87 lines
1.9 KiB
Go
87 lines
1.9 KiB
Go
package xenserver
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import (
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"github.com/mitchellh/multistep"
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"time"
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)
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type InterruptibleWait struct {
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Timeout time.Duration
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// optional:
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Predicate func() (result bool, err error)
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PredicateInterval time.Duration
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}
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type TimeoutError struct{}
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func (err TimeoutError) Error() string {
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return "Timed out"
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}
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type InterruptedError struct{}
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func (err InterruptedError) Error() string {
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return "Interrupted"
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}
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type PredicateResult struct {
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complete bool
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err error
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}
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/* Wait waits for up to Timeout duration, checking an optional Predicate every PredicateInterval duration.
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The first run of Predicate is immediately after Wait is called.
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If the command is interrupted by the user, then an InterruptedError is returned.
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If Predicate is not nil, a timeout leads to TimeoutError being returned, and a successful Predicate run leads to nil being returned.
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If Predicate is nil, a timeout is not an error, and nil is returned.
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*/
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func (wait InterruptibleWait) Wait(state multistep.StateBag) error {
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predicateResult := make(chan PredicateResult, 1)
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stopWaiting := make(chan struct{})
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defer close(stopWaiting)
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if wait.Predicate != nil {
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go func() {
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for {
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if complete, err := wait.Predicate(); err != nil || complete {
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predicateResult <- PredicateResult{complete, err}
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return
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}
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select {
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case <-time.After(wait.PredicateInterval):
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continue
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case <-stopWaiting:
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return
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}
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}
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}()
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}
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timeout := time.After(wait.Timeout)
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for {
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// wait for either install to complete/error,
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// an interrupt to come through, or a timeout to occur
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if _, ok := state.GetOk(multistep.StateCancelled); ok {
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return InterruptedError{}
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}
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select {
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case result := <-predicateResult:
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return result.err
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case <-time.After(1 * time.Second):
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continue
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case <-timeout:
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if wait.Predicate != nil {
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return TimeoutError{}
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} else {
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return nil
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}
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}
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}
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}
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