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
|
#ifndef UTIL_PCQUEUE_H
#define UTIL_PCQUEUE_H
#include "util/exception.hh"
#include <boost/interprocess/sync/interprocess_semaphore.hpp>
#include <boost/scoped_array.hpp>
#include <boost/thread/mutex.hpp>
#include <boost/utility.hpp>
#include <errno.h>
#ifdef __APPLE__
#include <mach/semaphore.h>
#include <mach/task.h>
#include <mach/mach_traps.h>
#include <mach/mach.h>
#endif // __APPLE__
namespace util {
/* OS X Maverick and Boost interprocess were doing "Function not implemented."
* So this is my own wrapper around the mach kernel APIs.
*/
#ifdef __APPLE__
#define MACH_CALL(call) UTIL_THROW_IF(KERN_SUCCESS != (call), Exception, "Mach call failure")
class Semaphore {
public:
explicit Semaphore(int value) : task_(mach_task_self()) {
MACH_CALL(semaphore_create(task_, &back_, SYNC_POLICY_FIFO, value));
}
~Semaphore() {
MACH_CALL(semaphore_destroy(task_, back_));
}
void wait() {
MACH_CALL(semaphore_wait(back_));
}
void post() {
MACH_CALL(semaphore_signal(back_));
}
private:
semaphore_t back_;
task_t task_;
};
inline void WaitSemaphore(Semaphore &semaphore) {
semaphore.wait();
}
#else
typedef boost::interprocess::interprocess_semaphore Semaphore;
inline void WaitSemaphore (Semaphore &on) {
while (1) {
try {
on.wait();
break;
}
catch (boost::interprocess::interprocess_exception &e) {
if (e.get_native_error() != EINTR) {
throw;
}
}
}
}
#endif // __APPLE__
/**
* Producer consumer queue safe for multiple producers and multiple consumers.
* T must be default constructable and have operator=.
* The value is copied twice for Consume(T &out) or three times for Consume(),
* so larger objects should be passed via pointer.
* Strong exception guarantee if operator= throws. Undefined if semaphores throw.
*/
template <class T> class PCQueue : boost::noncopyable {
public:
explicit PCQueue(size_t size)
: empty_(size), used_(0),
storage_(new T[size]),
end_(storage_.get() + size),
produce_at_(storage_.get()),
consume_at_(storage_.get()) {}
// Add a value to the queue.
void Produce(const T &val) {
WaitSemaphore(empty_);
{
boost::unique_lock<boost::mutex> produce_lock(produce_at_mutex_);
try {
*produce_at_ = val;
}
catch (...) {
empty_.post();
throw;
}
if (++produce_at_ == end_) produce_at_ = storage_.get();
}
used_.post();
}
// Consume a value, assigning it to out.
T& Consume(T &out) {
WaitSemaphore(used_);
{
boost::unique_lock<boost::mutex> consume_lock(consume_at_mutex_);
try {
out = *consume_at_;
}
catch (...) {
used_.post();
throw;
}
if (++consume_at_ == end_) consume_at_ = storage_.get();
}
empty_.post();
return out;
}
// Convenience version of Consume that copies the value to return.
// The other version is faster.
T Consume() {
T ret;
Consume(ret);
return ret;
}
private:
// Number of empty spaces in storage_.
Semaphore empty_;
// Number of occupied spaces in storage_.
Semaphore used_;
boost::scoped_array<T> storage_;
T *const end_;
// Index for next write in storage_.
T *produce_at_;
boost::mutex produce_at_mutex_;
// Index for next read from storage_.
T *consume_at_;
boost::mutex consume_at_mutex_;
};
} // namespace util
#endif // UTIL_PCQUEUE_H
|
