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ActiveSide.do() can only run sequentially, i.e. we cannot run replication and pruning in parallel. Why? * go-streamrpc only allows one active request at a time (this is bad design and should be fixed at some point) * replication and pruning are implemented independently, but work on the same resources (snapshots) A: pruning might destroy a snapshot that is planned to be replicated B: replication might replicate snapshots that should be pruned We do not have any resource management / locking for A and B, but we have a use case where users don't want their machine fill up with snapshots if replication does not work. That means we _have_ to run the pruners. A further complication is that we cannot just cancel the replication context after a timeout and move on to the pruner: it could be initial replication and we don't know how long it will take. (And we don't have resumable send & recv yet). With the previous commits, we can implement the watchdog using context cancellation. Note that the 'MadeProgress()' calls can only be placed right before non-error state transition. Otherwise, we could end up in a live-lock.
42 lines
699 B
Go
42 lines
699 B
Go
package watchdog
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import (
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"fmt"
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"sync"
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"time"
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)
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type Progress struct {
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lastUpd time.Time
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}
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func (p *Progress) String() string {
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return fmt.Sprintf("last update at %s", p.lastUpd)
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}
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func (p *Progress) madeProgressSince(p2 *Progress) bool {
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if p.lastUpd.IsZero() && p2.lastUpd.IsZero() {
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return false
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}
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return p.lastUpd.After(p2.lastUpd)
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}
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type KeepAlive struct {
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mtx sync.Mutex
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p Progress
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}
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func (k *KeepAlive) MadeProgress() {
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k.mtx.Lock()
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defer k.mtx.Unlock()
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k.p.lastUpd = time.Now()
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}
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func (k *KeepAlive) ExpectProgress(last *Progress) (madeProgress bool) {
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k.mtx.Lock()
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defer k.mtx.Unlock()
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madeProgress = k.p.madeProgressSince(last)
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*last = k.p
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return madeProgress
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}
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