LXR qemu/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
  22struct 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
  33static 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
  44static 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
  79static void iothread_stop_bh(void *opaque)
  80{
  81    IOThread *iothread = opaque;
  82
  83    iothread->stopping = true;
  84}
  85
  86void 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
  98IOThread *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
 117AioContext *iothread_get_aio_context(IOThread *iothread)
 118{
 119    return iothread->ctx;
 120}
 121