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
|
/*
*
* Copyright (c) 2006 The Apache Software Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
#ifndef _TaskQueue_
#define _TaskQueue_
#include <iostream>
#include <memory>
#include <queue>
#include "LockedQueue.h"
#include "Runnable.h"
#include "ThreadPool.h"
namespace qpid {
namespace concurrent {
template<class T, class L> class TaskQueue : public virtual Runnable
{
const int max_iterations_per_run;
L lock;
//LockedQueue<T, L> queue;
std::queue<T*> queue;
ThreadPool* const pool;
T* work;
bool running;
volatile bool stopped;
TaskQueue<T, L>* next;
volatile bool inrun;
bool hasWork();
void completed();
T* take();
protected:
/**
* Callback though which the task is executed
*/
virtual void execute(T* t) = 0;
/**
* Allows a task to be completed asynchronously to the
* execute() call if required.
*/
virtual bool isComplete(T* t);
/**
* Should be called to signal completion of a task that was
* signalled as not complete through the isComplete() methods
* return value. This will allow normal processing to resume.
*/
virtual void complete();
public:
TaskQueue(ThreadPool* const pool, int max_iterations_per_run = 100);
virtual void run();
void trigger();
bool append(T* t);
void stop(bool drain);
inline void setNext(TaskQueue<T, L>* next){ this->next = next; }
};
template<class T, class L> TaskQueue<T, L>::TaskQueue(ThreadPool* const _pool, int _max_iterations_per_run) :
pool(_pool),
max_iterations_per_run(_max_iterations_per_run),
work(0),
running(false),
stopped(false),
next(0), inrun(false){
}
template<class T, class L> void TaskQueue<T, L>::run(){
if(inrun) std::cout << "Already running" << std::endl;
inrun = true;
bool blocked = false;
int count = max_iterations_per_run;
while(!blocked && hasWork() && count){
execute(work);
if(isComplete(work)){
completed();
}else{
blocked = true;
}
count--;
}
inrun = false;
if(!blocked && count == 0){//performed max_iterations_per_run, requeue task to ensure fairness
//running will still be true at this point
lock.acquire();
running = false;
if(stopped) lock.notify();
lock.release();
trigger();
}else if(hasWork()){//task was added to queue after we exited the loop above; should not need this?
trigger();
}
}
template<class T, class L> void TaskQueue<T, L>::trigger(){
lock.acquire();
if(!running){
running = true;
pool->addTask(this);
}
lock.release();
}
template<class T, class L> bool TaskQueue<T, L>::hasWork(){
lock.acquire();
if(!work) work = take();//queue.take();
if(!work){
running = false;
if(stopped) lock.notify();
}
lock.release();
return work;
}
template<class T, class L> bool TaskQueue<T, L>::append(T* item){
if(!stopped){
lock.acquire();
//queue.put(item);
queue.push(item);
if(!running){
running = true;
pool->addTask(this);
}
lock.release();
//}
return true;
}else{
return false;
}
}
template<class T, class L> bool TaskQueue<T, L>::isComplete(T* item){
return true;//by default assume all tasks are synchronous w.r.t. execute()
}
template<class T, class L> void TaskQueue<T, L>::completed(){
if(next){
if(!next->append(work)){
std::cout << "Warning: dropping task as next queue appears to have stopped." << std::endl;
}
}else{
delete work;
}
work = 0;
}
template<class T, class L> void TaskQueue<T, L>::complete(){
completed();
lock.acquire();
running = false;
if(stopped) lock.notify();
lock.release();
}
template<class T, class L> void TaskQueue<T, L>::stop(bool drain){
//prevent new tasks from being added
stopped = true;
//wait until no longer running
lock.acquire();
while(running && (drain && hasWork())){
lock.wait();
}
lock.release();
}
template<class T, class L> T* TaskQueue<T, L>::take(){
T* item = 0;
if(!queue.empty()){
item = queue.front();
queue.pop();
}
return item;
}
}
}
#endif
|
