initial commit

Signed-off-by: Derek McQuay <derekmcquay@gmail.com>

vendor/cloud.google.com/go/bigtable/internal/gax/invoke.go

@@ -0,0 +1,84 @@
+/*
+Copyright 2015 Google Inc. All Rights Reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// This is ia snapshot from github.com/googleapis/gax-go with minor modifications.
+package gax
+
+import (
+	"math/rand"
+	"time"
+
+	"golang.org/x/net/context"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
+	"log"
+	"os"
+)
+
+var logger *log.Logger = log.New(os.Stderr, "", log.LstdFlags)
+
+// A user defined call stub.
+type APICall func(context.Context) error
+
+// scaleDuration returns the product of a and mult.
+func scaleDuration(a time.Duration, mult float64) time.Duration {
+	ns := float64(a) * mult
+	return time.Duration(ns)
+}
+
+// invokeWithRetry calls stub using an exponential backoff retry mechanism
+// based on the values provided in callSettings.
+func invokeWithRetry(ctx context.Context, stub APICall, callSettings CallSettings) error {
+	retrySettings := callSettings.RetrySettings
+	backoffSettings := callSettings.RetrySettings.BackoffSettings
+	delay := backoffSettings.DelayTimeoutSettings.Initial
+	for {
+		// If the deadline is exceeded...
+		if ctx.Err() != nil {
+			return ctx.Err()
+		}
+		err := stub(ctx)
+		code := grpc.Code(err)
+		if code == codes.OK {
+			return nil
+		}
+
+		if !retrySettings.RetryCodes[code] {
+			return err
+		}
+
+		// Sleep a random amount up to the current delay
+		d := time.Duration(rand.Int63n(int64(delay)))
+		delayCtx, _ := context.WithTimeout(ctx, delay)
+		logger.Printf("Retryable error: %v, retrying in %v", err, d)
+		<-delayCtx.Done()
+
+		delay = scaleDuration(delay, backoffSettings.DelayTimeoutSettings.Multiplier)
+		if delay > backoffSettings.DelayTimeoutSettings.Max {
+			delay = backoffSettings.DelayTimeoutSettings.Max
+		}
+	}
+}
+
+// Invoke calls stub with a child of context modified by the specified options.
+func Invoke(ctx context.Context, stub APICall, opts ...CallOption) error {
+	settings := &CallSettings{}
+	callOptions(opts).Resolve(settings)
+	if len(settings.RetrySettings.RetryCodes) > 0 {
+		return invokeWithRetry(ctx, stub, *settings)
+	}
+	return stub(ctx)
+}