tests/iothread.c

   1 /*
   2  * Event loop thread implementation for unit tests
   3  *
   4  * Copyright Red Hat Inc., 2013, 2016
   5  *
   6  * Authors:
   7  *  Stefan Hajnoczi   <stefanha@redhat.com>
   8  *  Paolo Bonzini     <pbonzini@redhat.com>
   9  *
  10  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  11  * See the COPYING file in the top-level directory.
  12  *
  13  */
  14
  15 #include "qemu/osdep.h"
  16 #include "qapi/error.h"
  17 #include "block/aio.h"
  18 #include "qemu/main-loop.h"
  19 #include "qemu/rcu.h"
  20 #include "iothread.h"
  21
  22 struct IOThread {
  23     AioContext *ctx;
  24     GMainContext *worker_context;
  25     GMainLoop *main_loop;
  26
  27     QemuThread thread;
  28     QemuMutex init_done_lock;
  29     QemuCond init_done_cond;    /* is thread initialization done? */
  30     bool stopping;
  31 };
  32
  33 static __thread IOThread *my_iothread;
  34
  35 AioContext *qemu_get_current_aio_context(void)
  36 {
  37     return my_iothread ? my_iothread->ctx : qemu_get_aio_context();
  38 }
  39
  40 static void iothread_init_gcontext(IOThread *iothread)
  41 {
  42     GSource *source;
  43
  44     iothread->worker_context = g_main_context_new();
  45     source = aio_get_g_source(iothread_get_aio_context(iothread));
  46     g_source_attach(source, iothread->worker_context);
  47     g_source_unref(source);
  48     iothread->main_loop = g_main_loop_new(iothread->worker_context, TRUE);
  49 }
  50
  51 static void *iothread_run(void *opaque)
  52 {
  53     IOThread *iothread = opaque;
  54
  55     rcu_register_thread();
  56
  57     my_iothread = iothread;
  58     qemu_mutex_lock(&iothread->init_done_lock);
  59     iothread->ctx = aio_context_new(&error_abort);
  60
  61     /*
  62      * We must connect the ctx to a GMainContext, because in older versions
  63      * of glib the g_source_ref()/unref() functions are not threadsafe
  64      * on sources without a context.
  65      */
  66     iothread_init_gcontext(iothread);
  67
  68     /*
  69      * g_main_context_push_thread_default() must be called before anything
  70      * in this new thread uses glib.
  71      */
  72     g_main_context_push_thread_default(iothread->worker_context);
  73
  74     qemu_cond_signal(&iothread->init_done_cond);
  75     qemu_mutex_unlock(&iothread->init_done_lock);
  76
  77     while (!qatomic_read(&iothread->stopping)) {
  78         aio_poll(iothread->ctx, true);
  79     }
  80
  81     g_main_context_pop_thread_default(iothread->worker_context);
  82     rcu_unregister_thread();
  83     return NULL;
  84 }
  85
  86 static void iothread_stop_bh(void *opaque)
  87 {
  88     IOThread *iothread = opaque;
  89
  90     iothread->stopping = true;
  91 }
  92
  93 void iothread_join(IOThread *iothread)
  94 {
  95     aio_bh_schedule_oneshot(iothread->ctx, iothread_stop_bh, iothread);
  96     qemu_thread_join(&iothread->thread);
  97     g_main_context_unref(iothread->worker_context);
  98     g_main_loop_unref(iothread->main_loop);
  99     qemu_cond_destroy(&iothread->init_done_cond);
 100     qemu_mutex_destroy(&iothread->init_done_lock);
 101     aio_context_unref(iothread->ctx);
 102     g_free(iothread);
 103 }
 104
 105 IOThread *iothread_new(void)
 106 {
 107     IOThread *iothread = g_new0(IOThread, 1);
 108
 109     qemu_mutex_init(&iothread->init_done_lock);
 110     qemu_cond_init(&iothread->init_done_cond);
 111     qemu_thread_create(&iothread->thread, NULL, iothread_run,
 112                        iothread, QEMU_THREAD_JOINABLE);
 113
 114     /* Wait for initialization to complete */
 115     qemu_mutex_lock(&iothread->init_done_lock);
 116     while (iothread->ctx == NULL) {
 117         qemu_cond_wait(&iothread->init_done_cond,
 118                        &iothread->init_done_lock);
 119     }
 120     qemu_mutex_unlock(&iothread->init_done_lock);
 121     return iothread;
 122 }
 123
 124 AioContext *iothread_get_aio_context(IOThread *iothread)
 125 {
 126     return iothread->ctx;
 127 }