mirror of
https://github.com/restic/restic.git
synced 2024-08-20 11:23:24 +02:00
237 lines
6.0 KiB
Go
237 lines
6.0 KiB
Go
// Copyright 2017 Google Inc. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package pubsub
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import (
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"errors"
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"fmt"
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"sync/atomic"
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"testing"
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"time"
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"golang.org/x/net/context"
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"golang.org/x/sync/errgroup"
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)
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func TestFlowControllerCancel(t *testing.T) {
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// Test canceling a flow controller's context.
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t.Parallel()
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fc := newFlowController(3, 10)
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if err := fc.acquire(context.Background(), 5); err != nil {
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t.Fatal(err)
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}
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// Experiment: a context that times out should always return an error.
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ctx, cancel := context.WithTimeout(context.Background(), 5*time.Millisecond)
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defer cancel()
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if err := fc.acquire(ctx, 6); err != context.DeadlineExceeded {
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t.Fatalf("got %v, expected DeadlineExceeded", err)
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}
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// Control: a context that is not done should always return nil.
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go func() {
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time.Sleep(5 * time.Millisecond)
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fc.release(5)
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}()
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if err := fc.acquire(context.Background(), 6); err != nil {
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t.Errorf("got %v, expected nil", err)
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}
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}
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func TestFlowControllerLargeRequest(t *testing.T) {
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// Large requests succeed, consuming the entire allotment.
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t.Parallel()
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fc := newFlowController(3, 10)
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err := fc.acquire(context.Background(), 11)
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if err != nil {
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t.Fatal(err)
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}
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}
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func TestFlowControllerNoStarve(t *testing.T) {
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// A large request won't starve, because the flowController is
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// (best-effort) FIFO.
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t.Parallel()
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ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
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defer cancel()
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fc := newFlowController(10, 10)
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first := make(chan int)
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for i := 0; i < 20; i++ {
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go func() {
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for {
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if err := fc.acquire(ctx, 1); err != nil {
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if err != context.Canceled {
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t.Error(err)
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}
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return
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}
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select {
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case first <- 1:
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default:
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}
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fc.release(1)
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}
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}()
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}
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<-first // Wait until the flowController's state is non-zero.
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if err := fc.acquire(ctx, 11); err != nil {
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t.Errorf("got %v, want nil", err)
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}
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}
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func TestFlowControllerSaturation(t *testing.T) {
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t.Parallel()
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const (
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maxCount = 6
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maxSize = 10
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)
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for _, test := range []struct {
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acquireSize int
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wantCount, wantSize int64
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}{
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{
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// Many small acquires cause the flow controller to reach its max count.
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acquireSize: 1,
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wantCount: 6,
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wantSize: 6,
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},
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{
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// Five acquires of size 2 will cause the flow controller to reach its max size,
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// but not its max count.
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acquireSize: 2,
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wantCount: 5,
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wantSize: 10,
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},
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{
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// If the requests are the right size (relatively prime to maxSize),
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// the flow controller will not saturate on size. (In this case, not on count either.)
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acquireSize: 3,
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wantCount: 3,
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wantSize: 9,
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},
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} {
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fc := newFlowController(maxCount, maxSize)
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// Atomically track flow controller state.
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var curCount, curSize int64
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success := errors.New("")
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// Time out if wantSize or wantCount is never reached.
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ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
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defer cancel()
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g, ctx := errgroup.WithContext(ctx)
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for i := 0; i < 10; i++ {
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g.Go(func() error {
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var hitCount, hitSize bool
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// Run at least until we hit the expected values, and at least
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// for enough iterations to exceed them if the flow controller
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// is broken.
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for i := 0; i < 100 || !hitCount || !hitSize; i++ {
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select {
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case <-ctx.Done():
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return ctx.Err()
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default:
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}
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if err := fc.acquire(ctx, test.acquireSize); err != nil {
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return err
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}
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c := atomic.AddInt64(&curCount, 1)
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if c > test.wantCount {
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return fmt.Errorf("count %d exceeds want %d", c, test.wantCount)
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}
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if c == test.wantCount {
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hitCount = true
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}
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s := atomic.AddInt64(&curSize, int64(test.acquireSize))
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if s > test.wantSize {
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return fmt.Errorf("size %d exceeds want %d", s, test.wantSize)
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}
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if s == test.wantSize {
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hitSize = true
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}
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time.Sleep(5 * time.Millisecond) // Let other goroutines make progress.
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if atomic.AddInt64(&curCount, -1) < 0 {
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return errors.New("negative count")
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}
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if atomic.AddInt64(&curSize, -int64(test.acquireSize)) < 0 {
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return errors.New("negative size")
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}
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fc.release(test.acquireSize)
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}
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return success
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})
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}
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if err := g.Wait(); err != success {
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t.Errorf("%+v: %v", test, err)
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continue
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}
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}
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}
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func TestFlowControllerTryAcquire(t *testing.T) {
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fc := newFlowController(3, 10)
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// Successfully tryAcquire 4 bytes.
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if !fc.tryAcquire(4) {
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t.Error("got false, wanted true")
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}
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// Fail to tryAcquire 7 bytes.
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if fc.tryAcquire(7) {
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t.Error("got true, wanted false")
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}
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// Successfully tryAcquire 6 byte.
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if !fc.tryAcquire(6) {
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t.Error("got false, wanted true")
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}
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}
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func TestFlowControllerUnboundedCount(t *testing.T) {
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ctx := context.Background()
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fc := newFlowController(0, 10)
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// Successfully acquire 4 bytes.
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if err := fc.acquire(ctx, 4); err != nil {
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t.Errorf("got %v, wanted no error", err)
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}
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// Successfully tryAcquire 4 bytes.
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if !fc.tryAcquire(4) {
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t.Error("got false, wanted true")
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}
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// Fail to tryAcquire 3 bytes.
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if fc.tryAcquire(3) {
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t.Error("got true, wanted false")
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}
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}
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func TestFlowControllerUnboundedBytes(t *testing.T) {
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ctx := context.Background()
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fc := newFlowController(2, 0)
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// Successfully acquire 4GB.
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if err := fc.acquire(ctx, 4e9); err != nil {
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t.Errorf("got %v, wanted no error", err)
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}
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// Successfully tryAcquire 4GB bytes.
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if !fc.tryAcquire(4e9) {
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t.Error("got false, wanted true")
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}
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// Fail to tryAcquire a third message.
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if fc.tryAcquire(3) {
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t.Error("got true, wanted false")
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}
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}
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