queue_test.go

     1  // Copyright 2020 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package par
     6  
     7  import (
     8  	"sync"
     9  	"testing"
    10  )
    11  
    12  func TestQueueIdle(t *testing.T) {
    13  	q := NewQueue(1)
    14  	select {
    15  	case <-q.Idle():
    16  	default:
    17  		t.Errorf("NewQueue(1) is not initially idle.")
    18  	}
    19  
    20  	started := make(chan struct{})
    21  	unblock := make(chan struct{})
    22  	q.Add(func() {
    23  		close(started)
    24  		<-unblock
    25  	})
    26  
    27  	<-started
    28  	idle := q.Idle()
    29  	select {
    30  	case <-idle:
    31  		t.Errorf("NewQueue(1) is marked idle while processing work.")
    32  	default:
    33  	}
    34  
    35  	close(unblock)
    36  	<-idle // Should be closed as soon as the Add callback returns.
    37  }
    38  
    39  func TestQueueBacklog(t *testing.T) {
    40  	const (
    41  		maxActive = 2
    42  		totalWork = 3 * maxActive
    43  	)
    44  
    45  	q := NewQueue(maxActive)
    46  	t.Logf("q = NewQueue(%d)", maxActive)
    47  
    48  	var wg sync.WaitGroup
    49  	wg.Add(totalWork)
    50  	started := make([]chan struct{}, totalWork)
    51  	unblock := make(chan struct{})
    52  	for i := range started {
    53  		started[i] = make(chan struct{})
    54  		i := i
    55  		q.Add(func() {
    56  			close(started[i])
    57  			<-unblock
    58  			wg.Done()
    59  		})
    60  	}
    61  
    62  	for i, c := range started {
    63  		if i < maxActive {
    64  			<-c // Work item i should be started immediately.
    65  		} else {
    66  			select {
    67  			case <-c:
    68  				t.Errorf("Work item %d started before previous items finished.", i)
    69  			default:
    70  			}
    71  		}
    72  	}
    73  
    74  	close(unblock)
    75  	for _, c := range started[maxActive:] {
    76  		<-c
    77  	}
    78  	wg.Wait()
    79  }
    80
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