blob: e5ca23bdfc9efee3e98f71b7cf2caf294654ea51 (
plain) (
blame)
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
|
#ifndef _GLIM_CHANNEL_INCLUDED
#define _GLIM_CHANNEL_INCLUDED
#include <atomic>
#include <mutex>
#include <thread>
namespace glim {
/// Unbuffered channel.
/// Optimized for a single value (busy-waits on a second one).
template <typename V>
struct Channel {
V _v;
std::mutex _mutex; // Locked when there is no value.
std::atomic_int_fast8_t _state; enum State {EMPTY = 0, WRITING = 1, FULL = 2};
Channel(): _state (EMPTY) {_mutex.lock();}
// Waits until the Channel is empty then stores the value.
template <typename VA> void send (VA&& v) {
for (;;) {
int_fast8_t expectEmpty = EMPTY; if (_state.compare_exchange_weak (expectEmpty, WRITING)) break;
std::this_thread::sleep_for (std::chrono::milliseconds (20));
}
try {_v = std::forward<V> (v);} catch (...) {_state = EMPTY; throw;}
_state = FULL;
_mutex.unlock(); // Allows the reader to proceed.
}
// Waits untill there is a value to receive.
V receive() {
_mutex.lock(); // Wait.
V tmp = std::move (_v);
assert (_state == FULL);
_state = EMPTY;
return tmp;
}
};
} // namespace glim
#endif
|
