diff options
Diffstat (limited to '')
-rw-r--r-- | dependencies/pkg/mod/golang.org/x/sync@v0.0.0-20210220032951-036812b2e83c/semaphore/semaphore_test.go | 202 |
1 files changed, 202 insertions, 0 deletions
diff --git a/dependencies/pkg/mod/golang.org/x/sync@v0.0.0-20210220032951-036812b2e83c/semaphore/semaphore_test.go b/dependencies/pkg/mod/golang.org/x/sync@v0.0.0-20210220032951-036812b2e83c/semaphore/semaphore_test.go new file mode 100644 index 0000000..6e8eca2 --- /dev/null +++ b/dependencies/pkg/mod/golang.org/x/sync@v0.0.0-20210220032951-036812b2e83c/semaphore/semaphore_test.go @@ -0,0 +1,202 @@ +// Copyright 2017 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package semaphore_test + +import ( + "context" + "math/rand" + "runtime" + "sync" + "testing" + "time" + + "golang.org/x/sync/errgroup" + "golang.org/x/sync/semaphore" +) + +const maxSleep = 1 * time.Millisecond + +func HammerWeighted(sem *semaphore.Weighted, n int64, loops int) { + for i := 0; i < loops; i++ { + sem.Acquire(context.Background(), n) + time.Sleep(time.Duration(rand.Int63n(int64(maxSleep/time.Nanosecond))) * time.Nanosecond) + sem.Release(n) + } +} + +func TestWeighted(t *testing.T) { + t.Parallel() + + n := runtime.GOMAXPROCS(0) + loops := 10000 / n + sem := semaphore.NewWeighted(int64(n)) + var wg sync.WaitGroup + wg.Add(n) + for i := 0; i < n; i++ { + i := i + go func() { + defer wg.Done() + HammerWeighted(sem, int64(i), loops) + }() + } + wg.Wait() +} + +func TestWeightedPanic(t *testing.T) { + t.Parallel() + + defer func() { + if recover() == nil { + t.Fatal("release of an unacquired weighted semaphore did not panic") + } + }() + w := semaphore.NewWeighted(1) + w.Release(1) +} + +func TestWeightedTryAcquire(t *testing.T) { + t.Parallel() + + ctx := context.Background() + sem := semaphore.NewWeighted(2) + tries := []bool{} + sem.Acquire(ctx, 1) + tries = append(tries, sem.TryAcquire(1)) + tries = append(tries, sem.TryAcquire(1)) + + sem.Release(2) + + tries = append(tries, sem.TryAcquire(1)) + sem.Acquire(ctx, 1) + tries = append(tries, sem.TryAcquire(1)) + + want := []bool{true, false, true, false} + for i := range tries { + if tries[i] != want[i] { + t.Errorf("tries[%d]: got %t, want %t", i, tries[i], want[i]) + } + } +} + +func TestWeightedAcquire(t *testing.T) { + t.Parallel() + + ctx := context.Background() + sem := semaphore.NewWeighted(2) + tryAcquire := func(n int64) bool { + ctx, cancel := context.WithTimeout(ctx, 10*time.Millisecond) + defer cancel() + return sem.Acquire(ctx, n) == nil + } + + tries := []bool{} + sem.Acquire(ctx, 1) + tries = append(tries, tryAcquire(1)) + tries = append(tries, tryAcquire(1)) + + sem.Release(2) + + tries = append(tries, tryAcquire(1)) + sem.Acquire(ctx, 1) + tries = append(tries, tryAcquire(1)) + + want := []bool{true, false, true, false} + for i := range tries { + if tries[i] != want[i] { + t.Errorf("tries[%d]: got %t, want %t", i, tries[i], want[i]) + } + } +} + +func TestWeightedDoesntBlockIfTooBig(t *testing.T) { + t.Parallel() + + const n = 2 + sem := semaphore.NewWeighted(n) + { + ctx, cancel := context.WithCancel(context.Background()) + defer cancel() + go sem.Acquire(ctx, n+1) + } + + g, ctx := errgroup.WithContext(context.Background()) + for i := n * 3; i > 0; i-- { + g.Go(func() error { + err := sem.Acquire(ctx, 1) + if err == nil { + time.Sleep(1 * time.Millisecond) + sem.Release(1) + } + return err + }) + } + if err := g.Wait(); err != nil { + t.Errorf("semaphore.NewWeighted(%v) failed to AcquireCtx(_, 1) with AcquireCtx(_, %v) pending", n, n+1) + } +} + +// TestLargeAcquireDoesntStarve times out if a large call to Acquire starves. +// Merely returning from the test function indicates success. +func TestLargeAcquireDoesntStarve(t *testing.T) { + t.Parallel() + + ctx := context.Background() + n := int64(runtime.GOMAXPROCS(0)) + sem := semaphore.NewWeighted(n) + running := true + + var wg sync.WaitGroup + wg.Add(int(n)) + for i := n; i > 0; i-- { + sem.Acquire(ctx, 1) + go func() { + defer func() { + sem.Release(1) + wg.Done() + }() + for running { + time.Sleep(1 * time.Millisecond) + sem.Release(1) + sem.Acquire(ctx, 1) + } + }() + } + + sem.Acquire(ctx, n) + running = false + sem.Release(n) + wg.Wait() +} + +// translated from https://github.com/zhiqiangxu/util/blob/master/mutex/crwmutex_test.go#L43 +func TestAllocCancelDoesntStarve(t *testing.T) { + sem := semaphore.NewWeighted(10) + + // Block off a portion of the semaphore so that Acquire(_, 10) can eventually succeed. + sem.Acquire(context.Background(), 1) + + // In the background, Acquire(_, 10). + ctx, cancel := context.WithCancel(context.Background()) + defer cancel() + go func() { + sem.Acquire(ctx, 10) + }() + + // Wait until the Acquire(_, 10) call blocks. + for sem.TryAcquire(1) { + sem.Release(1) + runtime.Gosched() + } + + // Now try to grab a read lock, and simultaneously unblock the Acquire(_, 10) call. + // Both Acquire calls should unblock and return, in either order. + go cancel() + + err := sem.Acquire(context.Background(), 1) + if err != nil { + t.Fatalf("Acquire(_, 1) failed unexpectedly: %v", err) + } + sem.Release(1) +} |