86 lines
2.5 KiB
Go
86 lines
2.5 KiB
Go
// Copyright 2016-2017, Pulumi Corporation. All rights reserved.
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package retry
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import (
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"context"
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"time"
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)
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type Acceptor struct {
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Accept Acceptance // a function that determines when to proceed.
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Progress Progress // an optional progress function.
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Delay *time.Duration // an optional delay duration.
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Backoff *float64 // an optional backoff multiplier.
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}
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type Progress func(int) bool
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const (
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DefaultDelay time.Duration = 250 * time.Millisecond // by default, delay by 250ms
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DefaultBackoff float64 = 2.0 // by default, backoff by 2.0
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)
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type Acceptance func() (bool, error)
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// Until waits until the acceptor accepts the current condition, or the context expires, whichever comes first. A
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// return boolean of true means the acceptor eventually accepted; a non-nil error means the acceptor returned an error.
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// If an acceptor accepts a condition after the context has expired, we ignore the expiration and return the condition.
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func Until(ctx context.Context, acceptor Acceptor) (bool, error) {
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expired := false
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// Prepare our delay and backoff variables.
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var delay time.Duration
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if acceptor.Delay == nil {
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delay = DefaultDelay
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} else {
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delay = *acceptor.Delay
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}
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var backoff float64
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if acceptor.Backoff == nil {
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backoff = DefaultBackoff
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} else {
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backoff = *acceptor.Backoff
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}
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// If the context expires before the waiter has accepted, return.
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go func() {
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<-ctx.Done()
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expired = true
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}()
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// Loop until the condition is accepted, or the context expires, whichever comes first.
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tries := 1
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for !expired {
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if b, err := acceptor.Accept(); b || err != nil {
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return b, err
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}
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if acceptor.Progress != nil && !acceptor.Progress(tries) {
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break // progress function asked to quit.
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}
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time.Sleep(delay)
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delay = time.Duration(float64(delay) * backoff)
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tries++
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}
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return false, nil
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}
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// UntilDeadline creates a child context with the given deadline, and then invokes the above Until function.
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func UntilDeadline(ctx context.Context, acceptor Acceptor, deadline time.Time) (bool, error) {
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var cancel context.CancelFunc
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ctx, cancel = context.WithDeadline(ctx, deadline)
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b, err := Until(ctx, acceptor)
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cancel()
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return b, err
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}
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// UntilTimeout creates a child context with the given timeout, and then invokes the above Until function.
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func UntilTimeout(ctx context.Context, acceptor Acceptor, timeout time.Duration) (bool, error) {
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var cancel context.CancelFunc
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ctx, cancel = context.WithTimeout(ctx, timeout)
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b, err := Until(ctx, acceptor)
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cancel()
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return b, err
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}
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