From ed77c6c17b88c15c0850b24236cac846b9179c26 Mon Sep 17 00:00:00 2001
From: Benjamin Manns <benmanns@gmail.com>
Date: Thu, 22 May 2014 11:59:11 -0700
Subject: [PATCH] Add -use-number flag that enables json.UseNumber(). Add
 deprecation warnings.

---
 README.md | 12 ++++++++++--
 doc.go    | 12 ++++++++++--
 flags.go  | 19 +++++++++++++++++++
 poller.go |  8 +++++++-
 4 files changed, 46 insertions(+), 5 deletions(-)

diff --git a/README.md b/README.md
index fedfc07..a7c8ec3 100644
--- a/README.md
+++ b/README.md
@@ -94,18 +94,26 @@ goworker worker functions receive the queue they are serving and a slice of inte
 ```go
 // Expecting (int, string, float64)
 func myFunc(queue, args ...interface{}) error {
-	id, ok := args[0].(int)
+	idNum, ok := args[0].(json.Number)
 	if !ok {
 		return errorInvalidParam
 	}
+	id, err := idNum.Int64()
+	if err != nil {
+		return errorInvalidParam
+	}
 	name, ok := args[1].(string)
 	if !ok {
 		return errorInvalidParam
 	}
-	weight, ok := args[2].(float64)
+	weightNum, ok := args[2].(json.Number)
 	if !ok {
 		return errorInvalidParam
 	}
+	weight, err := weightNum.Float64()
+	if err != nil {
+		return errorInvalidParam
+	}
 	doSomething(id, name, weight)
 	return nil
 }
diff --git a/doc.go b/doc.go
index 8236371..e658800 100644
--- a/doc.go
+++ b/doc.go
@@ -76,18 +76,26 @@
 //
 //	// Expecting (int, string, float64)
 //	func myFunc(queue, args ...interface{}) error {
-//		id, ok := args[0].(int)
+//		idNum, ok := args[0].(json.Number)
 //		if !ok {
 //			return errorInvalidParam
 //		}
+//		id, err := idNum.Int64()
+//		if err != nil {
+//			return errorInvalidParam
+//		}
 //		name, ok := args[1].(string)
 //		if !ok {
 //			return errorInvalidParam
 //		}
-//		weight, ok := args[2].(float64)
+//		weightNum, ok := args[2].(json.Number)
 //		if !ok {
 //			return errorInvalidParam
 //		}
+//		weight, err := weightNum.Float64()
+//		if err != nil {
+//			return errorInvalidParam
+//		}
 //		doSomething(id, name, weight)
 //		return nil
 //	}
diff --git a/flags.go b/flags.go
index 9e554b6..0c77bf8 100644
--- a/flags.go
+++ b/flags.go
@@ -69,6 +69,14 @@
 // with the time command to benchmark different
 // configurations.
 //
+// -use-number=false
+// — Uses json.Number when decoding numbers in the
+// job payloads. This will avoid issues that
+// occur when goworker and the json package decode
+// large numbers as floats, which then get
+// encoded in scientific notation, losing
+// pecision. This will default to true soon.
+//
 // You can also configure your own flags for use
 // within your workers. Be sure to set them
 // before calling goworker.Main(). It is okay to
@@ -94,6 +102,7 @@ var (
 	namespace      string
 	exitOnComplete bool
 	isStrict       bool
+	useNumber      bool
 )
 
 // Namespace returns the namespace flag for goworker. You
@@ -127,6 +136,8 @@ func init() {
 	flag.StringVar(&namespace, "namespace", "resque:", "the Redis namespace")
 
 	flag.BoolVar(&exitOnComplete, "exit-on-complete", false, "exit when the queue is empty")
+
+	flag.BoolVar(&useNumber, "use-number", false, "use json.Number instead of float64 when decoding numbers in JSON. will default to true soon")
 }
 
 func flags() error {
@@ -140,5 +151,13 @@ func flags() error {
 		return err
 	}
 	isStrict = strings.IndexRune(queuesString, '=') == -1
+
+	if !useNumber {
+		logger.Warn("== DEPRECATION WARNING ==")
+		logger.Warn("  Currently, encoding/json decodes numbers as float64.")
+		logger.Warn("  This can cause numbers to lose precision as they are read from the Resque queue.")
+		logger.Warn("  Set the -use-numbers flag to use json.Number when decoding numbers and remove this warning.")
+	}
+
 	return nil
 }
diff --git a/poller.go b/poller.go
index 840ecde..635c955 100644
--- a/poller.go
+++ b/poller.go
@@ -1,6 +1,7 @@
 package goworker
 
 import (
+	"bytes"
 	"encoding/json"
 	"fmt"
 	"time"
@@ -35,7 +36,12 @@ func (p *poller) getJob(conn *RedisConn) (*job, error) {
 
 			job := &job{Queue: queue}
 
-			if err := json.Unmarshal(reply.([]byte), &job.Payload); err != nil {
+			decoder := json.NewDecoder(bytes.NewReader(reply.([]byte)))
+			if useNumber {
+				decoder.UseNumber()
+			}
+
+			if err := decoder.Decode(&job.Payload); err != nil {
 				return nil, err
 			}
 			return job, nil