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)
+}