79 lines
2.6 KiB
Go
79 lines
2.6 KiB
Go
// Copyright 2018 The Go Cloud Development Kit Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Package retry provides retry logic.
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package retry // import "gocloud.dev/internal/retry"
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import (
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"context"
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"fmt"
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"time"
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"github.com/googleapis/gax-go/v2"
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)
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// Call calls the supplied function f repeatedly, using the isRetryable function and
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// the provided backoff parameters to control the repetition.
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//
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// When f returns nil, Call immediately returns nil.
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//
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// When f returns an error for which isRetryable returns false, Call immediately
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// returns that error.
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//
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// When f returns an error for which isRetryable returns true, Call sleeps for the
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// provided backoff value and invokes f again.
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//
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// When the provided context is done, Retry returns a ContextError that includes both
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// ctx.Error() and the last error returned by f, or nil if there isn't one.
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func Call(ctx context.Context, bo gax.Backoff, isRetryable func(error) bool, f func() error) error {
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return call(ctx, bo, isRetryable, f, gax.Sleep)
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}
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// Split out for testing.
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func call(ctx context.Context, bo gax.Backoff, isRetryable func(error) bool, f func() error,
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sleep func(context.Context, time.Duration) error) error {
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// Do nothing if context is done on entry.
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if err := ctx.Err(); err != nil {
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return &ContextError{CtxErr: err}
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}
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for {
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err := f()
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if err == nil {
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return nil
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}
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if !isRetryable(err) {
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return err
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}
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if cerr := sleep(ctx, bo.Pause()); cerr != nil {
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return &ContextError{CtxErr: cerr, FuncErr: err}
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}
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}
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}
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// A ContextError contains both a context error (either context.Canceled or
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// context.DeadlineExceeded), and the last error from the function being retried,
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// or nil if the function was never called.
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type ContextError struct {
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CtxErr error // The error obtained from ctx.Err()
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FuncErr error // The error obtained from the function being retried, or nil
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}
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func (e *ContextError) Error() string {
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return fmt.Sprintf("%v; last error: %v", e.CtxErr, e.FuncErr)
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}
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// Is returns true iff one of the two errors held in e is equal to target.
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func (e *ContextError) Is(target error) bool {
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return e.CtxErr == target || e.FuncErr == target
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}
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