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
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
|
/* Copyright (C) 1995, 1996 Free Software Foundation, Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2, or (at your option)
* any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this software; see the file COPYING. If not, write to
* the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
*
* As a special exception, the Free Software Foundation gives permission
* for additional uses of the text contained in its release of GUILE.
*
* The exception is that, if you link the GUILE library with other files
* to produce an executable, this does not by itself cause the
* resulting executable to be covered by the GNU General Public License.
* Your use of that executable is in no way restricted on account of
* linking the GUILE library code into it.
*
* This exception does not however invalidate any other reasons why
* the executable file might be covered by the GNU General Public License.
*
* This exception applies only to the code released by the
* Free Software Foundation under the name GUILE. If you copy
* code from other Free Software Foundation releases into a copy of
* GUILE, as the General Public License permits, the exception does
* not apply to the code that you add in this way. To avoid misleading
* anyone as to the status of such modified files, you must delete
* this exception notice from them.
*
* If you write modifications of your own for GUILE, it is your choice
* whether to permit this exception to apply to your modifications.
* If you do not wish that, delete this exception notice.
*/
#ifndef GSCM_COOP_THREADS_H
#define GSCM_COOP_THREADS_H
#include <qt.h>
#include <time.h>
/* This code is based on a sample thread libraru by David Keppel.
Portions of this file fall under the following copyright: */
/*
* QuickThreads -- Threads-building toolkit.
* Copyright (c) 1993 by David Keppel
*
* Permission to use, copy, modify and distribute this software and
* its documentation for any purpose and without fee is hereby
* granted, provided that the above copyright notice and this notice
* appear in all copies. This software is provided as a
* proof-of-concept and for demonstration purposes; there is no
* representation about the suitability of this software for any
* purpose.
*/
/* The notion of a thread is merged with the notion of a queue.
Thread stuff: thread status (sp) and stuff to use during
(re)initialization. Queue stuff: next thread in the queue
(next). */
typedef struct coop_t {
qt_t *sp; /* QuickThreads handle. */
void *sto; /* `malloc'-allocated stack. */
struct coop_t *next; /* Next thread in the queue. */
struct coop_t *all_next;
struct coop_t *all_prev;
void *data; /* Thread local data */
void *base; /* Base of stack */
void *top; /* Top of stack */
void *joining; /* A queue of threads waiting to join this
thread */
time_t wakeup_time; /* Time to stop sleeping */
} coop_t;
/* A queue is a circular list of threads. The queue head is a
designated list element. If this is a uniprocessor-only
implementation we can store the `main' thread in this, but in a
multiprocessor there are several `heavy' threads but only one run
queue. A fancier implementation might have private run queues,
which would lead to a simpler (trivial) implementation */
typedef struct coop_q_t {
coop_t t;
coop_t *tail;
} coop_q_t;
/* A Mutex variable is made up of a owner thread, and a queue of threads
waiting on the mutex */
typedef struct coop_m {
coop_t *owner; /* Mutex owner */
coop_q_t waiting; /* Queue of waiting threads */
} coop_m;
/* A Condition variable is made up of a list of threads waiting on the
condition. */
typedef struct coop_c {
coop_q_t waiting; /* Queue of waiting threads */
} coop_c;
/* Each thread starts by calling a user-supplied function of this
type. */
typedef void (coop_userf_t)(void *p0);
/* Call this before any other primitives. */
extern void coop_init();
/* When one or more threads are created by the main thread,
the system goes multithread when this is called. It is done
(no more runable threads) when this returns. */
extern void coop_start (void);
/* Create a thread and make it runable. When the thread starts
running it will call `f' with arguments `p0' and `p1'. */
extern coop_t *coop_create (coop_userf_t *f, void *p0);
/* The current thread stops running but stays runable.
It is an error to call `coop_yield' before `coop_start'
is called or after `coop_start' returns. */
extern void coop_yield (void);
/* Like `coop_yield' but the thread is discarded. Any intermediate
state is lost. The thread can also terminate by simply
returning. */
extern void coop_abort (void);
extern coop_q_t coop_global_allq; /* A queue of all threads. */
extern coop_t *coop_global_curr; /* Currently-executing thread. */
extern size_t scm_switch_counter;
extern size_t scm_thread_count;
/* Cooperative threads don't need to have these defined */
#define SCM_THREAD_CRITICAL_SECTION_START
#define SCM_THREAD_CRITICAL_SECTION_END
#define SCM_THREAD_INITIALIZE_STORAGE gscm_threads_init_coop_threads()
#define SCM_NO_CRITICAL_SECTION_OWNER 0
#define SCM_THREAD_SWITCH_COUNT 10
#define SCM_DEFER_INTS \
{ \
scm_ints_disabled = 1; \
}
#define SCM_ALLOW_INTS \
{ \
scm_ints_disabled = 0; \
SCM_CHECK_INTS; \
scm_switch_counter--; \
if (scm_switch_counter == 0) \
{ \
scm_switch_counter = SCM_THREAD_SWITCH_COUNT; \
if (scm_thread_count > 1) \
coop_yield(); \
} \
}
#define SCM_REDEFER_INTS \
{ \
++scm_ints_disabled; \
}
#define SCM_REALLOW_INTS \
{ \
--scm_ints_disabled; \
if (!scm_ints_disabled) \
{ \
SCM_CHECK_INTS; \
} \
scm_switch_counter--; \
if (scm_switch_counter == 0) \
{ \
scm_switch_counter = SCM_THREAD_SWITCH_COUNT; \
if (scm_thread_count > 1) \
coop_yield(); \
} \
}
/* This structure is used when creating new threads. */
struct scm_coop_create_info_type
{
SCM thunk;
SCM error;
};
extern struct scm_coop_create_info_type scm_coop_create_info;
#endif
|