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 "qemu-coroutine-int.h"
  24
  25 typedef struct {
  26     Coroutine base;
  27     GThread *thread;
  28     bool runnable;
  29     CoroutineAction action;
  30 } CoroutineGThread;
  31
  32 static GCond *coroutine_cond;
  33 static GStaticMutex coroutine_lock = G_STATIC_MUTEX_INIT;
  34 static GStaticPrivate coroutine_key = G_STATIC_PRIVATE_INIT;
  35
  36 static void __attribute__((constructor)) coroutine_init(void)
  37 {
  38     if (!g_thread_supported()) {
  39 #if !GLIB_CHECK_VERSION(2, 31, 0)
  40         g_thread_init(NULL);
  41 #else
  42         fprintf(stderr, "glib threading failed to initialize.\n");
  43         exit(1);
  44 #endif
  45     }
  46
  47     coroutine_cond = g_cond_new();
  48 }
  49
  50 static void coroutine_wait_runnable_locked(CoroutineGThread *co)
  51 {
  52     while (!co->runnable) {
  53         g_cond_wait(coroutine_cond, g_static_mutex_get_mutex(&coroutine_lock));
  54     }
  55 }
  56
  57 static void coroutine_wait_runnable(CoroutineGThread *co)
  58 {
  59     g_static_mutex_lock(&coroutine_lock);
  60     coroutine_wait_runnable_locked(co);
  61     g_static_mutex_unlock(&coroutine_lock);
  62 }
  63
  64 static gpointer coroutine_thread(gpointer opaque)
  65 {
  66     CoroutineGThread *co = opaque;
  67
  68     g_static_private_set(&coroutine_key, co, NULL);
  69     coroutine_wait_runnable(co);
  70     co->base.entry(co->base.entry_arg);
  71     qemu_coroutine_switch(&co->base, co->base.caller, COROUTINE_TERMINATE);
  72     return NULL;
  73 }
  74
  75 Coroutine *qemu_coroutine_new(void)
  76 {
  77     CoroutineGThread *co;
  78
  79     co = g_malloc0(sizeof(*co));
  80     co->thread = g_thread_create_full(coroutine_thread, co, 0, TRUE, TRUE,
  81                                       G_THREAD_PRIORITY_NORMAL, NULL);
  82     if (!co->thread) {
  83         g_free(co);
  84         return NULL;
  85     }
  86     return &co->base;
  87 }
  88
  89 void qemu_coroutine_delete(Coroutine *co_)
  90 {
  91     CoroutineGThread *co = DO_UPCAST(CoroutineGThread, base, co_);
  92
  93     g_thread_join(co->thread);
  94     g_free(co);
  95 }
  96
  97 CoroutineAction qemu_coroutine_switch(Coroutine *from_,
  98                                       Coroutine *to_,
  99                                       CoroutineAction action)
 100 {
 101     CoroutineGThread *from = DO_UPCAST(CoroutineGThread, base, from_);
 102     CoroutineGThread *to = DO_UPCAST(CoroutineGThread, base, to_);
 103
 104     g_static_mutex_lock(&coroutine_lock);
 105     from->runnable = false;
 106     from->action = action;
 107     to->runnable = true;
 108     to->action = action;
 109     g_cond_broadcast(coroutine_cond);
 110
 111     if (action != COROUTINE_TERMINATE) {
 112         coroutine_wait_runnable_locked(from);
 113     }
 114     g_static_mutex_unlock(&coroutine_lock);
 115     return from->action;
 116 }
 117
 118 Coroutine *qemu_coroutine_self(void)
 119 {
 120     CoroutineGThread *co = g_static_private_get(&coroutine_key);
 121
 122     if (!co) {
 123         co = g_malloc0(sizeof(*co));
 124         co->runnable = true;
 125         g_static_private_set(&coroutine_key, co, (GDestroyNotify)g_free);
 126     }
 127
 128     return &co->base;
 129 }
 130
 131 bool qemu_in_coroutine(void)
 132 {
 133     CoroutineGThread *co = g_static_private_get(&coroutine_key);
 134
 135     return co && co->base.caller;
 136 }