diff --git a/go.mod b/go.mod index 793d9311..bdf7daef 100644 --- a/go.mod +++ b/go.mod @@ -7,7 +7,7 @@ require ( github.com/pkg/errors v0.9.1 github.com/stretchr/testify v1.8.4 go.uber.org/zap v1.26.0 - golang.org/x/sync v0.6.0 + golang.org/x/sync v0.7.0 google.golang.org/protobuf v1.33.0 ) diff --git a/go.sum b/go.sum index 2b90fda6..e1f38690 100644 --- a/go.sum +++ b/go.sum @@ -24,8 +24,8 @@ go.uber.org/multierr v1.11.0 h1:blXXJkSxSSfBVBlC76pxqeO+LN3aDfLQo+309xJstO0= go.uber.org/multierr v1.11.0/go.mod h1:20+QtiLqy0Nd6FdQB9TLXag12DsQkrbs3htMFfDN80Y= go.uber.org/zap v1.26.0 h1:sI7k6L95XOKS281NhVKOFCUNIvv9e0w4BF8N3u+tCRo= go.uber.org/zap v1.26.0/go.mod h1:dtElttAiwGvoJ/vj4IwHBS/gXsEu/pZ50mUIRWuG0so= -golang.org/x/sync v0.6.0 h1:5BMeUDZ7vkXGfEr1x9B4bRcTH4lpkTkpdh0T/J+qjbQ= -golang.org/x/sync v0.6.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk= +golang.org/x/sync v0.7.0 h1:YsImfSBoP9QPYL0xyKJPq0gcaJdG3rInoqxTWbfQu9M= +golang.org/x/sync v0.7.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk= golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4= golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0= google.golang.org/protobuf v1.26.0-rc.1/go.mod h1:jlhhOSvTdKEhbULTjvd4ARK9grFBp09yW+WbY/TyQbw= diff --git a/vendor/golang.org/x/sync/semaphore/semaphore.go b/vendor/golang.org/x/sync/semaphore/semaphore.go index 30f632c5..b618162a 100644 --- a/vendor/golang.org/x/sync/semaphore/semaphore.go +++ b/vendor/golang.org/x/sync/semaphore/semaphore.go @@ -35,11 +35,25 @@ type Weighted struct { // Acquire acquires the semaphore with a weight of n, blocking until resources // are available or ctx is done. On success, returns nil. On failure, returns // ctx.Err() and leaves the semaphore unchanged. -// -// If ctx is already done, Acquire may still succeed without blocking. func (s *Weighted) Acquire(ctx context.Context, n int64) error { + done := ctx.Done() + s.mu.Lock() + select { + case <-done: + // ctx becoming done has "happened before" acquiring the semaphore, + // whether it became done before the call began or while we were + // waiting for the mutex. We prefer to fail even if we could acquire + // the mutex without blocking. + s.mu.Unlock() + return ctx.Err() + default: + } if s.size-s.cur >= n && s.waiters.Len() == 0 { + // Since we hold s.mu and haven't synchronized since checking done, if + // ctx becomes done before we return here, it becoming done must have + // "happened concurrently" with this call - it cannot "happen before" + // we return in this branch. So, we're ok to always acquire here. s.cur += n s.mu.Unlock() return nil @@ -48,7 +62,7 @@ func (s *Weighted) Acquire(ctx context.Context, n int64) error { if n > s.size { // Don't make other Acquire calls block on one that's doomed to fail. s.mu.Unlock() - <-ctx.Done() + <-done return ctx.Err() } @@ -58,14 +72,14 @@ func (s *Weighted) Acquire(ctx context.Context, n int64) error { s.mu.Unlock() select { - case <-ctx.Done(): - err := ctx.Err() + case <-done: s.mu.Lock() select { case <-ready: - // Acquired the semaphore after we were canceled. Rather than trying to - // fix up the queue, just pretend we didn't notice the cancelation. - err = nil + // Acquired the semaphore after we were canceled. + // Pretend we didn't and put the tokens back. + s.cur -= n + s.notifyWaiters() default: isFront := s.waiters.Front() == elem s.waiters.Remove(elem) @@ -75,9 +89,19 @@ func (s *Weighted) Acquire(ctx context.Context, n int64) error { } } s.mu.Unlock() - return err + return ctx.Err() case <-ready: + // Acquired the semaphore. Check that ctx isn't already done. + // We check the done channel instead of calling ctx.Err because we + // already have the channel, and ctx.Err is O(n) with the nesting + // depth of ctx. + select { + case <-done: + s.Release(n) + return ctx.Err() + default: + } return nil } } diff --git a/vendor/modules.txt b/vendor/modules.txt index 5ed2093c..57dddb3e 100644 --- a/vendor/modules.txt +++ b/vendor/modules.txt @@ -31,7 +31,7 @@ go.uber.org/zap/internal/exit go.uber.org/zap/internal/pool go.uber.org/zap/internal/stacktrace go.uber.org/zap/zapcore -# golang.org/x/sync v0.6.0 +# golang.org/x/sync v0.7.0 ## explicit; go 1.18 golang.org/x/sync/semaphore # google.golang.org/protobuf v1.33.0