iothread.c

   1 /*
   2  * Event loop thread
   3  *
   4  * Copyright Red Hat Inc., 2013
   5  *
   6  * Authors:
   7  *  Stefan Hajnoczi   <stefanha@redhat.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  10  * See the COPYING file in the top-level directory.
  11  *
  12  */
  13
  14 #include "qom/object.h"
  15 #include "qom/object_interfaces.h"
  16 #include "qemu/module.h"
  17 #include "qemu/thread.h"
  18 #include "block/aio.h"
  19 #include "sysemu/iothread.h"
  20
  21 #define IOTHREADS_PATH "/objects"
  22
  23 typedef ObjectClass IOThreadClass;
  24 struct IOThread {
  25     Object parent_obj;
  26
  27     QemuThread thread;
  28     AioContext *ctx;
  29     bool stopping;
  30 };
  31
  32 #define IOTHREAD_GET_CLASS(obj) \
  33    OBJECT_GET_CLASS(IOThreadClass, obj, TYPE_IOTHREAD)
  34 #define IOTHREAD_CLASS(klass) \
  35    OBJECT_CLASS_CHECK(IOThreadClass, klass, TYPE_IOTHREAD)
  36
  37 static void *iothread_run(void *opaque)
  38 {
  39     IOThread *iothread = opaque;
  40
  41     while (!iothread->stopping) {
  42         aio_context_acquire(iothread->ctx);
  43         while (!iothread->stopping && aio_poll(iothread->ctx, true)) {
  44             /* Progress was made, keep going */
  45         }
  46         aio_context_release(iothread->ctx);
  47     }
  48     return NULL;
  49 }
  50
  51 static void iothread_instance_finalize(Object *obj)
  52 {
  53     IOThread *iothread = IOTHREAD(obj);
  54
  55     iothread->stopping = true;
  56     aio_notify(iothread->ctx);
  57     qemu_thread_join(&iothread->thread);
  58     aio_context_unref(iothread->ctx);
  59 }
  60
  61 static void iothread_complete(UserCreatable *obj, Error **errp)
  62 {
  63     IOThread *iothread = IOTHREAD(obj);
  64
  65     iothread->stopping = false;
  66     iothread->ctx = aio_context_new();
  67
  68     /* This assumes we are called from a thread with useful CPU affinity for us
  69      * to inherit.
  70      */
  71     qemu_thread_create(&iothread->thread, "iothread", iothread_run,
  72                        iothread, QEMU_THREAD_JOINABLE);
  73 }
  74
  75 static void iothread_class_init(ObjectClass *klass, void *class_data)
  76 {
  77     UserCreatableClass *ucc = USER_CREATABLE_CLASS(klass);
  78     ucc->complete = iothread_complete;
  79 }
  80
  81 static const TypeInfo iothread_info = {
  82     .name = TYPE_IOTHREAD,
  83     .parent = TYPE_OBJECT,
  84     .class_init = iothread_class_init,
  85     .instance_size = sizeof(IOThread),
  86     .instance_finalize = iothread_instance_finalize,
  87     .interfaces = (InterfaceInfo[]) {
  88         {TYPE_USER_CREATABLE},
  89         {}
  90     },
  91 };
  92
  93 static void iothread_register_types(void)
  94 {
  95     type_register_static(&iothread_info);
  96 }
  97
  98 type_init(iothread_register_types)
  99
 100 IOThread *iothread_find(const char *id)
 101 {
 102     Object *container = container_get(object_get_root(), IOTHREADS_PATH);
 103     Object *child;
 104
 105     child = object_property_get_link(container, id, NULL);
 106     if (!child) {
 107         return NULL;
 108     }
 109     return (IOThread *)object_dynamic_cast(child, TYPE_IOTHREAD);
 110 }
 111
 112 char *iothread_get_id(IOThread *iothread)
 113 {
 114     return object_get_canonical_path_component(OBJECT(iothread));
 115 }
 116
 117 AioContext *iothread_get_aio_context(IOThread *iothread)
 118 {
 119     return iothread->ctx;
 120 }