Merge pull request #133 from ynori7/master

Adding the ability to specify a function to check if micro should retry a failed rpc call

client/client.go

@@ -68,6 +68,8 @@ var (
 	DefaultClient Client = newRpcClient()
 	// DefaultBackoff is the default backoff function for retries
 	DefaultBackoff = exponentialBackoff
+	// DefaultRetry is the default check-for-retry function for retries
+	DefaultRetry = alwaysRetry
 	// DefaultRetries is the default number of times a request is tried
 	DefaultRetries = 1
 	// DefaultRequestTimeout is the default request timeout

client/options.go

@@ -43,6 +43,8 @@ type CallOptions struct {
 
 	// Backoff func
 	Backoff BackoffFunc
+	// Check if retriable func
+	Retry RetryFunc
 	// Transport Dial Timeout
 	DialTimeout time.Duration
 	// Number of Call attempts
@@ -74,6 +76,7 @@ func newOptions(options ...Option) Options {
 		Codecs: make(map[string]codec.NewCodec),
 		CallOptions: CallOptions{
 			Backoff:        DefaultBackoff,
+			Retry:          DefaultRetry,
 			Retries:        DefaultRetries,
 			RequestTimeout: DefaultRequestTimeout,
 			DialTimeout:    transport.DefaultDialTimeout,
@@ -221,6 +224,14 @@ func WithBackoff(fn BackoffFunc) CallOption {
 	}
 }
 
+// WithRetry is a CallOption which overrides that which
+// set in Options.CallOptions
+func WithRetry(fn RetryFunc) CallOption {
+	return func(o *CallOptions) {
+		o.Retry = fn
+	}
+}
+
 // WithRetries is a CallOption which overrides that which
 // set in Options.CallOptions
 func WithRetries(i int) CallOption {

client/retry.go

@@ -0,0 +1,11 @@
+package client
+
+import "golang.org/x/net/context"
+
+// note that returning either true or a non-nil error will result in the call not being retried
+type RetryFunc func(ctx context.Context, req Request, retryCount int, err error) (bool, error)
+
+// always retry on error
+func alwaysRetry(ctx context.Context, req Request, retryCount int, err error) (bool, error) {
+	return true, nil
+}

client/rpc_client.go

@@ -299,6 +299,16 @@ func (r *rpcClient) Call(ctx context.Context, request Request, response interfac
 			if err == nil {
 				return nil
 			}
+
+			retry, rerr := callOpts.Retry(ctx, request, i, err)
+			if rerr != nil {
+				return rerr
+			}
+
+			if !retry {
+				return err
+			}
+
 			gerr = err
 		}
 	}
@@ -400,6 +410,16 @@ func (r *rpcClient) Stream(ctx context.Context, request Request, opts ...CallOpt
 			if rsp.err == nil {
 				return rsp.stream, nil
 			}
+
+			retry, rerr := callOpts.Retry(ctx, request, i, rsp.err)
+			if rerr != nil {
+				return nil, rerr
+			}
+
+			if !retry {
+				return nil, rsp.err
+			}
+
 			grr = rsp.err
 		}
 	}