zrepl/util/semaphore/semaphore.go
InsanePrawn 180c3d9ae1 Reformat all files with make format.
Signed-off-by: InsanePrawn <insane.prawny@gmail.com>
2020-08-31 23:57:45 +02:00

42 lines
752 B
Go

package semaphore
import (
"context"
wsemaphore "golang.org/x/sync/semaphore"
"github.com/zrepl/zrepl/daemon/logging/trace"
)
type S struct {
ws *wsemaphore.Weighted
}
func New(max int64) *S {
return &S{wsemaphore.NewWeighted(max)}
}
type AcquireGuard struct {
s *S
released bool
}
// The returned AcquireGuard is not goroutine-safe.
func (s *S) Acquire(ctx context.Context) (*AcquireGuard, error) {
defer trace.WithSpanFromStackUpdateCtx(&ctx)()
if err := s.ws.Acquire(ctx, 1); err != nil {
return nil, err
} else if err := ctx.Err(); err != nil {
return nil, err
}
return &AcquireGuard{s, false}, nil
}
func (g *AcquireGuard) Release() {
if g == nil || g.released {
return
}
g.released = true
g.s.ws.Release(1)
}