1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
|
// Copyright 2010 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/threading/simple_thread.h"
#include <memory>
#include <ostream>
#include "base/check.h"
#include "base/strings/string_number_conversions.h"
#include "base/synchronization/waitable_event.h"
#include "base/threading/platform_thread.h"
#include "base/threading/thread_restrictions.h"
namespace base {
SimpleThread::SimpleThread(const std::string& name)
: SimpleThread(name, Options()) {}
SimpleThread::SimpleThread(const std::string& name, const Options& options)
: name_(name),
options_(options),
event_(WaitableEvent::ResetPolicy::MANUAL,
WaitableEvent::InitialState::NOT_SIGNALED) {}
SimpleThread::~SimpleThread() {
DCHECK(HasBeenStarted()) << "SimpleThread was never started.";
DCHECK(!options_.joinable || HasBeenJoined())
<< "Joinable SimpleThread destroyed without being Join()ed.";
}
void SimpleThread::Start() {
StartAsync();
ScopedAllowBaseSyncPrimitives allow_wait;
event_.Wait(); // Wait for the thread to complete initialization.
}
void SimpleThread::Join() {
DCHECK(options_.joinable) << "A non-joinable thread can't be joined.";
DCHECK(HasStartBeenAttempted()) << "Tried to Join a never-started thread.";
DCHECK(!HasBeenJoined()) << "Tried to Join a thread multiple times.";
BeforeJoin();
PlatformThread::Join(thread_);
thread_ = PlatformThreadHandle();
joined_ = true;
}
void SimpleThread::StartAsync() {
DCHECK(!HasStartBeenAttempted()) << "Tried to Start a thread multiple times.";
start_called_ = true;
BeforeStart();
bool success =
options_.joinable
? PlatformThread::CreateWithType(options_.stack_size, this, &thread_,
options_.thread_type)
: PlatformThread::CreateNonJoinableWithType(options_.stack_size, this,
options_.thread_type);
CHECK(success);
}
PlatformThreadId SimpleThread::tid() {
DCHECK(HasBeenStarted());
return tid_;
}
bool SimpleThread::HasBeenStarted() {
return event_.IsSignaled();
}
void SimpleThread::ThreadMain() {
tid_ = PlatformThread::CurrentId();
PlatformThread::SetName(name_);
// We've initialized our new thread, signal that we're done to Start().
event_.Signal();
BeforeRun();
Run();
}
DelegateSimpleThread::DelegateSimpleThread(Delegate* delegate,
const std::string& name)
: DelegateSimpleThread(delegate, name, Options()) {}
DelegateSimpleThread::DelegateSimpleThread(Delegate* delegate,
const std::string& name,
const Options& options)
: SimpleThread(name, options), delegate_(delegate) {
DCHECK(delegate_);
}
DelegateSimpleThread::~DelegateSimpleThread() = default;
void DelegateSimpleThread::Run() {
DCHECK(delegate_) << "Tried to call Run without a delegate (called twice?)";
// Non-joinable DelegateSimpleThreads are allowed to be deleted during Run().
// Member state must not be accessed after invoking Run().
Delegate* delegate = delegate_;
delegate_ = nullptr;
delegate->Run();
}
DelegateSimpleThreadPool::DelegateSimpleThreadPool(
const std::string& name_prefix,
size_t num_threads)
: name_prefix_(name_prefix),
num_threads_(num_threads),
dry_(WaitableEvent::ResetPolicy::MANUAL,
WaitableEvent::InitialState::NOT_SIGNALED) {}
DelegateSimpleThreadPool::~DelegateSimpleThreadPool() {
DCHECK(threads_.empty());
DCHECK(delegates_.empty());
DCHECK(!dry_.IsSignaled());
}
void DelegateSimpleThreadPool::Start() {
DCHECK(threads_.empty()) << "Start() called with outstanding threads.";
for (size_t i = 0; i < num_threads_; ++i) {
std::string name(name_prefix_);
name.push_back('/');
name.append(NumberToString(i));
auto thread = std::make_unique<DelegateSimpleThread>(this, name);
thread->Start();
threads_.push_back(std::move(thread));
}
}
void DelegateSimpleThreadPool::JoinAll() {
DCHECK(!threads_.empty()) << "JoinAll() called with no outstanding threads.";
// Tell all our threads to quit their worker loop.
AddWork(nullptr, num_threads_);
// Join and destroy all the worker threads.
for (size_t i = 0; i < num_threads_; ++i) {
threads_[i]->Join();
}
threads_.clear();
DCHECK(delegates_.empty());
}
void DelegateSimpleThreadPool::AddWork(Delegate* delegate,
size_t repeat_count) {
AutoLock locked(lock_);
for (size_t i = 0; i < repeat_count; ++i) {
delegates_.push(delegate);
}
// If we were empty, signal that we have work now.
if (!dry_.IsSignaled()) {
dry_.Signal();
}
}
void DelegateSimpleThreadPool::Run() {
Delegate* work = nullptr;
while (true) {
dry_.Wait();
{
AutoLock locked(lock_);
if (!dry_.IsSignaled()) {
continue;
}
DCHECK(!delegates_.empty());
work = delegates_.front();
delegates_.pop();
// Signal to any other threads that we're currently out of work.
if (delegates_.empty()) {
dry_.Reset();
}
}
// A NULL delegate pointer signals us to quit.
if (!work) {
break;
}
work->Run();
}
}
} // namespace base
|
