[#147] Add sampling configuration

Signed-off-by: Pavel Pogodaev <p.pogodaev@yadro.com>

cmd/http-gw/settings.go

@@ -41,6 +41,8 @@ const (
 	defaultConnectTimeout = 10 * time.Second
 	defaultStreamTimeout  = 10 * time.Second
 
+	defaultLoggerSamplerInterval = 1 * time.Second
+
 	defaultShutdownTimeout = 15 * time.Second
 
 	defaultPoolErrorThreshold uint32 = 100
@@ -91,6 +93,11 @@ const (
 	cfgLoggerLevel       = "logger.level"
 	cfgLoggerDestination = "logger.destination"
 
+	cfgLoggerSamplingEnabled    = "logger.sampling.enabled"
+	cfgLoggerSamplingInitial    = "logger.sampling.initial"
+	cfgLoggerSamplingThereafter = "logger.sampling.thereafter"
+	cfgLoggerSamplingInterval   = "logger.sampling.interval"
+
 	// Wallet.
 	cfgWalletPassphrase = "wallet.passphrase"
 	cfgWalletPath       = "wallet.path"
@@ -188,6 +195,10 @@ func settings() *viper.Viper {
 	// logger:
 	v.SetDefault(cfgLoggerLevel, "debug")
 	v.SetDefault(cfgLoggerDestination, "stdout")
+	v.SetDefault(cfgLoggerSamplingEnabled, false)
+	v.SetDefault(cfgLoggerSamplingThereafter, 100)
+	v.SetDefault(cfgLoggerSamplingInitial, 100)
+	v.SetDefault(cfgLoggerSamplingInterval, defaultLoggerSamplerInterval)
 
 	// pool:
 	v.SetDefault(cfgPoolErrorThreshold, defaultPoolErrorThreshold)
@@ -386,9 +397,9 @@ func pickLogger(v *viper.Viper) (*zap.Logger, zap.AtomicLevel) {
 
 	switch dest {
 	case destinationStdout:
-		return newStdoutLogger(lvl)
+		return newStdoutLogger(v, lvl)
 	case destinationJournald:
-		return newJournaldLogger(lvl)
+		return newJournaldLogger(v, lvl)
 	default:
 		panic(fmt.Sprintf("wrong destination for logger: %s", dest))
 	}
@@ -405,39 +416,59 @@ func pickLogger(v *viper.Viper) (*zap.Logger, zap.AtomicLevel) {
 // Logger records a stack trace for all messages at or above fatal level.
 //
 // See also zapcore.Level, zap.NewProductionConfig, zap.AddStacktrace.
-func newStdoutLogger(lvl zapcore.Level) (*zap.Logger, zap.AtomicLevel) {
-	c := zap.NewProductionConfig()
-	c.Level = zap.NewAtomicLevelAt(lvl)
-	c.Encoding = "console"
-	c.EncoderConfig.EncodeTime = zapcore.ISO8601TimeEncoder
+func newStdoutLogger(v *viper.Viper, lvl zapcore.Level) (*zap.Logger, zap.AtomicLevel) {
+	stdout := zapcore.AddSync(os.Stderr)
+	level := zap.NewAtomicLevelAt(lvl)
 
-	l, err := c.Build(
-		zap.AddStacktrace(zap.NewAtomicLevelAt(zap.FatalLevel)),
-	)
-	if err != nil {
-		panic(fmt.Sprintf("build zap logger instance: %v", err))
-	}
+	consoleOutCore := zapcore.NewCore(newLogEncoder(), stdout, level)
+	consoleOutCore = samplingEnabling(v, consoleOutCore)
 
-	return l, c.Level
+	l := zap.New(consoleOutCore, zap.AddStacktrace(zap.NewAtomicLevelAt(zap.FatalLevel)))
+	return l, level
 }
 
-func newJournaldLogger(lvl zapcore.Level) (*zap.Logger, zap.AtomicLevel) {
-	c := zap.NewProductionConfig()
-	c.EncoderConfig.EncodeTime = zapcore.ISO8601TimeEncoder
-	c.Level = zap.NewAtomicLevelAt(lvl)
+func newJournaldLogger(v *viper.Viper, lvl zapcore.Level) (*zap.Logger, zap.AtomicLevel) {
+	level := zap.NewAtomicLevelAt(lvl)
 
-	encoder := zapjournald.NewPartialEncoder(zapcore.NewConsoleEncoder(c.EncoderConfig), zapjournald.SyslogFields)
+	encoder := zapjournald.NewPartialEncoder(newLogEncoder(), zapjournald.SyslogFields)
 
-	core := zapjournald.NewCore(c.Level, encoder, &journald.Journal{}, zapjournald.SyslogFields)
+	core := zapjournald.NewCore(level, encoder, &journald.Journal{}, zapjournald.SyslogFields)
 	coreWithContext := core.With([]zapcore.Field{
 		zapjournald.SyslogFacility(zapjournald.LogDaemon),
 		zapjournald.SyslogIdentifier(),
 		zapjournald.SyslogPid(),
 	})
 
+	coreWithContext = samplingEnabling(v, coreWithContext)
+
 	l := zap.New(coreWithContext, zap.AddStacktrace(zap.NewAtomicLevelAt(zap.FatalLevel)))
 
-	return l, c.Level
+	return l, level
+}
+
+func newLogEncoder() zapcore.Encoder {
+	c := zap.NewProductionEncoderConfig()
+	c.EncodeTime = zapcore.ISO8601TimeEncoder
+
+	return zapcore.NewConsoleEncoder(c)
+}
+
+func samplingEnabling(v *viper.Viper, core zapcore.Core) zapcore.Core {
+	// Zap samples by logging the first cgfLoggerSamplingInitial entries with a given level
+	// and message within the specified time interval.
+	// In the above config, only the first cgfLoggerSamplingInitial log entries with the same level and message
+	// are recorded in cfgLoggerSamplingInterval interval. Every other log entry will be dropped within the interval since
+	// cfgLoggerSamplingThereafter is specified here.
+	if v.GetBool(cfgLoggerSamplingEnabled) {
+		core = zapcore.NewSamplerWithOptions(
+			core,
+			v.GetDuration(cfgLoggerSamplingInterval),
+			v.GetInt(cfgLoggerSamplingInitial),
+			v.GetInt(cfgLoggerSamplingThereafter),
+		)
+	}
+
+	return core
 }
 
 func getLogLevel(v *viper.Viper) (zapcore.Level, error) {