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
|
/*
Title: Task farm for Multi-Threaded Garbage Collector
Copyright (c) 2010-12 David C. J. Matthews
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef GCTASKFARM_H_INCLUDED
#define GCTASKFARM_H_INCLUDED
#include "locking.h"
// An empty class just used as an ID.
class GCTaskId {
};
extern GCTaskId *globalTask; // The ID used when a function is run immediately
// Function for action. The usual C++ approach would be to use an
// object pointer but that requires lots of small objects to be created
// and deleted.
typedef void (*gctask)(GCTaskId*, void*, void*);
typedef struct {
gctask task;
void *arg1;
void *arg2;
} queue_entry;
class GCTaskFarm {
public:
GCTaskFarm();
~GCTaskFarm();
bool Initialise(unsigned threadCount, unsigned queueSize);
bool AddWork(gctask task, void *arg1, void *arg2);
void AddWorkOrRunNow(gctask task, void *arg1, void *arg2);
void WaitForCompletion(void);
void Terminate(void);
// See if the queue is draining. Used as a hint as to whether
// it's worth sparking off some new work.
bool Draining(void) const { return queuedItems == 0; }
unsigned ThreadCount(void) const { return threadCount; }
private:
// The semaphore is zero if there is no work or some value up to
// the number of threads if there is work.
PSemaphore waitForWork;
// The lock protects the queue and the item count.
PLock workLock;
// The condition variable is signalled when the queue is empty.
// This can only be waited for by a single thread because it's not a proper
// implementation of a condition variable in Windows.
PCondVar waitForCompletion;
unsigned queueSize, queueIn, queuedItems;
queue_entry *workQueue; // Array of unit->unit functions.
bool terminate; // Set to true to kill all workers.
unsigned threadCount; // Count of workers.
unsigned activeThreadCount; // Count of workers doing work.
void ThreadFunction(void);
#if ((!defined(_WIN32) || defined(__CYGWIN__)) && defined(HAVE_PTHREAD_H))
static void *WorkerThreadFunction(void *parameter);
pthread_t *threadHandles;
#elif defined(HAVE_WINDOWS_H)
static DWORD WINAPI WorkerThreadFunction(void *parameter);
HANDLE *threadHandles;
#endif
};
#endif
|
