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
176
177
178
179
180
181
182
183
184
|
/*
* Copyright (c) 2013, Ford Motor Company
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following
* disclaimer in the documentation and/or other materials provided with the
* distribution.
*
* Neither the name of the Ford Motor Company nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef SRC_COMPONENTS_INCLUDE_UTILS_LOCK_H_
#define SRC_COMPONENTS_INCLUDE_UTILS_LOCK_H_
#if defined(OS_POSIX)
#include <pthread.h>
#include <sched.h>
#else
#error Please implement lock for your OS
#endif
#include <stdint.h>
#include "utils/macro.h"
#include "utils/atomic.h"
#include "utils/memory_barrier.h"
namespace sync_primitives {
namespace impl {
#if defined(OS_POSIX)
typedef pthread_mutex_t PlatformMutex;
#endif
} // namespace impl
class SpinMutex {
public:
SpinMutex() : state_(0) {}
void Lock() {
// Comment below add exception for lint error
// Reason: FlexeLint doesn't know about compiler's built-in instructions
/*lint -e1055*/
if (atomic_post_set(&state_) == 0) {
return;
}
for (;;) {
sched_yield();
/*lint -e1055*/
if (state_ == 0 && atomic_post_set(&state_) == 0) {
return;
}
}
}
void Unlock() {
state_ = 0;
}
~SpinMutex() {}
private:
volatile unsigned int state_;
};
/* Platform-indepenednt NON-RECURSIVE lock (mutex) wrapper
Please use AutoLock to ackquire and (automatically) release it
It eases balancing of multple lock taking/releasing and makes it
Impossible to forget to release the lock:
...
ConcurentlyAccessedData data_;
sync_primitives::Lock data_lock_;
...
{
sync_primitives::AutoLock auto_lock(data_lock_);
data_.ReadOrWriteData();
} // lock is automatically released here
*/
class Lock {
public:
Lock();
Lock(bool is_recursive);
~Lock();
// Ackquire the lock. Must be called only once on a thread.
// Please consider using AutoLock to capture it.
void Acquire();
// Release the lock. Must be called only once on a thread after lock.
// was acquired. Please consider using AutoLock to automatically release
// the lock
void Release();
// Try if lock can be captured and lock it if it was possible.
// If it captured, lock must be manually released calling to Release
// when protected resource access was finished.
// @returns wether lock was captured.
bool Try();
private:
impl::PlatformMutex mutex_;
#ifndef NDEBUG
/**
* @brief Basic debugging aid, a flag that signals wether this lock is
* currently taken
* Allows detection of abandoned and recursively captured mutexes
*/
uint32_t lock_taken_;
/**
* @brief Describe if mutex is recurcive or not
*/
bool is_mutex_recursive_;
void AssertFreeAndMarkTaken();
void AssertTakenAndMarkFree();
#else
void AssertFreeAndMarkTaken() {}
void AssertTakenAndMarkFree() {}
#endif
void Init(bool is_recursive);
friend class ConditionalVariable;
DISALLOW_COPY_AND_ASSIGN(Lock);
};
// This class is used to automatically acquire and release the a lock
class AutoLock {
public:
explicit AutoLock(Lock& lock) : lock_(lock) {
lock_.Acquire();
}
~AutoLock() {
lock_.Release();
}
private:
Lock& GetLock() {
return lock_;
}
Lock& lock_;
private:
friend class AutoUnlock;
friend class ConditionalVariable;
DISALLOW_COPY_AND_ASSIGN(AutoLock);
};
// This class is used to temporarly unlock autolocked lock
class AutoUnlock {
public:
explicit AutoUnlock(Lock& lock) : lock_(lock) {
lock_.Release();
}
explicit AutoUnlock(AutoLock& lock) : lock_(lock.GetLock()) {
lock_.Release();
}
~AutoUnlock() {
lock_.Acquire();
}
private:
Lock& lock_;
private:
DISALLOW_COPY_AND_ASSIGN(AutoUnlock);
};
} // namespace sync_primitives
#endif // SRC_COMPONENTS_INCLUDE_UTILS_LOCK_H_
|
