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
|
// 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)),
_consumerMonitor(),
_producerMonitor(),
_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;
}
uint64_t
SingleExecutor::addTask(Task::UP task) {
MonitorGuard guard(_producerMonitor);
wait_for_room(guard);
uint64_t wp = _wp.load(std::memory_order_relaxed);
_tasks[index(wp)] = std::move(task);
_wp.store(wp + 1, std::memory_order_release);
return wp;
}
void
SingleExecutor::wakeupConsumer() {
MonitorGuard guard(_consumerMonitor);
guard.signal();
}
void
SingleExecutor::sleepConsumer() {
_wakeupConsumerAt.store(_wp.load(std::memory_order_relaxed) + (_taskLimit.load(std::memory_order_relaxed) >> 2), std::memory_order_relaxed);
MonitorGuard guard(_consumerMonitor);
guard.wait(10ms);
_wakeupConsumerAt.store(0, std::memory_order_relaxed);
}
void
SingleExecutor::wakeupProducer() {
MonitorGuard guard(_producerMonitor);
guard.signal();
}
void
SingleExecutor::sleepProducer(MonitorGuard & guard) {
_producerNeedWakeup.store(true, std::memory_order_relaxed);
guard.wait(10ms);
_producerNeedWakeup.store(false, std::memory_order_relaxed);
}
Executor::Task::UP
SingleExecutor::execute(Task::UP task) {
uint64_t wp = addTask(std::move(task));
if (wp == _wakeupConsumerAt.load(std::memory_order_relaxed)) {
wakeupConsumer();
}
return task;
}
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_acquire)) {
wakeupConsumer();
MonitorGuard guard(_producerMonitor);
guard.wait(1ms);
}
return *this;
}
void
SingleExecutor::run() {
while (!_thread.stopped()) {
drain_tasks();
wakeupProducer();
sleepConsumer();
}
}
void
SingleExecutor::drain_tasks() {
while (numTasks() > 0) {
run_tasks_till(_wp.load(std::memory_order_acquire));
}
}
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_release);
if (wakeupLimit == consumed) {
wakeupProducer();
}
}
}
void
SingleExecutor::wait_for_room(MonitorGuard & producerGuard) {
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)) {
sleepProducer(producerGuard);
}
}
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;
}
}
|
