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46 lines
1.1 KiB
46 lines
1.1 KiB
package blockvol
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import (
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"sync"
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)
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// MakeDistributedSync creates a sync function that runs local WAL fsync and
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// replica barrier in parallel. If no replica is configured or the replica is
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// degraded, it falls back to local-only sync (Phase 3 behavior).
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//
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// walSync: the local fsync function (typically fd.Sync)
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// shipper: the WAL shipper to the replica (may be nil)
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// vol: the BlockVol (used to read nextLSN and trigger degradation)
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func MakeDistributedSync(walSync func() error, shipper *WALShipper, vol *BlockVol) func() error {
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return func() error {
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if shipper == nil || shipper.IsDegraded() {
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return walSync()
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}
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// The highest LSN that needs to be durable is nextLSN-1.
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lsnMax := vol.nextLSN.Load() - 1
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var localErr, remoteErr error
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var wg sync.WaitGroup
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wg.Add(2)
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go func() {
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defer wg.Done()
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localErr = walSync()
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}()
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go func() {
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defer wg.Done()
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remoteErr = shipper.Barrier(lsnMax)
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}()
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wg.Wait()
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if localErr != nil {
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return localErr
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}
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if remoteErr != nil {
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// Local succeeded, replica failed --degrade but don't fail the client.
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vol.degradeReplica(remoteErr)
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return nil
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}
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return nil
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}
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}
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