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
|
// Copyright (c) 2011-2020 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#if defined(HAVE_CONFIG_H)
#include <config/bitcoin-config.h>
#endif
#include <sync.h>
#include <tinyformat.h>
#include <logging.h>
#include <util/strencodings.h>
#include <util/threadnames.h>
#include <map>
#include <set>
#include <system_error>
#ifdef DEBUG_LOCKCONTENTION
#if !defined(HAVE_THREAD_LOCAL)
static_assert(false, "thread_local is not supported");
#endif
void PrintLockContention(const char* pszName, const char* pszFile, int nLine)
{
LogPrintf("LOCKCONTENTION: %s\n", pszName);
LogPrintf("Locker: %s:%d\n", pszFile, nLine);
}
#endif /* DEBUG_LOCKCONTENTION */
#ifdef DEBUG_LOCKORDER
//
// Early deadlock detection.
// Problem being solved:
// Thread 1 locks A, then B, then C
// Thread 2 locks D, then C, then A
// --> may result in deadlock between the two threads, depending on when they run.
// Solution implemented here:
// Keep track of pairs of locks: (A before B), (A before C), etc.
// Complain if any thread tries to lock in a different order.
//
struct CLockLocation {
CLockLocation(
const char* pszName,
const char* pszFile,
int nLine,
bool fTryIn,
const std::string& thread_name)
: fTry(fTryIn),
mutexName(pszName),
sourceFile(pszFile),
m_thread_name(thread_name),
sourceLine(nLine) {}
std::string ToString() const
{
return strprintf(
"%s %s:%s%s (in thread %s)",
mutexName, sourceFile, sourceLine, (fTry ? " (TRY)" : ""), m_thread_name);
}
std::string Name() const
{
return mutexName;
}
private:
bool fTry;
std::string mutexName;
std::string sourceFile;
const std::string& m_thread_name;
int sourceLine;
};
typedef std::vector<std::pair<void*, CLockLocation> > LockStack;
typedef std::map<std::pair<void*, void*>, LockStack> LockOrders;
typedef std::set<std::pair<void*, void*> > InvLockOrders;
struct LockData {
// Very ugly hack: as the global constructs and destructors run single
// threaded, we use this boolean to know whether LockData still exists,
// as DeleteLock can get called by global RecursiveMutex destructors
// after LockData disappears.
bool available;
LockData() : available(true) {}
~LockData() { available = false; }
LockOrders lockorders;
InvLockOrders invlockorders;
std::mutex dd_mutex;
};
LockData& GetLockData() {
static LockData lockdata;
return lockdata;
}
static thread_local LockStack g_lockstack;
static void potential_deadlock_detected(const std::pair<void*, void*>& mismatch, const LockStack& s1, const LockStack& s2)
{
LogPrintf("POTENTIAL DEADLOCK DETECTED\n");
LogPrintf("Previous lock order was:\n");
for (const std::pair<void*, CLockLocation> & i : s2) {
if (i.first == mismatch.first) {
LogPrintf(" (1)"); /* Continued */
}
if (i.first == mismatch.second) {
LogPrintf(" (2)"); /* Continued */
}
LogPrintf(" %s\n", i.second.ToString());
}
LogPrintf("Current lock order is:\n");
for (const std::pair<void*, CLockLocation> & i : s1) {
if (i.first == mismatch.first) {
LogPrintf(" (1)"); /* Continued */
}
if (i.first == mismatch.second) {
LogPrintf(" (2)"); /* Continued */
}
LogPrintf(" %s\n", i.second.ToString());
}
if (g_debug_lockorder_abort) {
tfm::format(std::cerr, "Assertion failed: detected inconsistent lock order at %s:%i, details in debug log.\n", __FILE__, __LINE__);
abort();
}
throw std::logic_error("potential deadlock detected");
}
static void push_lock(void* c, const CLockLocation& locklocation)
{
LockData& lockdata = GetLockData();
std::lock_guard<std::mutex> lock(lockdata.dd_mutex);
g_lockstack.push_back(std::make_pair(c, locklocation));
for (const std::pair<void*, CLockLocation>& i : g_lockstack) {
if (i.first == c)
break;
std::pair<void*, void*> p1 = std::make_pair(i.first, c);
if (lockdata.lockorders.count(p1))
continue;
lockdata.lockorders.emplace(p1, g_lockstack);
std::pair<void*, void*> p2 = std::make_pair(c, i.first);
lockdata.invlockorders.insert(p2);
if (lockdata.lockorders.count(p2))
potential_deadlock_detected(p1, lockdata.lockorders[p2], lockdata.lockorders[p1]);
}
}
static void pop_lock()
{
g_lockstack.pop_back();
}
void EnterCritical(const char* pszName, const char* pszFile, int nLine, void* cs, bool fTry)
{
push_lock(cs, CLockLocation(pszName, pszFile, nLine, fTry, util::ThreadGetInternalName()));
}
void CheckLastCritical(void* cs, std::string& lockname, const char* guardname, const char* file, int line)
{
if (!g_lockstack.empty()) {
const auto& lastlock = g_lockstack.back();
if (lastlock.first == cs) {
lockname = lastlock.second.Name();
return;
}
}
throw std::system_error(EPERM, std::generic_category(), strprintf("%s:%s %s was not most recent critical section locked", file, line, guardname));
}
void LeaveCritical()
{
pop_lock();
}
std::string LocksHeld()
{
std::string result;
for (const std::pair<void*, CLockLocation>& i : g_lockstack)
result += i.second.ToString() + std::string("\n");
return result;
}
void AssertLockHeldInternal(const char* pszName, const char* pszFile, int nLine, void* cs)
{
for (const std::pair<void*, CLockLocation>& i : g_lockstack)
if (i.first == cs)
return;
tfm::format(std::cerr, "Assertion failed: lock %s not held in %s:%i; locks held:\n%s", pszName, pszFile, nLine, LocksHeld());
abort();
}
void AssertLockNotHeldInternal(const char* pszName, const char* pszFile, int nLine, void* cs)
{
for (const std::pair<void*, CLockLocation>& i : g_lockstack) {
if (i.first == cs) {
tfm::format(std::cerr, "Assertion failed: lock %s held in %s:%i; locks held:\n%s", pszName, pszFile, nLine, LocksHeld());
abort();
}
}
}
void DeleteLock(void* cs)
{
LockData& lockdata = GetLockData();
if (!lockdata.available) {
// We're already shutting down.
return;
}
std::lock_guard<std::mutex> lock(lockdata.dd_mutex);
std::pair<void*, void*> item = std::make_pair(cs, nullptr);
LockOrders::iterator it = lockdata.lockorders.lower_bound(item);
while (it != lockdata.lockorders.end() && it->first.first == cs) {
std::pair<void*, void*> invitem = std::make_pair(it->first.second, it->first.first);
lockdata.invlockorders.erase(invitem);
lockdata.lockorders.erase(it++);
}
InvLockOrders::iterator invit = lockdata.invlockorders.lower_bound(item);
while (invit != lockdata.invlockorders.end() && invit->first == cs) {
std::pair<void*, void*> invinvitem = std::make_pair(invit->second, invit->first);
lockdata.lockorders.erase(invinvitem);
lockdata.invlockorders.erase(invit++);
}
}
bool g_debug_lockorder_abort = true;
#endif /* DEBUG_LOCKORDER */
|
