From d0a1bd7e3ed563b83c27e90cf994f237c38c5f74 Mon Sep 17 00:00:00 2001
From: Olivier Poitrey <rs@rhapsodyk.net>
Date: Mon, 15 May 2017 11:16:13 -0700
Subject: [PATCH] Make GlobalLevel and DisableSampling thread safe

---
 README.md  |  6 +++---
 field.go   | 22 +---------------------
 globals.go | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 log.go     | 17 +++--------------
 4 files changed, 61 insertions(+), 38 deletions(-)
 create mode 100644 globals.go

diff --git a/README.md b/README.md
index 0eadb36..cbdee3d 100644
--- a/README.md
+++ b/README.md
@@ -85,7 +85,7 @@ sublogger.Info().Msg("hello world")
 ### Level logging
 
 ```go
-zerolog.GlobalLevel = zerolog.InfoLevel
+zerolog.SetGlobalLevel(zerolog.InfoLevel)
 
 log.Debug().Msg("filtered out message")
 log.Info().Msg("routed message")
@@ -138,8 +138,8 @@ sampled.Info().Msg("will be logged every 10 messages")
 Some settings can be changed and will by applied to all loggers:
 
 * `log.Logger`: You can set this value to customize the global logger (the one used by package level methods).
-* `zerolog.GlobalLevel`: Can raise the mimimum level of all loggers. Set this to `zerolog.Disable` to disable logging altogether (quiet mode).
-* `zerolog.SamplingDisable`: If set to `true`, all sampled loggers will stop sampling and issue 100% of their log events.
+* `zerolog.SetGlobalLevel`: Can raise the mimimum level of all loggers. Set this to `zerolog.Disable` to disable logging altogether (quiet mode).
+* `zerolog.DisableSampling`: If argument is `true`, all sampled loggers will stop sampling and issue 100% of their log events.
 * `zerolog.TimestampFieldName`: Can be set to customize `Timestamp` field name.
 * `zerolog.LevelFieldName`: Can be set to customize level field name.
 * `zerolog.MessageFieldName`: Can be set to customize message field name.
diff --git a/field.go b/field.go
index 4aca84b..c20e160 100644
--- a/field.go
+++ b/field.go
@@ -6,27 +6,7 @@ import (
 	"time"
 )
 
-var (
-	// TimestampFieldName is the field name used for the timestamp field.
-	TimestampFieldName = "time"
-
-	// LevelFieldName is the field name used for the level field.
-	LevelFieldName = "level"
-
-	// MessageFieldName is the field name used for the message field.
-	MessageFieldName = "message"
-
-	// ErrorFieldName is the field name used for error fields.
-	ErrorFieldName = "error"
-
-	// SampleFieldName is the name of the field used to report sampling.
-	SampleFieldName = "sample"
-
-	// TimeFieldFormat defines the time format of the Time field type.
-	TimeFieldFormat = time.RFC3339
-
-	now = time.Now
-)
+var now = time.Now
 
 type FieldMode uint8
 
diff --git a/globals.go b/globals.go
new file mode 100644
index 0000000..d600ea5
--- /dev/null
+++ b/globals.go
@@ -0,0 +1,54 @@
+package zerolog
+
+import "time"
+import "sync/atomic"
+
+var (
+	// TimestampFieldName is the field name used for the timestamp field.
+	TimestampFieldName = "time"
+
+	// LevelFieldName is the field name used for the level field.
+	LevelFieldName = "level"
+
+	// MessageFieldName is the field name used for the message field.
+	MessageFieldName = "message"
+
+	// ErrorFieldName is the field name used for error fields.
+	ErrorFieldName = "error"
+
+	// SampleFieldName is the name of the field used to report sampling.
+	SampleFieldName = "sample"
+
+	// TimeFieldFormat defines the time format of the Time field type.
+	TimeFieldFormat = time.RFC3339
+)
+
+var (
+	gLevel          = new(uint32)
+	disableSampling = new(uint32)
+)
+
+// SetGlobalLevel sets the global override for log level. If this
+// values is raised, all Loggers will use at least this value.
+//
+// To globally disable logs, set GlobalLevel to Disabled.
+func SetGlobalLevel(l Level) {
+	atomic.StoreUint32(gLevel, uint32(l))
+}
+
+func globalLevel() Level {
+	return Level(atomic.LoadUint32(gLevel))
+}
+
+// DisableSampling will disable sampling in all Loggers if true.
+func DisableSampling(v bool) {
+	var i uint32
+	if v {
+		i = 1
+	}
+	atomic.StoreUint32(disableSampling, i)
+}
+
+func samplingDisabled() bool {
+	return atomic.LoadUint32(gLevel) == 1
+}
diff --git a/log.go b/log.go
index 0ad0297..88fde42 100644
--- a/log.go
+++ b/log.go
@@ -30,7 +30,7 @@
 //
 // Level logging
 //
-//     zerolog.GlobalLevel = zerolog.InfoLevel
+//     zerolog.SetGlobalLevel(zerolog.InfoLevel)
 //
 //     log.Debug().Msg("filtered out message")
 //     log.Info().Msg("routed message")
@@ -124,17 +124,6 @@ const (
 	Rarely = int64(1000)
 )
 
-var (
-	// GlobalLevel defines the global override for log level. If this
-	// values is raised, all Loggers will use at least this value.
-	//
-	// To globally disable logs, set GlobalLevel to Disabled.
-	GlobalLevel = DebugLevel
-
-	// DisableSampling will disable sampling in all Loggers if true.
-	DisableSampling = false
-)
-
 // A Logger represents an active logging object that generates lines
 // of JSON output to an io.Writer. Each logging operation makes a single
 // call to the Writer's Write method. There is no guaranty on access
@@ -270,10 +259,10 @@ func (l Logger) newEvent(level Level, addLevelField bool, done func(string)) Eve
 
 // should returns true if the log event should be logged.
 func (l Logger) should(lvl Level) bool {
-	if lvl < l.level || lvl < GlobalLevel {
+	if lvl < l.level || lvl < globalLevel() {
 		return false
 	}
-	if !DisableSampling && l.sample > 0 && l.counter != nil {
+	if l.sample > 0 && l.counter != nil && !samplingDisabled() {
 		c := atomic.AddUint32(l.counter, 1)
 		return c%l.sample == 0
 	}