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[#6] refactor handlers

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This commit is contained in:
Michiel Borkent 2020-05-20 13:28:04 +02:00
parent a673ab4c8a
commit 57b86f301d
3 changed files with 50 additions and 43 deletions
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30
README.md
View file

@ -331,14 +331,16 @@ as client side code. An example from the
(defn watch
([path cb] (watch path cb {}))
([path cb opts]
(babashka.pods/invoke "pod.babashka.filewatcher"
'pod.babashka.filewatcher/watch*
[path opts]
{:on-success (fn [{:keys [:value :done]}] (cb value))
:on-error (fn [{:keys [:ex-message :ex-data]}]
(binding [*out* *err*]
(println "ERROR:" ex-message)))})
nil))
(babashka.pods/invoke
"pod.babashka.filewatcher"
'pod.babashka.filewatcher/watch*
[path opts]
{:handler {:success (fn [{:keys [:value]}] (cb value))
:error (fn [{:keys [:ex-message :ex-data]}]
(binding [*out* *err*]
(println "ERROR:" ex-message)))
:done (fn [_])}})
nil))
```
The wrapper function will then invoke `babashka.pods/invoke`, a lower level
@ -350,19 +352,17 @@ The arguments to `babashka.pods/invoke` are:
derived from the first described namespace.
- the symbol of the var to invoke
- the arguments to the var
- an opts map containing `:on-success` and `:on-error` callbacks.
- an opts map containing `:handler` containing callback functions: `:success`, `:error` and `:done`
The return value of `babashka.pods/invoke` is a map containing `:result`. When
not using callbacks, this is the return value from the pod var invocation. When
using callbacks, this value is undefined.
The callback `:on-success` is called with a map containing:
The callback `:success` is called with a map containing:
- `:value`: a return value from the pod var
- `:done`: a boolean indicating if the var invocation is done (`true`). If
`false` then more values can be expected.
The callback `:on-error` is called with a map containing:
The callback `:error` is called with a map containing:
- `:ex-message`: an error message
- `:ex-data`: an arbitrary additional error data map. Typically it will contain
@ -371,6 +371,10 @@ The callback `:on-error` is called with a map containing:
If desired, `:ex-message` and `:ex-data` can be reified into a
`java.lang.Exception` using `ex-info`.
The callback `:done` is called with one argument which is currently
undefined. This callback can be used to determine if the pod is done sending
values.
In the above example the wrapper function calls the pod identified by
`"pod.babashka.filewatcher"`. It calls the var
`pod.babashka.filewatcher/watch*`. In `:on-success` it pulls out received

44
src/babashka/pods/impl.clj
View file

@ -55,8 +55,8 @@
read-fn)
status (get reply "status")
status (set (map (comp keyword bytes->string) status))
done? (contains? status :done)
error? (contains? status :error)
done? (or error? (contains? status :done))
[ex-message ex-data]
(when error?
[(or (some-> (get reply "ex-message")
@ -70,8 +70,10 @@
promise? (instance? clojure.lang.IPending chan)
exception (when (and promise? error?)
(ex-info ex-message ex-data))
on-success (:on-success chan)
on-error (:on-error chan)
{error-handler :error
done-handler :done
success-handler :success} (when (map? chan)
chan)
out (some-> (get reply "out")
bytes->string)
err (some-> (get reply "err")
@ -79,14 +81,16 @@
(when (or value* error?)
(cond promise?
(deliver chan (if error? exception value))
(and (not error?) on-success)
(on-success {:value value
:done done?})
(and error? on-error)
(on-error {:ex-message ex-message
:ex-data ex-data})))
(when (and (or done? error?) promise?)
(deliver chan nil))
(and (not error?) success-handler)
(success-handler {:value value})
(and error? error-handler)
(error-handler {:ex-message ex-message
:ex-data ex-data})))
(when done?
(when promise?
(deliver chan nil))
(when done-handler
(done-handler {})))
(when out
(binding [*out* out-stream]
(println out)))
@ -100,30 +104,24 @@
(defn next-id []
(str (java.util.UUID/randomUUID)))
(defn invoke [pod pod-var args
{:keys [:on-success
:on-error
:async]}]
(let [stream (:stdin pod)
(defn invoke [pod pod-var args opts]
(let [handlers (:handlers opts)
stream (:stdin pod)
format (:format pod)
chans (:chans pod)
write-fn (case format
:edn pr-str
:json cheshire/generate-string)
id (next-id)
chan (cond async (async/chan)
(or on-success
on-error) {:on-success on-success
:on-error on-error}
:else (promise))
chan (if handlers handlers
(promise))
_ (swap! chans assoc id chan)
_ (write stream {"id" id
"op" "invoke"
"var" (str pod-var)
"args" (write-fn args)})]
;; see: https://blog.jakubholy.net/2019/core-async-error-handling/
(cond async chan
(or on-success on-error) nil
(cond handlers handlers
:else (let [v @chan]
(if (instance? Throwable v)
(throw v)

19
test-resources/test_program.clj
View file

@ -3,10 +3,13 @@
(require '[pod.test-pod :as pod])
(def stream-results (atom []))
(def done-prom (promise))
(pods/invoke "pod.test-pod" 'pod.test-pod/range-stream [1 10]
{:on-success (fn [{:keys [:value]}]
(swap! stream-results conj value))})
(while (< (count @stream-results) 9))
{:handlers {:success (fn [{:keys [:value]}]
(swap! stream-results conj value))
:done (fn [_]
(deliver done-prom :ok))}})
@done-prom
(def ex-result
(try (pod.test-pod/error 1 2 3)
@ -20,13 +23,15 @@
(def callback-result (promise))
(pods/invoke "pod.test-pod" 'pod.test-pod/add-sync [1 2]
{:on-success (fn [{:keys [:value :done]}]
(when done (deliver callback-result value)))})
{:handlers {:success
(fn [{:keys [:value]}]
(deliver callback-result value))}})
(def error-result (promise))
(pods/invoke "pod.test-pod" 'pod.test-pod/add-sync ["1" 2]
{:on-error (fn [m]
(deliver error-result m))})
{:handlers
{:error (fn [m]
(deliver error-result m))}})
[(pod/assoc {:a 1} :b 2)
(pod.test-pod/add-sync 1 2 3)