Add build flag for retrier implements

retrier/retrier.go

@@ -1,8 +1,9 @@
+// +build !go1.7
+
 // Package retrier implements the "retriable" resiliency pattern for Go.
 package retrier
 
 import (
-	"context"
 	"math/rand"
 	"sync"
 	"time"
@@ -34,23 +35,15 @@ func New(backoff []time.Duration, class Classifier) *Retrier {
 	}
 }
 
-// Run executes the given work function by executing RunCtx without context.Context.
-func (r *Retrier) Run(work func() error) error {
-	return r.RunCtx(context.Background(), func(ctx context.Context) error {
-		// never use ctx
-		return work()
-	})
-}
-
-// RunCtx executes the given work function, then classifies its return value based on the classifier used
+// Run executes the given work function, then classifies its return value based on the classifier used
 // to construct the Retrier. If the result is Succeed or Fail, the return value of the work function is
 // returned to the caller. If the result is Retry, then Run sleeps according to the its backoff policy
 // before retrying. If the total number of retries is exceeded then the return value of the work function
 // is returned to the caller regardless.
-func (r *Retrier) RunCtx(ctx context.Context, work func(ctx context.Context) error) error {
+func (r *Retrier) Run(work func() error) error {
 	retries := 0
 	for {
-		ret := work(ctx)
+		ret := work()
 
 		switch r.class.Classify(ret) {
 		case Succeed, Fail:
@@ -59,26 +52,12 @@ func (r *Retrier) RunCtx(ctx context.Context, work func(ctx context.Context) err
 			if retries >= len(r.backoff) {
 				return ret
 			}
-
-			timeout := time.After(r.calcSleep(retries))
-			if err := r.sleep(ctx, timeout); err != nil {
-				return err
-			}
-
+			time.Sleep(r.calcSleep(retries))
 			retries++
 		}
 	}
 }
 
-func (r *Retrier) sleep(ctx context.Context, t <-chan time.Time) error {
-	select {
-	case <-t:
-		return nil
-	case <-ctx.Done():
-		return ctx.Err()
-	}
-}
-
 func (r *Retrier) calcSleep(i int) time.Duration {
 	// lock unsafe rand prng
 	r.randMu.Lock()

retrier/retrier_go17.go

@@ -0,0 +1,99 @@
+// +build go1.7
+
+// Package retrier implements the "retriable" resiliency pattern for Go.
+package retrier
+
+import (
+	"context"
+	"math/rand"
+	"sync"
+	"time"
+)
+
+// Retrier implements the "retriable" resiliency pattern, abstracting out the process of retrying a failed action
+// a certain number of times with an optional back-off between each retry.
+type Retrier struct {
+	backoff []time.Duration
+	class   Classifier
+	jitter  float64
+	rand    *rand.Rand
+	randMu  sync.Mutex
+}
+
+// New constructs a Retrier with the given backoff pattern and classifier. The length of the backoff pattern
+// indicates how many times an action will be retried, and the value at each index indicates the amount of time
+// waited before each subsequent retry. The classifier is used to determine which errors should be retried and
+// which should cause the retrier to fail fast. The DefaultClassifier is used if nil is passed.
+func New(backoff []time.Duration, class Classifier) *Retrier {
+	if class == nil {
+		class = DefaultClassifier{}
+	}
+
+	return &Retrier{
+		backoff: backoff,
+		class:   class,
+		rand:    rand.New(rand.NewSource(time.Now().UnixNano())),
+	}
+}
+
+// Run executes the given work function by executing RunCtx without context.Context.
+func (r *Retrier) Run(work func() error) error {
+	return r.RunCtx(context.Background(), func(ctx context.Context) error {
+		// never use ctx
+		return work()
+	})
+}
+
+// RunCtx executes the given work function, then classifies its return value based on the classifier used
+// to construct the Retrier. If the result is Succeed or Fail, the return value of the work function is
+// returned to the caller. If the result is Retry, then Run sleeps according to the its backoff policy
+// before retrying. If the total number of retries is exceeded then the return value of the work function
+// is returned to the caller regardless.
+func (r *Retrier) RunCtx(ctx context.Context, work func(ctx context.Context) error) error {
+	retries := 0
+	for {
+		ret := work(ctx)
+
+		switch r.class.Classify(ret) {
+		case Succeed, Fail:
+			return ret
+		case Retry:
+			if retries >= len(r.backoff) {
+				return ret
+			}
+
+			timeout := time.After(r.calcSleep(retries))
+			if err := r.sleep(ctx, timeout); err != nil {
+				return err
+			}
+
+			retries++
+		}
+	}
+}
+
+func (r *Retrier) sleep(ctx context.Context, t <-chan time.Time) error {
+	select {
+	case <-t:
+		return nil
+	case <-ctx.Done():
+		return ctx.Err()
+	}
+}
+
+func (r *Retrier) calcSleep(i int) time.Duration {
+	// lock unsafe rand prng
+	r.randMu.Lock()
+	defer r.randMu.Unlock()
+	// take a random float in the range (-r.jitter, +r.jitter) and multiply it by the base amount
+	return r.backoff[i] + time.Duration(((r.rand.Float64()*2)-1)*r.jitter*float64(r.backoff[i]))
+}
+
+// SetJitter sets the amount of jitter on each back-off to a factor between 0.0 and 1.0 (values outside this range
+// are silently ignored). When a retry occurs, the back-off is adjusted by a random amount up to this value.
+func (r *Retrier) SetJitter(jit float64) {
+	if jit < 0 || jit > 1 {
+		return
+	}
+	r.jitter = jit
+}