blob: 830b878e8e8eba5e14081148266e98bcdb7b2c56 (
plain)
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
|
// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_SYNCHRONIZATION_LOCK_IMPL_H_
#define BASE_SYNCHRONIZATION_LOCK_IMPL_H_
#include "base/base_export.h"
#include "base/logging.h"
#include "base/macros.h"
#include "base/thread_annotations.h"
#include "build/build_config.h"
#if defined(OS_WIN)
#include "base/win/windows_types.h"
#elif defined(OS_POSIX) || defined(OS_FUCHSIA)
#include <errno.h>
#include <pthread.h>
#endif
namespace base {
namespace internal {
// This class implements the underlying platform-specific spin-lock mechanism
// used for the Lock class. Most users should not use LockImpl directly, but
// should instead use Lock.
class BASE_EXPORT LockImpl {
public:
#if defined(OS_WIN)
using NativeHandle = CHROME_SRWLOCK;
#elif defined(OS_POSIX) || defined(OS_FUCHSIA)
using NativeHandle = pthread_mutex_t;
#endif
LockImpl();
~LockImpl();
// If the lock is not held, take it and return true. If the lock is already
// held by something else, immediately return false.
bool Try();
// Take the lock, blocking until it is available if necessary.
void Lock();
// Release the lock. This must only be called by the lock's holder: after
// a successful call to Try, or a call to Lock.
inline void Unlock();
// Return the native underlying lock.
// TODO(awalker): refactor lock and condition variables so that this is
// unnecessary.
NativeHandle* native_handle() { return &native_handle_; }
#if defined(OS_POSIX) || defined(OS_FUCHSIA)
// Whether this lock will attempt to use priority inheritance.
static bool PriorityInheritanceAvailable();
#endif
private:
NativeHandle native_handle_;
DISALLOW_COPY_AND_ASSIGN(LockImpl);
};
#if defined(OS_WIN)
void LockImpl::Unlock() {
::ReleaseSRWLockExclusive(reinterpret_cast<PSRWLOCK>(&native_handle_));
}
#elif defined(OS_POSIX) || defined(OS_FUCHSIA)
void LockImpl::Unlock() {
int rv = pthread_mutex_unlock(&native_handle_);
DCHECK_EQ(rv, 0) << ". " << strerror(rv);
}
#endif
// This is an implementation used for AutoLock templated on the lock type.
template <class LockType>
class SCOPED_LOCKABLE BasicAutoLock {
public:
struct AlreadyAcquired {};
explicit BasicAutoLock(LockType& lock) EXCLUSIVE_LOCK_FUNCTION(lock)
: lock_(lock) {
lock_.Acquire();
}
BasicAutoLock(LockType& lock, const AlreadyAcquired&)
EXCLUSIVE_LOCKS_REQUIRED(lock)
: lock_(lock) {
lock_.AssertAcquired();
}
~BasicAutoLock() UNLOCK_FUNCTION() {
lock_.AssertAcquired();
lock_.Release();
}
private:
LockType& lock_;
DISALLOW_COPY_AND_ASSIGN(BasicAutoLock);
};
// This is an implementation used for AutoUnlock templated on the lock type.
template <class LockType>
class BasicAutoUnlock {
public:
explicit BasicAutoUnlock(LockType& lock) : lock_(lock) {
// We require our caller to have the lock.
lock_.AssertAcquired();
lock_.Release();
}
~BasicAutoUnlock() { lock_.Acquire(); }
private:
LockType& lock_;
DISALLOW_COPY_AND_ASSIGN(BasicAutoUnlock);
};
// This is an implementation used for AutoLockMaybe templated on the lock type.
template <class LockType>
class SCOPED_LOCKABLE BasicAutoLockMaybe {
public:
explicit BasicAutoLockMaybe(LockType* lock) EXCLUSIVE_LOCK_FUNCTION(lock)
: lock_(lock) {
if (lock_)
lock_->Acquire();
}
~BasicAutoLockMaybe() UNLOCK_FUNCTION() {
if (lock_) {
lock_->AssertAcquired();
lock_->Release();
}
}
private:
LockType* const lock_;
DISALLOW_COPY_AND_ASSIGN(BasicAutoLockMaybe);
};
// This is an implementation used for ReleasableAutoLock templated on the lock
// type.
template <class LockType>
class SCOPED_LOCKABLE BasicReleasableAutoLock {
public:
explicit BasicReleasableAutoLock(LockType* lock) EXCLUSIVE_LOCK_FUNCTION(lock)
: lock_(lock) {
DCHECK(lock_);
lock_->Acquire();
}
~BasicReleasableAutoLock() UNLOCK_FUNCTION() {
if (lock_) {
lock_->AssertAcquired();
lock_->Release();
}
}
void Release() UNLOCK_FUNCTION() {
DCHECK(lock_);
lock_->AssertAcquired();
lock_->Release();
lock_ = nullptr;
}
private:
LockType* lock_;
DISALLOW_COPY_AND_ASSIGN(BasicReleasableAutoLock);
};
} // namespace internal
} // namespace base
#endif // BASE_SYNCHRONIZATION_LOCK_IMPL_H_
|
