Introducing a circuit breaker for error control

Author: daichirata

glide.lock

@@ -1,6 +1,7 @@
 package: github.com/daichirata/fluent-logger-go
 import:
 - package: gopkg.in/vmihailenco/msgpack.v2
+- package: github.com/rubyist/circuitbreaker
 testImport:
 - package: github.com/stretchr/testify
   subpackages:

glide.yaml

@@ -6,17 +6,21 @@ import (
 	"strings"
 	"sync"
 	"time"
+
+	"github.com/rubyist/circuitbreaker"
 )
 
 var (
-	defaultAddress       = "127.0.0.1:24224"
-	defaultFlushInterval = 5 * time.Second
+	defaultAddress          = "127.0.0.1:24224"
+	defaultFlushInterval    = 5 * time.Second
+	defaultFailureThreshold = int64(1)
 )
 
 type Config struct {
 	Address           string
 	ConnectionTimeout time.Duration
 	FlushInterval     time.Duration
+	FailureThreshold  int64
 }
 
 func withDefaultConfig(c Config) Config {
@@ -26,23 +30,29 @@ func withDefaultConfig(c Config) Config {
 	if c.FlushInterval == 0 {
 		c.FlushInterval = defaultFlushInterval
 	}
+	if c.FailureThreshold == 0 {
+		c.FailureThreshold = defaultFailureThreshold
+	}
 	return c
 }
 
 type Logger struct {
-	conf Config
-	conn io.WriteCloser
-	mu   sync.Mutex
-	buf  buffer
-	wg   sync.WaitGroup
-	done chan struct{}
+	conf    Config
+	conn    io.WriteCloser
+	buf     buffer
+	breaker *circuit.Breaker
+	mu      sync.Mutex
+	wg      sync.WaitGroup
+	done    chan struct{}
 }
 
 func NewLogger(c Config) (*Logger, error) {
+	conf := withDefaultConfig(c)
 	logger := &Logger{
-		conf: withDefaultConfig(c),
-		buf:  newBuffer(),
-		done: make(chan struct{}),
+		conf:    conf,
+		buf:     newBuffer(),
+		breaker: circuit.NewConsecutiveBreaker(conf.FailureThreshold),
+		done:    make(chan struct{}),
 	}
 	if err := logger.connect(); err != nil {
 		return nil, err
@@ -70,6 +80,10 @@ func (logger *Logger) PostWithTime(tag string, t time.Time, obj interface{}) err
 	return nil
 }
 
+func (logger *Logger) Subscribe() <-chan circuit.BreakerEvent {
+	return logger.breaker.Subscribe()
+}
+
 func (logger *Logger) Close() error {
 	logger.stop()
 	return logger.disconnect()
@@ -111,38 +125,40 @@ func (logger *Logger) disconnect() error {
 	return err
 }
 
-const maxWriteAttempts = 2
-
-func (logger *Logger) write(messages []*Message) error {
-	if len(messages) == 0 {
-		return nil
-	}
-	var data []byte
-	for _, m := range messages {
-		data = append(data, m.buf.Bytes()...)
-	}
-	var err error
-	for i := 0; i < maxWriteAttempts; i++ {
-		err = logger.connect()
+func (logger *Logger) write(data []byte) error {
+	err := logger.connect()
+	if err == nil {
+		_, err = logger.conn.Write(data)
 		if err == nil {
-			_, err := logger.conn.Write(data)
-			if err == nil {
-				break
-			}
+			return nil
 		}
-		logger.disconnect()
 	}
+	logger.disconnect()
 	return err
 }
 
+func (logger *Logger) writeWithBreaker(data []byte) error {
+	return logger.breaker.Call(func() error {
+		return logger.write(data)
+	}, 0)
+}
+
 func (logger *Logger) send() error {
 	messages := logger.buf.Remove()
+	if len(messages) == 0 {
+		return nil
+	}
 
-	err := logger.write(messages)
+	var data []byte
+	for _, m := range messages {
+		data = append(data, m.buf.Bytes()...)
+	}
+	err := logger.write(data)
 	if err != nil {
 		logger.buf.Back(messages)
 		return err
 	}
+
 	for _, m := range messages {
 		putMessage(m)
 	}