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
|
// Copyright Verizon Media. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#include "singleexecutor.h"
#include <vespa/vespalib/util/time.h>
namespace vespalib {
SingleExecutor::SingleExecutor(uint32_t taskLimit)
: _taskLimit(vespalib::roundUp2inN(taskLimit)),
_wantedTaskLimit(_taskLimit.load()),
_rp(0),
_tasks(std::make_unique<Task::UP[]>(_taskLimit)),
_monitor(),
_thread(*this),
_lastAccepted(0),
_maxPending(0),
_wakeupConsumerAt(0),
_producerNeedWakeup(false),
_wp(0)
{
_thread.start();
}
SingleExecutor::~SingleExecutor() {
sync();
_thread.stop().join();
}
size_t
SingleExecutor::getNumThreads() const {
return 1;
}
Executor::Task::UP
SingleExecutor::execute(Task::UP task) {
wait_for_room();
uint64_t wp = _wp.load(std::memory_order_relaxed);
_tasks[index(wp)] = std::move(task);
_wp.store(wp + 1, std::memory_order_relaxed);
if (wp == _wakeupConsumerAt.load(std::memory_order_relaxed)) {
MonitorGuard guard(_monitor);
guard.signal();
}
return Task::UP();
}
void
SingleExecutor::setTaskLimit(uint32_t taskLimit) {
_wantedTaskLimit = vespalib::roundUp2inN(taskLimit);
}
SingleExecutor &
SingleExecutor::sync() {
uint64_t wp = _wp.load(std::memory_order_relaxed);
while (wp > _rp.load(std::memory_order_relaxed)) {
std::this_thread::sleep_for(1ms);
}
return *this;
}
void
SingleExecutor::run() {
while (!_thread.stopped()) {
drain_tasks();
_wakeupConsumerAt.store(_wp.load(std::memory_order_relaxed) + (_taskLimit.load(std::memory_order_relaxed) >> 2), std::memory_order_relaxed);
MonitorGuard guard(_monitor);
guard.wait(1ms);
_wakeupConsumerAt.store(0, std::memory_order_relaxed);
}
}
void
SingleExecutor::drain_tasks() {
while (numTasks() > 0) {
run_tasks_till(_wp.load(std::memory_order_relaxed));
}
}
void
SingleExecutor::run_tasks_till(uint64_t available) {
uint64_t consumed = _rp.load(std::memory_order_relaxed);
uint64_t left = available - consumed;
if (_maxPending.load(std::memory_order_relaxed) < left) {
_maxPending.store(left, std::memory_order_relaxed);
}
uint64_t wakeupLimit = _producerNeedWakeup.load(std::memory_order_relaxed)
? (available - (left >> 2))
: 0;
while (consumed < available) {
Task::UP task = std::move(_tasks[index(consumed)]);
task->run();
_rp.store(++consumed, std::memory_order_relaxed);
if (wakeupLimit == consumed) {
MonitorGuard guard(_monitor);
guard.signal();
}
}
}
void
SingleExecutor::wait_for_room() {
if (_taskLimit.load(std::memory_order_relaxed) != _wantedTaskLimit.load(std::memory_order_relaxed)) {
sync();
_tasks = std::make_unique<Task::UP[]>(_wantedTaskLimit);
_taskLimit = _wantedTaskLimit.load();
}
while (numTasks() >= _taskLimit.load(std::memory_order_relaxed)) {
_producerNeedWakeup.store(true, std::memory_order_relaxed);
MonitorGuard guard(_monitor);
guard.wait(1ms);
_producerNeedWakeup.store(false, std::memory_order_relaxed);
}
}
ThreadExecutor::Stats
SingleExecutor::getStats() {
uint64_t accepted = _wp.load(std::memory_order_relaxed);
Stats stats(_maxPending, (accepted - _lastAccepted), 0);
_lastAccepted = accepted;
_maxPending = 0;
return stats;
}
}
|
