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1 // Copyright 2016 The Chromium Authors. All rights reserved. | 1 // Copyright 2016 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 #include "base/task_scheduler/scheduler_lock_impl.h" | 5 #include "base/task_scheduler/scheduler_lock_impl.h" |
6 | 6 |
7 #include <algorithm> | 7 #include <algorithm> |
8 #include <unordered_map> | 8 #include <unordered_map> |
9 #include <vector> | 9 #include <vector> |
10 | 10 |
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60 void AssertSafeAcquire(const SchedulerLockImpl* const lock) { | 60 void AssertSafeAcquire(const SchedulerLockImpl* const lock) { |
61 const LockVector* acquired_locks = GetAcquiredLocksOnCurrentThread(); | 61 const LockVector* acquired_locks = GetAcquiredLocksOnCurrentThread(); |
62 | 62 |
63 // If the thread currently holds no locks, this is inherently safe. | 63 // If the thread currently holds no locks, this is inherently safe. |
64 if (acquired_locks->empty()) | 64 if (acquired_locks->empty()) |
65 return; | 65 return; |
66 | 66 |
67 // Otherwise, make sure that the previous lock acquired is an allowed | 67 // Otherwise, make sure that the previous lock acquired is an allowed |
68 // predecessor. | 68 // predecessor. |
69 AutoLock auto_lock(allowed_predecessor_map_lock_); | 69 AutoLock auto_lock(allowed_predecessor_map_lock_); |
70 // Using at() is exception-safe here as |lock| was registered already. | |
70 const SchedulerLockImpl* allowed_predecessor = | 71 const SchedulerLockImpl* allowed_predecessor = |
71 allowed_predecessor_map_.at(lock); | 72 allowed_predecessor_map_.at(lock); |
72 DCHECK_EQ(acquired_locks->back(), allowed_predecessor); | 73 DCHECK_EQ(acquired_locks->back(), allowed_predecessor); |
73 } | 74 } |
74 | 75 |
76 // This asserts that |lock|'s registered predecessor is safe (and by | |
robliao
2016/08/04 18:13:29
Iterating over chat.
gab
2016/08/04 18:15:06
Done.
| |
77 // indicution that the predecessor chain is safe -- cycle free). Since | |
78 // registration only happens at construction time, the predecessor is safe as | |
79 // long as it is either null or already registered. | |
75 void AssertSafePredecessor(const SchedulerLockImpl* lock) const { | 80 void AssertSafePredecessor(const SchedulerLockImpl* lock) const { |
76 allowed_predecessor_map_lock_.AssertAcquired(); | 81 allowed_predecessor_map_lock_.AssertAcquired(); |
77 for (const SchedulerLockImpl* predecessor = | 82 // Using at() is exception-safe here as |lock| was registered already. |
78 allowed_predecessor_map_.at(lock); | 83 const SchedulerLockImpl* predecessor = allowed_predecessor_map_.at(lock); |
79 predecessor != nullptr; | 84 if (predecessor) { |
80 predecessor = allowed_predecessor_map_.at(predecessor)) { | 85 DCHECK(allowed_predecessor_map_.find(predecessor) != |
81 DCHECK_NE(predecessor, lock) << | 86 allowed_predecessor_map_.end()) |
82 "Scheduler lock predecessor cycle detected."; | 87 << "SchedulerLock was registered before its predecessor. " |
88 << "Potential cycle detected"; | |
83 } | 89 } |
84 } | 90 } |
85 | 91 |
86 LockVector* GetAcquiredLocksOnCurrentThread() { | 92 LockVector* GetAcquiredLocksOnCurrentThread() { |
87 if (!tls_acquired_locks_.Get()) | 93 if (!tls_acquired_locks_.Get()) |
88 tls_acquired_locks_.Set(new LockVector); | 94 tls_acquired_locks_.Set(new LockVector); |
89 | 95 |
90 return reinterpret_cast<LockVector*>(tls_acquired_locks_.Get()); | 96 return reinterpret_cast<LockVector*>(tls_acquired_locks_.Get()); |
91 } | 97 } |
92 | 98 |
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136 lock_.AssertAcquired(); | 142 lock_.AssertAcquired(); |
137 } | 143 } |
138 | 144 |
139 std::unique_ptr<ConditionVariable> | 145 std::unique_ptr<ConditionVariable> |
140 SchedulerLockImpl::CreateConditionVariable() { | 146 SchedulerLockImpl::CreateConditionVariable() { |
141 return std::unique_ptr<ConditionVariable>(new ConditionVariable(&lock_)); | 147 return std::unique_ptr<ConditionVariable>(new ConditionVariable(&lock_)); |
142 } | 148 } |
143 | 149 |
144 } // namespace internal | 150 } // namespace internal |
145 } // base | 151 } // base |
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