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000d8bba66
ATM, the replication logic sends all dry-run requests in parallel, which might overwhelm the ZFS pool on the sending side. Since we use rpc/dataconn for dry sends, this also opens one TCP connection per dry-run request. Use a sempahore to limit the degree of concurrency where we know it is a problem ATM. As indicated by the comments, the cleaner solution would involve some kind of 'resource exhaustion' error code. refs #161 refs #164
39 lines
656 B
Go
39 lines
656 B
Go
package semaphore
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import (
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"context"
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wsemaphore "golang.org/x/sync/semaphore"
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)
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type S struct {
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ws *wsemaphore.Weighted
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}
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func New(max int64) *S {
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return &S{wsemaphore.NewWeighted(max)}
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}
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type AcquireGuard struct {
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s *S
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released bool
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}
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// The returned AcquireGuard is not goroutine-safe.
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func (s *S) Acquire(ctx context.Context) (*AcquireGuard, error) {
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if err := s.ws.Acquire(ctx, 1); err != nil {
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return nil, err
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} else if err := ctx.Err(); err != nil {
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return nil, err
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}
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return &AcquireGuard{s, false}, nil
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}
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func (g *AcquireGuard) Release() {
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if g == nil || g.released {
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return
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}
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g.released = true
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g.s.ws.Release(1)
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}
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