forked from bitcoin/bitcoin
-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathcheckqueue.h
More file actions
215 lines (187 loc) · 6.47 KB
/
checkqueue.h
File metadata and controls
215 lines (187 loc) · 6.47 KB
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
// Copyright (c) 2012-2014 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_CHECKQUEUE_H
#define BITCOIN_CHECKQUEUE_H
#include <algorithm>
#include <vector>
#include <boost/foreach.hpp>
#include <boost/thread/condition_variable.hpp>
#include <boost/thread/locks.hpp>
#include <boost/thread/mutex.hpp>
template <typename T>
class CCheckQueueControl;
/**
* Queue for verifications that have to be performed.
* The verifications are represented by a type T, which must provide an
* operator(), returning a bool.
*
* One thread (the master) is assumed to push batches of verifications
* onto the queue, where they are processed by N-1 worker threads. When
* the master is done adding work, it temporarily joins the worker pool
* as an N'th worker, until all jobs are done.
*/
template <typename T>
class CCheckQueue
{
private:
//! Mutex to protect the inner state
boost::mutex mutex;
//! Worker threads block on this when out of work
boost::condition_variable condWorker;
//! Master thread blocks on this when out of work
boost::condition_variable condMaster;
//! The queue of elements to be processed.
//! As the order of booleans doesn't matter, it is used as a LIFO (stack)
std::vector<T> queue;
//! The number of workers (including the master) that are idle.
int nIdle;
//! The total number of workers (including the master).
int nTotal;
//! The temporary evaluation result.
bool fAllOk;
/**
* Number of verifications that haven't completed yet.
* This includes elements that are no longer queued, but still in the
* worker's own batches.
*/
unsigned int nTodo;
//! Whether we're shutting down.
bool fQuit;
//! The maximum number of elements to be processed in one batch
unsigned int nBatchSize;
/** Internal function that does bulk of the verification work. */
bool Loop(bool fMaster = false)
{
boost::condition_variable& cond = fMaster ? condMaster : condWorker;
std::vector<T> vChecks;
vChecks.reserve(nBatchSize);
unsigned int nNow = 0;
bool fOk = true;
do {
{
boost::unique_lock<boost::mutex> lock(mutex);
// first do the clean-up of the previous loop run (allowing us to do it in the same critsect)
if (nNow) {
fAllOk &= fOk;
nTodo -= nNow;
if (nTodo == 0 && !fMaster)
// We processed the last element; inform the master it can exit and return the result
condMaster.notify_one();
} else {
// first iteration
nTotal++;
}
// logically, the do loop starts here
while (queue.empty()) {
if ((fMaster || fQuit) && nTodo == 0) {
nTotal--;
bool fRet = fAllOk;
// reset the status for new work later
if (fMaster)
fAllOk = true;
// return the current status
return fRet;
}
nIdle++;
cond.wait(lock); // wait
nIdle--;
}
// Decide how many work units to process now.
// * Do not try to do everything at once, but aim for increasingly smaller batches so
// all workers finish approximately simultaneously.
// * Try to account for idle jobs which will instantly start helping.
// * Don't do batches smaller than 1 (duh), or larger than nBatchSize.
nNow = std::max(1U, std::min(nBatchSize, (unsigned int)queue.size() / (nTotal + nIdle + 1)));
vChecks.resize(nNow);
for (unsigned int i = 0; i < nNow; i++) {
// We want the lock on the mutex to be as short as possible, so swap jobs from the global
// queue to the local batch vector instead of copying.
vChecks[i].swap(queue.back());
queue.pop_back();
}
// Check whether we need to do work at all
fOk = fAllOk;
}
// execute work
BOOST_FOREACH (T& check, vChecks)
if (fOk)
fOk = check();
vChecks.clear();
} while (true);
}
public:
//! Create a new check queue
CCheckQueue(unsigned int nBatchSizeIn) : nIdle(0), nTotal(0), fAllOk(true), nTodo(0), fQuit(false), nBatchSize(nBatchSizeIn) {}
//! Worker thread
void Thread()
{
Loop();
}
//! Wait until execution finishes, and return whether all evaluations were successful.
bool Wait()
{
return Loop(true);
}
//! Add a batch of checks to the queue
void Add(std::vector<T>& vChecks)
{
boost::unique_lock<boost::mutex> lock(mutex);
BOOST_FOREACH (T& check, vChecks) {
queue.push_back(T());
check.swap(queue.back());
}
nTodo += vChecks.size();
if (vChecks.size() == 1)
condWorker.notify_one();
else if (vChecks.size() > 1)
condWorker.notify_all();
}
~CCheckQueue()
{
}
bool IsIdle()
{
boost::unique_lock<boost::mutex> lock(mutex);
return (nTotal == nIdle && nTodo == 0 && fAllOk == true);
}
};
/**
* RAII-style controller object for a CCheckQueue that guarantees the passed
* queue is finished before continuing.
*/
template <typename T>
class CCheckQueueControl
{
private:
CCheckQueue<T>* pqueue;
bool fDone;
public:
CCheckQueueControl(CCheckQueue<T>* pqueueIn) : pqueue(pqueueIn), fDone(false)
{
// passed queue is supposed to be unused, or NULL
if (pqueue != NULL) {
bool isIdle = pqueue->IsIdle();
assert(isIdle);
}
}
bool Wait()
{
if (pqueue == NULL)
return true;
bool fRet = pqueue->Wait();
fDone = true;
return fRet;
}
void Add(std::vector<T>& vChecks)
{
if (pqueue != NULL)
pqueue->Add(vChecks);
}
~CCheckQueueControl()
{
if (!fDone)
Wait();
}
};
#endif // BITCOIN_CHECKQUEUE_H