1 // Copyright 2015 the V8 project authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "src/cancelable-task.h"
6
7 #include "src/base/platform/platform.h"
8 #include "src/isolate.h"
9
10 namespace v8 {
11 namespace internal {
12
13
Cancelable(CancelableTaskManager * parent)14 Cancelable::Cancelable(CancelableTaskManager* parent)
15 : parent_(parent), status_(kWaiting), id_(0), cancel_counter_(0) {
16 id_ = parent->Register(this);
17 }
18
19
~Cancelable()20 Cancelable::~Cancelable() {
21 // The following check is needed to avoid calling an already terminated
22 // manager object. This happens when the manager cancels all pending tasks
23 // in {CancelAndWait} only before destroying the manager object.
24 if (TryRun() || IsRunning()) {
25 parent_->RemoveFinishedTask(id_);
26 }
27 }
28
CancelableTaskManager()29 CancelableTaskManager::CancelableTaskManager()
30 : task_id_counter_(0), canceled_(false) {}
31
Register(Cancelable * task)32 uint32_t CancelableTaskManager::Register(Cancelable* task) {
33 base::LockGuard<base::Mutex> guard(&mutex_);
34 uint32_t id = ++task_id_counter_;
35 // The loop below is just used when task_id_counter_ overflows.
36 while (cancelable_tasks_.count(id) > 0) ++id;
37 CHECK(!canceled_);
38 cancelable_tasks_[id] = task;
39 return id;
40 }
41
42
RemoveFinishedTask(uint32_t id)43 void CancelableTaskManager::RemoveFinishedTask(uint32_t id) {
44 base::LockGuard<base::Mutex> guard(&mutex_);
45 size_t removed = cancelable_tasks_.erase(id);
46 USE(removed);
47 DCHECK_NE(0u, removed);
48 cancelable_tasks_barrier_.NotifyOne();
49 }
50
TryAbort(uint32_t id)51 CancelableTaskManager::TryAbortResult CancelableTaskManager::TryAbort(
52 uint32_t id) {
53 base::LockGuard<base::Mutex> guard(&mutex_);
54 auto entry = cancelable_tasks_.find(id);
55 if (entry != cancelable_tasks_.end()) {
56 Cancelable* value = entry->second;
57 if (value->Cancel()) {
58 // Cannot call RemoveFinishedTask here because of recursive locking.
59 cancelable_tasks_.erase(entry);
60 cancelable_tasks_barrier_.NotifyOne();
61 return kTaskAborted;
62 } else {
63 return kTaskRunning;
64 }
65 }
66 return kTaskRemoved;
67 }
68
69
CancelAndWait()70 void CancelableTaskManager::CancelAndWait() {
71 // Clean up all cancelable fore- and background tasks. Tasks are canceled on
72 // the way if possible, i.e., if they have not started yet. After each round
73 // of canceling we wait for the background tasks that have already been
74 // started.
75 base::LockGuard<base::Mutex> guard(&mutex_);
76 canceled_ = true;
77
78 // Cancelable tasks could be running or could potentially register new
79 // tasks, requiring a loop here.
80 while (!cancelable_tasks_.empty()) {
81 for (auto it = cancelable_tasks_.begin(); it != cancelable_tasks_.end();) {
82 auto current = it;
83 // We need to get to the next element before erasing the current.
84 ++it;
85 if (current->second->Cancel()) {
86 cancelable_tasks_.erase(current);
87 }
88 }
89 // Wait for already running background tasks.
90 if (!cancelable_tasks_.empty()) {
91 cancelable_tasks_barrier_.Wait(&mutex_);
92 }
93 }
94 }
95
TryAbortAll()96 CancelableTaskManager::TryAbortResult CancelableTaskManager::TryAbortAll() {
97 // Clean up all cancelable fore- and background tasks. Tasks are canceled on
98 // the way if possible, i.e., if they have not started yet.
99 base::LockGuard<base::Mutex> guard(&mutex_);
100
101 if (cancelable_tasks_.empty()) return kTaskRemoved;
102
103 for (auto it = cancelable_tasks_.begin(); it != cancelable_tasks_.end();) {
104 if (it->second->Cancel()) {
105 it = cancelable_tasks_.erase(it);
106 } else {
107 ++it;
108 }
109 }
110
111 return cancelable_tasks_.empty() ? kTaskAborted : kTaskRunning;
112 }
113
CancelableTask(Isolate * isolate)114 CancelableTask::CancelableTask(Isolate* isolate)
115 : CancelableTask(isolate, isolate->cancelable_task_manager()) {}
116
CancelableTask(Isolate * isolate,CancelableTaskManager * manager)117 CancelableTask::CancelableTask(Isolate* isolate, CancelableTaskManager* manager)
118 : Cancelable(manager), isolate_(isolate) {}
119
CancelableIdleTask(Isolate * isolate)120 CancelableIdleTask::CancelableIdleTask(Isolate* isolate)
121 : CancelableIdleTask(isolate, isolate->cancelable_task_manager()) {}
122
CancelableIdleTask(Isolate * isolate,CancelableTaskManager * manager)123 CancelableIdleTask::CancelableIdleTask(Isolate* isolate,
124 CancelableTaskManager* manager)
125 : Cancelable(manager), isolate_(isolate) {}
126
127 } // namespace internal
128 } // namespace v8
129