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
10namespace v8 {
11namespace internal {
12
13
14Cancelable::Cancelable(CancelableTaskManager* parent)
15    : parent_(parent), status_(kWaiting), id_(0), cancel_counter_(0) {
16  id_ = parent->Register(this);
17}
18
19
20Cancelable::~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
29CancelableTaskManager::CancelableTaskManager()
30    : task_id_counter_(0), canceled_(false) {}
31
32uint32_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
43void 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
51CancelableTaskManager::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
70void 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
96CancelableTaskManager::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
114CancelableTask::CancelableTask(Isolate* isolate)
115    : CancelableTask(isolate, isolate->cancelable_task_manager()) {}
116
117CancelableTask::CancelableTask(Isolate* isolate, CancelableTaskManager* manager)
118    : Cancelable(manager), isolate_(isolate) {}
119
120CancelableIdleTask::CancelableIdleTask(Isolate* isolate)
121    : CancelableIdleTask(isolate, isolate->cancelable_task_manager()) {}
122
123CancelableIdleTask::CancelableIdleTask(Isolate* isolate,
124                                       CancelableTaskManager* manager)
125    : Cancelable(manager), isolate_(isolate) {}
126
127}  // namespace internal
128}  // namespace v8
129