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         g_thread_init(NULL);
  40     }
  41
  42     coroutine_cond = g_cond_new();
  43 }
  44
  45 static void coroutine_wait_runnable_locked(CoroutineGThread *co)
  46 {
  47     while (!co->runnable) {
  48         g_cond_wait(coroutine_cond, g_static_mutex_get_mutex(&coroutine_lock));
  49     }
  50 }
  51
  52 static void coroutine_wait_runnable(CoroutineGThread *co)
  53 {
  54     g_static_mutex_lock(&coroutine_lock);
  55     coroutine_wait_runnable_locked(co);
  56     g_static_mutex_unlock(&coroutine_lock);
  57 }
  58
  59 static gpointer coroutine_thread(gpointer opaque)
  60 {
  61     CoroutineGThread *co = opaque;
  62
  63     g_static_private_set(&coroutine_key, co, NULL);
  64     coroutine_wait_runnable(co);
  65     co->base.entry(co->base.entry_arg);
  66     qemu_coroutine_switch(&co->base, co->base.caller, COROUTINE_TERMINATE);
  67     return NULL;
  68 }
  69
  70 Coroutine *qemu_coroutine_new(void)
  71 {
  72     CoroutineGThread *co;
  73
  74     co = g_malloc0(sizeof(*co));
  75     co->thread = g_thread_create_full(coroutine_thread, co, 0, TRUE, TRUE,
  76                                       G_THREAD_PRIORITY_NORMAL, NULL);
  77     if (!co->thread) {
  78         g_free(co);
  79         return NULL;
  80     }
  81     return &co->base;
  82 }
  83
  84 void qemu_coroutine_delete(Coroutine *co_)
  85 {
  86     CoroutineGThread *co = DO_UPCAST(CoroutineGThread, base, co_);
  87
  88     g_thread_join(co->thread);
  89     g_free(co);
  90 }
  91
  92 CoroutineAction qemu_coroutine_switch(Coroutine *from_,
  93                                       Coroutine *to_,
  94                                       CoroutineAction action)
  95 {
  96     CoroutineGThread *from = DO_UPCAST(CoroutineGThread, base, from_);
  97     CoroutineGThread *to = DO_UPCAST(CoroutineGThread, base, to_);
  98
  99     g_static_mutex_lock(&coroutine_lock);
 100     from->runnable = false;
 101     from->action = action;
 102     to->runnable = true;
 103     to->action = action;
 104     g_cond_broadcast(coroutine_cond);
 105
 106     if (action != COROUTINE_TERMINATE) {
 107         coroutine_wait_runnable_locked(from);
 108     }
 109     g_static_mutex_unlock(&coroutine_lock);
 110     return from->action;
 111 }
 112
 113 Coroutine *qemu_coroutine_self(void)
 114 {
 115     CoroutineGThread *co = g_static_private_get(&coroutine_key);
 116
 117     if (!co) {
 118         co = g_malloc0(sizeof(*co));
 119         co->runnable = true;
 120         g_static_private_set(&coroutine_key, co, (GDestroyNotify)g_free);
 121     }
 122
 123     return &co->base;
 124 }
 125
 126 bool qemu_in_coroutine(void)
 127 {
 128     CoroutineGThread *co = g_static_private_get(&coroutine_key);
 129
 130     return co && co->base.caller;
 131 }