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 CancelableTaskManager::Id CancelableTaskManager::Register(Cancelable* task) {
33 base::LockGuard<base::Mutex> guard(&mutex_);
34 CancelableTaskManager::Id id = ++task_id_counter_;
35 // Id overflows are not supported.
36 CHECK_NE(0, id);
37 CHECK(!canceled_);
38 cancelable_tasks_[id] = task;
39 return id;
40 }
41
RemoveFinishedTask(CancelableTaskManager::Id id)42 void CancelableTaskManager::RemoveFinishedTask(CancelableTaskManager::Id id) {
43 base::LockGuard<base::Mutex> guard(&mutex_);
44 size_t removed = cancelable_tasks_.erase(id);
45 USE(removed);
46 DCHECK_NE(0u, removed);
47 cancelable_tasks_barrier_.NotifyOne();
48 }
49
TryAbort(CancelableTaskManager::Id id)50 CancelableTaskManager::TryAbortResult CancelableTaskManager::TryAbort(
51 CancelableTaskManager::Id id) {
52 base::LockGuard<base::Mutex> guard(&mutex_);
53 auto entry = cancelable_tasks_.find(id);
54 if (entry != cancelable_tasks_.end()) {
55 Cancelable* value = entry->second;
56 if (value->Cancel()) {
57 // Cannot call RemoveFinishedTask here because of recursive locking.
58 cancelable_tasks_.erase(entry);
59 cancelable_tasks_barrier_.NotifyOne();
60 return kTaskAborted;
61 } else {
62 return kTaskRunning;
63 }
64 }
65 return kTaskRemoved;
66 }
67
CancelAndWait()68 void CancelableTaskManager::CancelAndWait() {
69 // Clean up all cancelable fore- and background tasks. Tasks are canceled on
70 // the way if possible, i.e., if they have not started yet. After each round
71 // of canceling we wait for the background tasks that have already been
72 // started.
73 base::LockGuard<base::Mutex> guard(&mutex_);
74 canceled_ = true;
75
76 // Cancelable tasks could be running or could potentially register new
77 // tasks, requiring a loop here.
78 while (!cancelable_tasks_.empty()) {
79 for (auto it = cancelable_tasks_.begin(); it != cancelable_tasks_.end();) {
80 auto current = it;
81 // We need to get to the next element before erasing the current.
82 ++it;
83 if (current->second->Cancel()) {
84 cancelable_tasks_.erase(current);
85 }
86 }
87 // Wait for already running background tasks.
88 if (!cancelable_tasks_.empty()) {
89 cancelable_tasks_barrier_.Wait(&mutex_);
90 }
91 }
92 }
93
TryAbortAll()94 CancelableTaskManager::TryAbortResult CancelableTaskManager::TryAbortAll() {
95 // Clean up all cancelable fore- and background tasks. Tasks are canceled on
96 // the way if possible, i.e., if they have not started yet.
97 base::LockGuard<base::Mutex> guard(&mutex_);
98
99 if (cancelable_tasks_.empty()) return kTaskRemoved;
100
101 for (auto it = cancelable_tasks_.begin(); it != cancelable_tasks_.end();) {
102 if (it->second->Cancel()) {
103 it = cancelable_tasks_.erase(it);
104 } else {
105 ++it;
106 }
107 }
108
109 return cancelable_tasks_.empty() ? kTaskAborted : kTaskRunning;
110 }
111
CancelableTask(Isolate * isolate)112 CancelableTask::CancelableTask(Isolate* isolate)
113 : CancelableTask(isolate->cancelable_task_manager()) {}
114
CancelableTask(CancelableTaskManager * manager)115 CancelableTask::CancelableTask(CancelableTaskManager* manager)
116 : Cancelable(manager) {}
117
CancelableIdleTask(Isolate * isolate)118 CancelableIdleTask::CancelableIdleTask(Isolate* isolate)
119 : CancelableIdleTask(isolate->cancelable_task_manager()) {}
120
CancelableIdleTask(CancelableTaskManager * manager)121 CancelableIdleTask::CancelableIdleTask(CancelableTaskManager* manager)
122 : Cancelable(manager) {}
123
124 } // namespace internal
125 } // namespace v8
126