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
191
192
193
194
195
196
|
// Copyright 2016 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "components/offline_pages/task/task_queue.h"
#include <utility>
#include "base/functional/bind.h"
#include "base/logging.h"
#include "base/memory/scoped_refptr.h"
#include "base/memory/weak_ptr.h"
#include "base/notreached.h"
#include "base/task/single_thread_task_runner.h"
namespace offline_pages {
struct TaskQueue::Entry {
Entry() = default;
explicit Entry(std::unique_ptr<Task> task) : task(std::move(task)) {}
Entry(const base::Location& location, std::unique_ptr<Task> task)
: task(std::move(task)), from_here(location) {}
Entry(std::unique_ptr<Task> task, base::OnceClosure resume_callback)
: task(std::move(task)), resume_callback(std::move(resume_callback)) {}
std::unique_ptr<Task> task;
base::OnceClosure resume_callback;
base::Location from_here;
};
TaskQueue::TaskQueue(Delegate* delegate)
: task_runner_(base::SingleThreadTaskRunner::GetCurrentDefault()),
delegate_(delegate) {
DCHECK(delegate_);
}
TaskQueue::~TaskQueue() = default;
void TaskQueue::AddTask(std::unique_ptr<Task> task) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
task->task_queue_ = this;
tasks_.emplace_back(std::move(task));
StartTaskIfAvailable();
}
void TaskQueue::AddTask(const base::Location& from_here,
std::unique_ptr<Task> task) {
DVLOG(2) << "Adding task " << from_here.ToString();
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
task->task_queue_ = this;
tasks_.emplace_back(from_here, std::move(task));
StartTaskIfAvailable();
}
bool TaskQueue::HasPendingTasks() const {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
return !tasks_.empty() || HasRunningTask();
}
bool TaskQueue::HasRunningTask() const {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
return current_task_ != nullptr;
}
void TaskQueue::StartTaskIfAvailable() {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
DVLOG(2) << "running? " << HasRunningTask() << ", pending? "
<< HasPendingTasks() << " " << __func__;
if (HasRunningTask())
return;
if (!HasPendingTasks()) {
task_runner_->PostTask(FROM_HERE,
base::BindOnce(&TaskQueue::InformTaskQueueIsIdle,
weak_ptr_factory_.GetWeakPtr()));
return;
}
current_task_ = std::move(tasks_.front().task);
current_task_location_ = tasks_.front().from_here;
base::OnceClosure resume_callback = std::move(tasks_.front().resume_callback);
tasks_.pop_front();
if (resume_callback) {
task_runner_->PostTask(FROM_HERE,
base::BindOnce(&TaskQueue::ResumeCurrentTask,
weak_ptr_factory_.GetWeakPtr(),
std::move(resume_callback)));
} else {
task_runner_->PostTask(FROM_HERE,
base::BindOnce(&TaskQueue::RunCurrentTask,
weak_ptr_factory_.GetWeakPtr()));
}
}
void TaskQueue::RunCurrentTask() {
DVLOG(2) << "Running task " << current_task_location_.ToString();
current_task_->Execute(base::BindOnce(&TaskCompletedCallback, task_runner_,
weak_ptr_factory_.GetWeakPtr(),
current_task_.get()));
}
void TaskQueue::ResumeCurrentTask(base::OnceClosure on_resume) {
DVLOG(2) << "Resuming task " << current_task_location_.ToString();
DCHECK_EQ(Task::TaskState::kPendingResume, current_task_->state_);
current_task_->state_ = Task::TaskState::kRunning;
std::move(on_resume).Run();
}
// static
void TaskQueue::TaskCompletedCallback(
scoped_refptr<base::SingleThreadTaskRunner> task_runner,
base::WeakPtr<TaskQueue> task_queue,
Task* task) {
task_runner->PostTask(
FROM_HERE, base::BindOnce(&TaskQueue::TaskCompleted, task_queue, task));
}
void TaskQueue::TaskCompleted(Task* task) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
// Normally, the completed task is the current task.
if (task == current_task_.get()) {
current_task_.reset(nullptr);
DVLOG(2) << "Current task completed " << current_task_location_.ToString();
StartTaskIfAvailable();
return;
}
// If the task is in the suspended_tasks_ list, remove it.
for (auto iter = suspended_tasks_.begin(); iter != suspended_tasks_.end();
++iter) {
if (iter->task.get() == task) {
DVLOG(2) << "Suspended task completed " << iter->from_here.ToString();
suspended_tasks_.erase(iter);
return;
}
}
NOTREACHED() << "TaskCompleted: cannot find task";
}
void TaskQueue::SuspendTask(Task* task) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
// Task::Suspend() sets state to kSuspended.
DCHECK_EQ(Task::TaskState::kSuspended, task->state_);
DCHECK_EQ(task, current_task_.get());
suspended_tasks_.emplace_back(current_task_location_,
std::move(current_task_));
StartTaskIfAvailable();
}
void TaskQueue::ResumeTask(Task* task, base::OnceClosure on_resume) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
DCHECK_EQ(Task::TaskState::kSuspended, task->state_);
for (auto iter = suspended_tasks_.begin(); iter != suspended_tasks_.end();
++iter) {
if (iter->task.get() == task) {
iter->resume_callback = std::move(on_resume);
tasks_.push_back(std::move(*iter));
suspended_tasks_.erase(iter);
task->state_ = Task::TaskState::kPendingResume;
StartTaskIfAvailable();
return;
}
}
NOTREACHED() << "Trying to resume task that's not suspended";
}
void TaskQueue::InformTaskQueueIsIdle() {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
delegate_->OnTaskQueueIsIdle();
}
// Returns a human-readable string describing the contents of the task queue.
std::string TaskQueue::GetStateForTesting() const {
std::stringstream ss;
if (current_task_) {
ss << "Current task: " << current_task_location_.ToString() << '\n';
} else {
ss << "No current task\n";
}
int number = 1;
for (const auto& entry : tasks_) {
ss << "Pending task " << number++ << ": " << entry.from_here.ToString()
<< '\n';
}
number = 1;
for (const auto& entry : suspended_tasks_) {
ss << "Suspended task " << number++ << ": " << entry.from_here.ToString()
<< '\n';
}
return ss.str();
}
} // namespace offline_pages
|
