trap signals for "-serial mon:stdio"
[qemu.git] / coroutine-gthread.c
1 /*
2 * GThread coroutine initialization code
3 *
4 * Copyright (C) 2006 Anthony Liguori <anthony@codemonkey.ws>
5 * Copyright (C) 2011 Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
6 *
7 * This library is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.0 of the License, or (at your option) any later version.
11 *
12 * This library is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with this library; if not, see <http://www.gnu.org/licenses/>.
19 */
20
21 #include <glib.h>
22 #include "qemu-common.h"
23 #include "block/coroutine_int.h"
24
25 typedef struct {
26 Coroutine base;
27 GThread *thread;
28 bool runnable;
29 bool free_on_thread_exit;
30 CoroutineAction action;
31 } CoroutineGThread;
32
33 static GStaticMutex coroutine_lock = G_STATIC_MUTEX_INIT;
34
35 /* GLib 2.31 and beyond deprecated various parts of the thread API,
36 * but the new interfaces are not available in older GLib versions
37 * so we have to cope with both.
38 */
39 #if GLIB_CHECK_VERSION(2, 31, 0)
40 /* Default zero-initialisation is sufficient for 2.31+ GCond */
41 static GCond the_coroutine_cond;
42 static GCond *coroutine_cond = &the_coroutine_cond;
43 static inline void init_coroutine_cond(void)
44 {
45 }
46
47 /* Awkwardly, the GPrivate API doesn't provide a way to update the
48 * GDestroyNotify handler for the coroutine key dynamically. So instead
49 * we track whether or not the CoroutineGThread should be freed on
50 * thread exit / coroutine key update using the free_on_thread_exit
51 * field.
52 */
53 static void coroutine_destroy_notify(gpointer data)
54 {
55 CoroutineGThread *co = data;
56 if (co && co->free_on_thread_exit) {
57 g_free(co);
58 }
59 }
60
61 static GPrivate coroutine_key = G_PRIVATE_INIT(coroutine_destroy_notify);
62
63 static inline CoroutineGThread *get_coroutine_key(void)
64 {
65 return g_private_get(&coroutine_key);
66 }
67
68 static inline void set_coroutine_key(CoroutineGThread *co,
69 bool free_on_thread_exit)
70 {
71 /* Unlike g_static_private_set() this does not call the GDestroyNotify
72 * if the previous value of the key was NULL. Fortunately we only need
73 * the GDestroyNotify in the non-NULL key case.
74 */
75 co->free_on_thread_exit = free_on_thread_exit;
76 g_private_replace(&coroutine_key, co);
77 }
78
79 static inline GThread *create_thread(GThreadFunc func, gpointer data)
80 {
81 return g_thread_new("coroutine", func, data);
82 }
83
84 #else
85
86 /* Handle older GLib versions */
87 static GCond *coroutine_cond;
88 static inline void init_coroutine_cond(void)
89 {
90 coroutine_cond = g_cond_new();
91 }
92
93 static GStaticPrivate coroutine_key = G_STATIC_PRIVATE_INIT;
94
95 static inline CoroutineGThread *get_coroutine_key(void)
96 {
97 return g_static_private_get(&coroutine_key);
98 }
99
100 static inline void set_coroutine_key(CoroutineGThread *co,
101 bool free_on_thread_exit)
102 {
103 g_static_private_set(&coroutine_key, co,
104 free_on_thread_exit ? (GDestroyNotify)g_free : NULL);
105 }
106
107 static inline GThread *create_thread(GThreadFunc func, gpointer data)
108 {
109 return g_thread_create_full(func, data, 0, TRUE, TRUE,
110 G_THREAD_PRIORITY_NORMAL, NULL);
111 }
112
113 #endif
114
115
116 static void __attribute__((constructor)) coroutine_init(void)
117 {
118 if (!g_thread_supported()) {
119 #if !GLIB_CHECK_VERSION(2, 31, 0)
120 g_thread_init(NULL);
121 #else
122 fprintf(stderr, "glib threading failed to initialize.\n");
123 exit(1);
124 #endif
125 }
126
127 init_coroutine_cond();
128 }
129
130 static void coroutine_wait_runnable_locked(CoroutineGThread *co)
131 {
132 while (!co->runnable) {
133 g_cond_wait(coroutine_cond, g_static_mutex_get_mutex(&coroutine_lock));
134 }
135 }
136
137 static void coroutine_wait_runnable(CoroutineGThread *co)
138 {
139 g_static_mutex_lock(&coroutine_lock);
140 coroutine_wait_runnable_locked(co);
141 g_static_mutex_unlock(&coroutine_lock);
142 }
143
144 static gpointer coroutine_thread(gpointer opaque)
145 {
146 CoroutineGThread *co = opaque;
147
148 set_coroutine_key(co, false);
149 coroutine_wait_runnable(co);
150 co->base.entry(co->base.entry_arg);
151 qemu_coroutine_switch(&co->base, co->base.caller, COROUTINE_TERMINATE);
152 return NULL;
153 }
154
155 Coroutine *qemu_coroutine_new(void)
156 {
157 CoroutineGThread *co;
158
159 co = g_malloc0(sizeof(*co));
160 co->thread = create_thread(coroutine_thread, co);
161 if (!co->thread) {
162 g_free(co);
163 return NULL;
164 }
165 return &co->base;
166 }
167
168 void qemu_coroutine_delete(Coroutine *co_)
169 {
170 CoroutineGThread *co = DO_UPCAST(CoroutineGThread, base, co_);
171
172 g_thread_join(co->thread);
173 g_free(co);
174 }
175
176 CoroutineAction qemu_coroutine_switch(Coroutine *from_,
177 Coroutine *to_,
178 CoroutineAction action)
179 {
180 CoroutineGThread *from = DO_UPCAST(CoroutineGThread, base, from_);
181 CoroutineGThread *to = DO_UPCAST(CoroutineGThread, base, to_);
182
183 g_static_mutex_lock(&coroutine_lock);
184 from->runnable = false;
185 from->action = action;
186 to->runnable = true;
187 to->action = action;
188 g_cond_broadcast(coroutine_cond);
189
190 if (action != COROUTINE_TERMINATE) {
191 coroutine_wait_runnable_locked(from);
192 }
193 g_static_mutex_unlock(&coroutine_lock);
194 return from->action;
195 }
196
197 Coroutine *qemu_coroutine_self(void)
198 {
199 CoroutineGThread *co = get_coroutine_key();
200 if (!co) {
201 co = g_malloc0(sizeof(*co));
202 co->runnable = true;
203 set_coroutine_key(co, true);
204 }
205
206 return &co->base;
207 }
208
209 bool qemu_in_coroutine(void)
210 {
211 CoroutineGThread *co = get_coroutine_key();
212
213 return co && co->base.caller;
214 }