From bde3e96ad9750c505449ced2bfd43ecdbbfd91fb Mon Sep 17 00:00:00 2001
From: Harlow Ward <harlow@hward.com>
Date: Fri, 22 May 2015 23:38:06 -0700
Subject: [PATCH] Add Discard Logger

For situations where we don't want any logs produced by the application.

* Remove references to Logger from README
* Add implementation of DiscardLogger
---
 README.md         | 10 ++--------
 default_logger.go | 21 ++++++++-------------
 discard_logger.go | 15 +++++++++++++++
 logger.go         |  6 ++++++
 4 files changed, 31 insertions(+), 21 deletions(-)
 create mode 100644 discard_logger.go

diff --git a/README.md b/README.md
index c461443..8f66c43 100644
--- a/README.md
+++ b/README.md
@@ -42,8 +42,6 @@ package main
 
 import (
 	"fmt"
-	"log"
-	"net/http"
 	"os"
 
 	"code.google.com/p/gcfg"
@@ -75,7 +73,7 @@ func newS3Pipeline(cfg Config) *connector.Pipeline {
 		AppName:    cfg.Pipeline.Name,
 		StreamName: cfg.Kinesis.StreamName,
 	}
-	e := &connector.S3ManifestEmitter{
+	e := &connector.S3Emitter{
 		S3Bucket: cfg.S3.BucketName,
 	}
 	return &connector.Pipeline{
@@ -83,7 +81,6 @@ func newS3Pipeline(cfg Config) *connector.Pipeline {
 		Checkpoint:  c,
 		Emitter:     e,
 		Filter:      f,
-		Logger:      log.New(os.Stdout, "KINESIS: ", log.Ldate|log.Ltime|log.Lshortfile),
 		StreamName:  cfg.Kinesis.StreamName,
 		Transformer: t,
 	}
@@ -94,19 +91,16 @@ func main() {
 	var cfg Config
 	err := gcfg.ReadFileInto(&cfg, "pipeline.cfg")
 
-	// Set up kinesis client
+	// Set up kinesis client and stream
 	accessKey := os.Getenv("AWS_ACCESS_KEY")
 	secretKey := os.Getenv("AWS_SECRET_KEY")
 	ksis := kinesis.New(accessKey, secretKey, kinesis.Region{})
-
-	// Create and wait for streams
 	connector.CreateStream(ksis, cfg.Kinesis.StreamName, cfg.Kinesis.ShardCount)
 
 	// Fetch stream info
 	args := kinesis.NewArgs()
 	args.Add("StreamName", cfg.Kinesis.StreamName)
 	streamInfo, err := ksis.DescribeStream(args)
-
 	if err != nil {
 		fmt.Printf("Unable to connect to %s stream. Aborting.", cfg.Kinesis.StreamName)
 		return
diff --git a/default_logger.go b/default_logger.go
index 2679cc4..1825723 100644
--- a/default_logger.go
+++ b/default_logger.go
@@ -2,25 +2,20 @@ package connector
 
 import "log"
 
-// the default implementation for a logger
-// for this package.
-type DefaultLogger struct {
-}
+// DefaultLogger is an implementation for std lib logger.
+type DefaultLogger struct{}
 
+// Fatalf is equivalent to Printf() followed by a call to os.Exit(1).
 func (l *DefaultLogger) Fatalf(format string, v ...interface{}) {
 	log.Fatalf(format, v...)
 }
+
+// Printf calls Output to print to the standard logger. Arguments are
+// handled in the manner of fmt.Printf.
 func (l *DefaultLogger) Printf(format string, v ...interface{}) {
 	log.Printf(format, v...)
 }
 
-// make sure that there is a default logger instance
-// initialized, so that we don't end up with panics
+// Make sure that there is a default logger instance initialized, so
+// that we don't end up with panics.
 var logger Logger = &DefaultLogger{}
-
-// expose the ability to change the logger so that
-// external packages can control the logging for
-// this package
-func SetLogger(l Logger) {
-	logger = l
-}
diff --git a/discard_logger.go b/discard_logger.go
new file mode 100644
index 0000000..1f39f0d
--- /dev/null
+++ b/discard_logger.go
@@ -0,0 +1,15 @@
+package connector
+
+import "os"
+
+// DiscardLogger is the an implementation of a Logger that does not
+// send any output. It can be used in scenarios when logging is not desired.
+type DiscardLogger struct{}
+
+// Fatalf is equivalent to Printf() followed by a call to os.Exit(1).
+func (l *DiscardLogger) Fatalf(format string, v ...interface{}) {
+	os.Exit(1)
+}
+
+// Printf is noop and does not have any output.
+func (l *DiscardLogger) Printf(format string, v ...interface{}) {}
diff --git a/logger.go b/logger.go
index 916807f..103f023 100644
--- a/logger.go
+++ b/logger.go
@@ -6,3 +6,9 @@ type Logger interface {
 	Fatalf(format string, v ...interface{})
 	Printf(format string, v ...interface{})
 }
+
+// SetLogger adds the ability to change the logger so that external packages
+// can control the logging for this package
+func SetLogger(l Logger) {
+	logger = l
+}