tests/unit/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 void iothread_init_gcontext(IOThread *iothread)
  34 {
  35     GSource *source;
  36
  37     iothread->worker_context = g_main_context_new();
  38     source = aio_get_g_source(iothread_get_aio_context(iothread));
  39     g_source_attach(source, iothread->worker_context);
  40     g_source_unref(source);
  41     iothread->main_loop = g_main_loop_new(iothread->worker_context, TRUE);
  42 }
  43
  44 static void *iothread_run(void *opaque)
  45 {
  46     IOThread *iothread = opaque;
  47
  48     rcu_register_thread();
  49
  50     qemu_mutex_lock(&iothread->init_done_lock);
  51     iothread->ctx = aio_context_new(&error_abort);
  52     qemu_set_current_aio_context(iothread->ctx);
  53
  54     /*
  55      * We must connect the ctx to a GMainContext, because in older versions
  56      * of glib the g_source_ref()/unref() functions are not threadsafe
  57      * on sources without a context.
  58      */
  59     iothread_init_gcontext(iothread);
  60
  61     /*
  62      * g_main_context_push_thread_default() must be called before anything
  63      * in this new thread uses glib.
  64      */
  65     g_main_context_push_thread_default(iothread->worker_context);
  66
  67     qemu_cond_signal(&iothread->init_done_cond);
  68     qemu_mutex_unlock(&iothread->init_done_lock);
  69
  70     while (!qatomic_read(&iothread->stopping)) {
  71         aio_poll(iothread->ctx, true);
  72     }
  73
  74     g_main_context_pop_thread_default(iothread->worker_context);
  75     rcu_unregister_thread();
  76     return NULL;
  77 }
  78
  79 static void iothread_stop_bh(void *opaque)
  80 {
  81     IOThread *iothread = opaque;
  82
  83     iothread->stopping = true;
  84 }
  85
  86 void iothread_join(IOThread *iothread)
  87 {
  88     aio_bh_schedule_oneshot(iothread->ctx, iothread_stop_bh, iothread);
  89     qemu_thread_join(&iothread->thread);
  90     g_main_context_unref(iothread->worker_context);
  91     g_main_loop_unref(iothread->main_loop);
  92     qemu_cond_destroy(&iothread->init_done_cond);
  93     qemu_mutex_destroy(&iothread->init_done_lock);
  94     aio_context_unref(iothread->ctx);
  95     g_free(iothread);
  96 }
  97
  98 IOThread *iothread_new(void)
  99 {
 100     IOThread *iothread = g_new0(IOThread, 1);
 101
 102     qemu_mutex_init(&iothread->init_done_lock);
 103     qemu_cond_init(&iothread->init_done_cond);
 104     qemu_thread_create(&iothread->thread, NULL, iothread_run,
 105                        iothread, QEMU_THREAD_JOINABLE);
 106
 107     /* Wait for initialization to complete */
 108     qemu_mutex_lock(&iothread->init_done_lock);
 109     while (iothread->ctx == NULL) {
 110         qemu_cond_wait(&iothread->init_done_cond,
 111                        &iothread->init_done_lock);
 112     }
 113     qemu_mutex_unlock(&iothread->init_done_lock);
 114     return iothread;
 115 }
 116
 117 AioContext *iothread_get_aio_context(IOThread *iothread)
 118 {
 119     return iothread->ctx;
 120 }