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
188
189
190
|
// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/threading/worker_pool_posix.h"
#include <stddef.h>
#include <utility>
#include "base/bind.h"
#include "base/callback.h"
#include "base/lazy_instance.h"
#include "base/logging.h"
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/strings/stringprintf.h"
#include "base/threading/platform_thread.h"
#include "base/threading/thread_local.h"
#include "base/threading/worker_pool.h"
#include "base/trace_event/trace_event.h"
#include "base/tracked_objects.h"
using tracked_objects::TrackedTime;
namespace base {
namespace {
base::LazyInstance<ThreadLocalBoolean>::Leaky
g_worker_pool_running_on_this_thread = LAZY_INSTANCE_INITIALIZER;
const int kIdleSecondsBeforeExit = 10 * 60;
#if defined(OS_MACOSX)
// On Mac OS X a background thread's default stack size is 512Kb. We need at
// least 1MB for compilation tasks in V8, so increase this default.
const int kStackSize = 1 * 1024 * 1024;
#else
const int kStackSize = 0;
#endif
class WorkerPoolImpl {
public:
WorkerPoolImpl();
// WorkerPoolImpl is only instantiated as a leaky LazyInstance, so the
// destructor is never called.
~WorkerPoolImpl() = delete;
void PostTask(const tracked_objects::Location& from_here,
base::OnceClosure task,
bool task_is_slow);
private:
scoped_refptr<base::PosixDynamicThreadPool> pool_;
};
WorkerPoolImpl::WorkerPoolImpl()
: pool_(new base::PosixDynamicThreadPool("WorkerPool",
kIdleSecondsBeforeExit)) {}
void WorkerPoolImpl::PostTask(const tracked_objects::Location& from_here,
base::OnceClosure task,
bool task_is_slow) {
pool_->PostTask(from_here, std::move(task));
}
base::LazyInstance<WorkerPoolImpl>::Leaky g_lazy_worker_pool =
LAZY_INSTANCE_INITIALIZER;
class WorkerThread : public PlatformThread::Delegate {
public:
WorkerThread(const std::string& name_prefix,
base::PosixDynamicThreadPool* pool)
: name_prefix_(name_prefix), pool_(pool) {}
void ThreadMain() override;
private:
const std::string name_prefix_;
scoped_refptr<base::PosixDynamicThreadPool> pool_;
DISALLOW_COPY_AND_ASSIGN(WorkerThread);
};
void WorkerThread::ThreadMain() {
g_worker_pool_running_on_this_thread.Get().Set(true);
const std::string name = base::StringPrintf("%s/%d", name_prefix_.c_str(),
PlatformThread::CurrentId());
// Note |name.c_str()| must remain valid for for the whole life of the thread.
PlatformThread::SetName(name);
for (;;) {
PendingTask pending_task = pool_->WaitForTask();
if (pending_task.task.is_null())
break;
TRACE_TASK_EXECUTION("WorkerThread::ThreadMain::Run", pending_task);
tracked_objects::TaskStopwatch stopwatch;
stopwatch.Start();
std::move(pending_task.task).Run();
stopwatch.Stop();
tracked_objects::ThreadData::TallyRunOnWorkerThreadIfTracking(
pending_task.birth_tally, pending_task.time_posted, stopwatch);
}
// The WorkerThread is non-joinable, so it deletes itself.
delete this;
}
} // namespace
// static
bool WorkerPool::PostTask(const tracked_objects::Location& from_here,
base::OnceClosure task,
bool task_is_slow) {
g_lazy_worker_pool.Pointer()->PostTask(from_here, std::move(task),
task_is_slow);
return true;
}
// static
bool WorkerPool::RunsTasksOnCurrentThread() {
return g_worker_pool_running_on_this_thread.Get().Get();
}
PosixDynamicThreadPool::PosixDynamicThreadPool(const std::string& name_prefix,
int idle_seconds_before_exit)
: name_prefix_(name_prefix),
idle_seconds_before_exit_(idle_seconds_before_exit),
pending_tasks_available_cv_(&lock_),
num_idle_threads_(0) {}
PosixDynamicThreadPool::~PosixDynamicThreadPool() {
while (!pending_tasks_.empty())
pending_tasks_.pop();
}
void PosixDynamicThreadPool::PostTask(
const tracked_objects::Location& from_here,
base::OnceClosure task) {
PendingTask pending_task(from_here, std::move(task));
AddTask(&pending_task);
}
void PosixDynamicThreadPool::AddTask(PendingTask* pending_task) {
DCHECK(pending_task);
DCHECK(pending_task->task);
AutoLock locked(lock_);
pending_tasks_.push(std::move(*pending_task));
// We have enough worker threads.
if (static_cast<size_t>(num_idle_threads_) >= pending_tasks_.size()) {
pending_tasks_available_cv_.Signal();
} else {
// The new PlatformThread will take ownership of the WorkerThread object,
// which will delete itself on exit.
WorkerThread* worker = new WorkerThread(name_prefix_, this);
PlatformThread::CreateNonJoinable(kStackSize, worker);
}
}
PendingTask PosixDynamicThreadPool::WaitForTask() {
AutoLock locked(lock_);
if (pending_tasks_.empty()) { // No work available, wait for work.
num_idle_threads_++;
if (num_idle_threads_cv_.get())
num_idle_threads_cv_->Signal();
pending_tasks_available_cv_.TimedWait(
TimeDelta::FromSeconds(idle_seconds_before_exit_));
num_idle_threads_--;
if (num_idle_threads_cv_.get())
num_idle_threads_cv_->Signal();
if (pending_tasks_.empty()) {
// We waited for work, but there's still no work. Return NULL to signal
// the thread to terminate.
return PendingTask(FROM_HERE, base::Closure());
}
}
PendingTask pending_task = std::move(pending_tasks_.front());
pending_tasks_.pop();
return pending_task;
}
} // namespace base
|
