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retry.go
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retry.go
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// The MIT License
//
// Copyright (c) 2020 Temporal Technologies Inc. All rights reserved.
//
// Copyright (c) 2020 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
package backoff
import (
"context"
"sync"
"time"
"go.temporal.io/api/serviceerror"
)
const (
throttleRetryInitialInterval = time.Second
throttleRetryMaxInterval = 10 * time.Second
throttleRetryExpirationInterval = NoInterval
)
var (
throttleRetryPolicy = NewExponentialRetryPolicy(throttleRetryInitialInterval).
WithMaximumInterval(throttleRetryMaxInterval).
WithExpirationInterval(throttleRetryExpirationInterval)
)
type (
// Operation to retry
Operation func() error
// OperationCtx plays the same role as Operation but for context-aware
// retryable functions.
OperationCtx func(context.Context) error
// IsRetryable handler can be used to exclude certain errors during retry
IsRetryable func(error) bool
// ConcurrentRetrier is used for client-side throttling. It determines whether to
// throttle outgoing traffic in case downstream backend server rejects
// requests due to out-of-quota or server busy errors.
ConcurrentRetrier struct {
sync.Mutex
retrier Retrier // Backoff retrier
failureCount int64 // Number of consecutive failures seen
}
)
// Throttle Sleep if there were failures since the last success call.
func (c *ConcurrentRetrier) Throttle() {
c.throttleInternal()
}
func (c *ConcurrentRetrier) throttleInternal() time.Duration {
next := done
// Check if we have failure count.
failureCount := c.failureCount
if failureCount > 0 {
defer c.Unlock()
c.Lock()
if c.failureCount > 0 {
next = c.retrier.NextBackOff()
}
}
if next != done {
time.Sleep(next)
}
return next
}
// Succeeded marks client request succeeded.
func (c *ConcurrentRetrier) Succeeded() {
defer c.Unlock()
c.Lock()
c.failureCount = 0
c.retrier.Reset()
}
// Failed marks client request failed because backend is busy.
func (c *ConcurrentRetrier) Failed() {
defer c.Unlock()
c.Lock()
c.failureCount++
}
// NewConcurrentRetrier returns an instance of concurrent backoff retrier.
func NewConcurrentRetrier(retryPolicy RetryPolicy) *ConcurrentRetrier {
retrier := NewRetrier(retryPolicy, SystemClock)
return &ConcurrentRetrier{retrier: retrier}
}
// ThrottleRetry is a resource aware version of Retry.
// Resource exhausted error will be retried using a different throttle retry policy, instead of the specified one.
func ThrottleRetry(operation Operation, policy RetryPolicy, isRetryable IsRetryable) error {
ctxOp := func(context.Context) error { return operation() }
return ThrottleRetryContext(context.Background(), ctxOp, policy, isRetryable)
}
// ThrottleRetryContext is a context and resource aware version of Retry.
// Context timeout/cancellation errors are never retried, regardless of IsRetryable.
// Resource exhausted error will be retried using a different throttle retry policy, instead of the specified one.
// TODO: allow customizing throttle retry policy and what kind of error are categorized as throttle error.
func ThrottleRetryContext(
ctx context.Context,
operation OperationCtx,
policy RetryPolicy,
isRetryable IsRetryable,
) error {
var err error
var next time.Duration
if isRetryable == nil {
isRetryable = func(error) bool { return true }
}
deadline, hasDeadline := ctx.Deadline()
r := NewRetrier(policy, SystemClock)
t := NewRetrier(throttleRetryPolicy, SystemClock)
for ctx.Err() == nil {
if err = operation(ctx); err == nil {
return nil
}
if next = r.NextBackOff(); next == done {
return err
}
if err == ctx.Err() || !isRetryable(err) {
return err
}
if _, ok := err.(*serviceerror.ResourceExhausted); ok {
next = max(next, t.NextBackOff())
}
if hasDeadline && SystemClock.Now().Add(next).After(deadline) {
break
}
timer := time.NewTimer(next)
select {
case <-timer.C:
case <-ctx.Done():
timer.Stop()
}
}
// always return the last error we got from operation, even if it is not useful
// this retry utility does not have enough information to do any filtering/mapping
if err != nil {
return err
}
return ctx.Err()
}
// IgnoreErrors can be used as IsRetryable handler for Retry function to exclude certain errors from the retry list
func IgnoreErrors(errorsToExclude []error) func(error) bool {
return func(err error) bool {
for _, errorToExclude := range errorsToExclude {
if err == errorToExclude {
return false
}
}
return true
}
}