a></li><li class="depth-1 "><a href="03-Builtin-Types.html"><div class="inner"><span>Built-in Types</span></div></a></li><li class="depth-1 "><a href="04-Custom-Types.html"><div class="inner"><span>Custom Types</span></div></a></li><li class="depth-1 "><a href="05-Low-Level-Wrappers.html"><div class="inner"><span>Low-Level Wrappers</span></div></a></li><li class="depth-1 current"><a href="50-Data-Model.html"><div class="inner"><span>Data Model</span></div></a></li><li class="depth-1 "><a href="99-Benchmarks.html"><div class="inner"><span>Benchmarks</span></div></a></li></ul><h3 class="no-link"><span class="inner">Namespaces</span></h3><ul><li class="depth-1"><div class="no-link"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>coffi</span></div></div></li><li class="depth-2 branch"><a href="coffi.ffi.html"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>ffi</span></div></a></li><li class="depth-2 branch"><a href="coffi.layout.html"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>layout</span></div></a></li><li class="depth-2"><a href="coffi.mem.html"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>mem</span></div></a></li></ul></div><div class="document" id="content"><div class="doc"><div class="markdown"><h1><a href="#data-model" id="data-model"></a>Data Model</h1>
|
||||
<p>In addition to the macros and functions provided to build a Clojure API for native libraries, facilities are provided for taking data and loading all the symbols specified by it. This can be useful if a library provides (or an external provider maintains) a data representation of their API, as Clojure data to represent it may be programmatically generated from these sources.</p>
|
||||
<p>The data to represent an API is a map with the following form:</p>
|
||||
<pre><code class="language-clojure">(def strlen-libspec
|
||||
{:strlen {:type :function
|
||||
:symbol "strlen"
|
||||
:function/args [::mem/c-string]
|
||||
:function/ret ::mem/long}})
|
||||
</code></pre>
|
||||
<p>Each key in this map represents a single symbol to be loaded. The value is a map with at least the keys <code>:type</code> and <code>:symbol</code>. These are the currently recognized types:</p>
|
||||
<ul>
|
||||
<li>function</li>
|
||||
<li>varargs-factory</li>
|
||||
<li>const</li>
|
||||
<li>static-var</li>
|
||||
</ul>
|
||||
<p>Each one has its own set of additional keys which can be added to the map. Both <code>function</code> and <code>varargs-factory</code> have the three keys <code>:function/args</code>, <code>:function/ret</code>, and <code>:function/raw-fn?</code>. The <code>const</code> type has <code>:const/type</code> and <code>static-var</code> has <code>:static-var/type</code>.</p>
|
||||
<p>This data can be passed to the function <code>reify-libspec</code>, which will take the data and return a map from the same keys as the input map to whatever value is appropriate for a given symbol type (e.g. a Clojure function for <code>function</code>, a value for <code>const</code>, etc.).</p>
|
||||
<pre><code class="language-clojure">(ffi/reify-libspec strlen-libspec)
|
||||
;; => {:strlen #function[...]}
|
||||
</code></pre>
|
||||
<p>This functionality can be extended by specifying new types as implementations of the multimethod <code>reify-symbolspec</code>, although it’s recommended that for any library authors who do so, namespaced keywords be used to name types.</p>
|
||||
</div></div></div></body></html>
|
||||
258
docs/99-Benchmarks.html
Normal file
258
docs/99-Benchmarks.html
Normal file
|
|
@ -0,0 +1,258 @@
|
|||
<!DOCTYPE html PUBLIC ""
|
||||
"">
|
||||
<html><head><meta charset="UTF-8" /><title>Benchmarks</title><link rel="stylesheet" type="text/css" href="css/default.css" /><link rel="stylesheet" type="text/css" href="css/highlight.css" /><script type="text/javascript" src="js/highlight.min.js"></script><script type="text/javascript" src="js/jquery.min.js"></script><script type="text/javascript" src="js/page_effects.js"></script><script>hljs.initHighlightingOnLoad();</script></head><body><div id="header"><h2>Generated by <a href="https://github.com/weavejester/codox">Codox</a></h2><h1><a href="index.html"><span class="project-title"><span class="project-name">coffi</span> <span class="project-version">v1.0.486</span></span></a></h1></div><div class="sidebar primary"><h3 class="no-link"><span class="inner">Project</span></h3><ul class="index-link"><li class="depth-1 "><a href="index.html"><div class="inner">Index</div></a></li></ul><h3 class="no-link"><span class="inner">Topics</span></h3><ul><li class="depth-1 "><a href="01-Getting-Started.html"><div class="inner"><span>Getting Started</span></div></a></li><li class="depth-1 "><a href="02-Memory-Management.html"><div class="inner"><span>Memory Management</span></div></a></li><li class="depth-1 "><a href="03-Builtin-Types.html"><div class="inner"><span>Built-in Types</span></div></a></li><li class="depth-1 "><a href="04-Custom-Types.html"><div class="inner"><span>Custom Types</span></div></a></li><li class="depth-1 "><a href="05-Low-Level-Wrappers.html"><div class="inner"><span>Low-Level Wrappers</span></div></a></li><li class="depth-1 "><a href="50-Data-Model.html"><div class="inner"><span>Data Model</span></div></a></li><li class="depth-1 current"><a href="99-Benchmarks.html"><div class="inner"><span>Benchmarks</span></div></a></li></ul><h3 class="no-link"><span class="inner">Namespaces</span></h3><ul><li class="depth-1"><div class="no-link"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>coffi</span></div></div></li><li class="depth-2 branch"><a href="coffi.ffi.html"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>ffi</span></div></a></li><li class="depth-2 branch"><a href="coffi.layout.html"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>layout</span></div></a></li><li class="depth-2"><a href="coffi.mem.html"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>mem</span></div></a></li></ul></div><div class="document" id="content"><div class="doc"><div class="markdown"><h1><a href="#benchmarks" id="benchmarks"></a>Benchmarks</h1>
|
||||
<p><strong>BENCHMARKS FOR COFFI AND DTYPE-NEXT ARE BASED ON AN OLD VERSION. NEW BENCHMARKS WILL BE CREATED SOON.</strong></p>
|
||||
<p>An additional consideration when thinking about alternatives is the performance of each available option. It’s an established fact that JNA (used by all three alternative libraries on JDK <16) introduces more overhead when calling native code than JNI does.</p>
|
||||
<p>In order to provide a benchmark to see how much of a difference the different native interfaces make, we can use <a href="https://github.com/hugoduncan/criterium">criterium</a> to benchmark each. <a href="https://www.glfw.org">GLFW</a>’s <a href="https://www.glfw.org/docs/latest/group__input.html#gaa6cf4e7a77158a3b8fd00328b1720a4a"><code>glfwGetTime</code></a> function will be used for the test as it performs a simple operation, and is conveniently already wrapped in JNI by the excellent <a href="https://www.lwjgl.org/">LWJGL</a> library.</p>
|
||||
<p>The following benchmarks were run on a Lenovo Thinkpad with an Intel i7-10610U running Manjaro Linux, using Clojure 1.10.3 on Java 17.</p>
|
||||
<h3><a href="#jni" id="jni"></a>JNI</h3>
|
||||
<p>The baseline for performance is the JNI. Using LWJGL it’s relatively simple to benchmark. The following Clojure CLI command will start a repl with LWJGL and criterium loaded.</p>
|
||||
<pre><code class="language-sh">$ clj -Sdeps '{:deps {org.lwjgl/lwjgl {:mvn/version "3.2.3"}
|
||||
org.lwjgl/lwjgl-glfw {:mvn/version "3.2.3"}
|
||||
org.lwjgl/lwjgl$natives-linux {:mvn/version "3.2.3"}
|
||||
org.lwjgl/lwjgl-glfw$natives-linux {:mvn/version "3.2.3"}
|
||||
criterium/criterium {:mvn/version "0.4.6"}}}'
|
||||
</code></pre>
|
||||
<p>Then from the repl</p>
|
||||
<pre><code class="language-clojure">user=> (import 'org.lwjgl.glfw.GLFW)
|
||||
org.lwjgl.glfw.GLFW
|
||||
user=> (require '[criterium.core :as bench])
|
||||
nil
|
||||
user=> (GLFW/glfwInit)
|
||||
true
|
||||
user=> (bench/bench (GLFW/glfwGetTime) :verbose)
|
||||
amd64 Linux 5.10.68-1-MANJARO 8 cpu(s)
|
||||
OpenJDK 64-Bit Server VM 17+35-2724
|
||||
Runtime arguments: -Dclojure.basis=/home/jsusk/.clojure/.cpcache/2667074721.basis
|
||||
Evaluation count : 1613349900 in 60 samples of 26889165 calls.
|
||||
Execution time sample mean : 32.698446 ns
|
||||
Execution time mean : 32.697811 ns
|
||||
Execution time sample std-deviation : 1.274600 ns
|
||||
Execution time std-deviation : 1.276437 ns
|
||||
Execution time lower quantile : 30.750813 ns ( 2.5%)
|
||||
Execution time upper quantile : 33.757662 ns (97.5%)
|
||||
Overhead used : 6.400704 ns
|
||||
nil
|
||||
</code></pre>
|
||||
<p>GLFW requires that we initialize it before calling the <code>glfwGetTime</code> function. Besides that this is a simple interop call which directly maps to the native function.</p>
|
||||
<p>This gives us a basis of 32.7 ns +/-1.3 ns. All other libraries will be evaluated relative to this result.</p>
|
||||
<p>To ensure fairness, we’ll also get that overhead value to be used in further tests.</p>
|
||||
<pre><code class="language-clojure">user=> bench/estimated-overhead-cache
|
||||
6.400703613065185E-9
|
||||
</code></pre>
|
||||
<h3><a href="#coffi" id="coffi"></a>Coffi</h3>
|
||||
<p>The dependencies when using coffi are simpler, but it also requires some JVM options to support the foreign access api.</p>
|
||||
<pre><code class="language-sh">$ clj -Sdeps '{:deps {org.suskalo/coffi {:mvn/version "0.1.205"}
|
||||
criterium/criterium {:mvn/version "0.4.6"}}}' \
|
||||
-J--add-modules=jdk.incubator.foreign \
|
||||
-J--enable-native-access=ALL-UNNAMED
|
||||
</code></pre>
|
||||
<p>In order to ensure fair comparisons, we’re going to use the same overhead value on each run, so before we do the benchmark we’ll set it to the observed value from last time.</p>
|
||||
<pre><code class="language-clojure">user=> (require '[criterium.core :as bench])
|
||||
nil
|
||||
user=> (alter-var-root #'bench/estimated-overhead-cache (constantly 6.400703613065185E-9))
|
||||
6.400703613065185E-9
|
||||
user=> (require '[coffi.ffi :as ffi])
|
||||
nil
|
||||
user=> (require '[coffi.mem :as mem])
|
||||
nil
|
||||
user=> (ffi/load-system-library "glfw")
|
||||
nil
|
||||
user=> ((ffi/cfn "glfwInit" [] ::mem/int))
|
||||
1
|
||||
user=> (let [f (ffi/cfn "glfwGetTime" [] ::mem/double)]
|
||||
(bench/bench (f) :verbose))
|
||||
amd64 Linux 5.10.68-1-MANJARO 8 cpu(s)
|
||||
OpenJDK 64-Bit Server VM 17+35-2724
|
||||
Runtime arguments: --add-modules=jdk.incubator.foreign --enable-native-access=ALL-UNNAMED -Dclojure.basis=/home/jsusk/.clojure/.cpcache/72793624.basis
|
||||
Evaluation count : 1657995600 in 60 samples of 27633260 calls.
|
||||
Execution time sample mean : 31.382665 ns
|
||||
Execution time mean : 31.386493 ns
|
||||
Execution time sample std-deviation : 1.598571 ns
|
||||
Execution time std-deviation : 1.608818 ns
|
||||
Execution time lower quantile : 29.761194 ns ( 2.5%)
|
||||
Execution time upper quantile : 33.228276 ns (97.5%)
|
||||
Overhead used : 6.400704 ns
|
||||
nil
|
||||
</code></pre>
|
||||
<p>This result is about 1.3 ns faster, and while that is less than the standard deviation of 1.6, it’s quite close to it.</p>
|
||||
<h3><a href="#clojure-jna" id="clojure-jna"></a>Clojure-JNA</h3>
|
||||
<p>Clojure-JNA uses the JNA library, which was designed to provide Java with an easy way to access native libraries, but which is known for not having the greatest performance. Since this is an older project, I’m also including the clojure dependency to ensure the correct version is used.</p>
|
||||
<pre><code class="language-sh">$ clj -Sdeps '{:deps {org.clojure/clojure {:mvn/version "1.10.3"}
|
||||
net.n01se/clojure-jna {:mvn/version "1.0.0"}
|
||||
criterium/criterium {:mvn/version "0.4.6"}}}'
|
||||
</code></pre>
|
||||
<p>The naive way to call the function using Clojure-JNA is to use <code>jna/invoke</code>.</p>
|
||||
<pre><code class="language-clojure">user=> (require '[criterium.core :as bench])
|
||||
nil
|
||||
user=> (alter-var-root #'bench/estimated-overhead-cache (constantly 6.400703613065185E-9))
|
||||
6.400703613065185E-9
|
||||
user=> (require '[net.n01se.clojure-jna :as jna])
|
||||
nil
|
||||
user=> (jna/invoke Integer glfw/glfwInit)
|
||||
1
|
||||
user=> (bench/bench (jna/invoke Double glfw/glfwGetTime) :verbose)
|
||||
amd64 Linux 5.10.68-1-MANJARO 8 cpu(s)
|
||||
OpenJDK 64-Bit Server VM 17+35-2724
|
||||
Runtime arguments: -Dclojure.basis=/home/jsusk/.clojure/.cpcache/3229486237.basis
|
||||
Evaluation count : 195948720 in 60 samples of 3265812 calls.
|
||||
Execution time sample mean : 350.335614 ns
|
||||
Execution time mean : 350.373520 ns
|
||||
Execution time sample std-deviation : 24.833070 ns
|
||||
Execution time std-deviation : 24.755929 ns
|
||||
Execution time lower quantile : 300.000019 ns ( 2.5%)
|
||||
Execution time upper quantile : 365.759273 ns (97.5%)
|
||||
Overhead used : 6.400704 ns
|
||||
|
||||
Found 13 outliers in 60 samples (21.6667 %)
|
||||
low-severe 12 (20.0000 %)
|
||||
low-mild 1 (1.6667 %)
|
||||
Variance from outliers : 53.4220 % Variance is severely inflated by outliers
|
||||
nil
|
||||
</code></pre>
|
||||
<p>As you can see, this method of calling functions is very bad for performance, with call overhead dominating function runtime by an order of magnitude. That said, this isn’t a completely fair comparison, nor the most realistic, because this way of calling functions looks the function up on each invocation.</p>
|
||||
<p>To adjust for this, we’ll use the <code>jna/to-fn</code> function to give a persistent handle to the function that we can call.</p>
|
||||
<pre><code class="language-clojure">user=> (let [f (jna/to-fn Double glfw/glfwGetTime)]
|
||||
(bench/bench (f) :verbose))
|
||||
amd64 Linux 5.10.68-1-MANJARO 8 cpu(s)
|
||||
OpenJDK 64-Bit Server VM 17+35-2724
|
||||
Runtime arguments: -Dclojure.basis=/home/jsusk/.clojure/.cpcache/3229486237.basis
|
||||
Evaluation count : 611095020 in 60 samples of 10184917 calls.
|
||||
Execution time sample mean : 104.623634 ns
|
||||
Execution time mean : 104.638406 ns
|
||||
Execution time sample std-deviation : 7.649296 ns
|
||||
Execution time std-deviation : 7.638963 ns
|
||||
Execution time lower quantile : 92.446016 ns ( 2.5%)
|
||||
Execution time upper quantile : 110.258832 ns (97.5%)
|
||||
Overhead used : 6.400704 ns
|
||||
nil
|
||||
</code></pre>
|
||||
<p>This is much better, but is still about 3x slower than JNI, meaning the overhead from using JNA is still bigger than the function runtime.</p>
|
||||
<p>This performance penalty is still small in the scope of longer-running functions, and so may not be a concern for your application, but it is something to be aware of.</p>
|
||||
<h3><a href="#techjna" id="techjna"></a>tech.jna</h3>
|
||||
<p>The tech.jna library is similar in scope to Clojure-JNA, however was written to fit into an ecosystem of libraries meant for array-based programming for machine learning and data science.</p>
|
||||
<pre><code class="language-sh">$ clj -Sdeps '{:deps {techascent/tech.jna {:mvn/version "4.05"}
|
||||
criterium/criterium {:mvn/version "0.4.6"}}}'
|
||||
</code></pre>
|
||||
<p>This library is also quite simple to use, the only slightly odd thing I’m doing here is to dereference the var outside the benchmark in order to ensure it’s an apples-to-apples comparison. We don’t want var dereference time mucking up our benchmark.</p>
|
||||
<pre><code class="language-clojure">user=> (require '[criterium.core :as bench])
|
||||
nil
|
||||
user=> (alter-var-root #'bench/estimated-overhead-cache (constantly 6.400703613065185E-9))
|
||||
6.400703613065185E-9
|
||||
user=> (require '[tech.v3.jna :as jna])
|
||||
nil
|
||||
user=> (jna/def-jna-fn "glfw" glfwInit "initialize glfw" Integer)
|
||||
#'user/glfwInit
|
||||
user=> (glfwInit)
|
||||
Oct 09, 2021 10:30:50 AM clojure.tools.logging$eval1122$fn__1125 invoke
|
||||
INFO: Library glfw found at [:system "glfw"]
|
||||
1
|
||||
user=> (jna/def-jna-fn "glfw" glfwGetTime "gets the time as a double since init" Double)
|
||||
#'user/glfwGetTime
|
||||
user=> (let [f @#'glfwGetTime]
|
||||
(bench/bench (f) :verbose))
|
||||
amd64 Linux 5.10.68-1-MANJARO 8 cpu(s)
|
||||
OpenJDK 64-Bit Server VM 17+35-2724
|
||||
Runtime arguments: -Dclojure.basis=/home/jsusk/.clojure/.cpcache/2910209237.basis
|
||||
Evaluation count : 323281680 in 60 samples of 5388028 calls.
|
||||
Execution time sample mean : 203.976803 ns
|
||||
Execution time mean : 203.818712 ns
|
||||
Execution time sample std-deviation : 14.557312 ns
|
||||
Execution time std-deviation : 14.614080 ns
|
||||
Execution time lower quantile : 179.732593 ns ( 2.5%)
|
||||
Execution time upper quantile : 213.929374 ns (97.5%)
|
||||
Overhead used : 6.400704 ns
|
||||
nil
|
||||
</code></pre>
|
||||
<p>This version is even slower than Clojure-JNA. I’m unsure where this overhead is coming from, but I’ll admit that I haven’t looked at their implementations very closely.</p>
|
||||
<h3><a href="#dtype-next" id="dtype-next"></a>dtype-next</h3>
|
||||
<p>The library dtype-next replaced tech.jna in the toolkit of the group working on machine learning and array-based programming, and it includes support for composite data types including structs, as well as primitive functions and callbacks.</p>
|
||||
<p>In addition, dtype-next has two different ffi backends. First is JNA, which is usable on any JDK version, and is what we’ll use for the first benchmark. Second is the Java 16 version of Project Panama, which will be shown next.</p>
|
||||
<p>In order to use the dtype-next ffi with the JNA backend, the JNA library has to be included in the dependencies.</p>
|
||||
<pre><code class="language-sh">$ clj -Sdeps '{:deps {cnuernber/dtype-next {:mvn/version "8.032"}
|
||||
net.java.dev.jna/jna {:mvn/version "5.8.0"}
|
||||
criterium/criterium {:mvn/version "0.4.6"}}}'
|
||||
</code></pre>
|
||||
<p>The dtype-next library also requires some more ceremony around declaring native functions. One advantage this has is that multiple symbols with the same name can be loaded from different shared libraries, but it also does increase friction when defining native wrappers.</p>
|
||||
<p>Some easier ways to define native wrappers are provided than what is seen here, but they share some disadvantages in documentation over the core methods provided in coffi, although they are comparable to the data model provided in coffi.</p>
|
||||
<pre><code class="language-clojure">user=> (require '[criterium.core :as bench])
|
||||
nil
|
||||
user=> (alter-var-root #'bench/estimated-overhead-cache (constantly 6.400703613065185E-9))
|
||||
6.400703613065185E-9
|
||||
user=> (require '[tech.v3.datatype.ffi :as dt-ffi])
|
||||
nil
|
||||
user=> (def fn-defs {:glfwInit {:rettype :int32} :glfwGetTime {:rettype :float64}})
|
||||
#'user/fn-defs
|
||||
user=> (def library-def (dt-ffi/define-library fn-defs))
|
||||
#'user/library-def
|
||||
user=> (def library-instance (dt-ffi/instantiate-library library-def "/usr/lib/libglfw.so"))
|
||||
#'user/library-instance
|
||||
user=> (def init (:glfwInit @library-instance))
|
||||
#'user/init
|
||||
user=> (init)
|
||||
1
|
||||
user=> (let [f (:glfwGetTime @library-instance)]
|
||||
(bench/bench (f) :verbose))
|
||||
amd64 Linux 5.10.68-1-MANJARO 8 cpu(s)
|
||||
OpenJDK 64-Bit Server VM 17+35-2724
|
||||
Runtime arguments: -Dclojure.basis=/home/jsusk/.clojure/.cpcache/643862289.basis
|
||||
Evaluation count : 710822100 in 60 samples of 11847035 calls.
|
||||
Execution time sample mean : 90.900112 ns
|
||||
Execution time mean : 90.919917 ns
|
||||
Execution time sample std-deviation : 6.463312 ns
|
||||
Execution time std-deviation : 6.470108 ns
|
||||
Execution time lower quantile : 79.817126 ns ( 2.5%)
|
||||
Execution time upper quantile : 95.454652 ns (97.5%)
|
||||
Overhead used : 6.400704 ns
|
||||
nil
|
||||
</code></pre>
|
||||
<p>This version of JNA usage is significantly faster than either of the other JNA libraries, but is still substantially slower than using JNI or coffi.</p>
|
||||
<p>In addition to the JNA backend, dtype-next has a Java 16-specific backend that uses an older version of Panama. This version requires similar setup to coffi in order to run.</p>
|
||||
<pre><code class="language-sh">$ clj -Sdeps '{:deps {cnuernber/dtype-next {:mvn/version "8.032"}
|
||||
criterium/criterium {:mvn/version "0.4.6"}}}' \
|
||||
-J--add-modules=jdk.incubator.foreign \
|
||||
-J-Dforeign.restricted=permit \
|
||||
-J--add-opens=java.base/java.lang=ALL-UNNAMED \
|
||||
-J-Djava.library.path=/usr/lib/x86_64-linux-gnu
|
||||
</code></pre>
|
||||
<p>The actual code to run the benchmark is identical to the last example, but is reproduced here for completeness.</p>
|
||||
<pre><code class="language-clojure">user=> (require '[criterium.core :as bench])
|
||||
nil
|
||||
user=> (alter-var-root #'bench/estimated-overhead-cache (constantly 6.400703613065185E-9))
|
||||
6.400703613065185E-9
|
||||
user=> (require '[tech.v3.datatype.ffi :as dt-ffi])
|
||||
nil
|
||||
user=> (def fn-defs {:glfwInit {:rettype :int32} :glfwGetTime {:rettype :float64}})
|
||||
#'user/fn-defs
|
||||
user=> (def library-def (dt-ffi/define-library fn-defs))
|
||||
#'user/library-def
|
||||
user=> (def library-instance (dt-ffi/instantiate-library library-def "/usr/lib/libglfw.so"))
|
||||
#'user/library-instance
|
||||
user=> (def init (:glfwInit @library-instance))
|
||||
#'user/init
|
||||
user=> (init)
|
||||
1
|
||||
user=> (let [f (:glfwGetTime @library-instance)]
|
||||
(bench/bench (f) :verbose))
|
||||
amd64 Linux 5.10.68-1-MANJARO 8 cpu(s)
|
||||
OpenJDK 64-Bit Server VM 16.0.2+7
|
||||
Runtime arguments: --add-modules=jdk.incubator.foreign -Dforeign.restricted=permit --add-opens=java.base/java.lang=ALL-UNNAMED -Djava.library.path=/usr/lib/x86_64-linux-gnu -Dclojure.basis=/home/jsusk/.clojure/.cpcache/2337051659.basis
|
||||
Evaluation count : 1588513080 in 60 samples of 26475218 calls.
|
||||
Execution time sample mean : 58.732468 ns
|
||||
Execution time mean : 58.647361 ns
|
||||
Execution time sample std-deviation : 9.732389 ns
|
||||
Execution time std-deviation : 9.791738 ns
|
||||
Execution time lower quantile : 31.318115 ns ( 2.5%)
|
||||
Execution time upper quantile : 65.449222 ns (97.5%)
|
||||
Overhead used : 6.400704 ns
|
||||
|
||||
Found 14 outliers in 60 samples (23.3333 %)
|
||||
low-severe 8 (13.3333 %)
|
||||
low-mild 4 (6.6667 %)
|
||||
high-mild 2 (3.3333 %)
|
||||
Variance from outliers : 87.6044 % Variance is severely inflated by outliers
|
||||
nil
|
||||
</code></pre>
|
||||
<p>Not reproduced here, but notable for comparison, in my testing Java 16’s version of the JNI version performed about the same.</p>
|
||||
<p>This is significantly faster than the JNA version of dtype-next, but it is still slower than modern Panama. This is likely to simply be a result of optimizations and changes to the Panama API, and when dtype-next is updated to use the Java 17 version of Panama I expect it will perform in line with coffi, but this benchmark will be reproduced when this happens. Still, this shows that as it stands, coffi is the fastest FFI available to Clojure developers.</p>
|
||||
</div></div></div></body></html>
|
||||
|
|
@ -307,3 +307,37 @@ atomic semantics either.
|
|||
The memory that backs the static variable can be fetched with the function
|
||||
`static-variable-segment`, which can be used to pass a pointer to the static
|
||||
variable to native functions that require it.
|
||||
|
||||
### Complex Wrappers
|
||||
Some functions require more complex code to map nicely to a Clojure function.
|
||||
The `defcfn` macro provides facilities to wrap the native function with some
|
||||
Clojure code to make this easier.
|
||||
|
||||
```clojure
|
||||
(defcfn takes-array
|
||||
"takes_array_with_count" [::mem/pointer ::mem/long] ::mem/void
|
||||
native-fn
|
||||
[ints]
|
||||
(let [arr-len (count ints)
|
||||
int-array (mem/serialize ints [::mem/array ::mem/int arr-len])]
|
||||
(native-fn int-array arr-len)))
|
||||
```
|
||||
|
||||
The symbol `native-fn` can be any unqualified symbol, and names the native
|
||||
function being wrapped. It must be called in the function body below if you want
|
||||
to call the native code.
|
||||
|
||||
This `serialize` function has a paired `deserialize`, and allows marshaling
|
||||
Clojure data back and forth to native data structures.
|
||||
|
||||
This can be used to implement out variables often seen in native code.
|
||||
|
||||
```clojure
|
||||
(defcfn out-int
|
||||
"out_int" [::mem/pointer] ::mem/void
|
||||
native-fn
|
||||
[i]
|
||||
(let [int-ptr (mem/serialize i [::mem/pointer ::mem/int])]
|
||||
(native-fn int-ptr)
|
||||
(mem/deserialize int-ptr [::mem/pointer ::mem/int])))
|
||||
```
|
||||
|
|
|
|||
38
docs/articles/02-Memory-Management.md
Normal file
38
docs/articles/02-Memory-Management.md
Normal file
|
|
@ -0,0 +1,38 @@
|
|||
# Memory Management
|
||||
In order to serialize any non-primitive type, off-heap memory needs to be
|
||||
allocated. When memory is allocated inside the JVM, the memory is associated
|
||||
with an arena. If none is provided, the arena is an implicit arena, and the
|
||||
memory will be freed when the serialized object is garbage collected.
|
||||
|
||||
In many cases this is not desirable, because the memory is not freed in a
|
||||
deterministic manner, causing garbage collection pauses to become longer, as
|
||||
well as changing allocation performance. Instead of an implicit arena, there
|
||||
are other kinds of arenas as well. A `confined-arena` is a thread-local arena.
|
||||
Confined arenas are `Closeable`, which means they should usually be used in a
|
||||
`with-open` form. When a `confined-arena` is closed, it immediately frees all
|
||||
the memory associated with it. The previous example, `out-int`, can be
|
||||
implemented with a confined arena.
|
||||
|
||||
```clojure
|
||||
(defcfn out-int
|
||||
"out_int" [::mem/pointer] ::mem/void
|
||||
native-fn
|
||||
[i]
|
||||
(with-open [arena (mem/confined-arena)]
|
||||
(let [int-ptr (mem/serialize i [::mem/pointer ::mem/int] arena)]
|
||||
(native-fn int-ptr)
|
||||
(mem/deserialize int-ptr [::mem/pointer ::mem/int]))))
|
||||
```
|
||||
|
||||
This will free the pointer immediately upon leaving the function.
|
||||
|
||||
When memory needs to be accessible from multiple threads, there's
|
||||
`shared-arena`. When a `shared-arena` is `.close`d, it will release all its
|
||||
associated memory immediately, and so this should only be done once all other
|
||||
threads are done accessing memory associated with it.
|
||||
|
||||
In addition, two non-`Closeable` arenas are `global-arena`, which never frees
|
||||
the resources associated with it, and `auto-arena`, which is an arena that frees
|
||||
its resources once all of them are unreachable during a garbage collection
|
||||
cycle, like an implicit arena, but potentially for multiple allocations rather
|
||||
than just one.
|
||||
53
docs/articles/03-Builtin-Types.md
Normal file
53
docs/articles/03-Builtin-Types.md
Normal file
|
|
@ -0,0 +1,53 @@
|
|||
# Built-in Types
|
||||
|
||||
### Primitives
|
||||
|
||||
### Arrays
|
||||
|
||||
### Pointers
|
||||
|
||||
### Structs
|
||||
|
||||
### Enums
|
||||
|
||||
### Flagsets
|
||||
|
||||
### Unions
|
||||
Unions in coffi are rather limited. They can be serialized, but not deserialized
|
||||
without external information.
|
||||
|
||||
```clojure
|
||||
[::mem/union
|
||||
#{::mem/float ::mem/double}
|
||||
:dispatch #(cond
|
||||
(float? %) ::mem/float
|
||||
(double? %) ::mem/double)]
|
||||
```
|
||||
|
||||
This is a minimal union in coffi. If the `:dispatch` keyword argument is not
|
||||
passed, then the union cannot be serialized, as coffi would not know which type
|
||||
to serialize the values as. In the example with a tagged union, a dispatch
|
||||
function was not provided because the type was only used for the native layout.
|
||||
|
||||
In addition to a dispatch function, when serializing a union an extract function
|
||||
may also be provided. In the case of the value in the tagged union from before,
|
||||
it could be represented for serialization purposes like so:
|
||||
|
||||
```clojure
|
||||
[::mem/union
|
||||
#{::mem/int ::mem/c-string}
|
||||
:dispatch #(case (first %)
|
||||
:ok ::mem/int
|
||||
:err ::mem/c-string)
|
||||
:extract second]
|
||||
```
|
||||
|
||||
This union however would not include the tag when serialized.
|
||||
|
||||
If a union is deserialized, then all that coffi does is to allocate a new
|
||||
segment of the appropriate size with an implicit arena so that it may later be
|
||||
garbage collected, and copies the data from the source segment into it. It's up
|
||||
to the user to call `deserialize-from` on that segment with the appropriate
|
||||
type.
|
||||
|
||||
### Raw Types
|
||||
136
docs/articles/04-Custom-Types.md
Normal file
136
docs/articles/04-Custom-Types.md
Normal file
|
|
@ -0,0 +1,136 @@
|
|||
# Custom Types
|
||||
Custom types with serializers and deserializers may be created. This is done
|
||||
using two sets of three multimethods which can be extended by the user. For any
|
||||
given type, only one set need be implemented.
|
||||
|
||||
Two examples of custom types are given here, one is a 3d vector, and the other
|
||||
an example of a tagged union.
|
||||
|
||||
### Vector3
|
||||
For the vector type, it will serialize to a pointer to an array of three floats.
|
||||
|
||||
The multimethod `primitive-type` returns the primitive type that a given type
|
||||
serializes to. For this example, it should be a pointer.
|
||||
|
||||
```clojure
|
||||
(defmethod mem/primitive-type ::vector
|
||||
[_type]
|
||||
::mem/pointer)
|
||||
```
|
||||
|
||||
For any type which doesn't serialize to a primitive, it returns nil, and
|
||||
therefore need not be overriden.
|
||||
|
||||
Next is `serialize*` and `deserialize*`, multimethods that work with types that
|
||||
serialize to primitives.
|
||||
|
||||
```clojure
|
||||
(defmethod mem/serialize* ::vector
|
||||
[obj _type arena]
|
||||
(mem/serialize obj [::mem/array ::mem/float 3] arena))
|
||||
|
||||
(defmethod mem/deserialize* ::vector
|
||||
[segment _type]
|
||||
(mem/deserialize (mem/reinterpret segment (mem/size-of [::mem/array ::mem/float 3]))
|
||||
[::mem/array ::mem/float 3]))
|
||||
```
|
||||
|
||||
The `reinterpret` function allows you to take a segment and decorate it with a
|
||||
new size, and possibly associate it with an arena or add cleanup functions on
|
||||
it.
|
||||
|
||||
In cases like this where we don't know the arena of the pointer, we could use
|
||||
`reinterpret` to ensure it's freed. For example if a `free-vector!` function
|
||||
that takes a pointer exists, we could use this:
|
||||
|
||||
```clojure
|
||||
(defcfn returns-vector
|
||||
"returns_vector" [] ::mem/pointer
|
||||
native-fn
|
||||
[arena]
|
||||
(let [ret-ptr (native-fn)]
|
||||
(-> (reinterpret ret-ptr (mem/size-of ::vector) arena free-vector!)
|
||||
(deserialize ::vector))))
|
||||
```
|
||||
|
||||
This function takes an arena and returns the deserialized vector, and it will
|
||||
free the pointer when the arena closes.
|
||||
|
||||
### Tagged Union
|
||||
For the tagged union type, we will represent the value as a vector of a keyword
|
||||
naming the tag and the value. The type itself will need to take arguments,
|
||||
similar to `struct`. For example, if we were to represent a result type like in
|
||||
Rust, we might have the following values:
|
||||
|
||||
```clojure
|
||||
[:ok 5]
|
||||
[:err "Invalid number format"]
|
||||
```
|
||||
|
||||
To represent this, we can have a `tagged-union` type. For this instance of the
|
||||
result type, it may look like this:
|
||||
|
||||
```clojure
|
||||
[::tagged-union [:ok :err] {:ok ::mem/int :err ::mem/c-string}]
|
||||
```
|
||||
|
||||
The native representation of these objects is a struct of the tag and a union of
|
||||
the value. In order to correctly serialize the data and pass it to native code,
|
||||
we need a representation of the native layout of the data. The `c-layout`
|
||||
multimethod provides that.
|
||||
|
||||
```clojure
|
||||
(defmethod mem/c-layout ::tagged-union
|
||||
[[_tagged-union tags type-map]]
|
||||
(mem/c-layout [::mem/struct
|
||||
[[:tag ::mem/long]
|
||||
[:value [::mem/union (vals type-map)]]]]))
|
||||
```
|
||||
|
||||
Types with type arguments are represented as vectors of the type name and any
|
||||
additional arguments. The type name is what is dispatched on for the
|
||||
multimethods.
|
||||
|
||||
Now that we have a native layout, we need to be able to serialize and
|
||||
deserialize the value into and out of memory segments. This is accomplished with
|
||||
`serialize-into` and `deserialize-from`.
|
||||
|
||||
```clojure
|
||||
(defn item-index
|
||||
"Gets the index of the first occurance of `item` in `coll`."
|
||||
[coll item]
|
||||
(first
|
||||
(->> coll
|
||||
(map-indexed vector)
|
||||
(filter (comp #{item} second))
|
||||
(map first))))
|
||||
|
||||
(defmethod mem/serialize-into ::tagged-union
|
||||
[obj [_tagged-union tags type-map] segment arena]
|
||||
(mem/serialize-into
|
||||
{:tag (item-index tags (first obj))
|
||||
:value (second obj)}
|
||||
[::mem/struct
|
||||
[[:tag ::mem/long]
|
||||
[:value (get type-map (first obj))]]]
|
||||
segment
|
||||
arena))
|
||||
```
|
||||
|
||||
This serialization method is rather simple, it just turns the vector value into
|
||||
a map, and serializes it as a struct, choosing the type of the value based on
|
||||
the tag.
|
||||
|
||||
```clojure
|
||||
(defmethod mem/deserialize-from ::tagged-union
|
||||
[segment [_tagged-union tags type-map]]
|
||||
(let [tag (mem/deserialize-from segment ::mem/long)]
|
||||
[(nth tags tag)
|
||||
(mem/deserialize-from
|
||||
(mem/slice segment (mem/size-of ::mem/long))
|
||||
(get type-map tag))]))
|
||||
```
|
||||
|
||||
Deserialization is a little more complex. First the tag is retrieved from the
|
||||
beginning of the segment, and then the type of the value is decided based on
|
||||
that before it is deserialized.
|
||||
95
docs/articles/05-Low-Level-Wrappers.md
Normal file
95
docs/articles/05-Low-Level-Wrappers.md
Normal file
|
|
@ -0,0 +1,95 @@
|
|||
# Low-Level Wrappers
|
||||
|
||||
### Unwrapped Native Handles
|
||||
Some native libraries work with handles to large amounts of data at once, making
|
||||
it undesirable to marshal data back and forth from Clojure, both because it's
|
||||
not necessary to work with the data in Clojure directly, or also because of the
|
||||
high (de)serialization costs associated with marshaling. In cases like these,
|
||||
unwrapped native handles are desirable.
|
||||
|
||||
The functions `make-downcall` and `make-varargs-factory` are also provided to
|
||||
create raw function handles.
|
||||
|
||||
```clojure
|
||||
(def raw-strlen (ffi/make-downcall "strlen" [::mem/c-string] ::mem/long))
|
||||
(raw-strlen (mem/serialize "hello" ::mem/c-string))
|
||||
;; => 5
|
||||
```
|
||||
|
||||
With raw handles, the argument types are expected to exactly match the types
|
||||
expected by the native function. For primitive types, those are primitives. For
|
||||
pointers, that is `MemorySegment`, and for composite types like structs and
|
||||
unions, that is also `MemorySegment`. `MemorySegment` comes from the
|
||||
`java.lang.foreign` package.
|
||||
|
||||
In addition, when a raw handle returns a composite type represented with a
|
||||
`MemorySegment`, it requires an additional first argument, a `SegmentAllocator`,
|
||||
which can be acquired with `arena-allocator` to get one associated with a
|
||||
specific arena. The returned value will live until that arena is released.
|
||||
|
||||
In addition, function types can be specified as being raw, in the following
|
||||
manner:
|
||||
|
||||
```clojure
|
||||
[::ffi/fn [::mem/int] ::mem/int :raw-fn? true]
|
||||
```
|
||||
|
||||
Clojure functions serialized to this type will have their arguments and return
|
||||
value exactly match the types specified and will not perform any serialization
|
||||
or deserialization at their boundaries.
|
||||
|
||||
One important caveat to consider when writing wrappers for performance-sensitive
|
||||
functions is that the convenience macro `defcfn` that coffi provides will
|
||||
already perform no serialization or deserialization on primitive arguments and
|
||||
return types, so for functions with only primitive argument and return types
|
||||
there is no performance reason to choose unwrapped native handles over the
|
||||
convenience macro.
|
||||
|
||||
### Manual (De)Serialization
|
||||
Coffi uses multimethods to dispatch to (de)serialization functions to enable
|
||||
code that's generic over the types it operates on. However, in cases where you
|
||||
know the exact types that you will be (de)serializing and the multimethod
|
||||
dispatch overhead is too high a cost, it may be appropriate to manually handle
|
||||
(de)serializing data. This will often be done paired with [Unwrapped Native
|
||||
Handles](#unwrapped-native-handles).
|
||||
|
||||
Convenience functions are provided to both read and write all primitive types
|
||||
and addresses, including byte order.
|
||||
|
||||
As an example, when wrapping a function that returns an array of big-endian
|
||||
floats, the following code might be used.
|
||||
|
||||
``` clojure
|
||||
;; int returns_float_array(float **arr)
|
||||
(def ^:private returns-float-array* (ffi/make-downcall "returns_float_array" [::mem/pointer] ::mem/int))
|
||||
;; void releases_float_array(float *arr)
|
||||
(def ^:private release-floats* (ffi/make-downcall "releases_float_array" [::mem/pointer] ::mem/void))
|
||||
|
||||
(defn returns-float-array
|
||||
[]
|
||||
(with-open [arena (mem/confined-arena)]
|
||||
;; float *out_floats;
|
||||
;; int num_floats = returns_float_array(&out_floats);
|
||||
(let [out-floats (mem/alloc mem/pointer-size arena)
|
||||
num-floats (returns-float-array* out-floats)
|
||||
floats-addr (mem/read-address out-floats)
|
||||
floats-slice (mem/reinterpret floats-addr (unchecked-multiply-int mem/float-size num-floats))]
|
||||
;; Using a try/finally to perform an operation when the stack frame exits,
|
||||
;; but not to try to catch anything.
|
||||
(try
|
||||
(loop [floats (transient [])
|
||||
index 0]
|
||||
(if (>= index num-floats)
|
||||
(persistent! floats)
|
||||
(recur (conj! floats (mem/read-float floats-slice
|
||||
(unchecked-multiply-int index mem/float-size)
|
||||
mem/big-endian))
|
||||
(unchecked-inc-int index))))
|
||||
(finally
|
||||
(release-floats* floats-addr))))))
|
||||
```
|
||||
|
||||
The above code manually performs all memory operations rather than relying on
|
||||
coffi's dispatch. This will be more performant, but because multimethod overhead
|
||||
is usually relatively low, it's recommended to use the multimethod variants for
|
||||
convenience in colder functions.
|
||||
44
docs/articles/50-Data-Model.md
Normal file
44
docs/articles/50-Data-Model.md
Normal file
|
|
@ -0,0 +1,44 @@
|
|||
# Data Model
|
||||
In addition to the macros and functions provided to build a Clojure API for
|
||||
native libraries, facilities are provided for taking data and loading all the
|
||||
symbols specified by it. This can be useful if a library provides (or an
|
||||
external provider maintains) a data representation of their API, as Clojure data
|
||||
to represent it may be programmatically generated from these sources.
|
||||
|
||||
The data to represent an API is a map with the following form:
|
||||
|
||||
```clojure
|
||||
(def strlen-libspec
|
||||
{:strlen {:type :function
|
||||
:symbol "strlen"
|
||||
:function/args [::mem/c-string]
|
||||
:function/ret ::mem/long}})
|
||||
```
|
||||
|
||||
Each key in this map represents a single symbol to be loaded. The value is a map
|
||||
with at least the keys `:type` and `:symbol`. These are the currently recognized
|
||||
types:
|
||||
|
||||
- function
|
||||
- varargs-factory
|
||||
- const
|
||||
- static-var
|
||||
|
||||
Each one has its own set of additional keys which can be added to the map. Both
|
||||
`function` and `varargs-factory` have the three keys `:function/args`,
|
||||
`:function/ret`, and `:function/raw-fn?`. The `const` type has `:const/type` and
|
||||
`static-var` has `:static-var/type`.
|
||||
|
||||
This data can be passed to the function `reify-libspec`, which will take the
|
||||
data and return a map from the same keys as the input map to whatever value is
|
||||
appropriate for a given symbol type (e.g. a Clojure function for `function`, a
|
||||
value for `const`, etc.).
|
||||
|
||||
```clojure
|
||||
(ffi/reify-libspec strlen-libspec)
|
||||
;; => {:strlen #function[...]}
|
||||
```
|
||||
|
||||
This functionality can be extended by specifying new types as implementations of
|
||||
the multimethod `reify-symbolspec`, although it's recommended that for any
|
||||
library authors who do so, namespaced keywords be used to name types.
|
||||
373
docs/articles/99-Benchmarks.md
Normal file
373
docs/articles/99-Benchmarks.md
Normal file
|
|
@ -0,0 +1,373 @@
|
|||
# Benchmarks
|
||||
**BENCHMARKS FOR COFFI AND DTYPE-NEXT ARE BASED ON AN OLD VERSION. NEW BENCHMARKS WILL BE CREATED SOON.**
|
||||
|
||||
An additional consideration when thinking about alternatives is the performance
|
||||
of each available option. It's an established fact that JNA (used by all three
|
||||
alternative libraries on JDK <16) introduces more overhead when calling native
|
||||
code than JNI does.
|
||||
|
||||
In order to provide a benchmark to see how much of a difference the different
|
||||
native interfaces make, we can use
|
||||
[criterium](https://github.com/hugoduncan/criterium) to benchmark each.
|
||||
[GLFW](https://www.glfw.org)'s
|
||||
[`glfwGetTime`](https://www.glfw.org/docs/latest/group__input.html#gaa6cf4e7a77158a3b8fd00328b1720a4a)
|
||||
function will be used for the test as it performs a simple operation, and is
|
||||
conveniently already wrapped in JNI by the excellent
|
||||
[LWJGL](https://www.lwjgl.org/) library.
|
||||
|
||||
The following benchmarks were run on a Lenovo Thinkpad with an Intel i7-10610U
|
||||
running Manjaro Linux, using Clojure 1.10.3 on Java 17.
|
||||
|
||||
### JNI
|
||||
The baseline for performance is the JNI. Using LWJGL it's relatively simple to
|
||||
benchmark. The following Clojure CLI command will start a repl with LWJGL and
|
||||
criterium loaded.
|
||||
|
||||
```sh
|
||||
$ clj -Sdeps '{:deps {org.lwjgl/lwjgl {:mvn/version "3.2.3"}
|
||||
org.lwjgl/lwjgl-glfw {:mvn/version "3.2.3"}
|
||||
org.lwjgl/lwjgl$natives-linux {:mvn/version "3.2.3"}
|
||||
org.lwjgl/lwjgl-glfw$natives-linux {:mvn/version "3.2.3"}
|
||||
criterium/criterium {:mvn/version "0.4.6"}}}'
|
||||
```
|
||||
|
||||
Then from the repl
|
||||
|
||||
```clojure
|
||||
user=> (import 'org.lwjgl.glfw.GLFW)
|
||||
org.lwjgl.glfw.GLFW
|
||||
user=> (require '[criterium.core :as bench])
|
||||
nil
|
||||
user=> (GLFW/glfwInit)
|
||||
true
|
||||
user=> (bench/bench (GLFW/glfwGetTime) :verbose)
|
||||
amd64 Linux 5.10.68-1-MANJARO 8 cpu(s)
|
||||
OpenJDK 64-Bit Server VM 17+35-2724
|
||||
Runtime arguments: -Dclojure.basis=/home/jsusk/.clojure/.cpcache/2667074721.basis
|
||||
Evaluation count : 1613349900 in 60 samples of 26889165 calls.
|
||||
Execution time sample mean : 32.698446 ns
|
||||
Execution time mean : 32.697811 ns
|
||||
Execution time sample std-deviation : 1.274600 ns
|
||||
Execution time std-deviation : 1.276437 ns
|
||||
Execution time lower quantile : 30.750813 ns ( 2.5%)
|
||||
Execution time upper quantile : 33.757662 ns (97.5%)
|
||||
Overhead used : 6.400704 ns
|
||||
nil
|
||||
```
|
||||
|
||||
GLFW requires that we initialize it before calling the `glfwGetTime` function.
|
||||
Besides that this is a simple interop call which directly maps to the native
|
||||
function.
|
||||
|
||||
This gives us a basis of 32.7 ns +/-1.3 ns. All other libraries will be
|
||||
evaluated relative to this result.
|
||||
|
||||
To ensure fairness, we'll also get that overhead value to be used in further
|
||||
tests.
|
||||
|
||||
```clojure
|
||||
user=> bench/estimated-overhead-cache
|
||||
6.400703613065185E-9
|
||||
```
|
||||
|
||||
### Coffi
|
||||
The dependencies when using coffi are simpler, but it also requires some JVM
|
||||
options to support the foreign access api.
|
||||
|
||||
```sh
|
||||
$ clj -Sdeps '{:deps {org.suskalo/coffi {:mvn/version "0.1.205"}
|
||||
criterium/criterium {:mvn/version "0.4.6"}}}' \
|
||||
-J--add-modules=jdk.incubator.foreign \
|
||||
-J--enable-native-access=ALL-UNNAMED
|
||||
```
|
||||
|
||||
In order to ensure fair comparisons, we're going to use the same overhead value
|
||||
on each run, so before we do the benchmark we'll set it to the observed value
|
||||
from last time.
|
||||
|
||||
```clojure
|
||||
user=> (require '[criterium.core :as bench])
|
||||
nil
|
||||
user=> (alter-var-root #'bench/estimated-overhead-cache (constantly 6.400703613065185E-9))
|
||||
6.400703613065185E-9
|
||||
user=> (require '[coffi.ffi :as ffi])
|
||||
nil
|
||||
user=> (require '[coffi.mem :as mem])
|
||||
nil
|
||||
user=> (ffi/load-system-library "glfw")
|
||||
nil
|
||||
user=> ((ffi/cfn "glfwInit" [] ::mem/int))
|
||||
1
|
||||
user=> (let [f (ffi/cfn "glfwGetTime" [] ::mem/double)]
|
||||
(bench/bench (f) :verbose))
|
||||
amd64 Linux 5.10.68-1-MANJARO 8 cpu(s)
|
||||
OpenJDK 64-Bit Server VM 17+35-2724
|
||||
Runtime arguments: --add-modules=jdk.incubator.foreign --enable-native-access=ALL-UNNAMED -Dclojure.basis=/home/jsusk/.clojure/.cpcache/72793624.basis
|
||||
Evaluation count : 1657995600 in 60 samples of 27633260 calls.
|
||||
Execution time sample mean : 31.382665 ns
|
||||
Execution time mean : 31.386493 ns
|
||||
Execution time sample std-deviation : 1.598571 ns
|
||||
Execution time std-deviation : 1.608818 ns
|
||||
Execution time lower quantile : 29.761194 ns ( 2.5%)
|
||||
Execution time upper quantile : 33.228276 ns (97.5%)
|
||||
Overhead used : 6.400704 ns
|
||||
nil
|
||||
```
|
||||
|
||||
This result is about 1.3 ns faster, and while that is less than the standard
|
||||
deviation of 1.6, it's quite close to it.
|
||||
|
||||
### Clojure-JNA
|
||||
Clojure-JNA uses the JNA library, which was designed to provide Java with an
|
||||
easy way to access native libraries, but which is known for not having the
|
||||
greatest performance. Since this is an older project, I'm also including the
|
||||
clojure dependency to ensure the correct version is used.
|
||||
|
||||
```sh
|
||||
$ clj -Sdeps '{:deps {org.clojure/clojure {:mvn/version "1.10.3"}
|
||||
net.n01se/clojure-jna {:mvn/version "1.0.0"}
|
||||
criterium/criterium {:mvn/version "0.4.6"}}}'
|
||||
```
|
||||
|
||||
The naive way to call the function using Clojure-JNA is to use `jna/invoke`.
|
||||
|
||||
```clojure
|
||||
user=> (require '[criterium.core :as bench])
|
||||
nil
|
||||
user=> (alter-var-root #'bench/estimated-overhead-cache (constantly 6.400703613065185E-9))
|
||||
6.400703613065185E-9
|
||||
user=> (require '[net.n01se.clojure-jna :as jna])
|
||||
nil
|
||||
user=> (jna/invoke Integer glfw/glfwInit)
|
||||
1
|
||||
user=> (bench/bench (jna/invoke Double glfw/glfwGetTime) :verbose)
|
||||
amd64 Linux 5.10.68-1-MANJARO 8 cpu(s)
|
||||
OpenJDK 64-Bit Server VM 17+35-2724
|
||||
Runtime arguments: -Dclojure.basis=/home/jsusk/.clojure/.cpcache/3229486237.basis
|
||||
Evaluation count : 195948720 in 60 samples of 3265812 calls.
|
||||
Execution time sample mean : 350.335614 ns
|
||||
Execution time mean : 350.373520 ns
|
||||
Execution time sample std-deviation : 24.833070 ns
|
||||
Execution time std-deviation : 24.755929 ns
|
||||
Execution time lower quantile : 300.000019 ns ( 2.5%)
|
||||
Execution time upper quantile : 365.759273 ns (97.5%)
|
||||
Overhead used : 6.400704 ns
|
||||
|
||||
Found 13 outliers in 60 samples (21.6667 %)
|
||||
low-severe 12 (20.0000 %)
|
||||
low-mild 1 (1.6667 %)
|
||||
Variance from outliers : 53.4220 % Variance is severely inflated by outliers
|
||||
nil
|
||||
```
|
||||
|
||||
As you can see, this method of calling functions is very bad for performance,
|
||||
with call overhead dominating function runtime by an order of magnitude. That
|
||||
said, this isn't a completely fair comparison, nor the most realistic, because
|
||||
this way of calling functions looks the function up on each invocation.
|
||||
|
||||
To adjust for this, we'll use the `jna/to-fn` function to give a persistent
|
||||
handle to the function that we can call.
|
||||
|
||||
```clojure
|
||||
user=> (let [f (jna/to-fn Double glfw/glfwGetTime)]
|
||||
(bench/bench (f) :verbose))
|
||||
amd64 Linux 5.10.68-1-MANJARO 8 cpu(s)
|
||||
OpenJDK 64-Bit Server VM 17+35-2724
|
||||
Runtime arguments: -Dclojure.basis=/home/jsusk/.clojure/.cpcache/3229486237.basis
|
||||
Evaluation count : 611095020 in 60 samples of 10184917 calls.
|
||||
Execution time sample mean : 104.623634 ns
|
||||
Execution time mean : 104.638406 ns
|
||||
Execution time sample std-deviation : 7.649296 ns
|
||||
Execution time std-deviation : 7.638963 ns
|
||||
Execution time lower quantile : 92.446016 ns ( 2.5%)
|
||||
Execution time upper quantile : 110.258832 ns (97.5%)
|
||||
Overhead used : 6.400704 ns
|
||||
nil
|
||||
```
|
||||
|
||||
This is much better, but is still about 3x slower than JNI, meaning the overhead
|
||||
from using JNA is still bigger than the function runtime.
|
||||
|
||||
This performance penalty is still small in the scope of longer-running
|
||||
functions, and so may not be a concern for your application, but it is something
|
||||
to be aware of.
|
||||
|
||||
### tech.jna
|
||||
The tech.jna library is similar in scope to Clojure-JNA, however was written to
|
||||
fit into an ecosystem of libraries meant for array-based programming for machine
|
||||
learning and data science.
|
||||
|
||||
```sh
|
||||
$ clj -Sdeps '{:deps {techascent/tech.jna {:mvn/version "4.05"}
|
||||
criterium/criterium {:mvn/version "0.4.6"}}}'
|
||||
```
|
||||
|
||||
This library is also quite simple to use, the only slightly odd thing I'm doing
|
||||
here is to dereference the var outside the benchmark in order to ensure it's an
|
||||
apples-to-apples comparison. We don't want var dereference time mucking up our
|
||||
benchmark.
|
||||
|
||||
```clojure
|
||||
user=> (require '[criterium.core :as bench])
|
||||
nil
|
||||
user=> (alter-var-root #'bench/estimated-overhead-cache (constantly 6.400703613065185E-9))
|
||||
6.400703613065185E-9
|
||||
user=> (require '[tech.v3.jna :as jna])
|
||||
nil
|
||||
user=> (jna/def-jna-fn "glfw" glfwInit "initialize glfw" Integer)
|
||||
#'user/glfwInit
|
||||
user=> (glfwInit)
|
||||
Oct 09, 2021 10:30:50 AM clojure.tools.logging$eval1122$fn__1125 invoke
|
||||
INFO: Library glfw found at [:system "glfw"]
|
||||
1
|
||||
user=> (jna/def-jna-fn "glfw" glfwGetTime "gets the time as a double since init" Double)
|
||||
#'user/glfwGetTime
|
||||
user=> (let [f @#'glfwGetTime]
|
||||
(bench/bench (f) :verbose))
|
||||
amd64 Linux 5.10.68-1-MANJARO 8 cpu(s)
|
||||
OpenJDK 64-Bit Server VM 17+35-2724
|
||||
Runtime arguments: -Dclojure.basis=/home/jsusk/.clojure/.cpcache/2910209237.basis
|
||||
Evaluation count : 323281680 in 60 samples of 5388028 calls.
|
||||
Execution time sample mean : 203.976803 ns
|
||||
Execution time mean : 203.818712 ns
|
||||
Execution time sample std-deviation : 14.557312 ns
|
||||
Execution time std-deviation : 14.614080 ns
|
||||
Execution time lower quantile : 179.732593 ns ( 2.5%)
|
||||
Execution time upper quantile : 213.929374 ns (97.5%)
|
||||
Overhead used : 6.400704 ns
|
||||
nil
|
||||
```
|
||||
|
||||
This version is even slower than Clojure-JNA. I'm unsure where this overhead is
|
||||
coming from, but I'll admit that I haven't looked at their implementations very
|
||||
closely.
|
||||
|
||||
### dtype-next
|
||||
The library dtype-next replaced tech.jna in the toolkit of the group working on
|
||||
machine learning and array-based programming, and it includes support for
|
||||
composite data types including structs, as well as primitive functions and
|
||||
callbacks.
|
||||
|
||||
In addition, dtype-next has two different ffi backends. First is JNA, which is
|
||||
usable on any JDK version, and is what we'll use for the first benchmark. Second
|
||||
is the Java 16 version of Project Panama, which will be shown next.
|
||||
|
||||
In order to use the dtype-next ffi with the JNA backend, the JNA library has to
|
||||
be included in the dependencies.
|
||||
|
||||
```sh
|
||||
$ clj -Sdeps '{:deps {cnuernber/dtype-next {:mvn/version "8.032"}
|
||||
net.java.dev.jna/jna {:mvn/version "5.8.0"}
|
||||
criterium/criterium {:mvn/version "0.4.6"}}}'
|
||||
```
|
||||
|
||||
The dtype-next library also requires some more ceremony around declaring native
|
||||
functions. One advantage this has is that multiple symbols with the same name
|
||||
can be loaded from different shared libraries, but it also does increase
|
||||
friction when defining native wrappers.
|
||||
|
||||
Some easier ways to define native wrappers are provided than what is seen here,
|
||||
but they share some disadvantages in documentation over the core methods
|
||||
provided in coffi, although they are comparable to the data model provided in
|
||||
coffi.
|
||||
|
||||
```clojure
|
||||
user=> (require '[criterium.core :as bench])
|
||||
nil
|
||||
user=> (alter-var-root #'bench/estimated-overhead-cache (constantly 6.400703613065185E-9))
|
||||
6.400703613065185E-9
|
||||
user=> (require '[tech.v3.datatype.ffi :as dt-ffi])
|
||||
nil
|
||||
user=> (def fn-defs {:glfwInit {:rettype :int32} :glfwGetTime {:rettype :float64}})
|
||||
#'user/fn-defs
|
||||
user=> (def library-def (dt-ffi/define-library fn-defs))
|
||||
#'user/library-def
|
||||
user=> (def library-instance (dt-ffi/instantiate-library library-def "/usr/lib/libglfw.so"))
|
||||
#'user/library-instance
|
||||
user=> (def init (:glfwInit @library-instance))
|
||||
#'user/init
|
||||
user=> (init)
|
||||
1
|
||||
user=> (let [f (:glfwGetTime @library-instance)]
|
||||
(bench/bench (f) :verbose))
|
||||
amd64 Linux 5.10.68-1-MANJARO 8 cpu(s)
|
||||
OpenJDK 64-Bit Server VM 17+35-2724
|
||||
Runtime arguments: -Dclojure.basis=/home/jsusk/.clojure/.cpcache/643862289.basis
|
||||
Evaluation count : 710822100 in 60 samples of 11847035 calls.
|
||||
Execution time sample mean : 90.900112 ns
|
||||
Execution time mean : 90.919917 ns
|
||||
Execution time sample std-deviation : 6.463312 ns
|
||||
Execution time std-deviation : 6.470108 ns
|
||||
Execution time lower quantile : 79.817126 ns ( 2.5%)
|
||||
Execution time upper quantile : 95.454652 ns (97.5%)
|
||||
Overhead used : 6.400704 ns
|
||||
nil
|
||||
```
|
||||
|
||||
This version of JNA usage is significantly faster than either of the other JNA
|
||||
libraries, but is still substantially slower than using JNI or coffi.
|
||||
|
||||
In addition to the JNA backend, dtype-next has a Java 16-specific backend that
|
||||
uses an older version of Panama. This version requires similar setup to coffi in
|
||||
order to run.
|
||||
|
||||
```sh
|
||||
$ clj -Sdeps '{:deps {cnuernber/dtype-next {:mvn/version "8.032"}
|
||||
criterium/criterium {:mvn/version "0.4.6"}}}' \
|
||||
-J--add-modules=jdk.incubator.foreign \
|
||||
-J-Dforeign.restricted=permit \
|
||||
-J--add-opens=java.base/java.lang=ALL-UNNAMED \
|
||||
-J-Djava.library.path=/usr/lib/x86_64-linux-gnu
|
||||
```
|
||||
|
||||
The actual code to run the benchmark is identical to the last example, but is
|
||||
reproduced here for completeness.
|
||||
|
||||
```clojure
|
||||
user=> (require '[criterium.core :as bench])
|
||||
nil
|
||||
user=> (alter-var-root #'bench/estimated-overhead-cache (constantly 6.400703613065185E-9))
|
||||
6.400703613065185E-9
|
||||
user=> (require '[tech.v3.datatype.ffi :as dt-ffi])
|
||||
nil
|
||||
user=> (def fn-defs {:glfwInit {:rettype :int32} :glfwGetTime {:rettype :float64}})
|
||||
#'user/fn-defs
|
||||
user=> (def library-def (dt-ffi/define-library fn-defs))
|
||||
#'user/library-def
|
||||
user=> (def library-instance (dt-ffi/instantiate-library library-def "/usr/lib/libglfw.so"))
|
||||
#'user/library-instance
|
||||
user=> (def init (:glfwInit @library-instance))
|
||||
#'user/init
|
||||
user=> (init)
|
||||
1
|
||||
user=> (let [f (:glfwGetTime @library-instance)]
|
||||
(bench/bench (f) :verbose))
|
||||
amd64 Linux 5.10.68-1-MANJARO 8 cpu(s)
|
||||
OpenJDK 64-Bit Server VM 16.0.2+7
|
||||
Runtime arguments: --add-modules=jdk.incubator.foreign -Dforeign.restricted=permit --add-opens=java.base/java.lang=ALL-UNNAMED -Djava.library.path=/usr/lib/x86_64-linux-gnu -Dclojure.basis=/home/jsusk/.clojure/.cpcache/2337051659.basis
|
||||
Evaluation count : 1588513080 in 60 samples of 26475218 calls.
|
||||
Execution time sample mean : 58.732468 ns
|
||||
Execution time mean : 58.647361 ns
|
||||
Execution time sample std-deviation : 9.732389 ns
|
||||
Execution time std-deviation : 9.791738 ns
|
||||
Execution time lower quantile : 31.318115 ns ( 2.5%)
|
||||
Execution time upper quantile : 65.449222 ns (97.5%)
|
||||
Overhead used : 6.400704 ns
|
||||
|
||||
Found 14 outliers in 60 samples (23.3333 %)
|
||||
low-severe 8 (13.3333 %)
|
||||
low-mild 4 (6.6667 %)
|
||||
high-mild 2 (3.3333 %)
|
||||
Variance from outliers : 87.6044 % Variance is severely inflated by outliers
|
||||
nil
|
||||
```
|
||||
|
||||
Not reproduced here, but notable for comparison, in my testing Java 16's version
|
||||
of the JNI version performed about the same.
|
||||
|
||||
This is significantly faster than the JNA version of dtype-next, but it is still
|
||||
slower than modern Panama. This is likely to simply be a result of optimizations
|
||||
and changes to the Panama API, and when dtype-next is updated to use the Java 17
|
||||
version of Panama I expect it will perform in line with coffi, but this
|
||||
benchmark will be reproduced when this happens. Still, this shows that as it
|
||||
stands, coffi is the fastest FFI available to Clojure developers.
|
||||
File diff suppressed because one or more lines are too long
|
|
@ -1,6 +1,6 @@
|
|||
<!DOCTYPE html PUBLIC ""
|
||||
"">
|
||||
<html><head><meta charset="UTF-8" /><title>coffi.layout documentation</title><link rel="stylesheet" type="text/css" href="css/default.css" /><link rel="stylesheet" type="text/css" href="css/highlight.css" /><script type="text/javascript" src="js/highlight.min.js"></script><script type="text/javascript" src="js/jquery.min.js"></script><script type="text/javascript" src="js/page_effects.js"></script><script>hljs.initHighlightingOnLoad();</script></head><body><div id="header"><h2>Generated by <a href="https://github.com/weavejester/codox">Codox</a></h2><h1><a href="index.html"><span class="project-title"><span class="project-name">coffi</span> <span class="project-version">v1.0.486</span></span></a></h1></div><div class="sidebar primary"><h3 class="no-link"><span class="inner">Project</span></h3><ul class="index-link"><li class="depth-1 "><a href="index.html"><div class="inner">Index</div></a></li></ul><h3 class="no-link"><span class="inner">Topics</span></h3><ul><li class="depth-1 "><a href="01-Getting-Started.html"><div class="inner"><span>Getting Started</span></div></a></li></ul><h3 class="no-link"><span class="inner">Namespaces</span></h3><ul><li class="depth-1"><div class="no-link"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>coffi</span></div></div></li><li class="depth-2 branch"><a href="coffi.ffi.html"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>ffi</span></div></a></li><li class="depth-2 branch current"><a href="coffi.layout.html"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>layout</span></div></a></li><li class="depth-2"><a href="coffi.mem.html"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>mem</span></div></a></li></ul></div><div class="sidebar secondary"><h3><a href="#top"><span class="inner">Public Vars</span></a></h3><ul><li class="depth-1"><a href="coffi.layout.html#var-with-c-layout"><div class="inner"><span>with-c-layout</span></div></a></li></ul></div><div class="namespace-docs" id="content"><h1 class="anchor" id="top">coffi.layout</h1><div class="doc"><div class="markdown"><p>Functions for adjusting the layout of structs.</p>
|
||||
<html><head><meta charset="UTF-8" /><title>coffi.layout documentation</title><link rel="stylesheet" type="text/css" href="css/default.css" /><link rel="stylesheet" type="text/css" href="css/highlight.css" /><script type="text/javascript" src="js/highlight.min.js"></script><script type="text/javascript" src="js/jquery.min.js"></script><script type="text/javascript" src="js/page_effects.js"></script><script>hljs.initHighlightingOnLoad();</script></head><body><div id="header"><h2>Generated by <a href="https://github.com/weavejester/codox">Codox</a></h2><h1><a href="index.html"><span class="project-title"><span class="project-name">coffi</span> <span class="project-version">v1.0.486</span></span></a></h1></div><div class="sidebar primary"><h3 class="no-link"><span class="inner">Project</span></h3><ul class="index-link"><li class="depth-1 "><a href="index.html"><div class="inner">Index</div></a></li></ul><h3 class="no-link"><span class="inner">Topics</span></h3><ul><li class="depth-1 "><a href="01-Getting-Started.html"><div class="inner"><span>Getting Started</span></div></a></li><li class="depth-1 "><a href="02-Memory-Management.html"><div class="inner"><span>Memory Management</span></div></a></li><li class="depth-1 "><a href="03-Builtin-Types.html"><div class="inner"><span>Built-in Types</span></div></a></li><li class="depth-1 "><a href="04-Custom-Types.html"><div class="inner"><span>Custom Types</span></div></a></li><li class="depth-1 "><a href="05-Low-Level-Wrappers.html"><div class="inner"><span>Low-Level Wrappers</span></div></a></li><li class="depth-1 "><a href="50-Data-Model.html"><div class="inner"><span>Data Model</span></div></a></li><li class="depth-1 "><a href="99-Benchmarks.html"><div class="inner"><span>Benchmarks</span></div></a></li></ul><h3 class="no-link"><span class="inner">Namespaces</span></h3><ul><li class="depth-1"><div class="no-link"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>coffi</span></div></div></li><li class="depth-2 branch"><a href="coffi.ffi.html"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>ffi</span></div></a></li><li class="depth-2 branch current"><a href="coffi.layout.html"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>layout</span></div></a></li><li class="depth-2"><a href="coffi.mem.html"><div class="inner"><span class="tree"><span class="top"></span><span class="bottom"></span></span><span>mem</span></div></a></li></ul></div><div class="sidebar secondary"><h3><a href="#top"><span class="inner">Public Vars</span></a></h3><ul><li class="depth-1"><a href="coffi.layout.html#var-with-c-layout"><div class="inner"><span>with-c-layout</span></div></a></li></ul></div><div class="namespace-docs" id="content"><h1 class="anchor" id="top">coffi.layout</h1><div class="doc"><div class="markdown"><p>Functions for adjusting the layout of structs.</p>
|
||||
</div></div><div class="public anchor" id="var-with-c-layout"><h3>with-c-layout</h3><div class="usage"><code>(with-c-layout struct-spec)</code></div><div class="doc"><div class="markdown"><p>Forces a struct specification to C layout rules.</p>
|
||||
<p>This will add padding fields between fields to match C alignment requirements.</p>
|
||||
</div></div><div class="src-link"><a href="https://github.com/IGJoshua/coffi/blob/be58ac5d8037811e7d5bbb55045042a2b5a32c18/src/clj/coffi/layout.clj#L6">view source</a></div></div></div></body></html>
|
||||
</div></div><div class="src-link"><a href="https://github.com/IGJoshua/coffi/blob/3c16e00fc1b7ca4d34d90c00003b7ea3785d9099/src/clj/coffi/layout.clj#L6">view source</a></div></div></div></body></html>
|
||||
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Reference in a new issue