aboutsummaryrefslogtreecommitdiff
path: root/src/sync.h
blob: 2790fc6f23a3ff5770f5bc9e6333267bf24d1e39 (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
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2016 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#ifndef BITCOIN_SYNC_H
#define BITCOIN_SYNC_H

#include "threadsafety.h"

#include <boost/thread/condition_variable.hpp>
#include <boost/thread/mutex.hpp>
#include <boost/thread/recursive_mutex.hpp>


////////////////////////////////////////////////
//                                            //
// THE SIMPLE DEFINITION, EXCLUDING DEBUG CODE //
//                                            //
////////////////////////////////////////////////

/*
CCriticalSection mutex;
    boost::recursive_mutex mutex;

LOCK(mutex);
    boost::unique_lock<boost::recursive_mutex> criticalblock(mutex);

LOCK2(mutex1, mutex2);
    boost::unique_lock<boost::recursive_mutex> criticalblock1(mutex1);
    boost::unique_lock<boost::recursive_mutex> criticalblock2(mutex2);

TRY_LOCK(mutex, name);
    boost::unique_lock<boost::recursive_mutex> name(mutex, boost::try_to_lock_t);

ENTER_CRITICAL_SECTION(mutex); // no RAII
    mutex.lock();

LEAVE_CRITICAL_SECTION(mutex); // no RAII
    mutex.unlock();
 */

///////////////////////////////
//                           //
// THE ACTUAL IMPLEMENTATION //
//                           //
///////////////////////////////

/**
 * Template mixin that adds -Wthread-safety locking
 * annotations to a subset of the mutex API.
 */
template <typename PARENT>
class LOCKABLE AnnotatedMixin : public PARENT
{
public:
    void lock() EXCLUSIVE_LOCK_FUNCTION()
    {
        PARENT::lock();
    }

    void unlock() UNLOCK_FUNCTION()
    {
        PARENT::unlock();
    }

    bool try_lock() EXCLUSIVE_TRYLOCK_FUNCTION(true)
    {
        return PARENT::try_lock();
    }
};

#ifdef DEBUG_LOCKORDER
void EnterCritical(const char* pszName, const char* pszFile, int nLine, void* cs, bool fTry = false);
void LeaveCritical();
std::string LocksHeld();
void AssertLockHeldInternal(const char* pszName, const char* pszFile, int nLine, void* cs);
void AssertLockNotHeldInternal(const char* pszName, const char* pszFile, int nLine, void* cs);
void DeleteLock(void* cs);
#else
void static inline EnterCritical(const char* pszName, const char* pszFile, int nLine, void* cs, bool fTry = false) {}
void static inline LeaveCritical() {}
void static inline AssertLockHeldInternal(const char* pszName, const char* pszFile, int nLine, void* cs) {}
void static inline AssertLockNotHeldInternal(const char* pszName, const char* pszFile, int nLine, void* cs) {}
void static inline DeleteLock(void* cs) {}
#endif
#define AssertLockHeld(cs) AssertLockHeldInternal(#cs, __FILE__, __LINE__, &cs)
#define AssertLockNotHeld(cs) AssertLockNotHeldInternal(#cs, __FILE__, __LINE__, &cs)

/**
 * Wrapped boost mutex: supports recursive locking, but no waiting
 * TODO: We should move away from using the recursive lock by default.
 */
class CCriticalSection : public AnnotatedMixin<boost::recursive_mutex>
{
public:
    ~CCriticalSection() {
        DeleteLock((void*)this);
    }
};

/** Wrapped boost mutex: supports waiting but not recursive locking */
typedef AnnotatedMixin<boost::mutex> CWaitableCriticalSection;

/** Just a typedef for boost::condition_variable, can be wrapped later if desired */
typedef boost::condition_variable CConditionVariable;

#ifdef DEBUG_LOCKCONTENTION
void PrintLockContention(const char* pszName, const char* pszFile, int nLine);
#endif

/** Wrapper around boost::unique_lock<Mutex> */
template <typename Mutex>
class SCOPED_LOCKABLE CMutexLock
{
private:
    boost::unique_lock<Mutex> lock;

    void Enter(const char* pszName, const char* pszFile, int nLine)
    {
        EnterCritical(pszName, pszFile, nLine, (void*)(lock.mutex()));
#ifdef DEBUG_LOCKCONTENTION
        if (!lock.try_lock()) {
            PrintLockContention(pszName, pszFile, nLine);
#endif
            lock.lock();
#ifdef DEBUG_LOCKCONTENTION
        }
#endif
    }

    bool TryEnter(const char* pszName, const char* pszFile, int nLine)
    {
        EnterCritical(pszName, pszFile, nLine, (void*)(lock.mutex()), true);
        lock.try_lock();
        if (!lock.owns_lock())
            LeaveCritical();
        return lock.owns_lock();
    }

public:
    CMutexLock(Mutex& mutexIn, const char* pszName, const char* pszFile, int nLine, bool fTry = false) EXCLUSIVE_LOCK_FUNCTION(mutexIn) : lock(mutexIn, boost::defer_lock)
    {
        if (fTry)
            TryEnter(pszName, pszFile, nLine);
        else
            Enter(pszName, pszFile, nLine);
    }

    CMutexLock(Mutex* pmutexIn, const char* pszName, const char* pszFile, int nLine, bool fTry = false) EXCLUSIVE_LOCK_FUNCTION(pmutexIn)
    {
        if (!pmutexIn) return;

        lock = boost::unique_lock<Mutex>(*pmutexIn, boost::defer_lock);
        if (fTry)
            TryEnter(pszName, pszFile, nLine);
        else
            Enter(pszName, pszFile, nLine);
    }

    ~CMutexLock() UNLOCK_FUNCTION()
    {
        if (lock.owns_lock())
            LeaveCritical();
    }

    operator bool()
    {
        return lock.owns_lock();
    }
};

typedef CMutexLock<CCriticalSection> CCriticalBlock;

#define PASTE(x, y) x ## y
#define PASTE2(x, y) PASTE(x, y)

#define LOCK(cs) CCriticalBlock PASTE2(criticalblock, __COUNTER__)(cs, #cs, __FILE__, __LINE__)
#define LOCK2(cs1, cs2) CCriticalBlock criticalblock1(cs1, #cs1, __FILE__, __LINE__), criticalblock2(cs2, #cs2, __FILE__, __LINE__)
#define TRY_LOCK(cs, name) CCriticalBlock name(cs, #cs, __FILE__, __LINE__, true)

#define ENTER_CRITICAL_SECTION(cs)                            \
    {                                                         \
        EnterCritical(#cs, __FILE__, __LINE__, (void*)(&cs)); \
        (cs).lock();                                          \
    }

#define LEAVE_CRITICAL_SECTION(cs) \
    {                              \
        (cs).unlock();             \
        LeaveCritical();           \
    }

class CSemaphore
{
private:
    boost::condition_variable condition;
    boost::mutex mutex;
    int value;

public:
    explicit CSemaphore(int init) : value(init) {}

    void wait()
    {
        boost::unique_lock<boost::mutex> lock(mutex);
        while (value < 1) {
            condition.wait(lock);
        }
        value--;
    }

    bool try_wait()
    {
        boost::unique_lock<boost::mutex> lock(mutex);
        if (value < 1)
            return false;
        value--;
        return true;
    }

    void post()
    {
        {
            boost::unique_lock<boost::mutex> lock(mutex);
            value++;
        }
        condition.notify_one();
    }
};

/** RAII-style semaphore lock */
class CSemaphoreGrant
{
private:
    CSemaphore* sem;
    bool fHaveGrant;

public:
    void Acquire()
    {
        if (fHaveGrant)
            return;
        sem->wait();
        fHaveGrant = true;
    }

    void Release()
    {
        if (!fHaveGrant)
            return;
        sem->post();
        fHaveGrant = false;
    }

    bool TryAcquire()
    {
        if (!fHaveGrant && sem->try_wait())
            fHaveGrant = true;
        return fHaveGrant;
    }

    void MoveTo(CSemaphoreGrant& grant)
    {
        grant.Release();
        grant.sem = sem;
        grant.fHaveGrant = fHaveGrant;
        fHaveGrant = false;
    }

    CSemaphoreGrant() : sem(nullptr), fHaveGrant(false) {}

    explicit CSemaphoreGrant(CSemaphore& sema, bool fTry = false) : sem(&sema), fHaveGrant(false)
    {
        if (fTry)
            TryAcquire();
        else
            Acquire();
    }

    ~CSemaphoreGrant()
    {
        Release();
    }

    operator bool() const
    {
        return fHaveGrant;
    }
};

#endif // BITCOIN_SYNC_H