1 /*
2 * GTK VNC Widget
3 *
4 * Copyright (C) 2006 Anthony Liguori <anthony@codemonkey.ws>
5 *
6 * This library is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.0 of the License, or (at your option) any later version.
10 *
11 * This library is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with this library; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20
21 #include <config.h>
22
23 #include "coroutine.h"
24 #include <stdio.h>
25 #include <stdlib.h>
26
27 static GCond *run_cond;
28 static GMutex *run_lock;
29 static struct coroutine *current;
30 static struct coroutine leader;
31
32 #if 0
33 #define CO_DEBUG(OP) fprintf(stderr, "%s %p %s %d\n", OP, g_thread_self(), __FUNCTION__, __LINE__)
34 #else
35 #define CO_DEBUG(OP)
36 #endif
37
coroutine_system_init(void)38 static void coroutine_system_init(void)
39 {
40 if (!g_thread_supported()) {
41 CO_DEBUG("INIT");
42 g_thread_init(NULL);
43 }
44
45
46 run_cond = g_cond_new();
47 run_lock = g_mutex_new();
48 CO_DEBUG("LOCK");
49 g_mutex_lock(run_lock);
50
51 /* The thread that creates the first coroutine is the system coroutine
52 * so let's fill out a structure for it */
53 leader.entry = NULL;
54 leader.release = NULL;
55 leader.stack_size = 0;
56 leader.exited = 0;
57 leader.thread = g_thread_self();
58 leader.runnable = TRUE; /* we're the one running right now */
59 leader.caller = NULL;
60 leader.data = NULL;
61
62 current = &leader;
63 }
64
coroutine_thread(gpointer opaque)65 static gpointer coroutine_thread(gpointer opaque)
66 {
67 struct coroutine *co = opaque;
68 CO_DEBUG("LOCK");
69 g_mutex_lock(run_lock);
70 while (!co->runnable) {
71 CO_DEBUG("WAIT");
72 g_cond_wait(run_cond, run_lock);
73 }
74
75 CO_DEBUG("RUNNABLE");
76 current = co;
77 co->data = co->entry(co->data);
78 co->exited = 1;
79
80 co->caller->runnable = TRUE;
81 CO_DEBUG("BROADCAST");
82 g_cond_broadcast(run_cond);
83 CO_DEBUG("UNLOCK");
84 g_mutex_unlock(run_lock);
85
86 return NULL;
87 }
88
coroutine_init(struct coroutine * co)89 int coroutine_init(struct coroutine *co)
90 {
91 if (run_cond == NULL)
92 coroutine_system_init();
93
94 CO_DEBUG("NEW");
95 co->thread = g_thread_create_full(coroutine_thread, co, co->stack_size,
96 FALSE, TRUE,
97 G_THREAD_PRIORITY_NORMAL,
98 NULL);
99 if (co->thread == NULL)
100 return -1;
101
102 co->exited = 0;
103 co->runnable = FALSE;
104 co->caller = NULL;
105
106 return 0;
107 }
108
coroutine_release(struct coroutine * co G_GNUC_UNUSED)109 int coroutine_release(struct coroutine *co G_GNUC_UNUSED)
110 {
111 return 0;
112 }
113
coroutine_swap(struct coroutine * from,struct coroutine * to,void * arg)114 void *coroutine_swap(struct coroutine *from, struct coroutine *to, void *arg)
115 {
116 from->runnable = FALSE;
117 to->runnable = TRUE;
118 to->data = arg;
119 to->caller = from;
120 CO_DEBUG("BROADCAST");
121 g_cond_broadcast(run_cond);
122 CO_DEBUG("UNLOCK");
123 g_mutex_unlock(run_lock);
124 CO_DEBUG("LOCK");
125 g_mutex_lock(run_lock);
126 while (!from->runnable) {
127 CO_DEBUG("WAIT");
128 g_cond_wait(run_cond, run_lock);
129 }
130 current = from;
131
132 CO_DEBUG("SWAPPED");
133 return from->data;
134 }
135
coroutine_self(void)136 struct coroutine *coroutine_self(void)
137 {
138 return current;
139 }
140
coroutine_yieldto(struct coroutine * to,void * arg)141 void *coroutine_yieldto(struct coroutine *to, void *arg)
142 {
143 if (to->caller) {
144 fprintf(stderr, "Co-routine is re-entering itself\n");
145 abort();
146 }
147 CO_DEBUG("SWAP");
148 return coroutine_swap(coroutine_self(), to, arg);
149 }
150
coroutine_yield(void * arg)151 void *coroutine_yield(void *arg)
152 {
153 struct coroutine *to = coroutine_self()->caller;
154 if (!to) {
155 fprintf(stderr, "Co-routine is yielding to no one\n");
156 abort();
157 }
158
159 CO_DEBUG("SWAP");
160 coroutine_self()->caller = NULL;
161 return coroutine_swap(coroutine_self(), to, arg);
162 }
163 /*
164 * Local variables:
165 * c-indent-level: 4
166 * c-basic-offset: 4
167 * indent-tabs-mode: nil
168 * End:
169 */
170