[Qemu-devel] [PATCH 03/14] qio: introduce qio_channel_add_watch_full()

[Peter Xu <peterx@redhat.com>]

It's a more powerful version of qio_channel_add_watch(), which supports
non-default gcontext.  It's stripped from the old one, then we have
g_source_get_id() to fetch the tag ID to keep the old interface.

Note that the new API will return a gsource, meanwhile keep a reference
of it so that callers need to unref them explicitly.

Signed-off-by: Peter Xu <peterx@redhat.com>
---
 include/io/channel.h | 31 ++++++++++++++++++++++++++++---
 io/channel.c         | 24 +++++++++++++++++++-----
 2 files changed, 47 insertions(+), 8 deletions(-)

diff --git a/include/io/channel.h b/include/io/channel.h
index 3995e243a3..36af5e58ae 100644
--- a/include/io/channel.h
+++ b/include/io/channel.h
@@ -620,20 +620,45 @@ GSource *qio_channel_create_watch(QIOChannel *ioc,
                                   GIOCondition condition);
 
 /**
- * qio_channel_add_watch:
+ * qio_channel_add_watch_full:
  * @ioc: the channel object
  * @condition: the I/O condition to monitor
  * @func: callback to invoke when the source becomes ready
  * @user_data: opaque data to pass to @func
  * @notify: callback to free @user_data
+ * @context: gcontext to bind the source to
  *
- * Create a new main loop source that is used to watch
+ * Create a new source that is used to watch
  * for the I/O condition @condition. The callback @func
  * will be registered against the source, to be invoked
  * when the source becomes ready. The optional @user_data
  * will be passed to @func when it is invoked. The @notify
  * callback will be used to free @user_data when the
- * watch is deleted
+ * watch is deleted.  The source will be bound to @context if
+ * provided, or main context if it is NULL.
+ *
+ * Note: if a valid source is returned, we need to explicitly unref
+ * the source to destroy it.
+ *
+ * Returns: the source pointer
+ */
+GSource *qio_channel_add_watch_full(QIOChannel *ioc,
+                                    GIOCondition condition,
+                                    QIOChannelFunc func,
+                                    gpointer user_data,
+                                    GDestroyNotify notify,
+                                    GMainContext *context);
+
+/**
+ * qio_channel_add_watch:
+ * @ioc: the channel object
+ * @condition: the I/O condition to monitor
+ * @func: callback to invoke when the source becomes ready
+ * @user_data: opaque data to pass to @func
+ * @notify: callback to free @user_data
+ *
+ * Wrapper of qio_channel_add_watch_full(), but it'll only bind the
+ * source object to default main context.
  *
  * The returned source ID can be used with g_source_remove()
  * to remove and free the source when no longer required.
diff --git a/io/channel.c b/io/channel.c
index ec4b86de7c..3e734cc9a5 100644
--- a/io/channel.c
+++ b/io/channel.c
@@ -299,6 +299,22 @@ void qio_channel_set_aio_fd_handler(QIOChannel *ioc,
     klass->io_set_aio_fd_handler(ioc, ctx, io_read, io_write, opaque);
 }
 
+GSource *qio_channel_add_watch_full(QIOChannel *ioc,
+                                    GIOCondition condition,
+                                    QIOChannelFunc func,
+                                    gpointer user_data,
+                                    GDestroyNotify notify,
+                                    GMainContext *context)
+{
+    GSource *source;
+
+    source = qio_channel_create_watch(ioc, condition);
+    g_source_set_callback(source, (GSourceFunc)func, user_data, notify);
+    g_source_attach(source, context);
+
+    return source;
+}
+
 guint qio_channel_add_watch(QIOChannel *ioc,
                             GIOCondition condition,
                             QIOChannelFunc func,
@@ -308,11 +324,9 @@ guint qio_channel_add_watch(QIOChannel *ioc,
     GSource *source;
     guint id;
 
-    source = qio_channel_create_watch(ioc, condition);
-
-    g_source_set_callback(source, (GSourceFunc)func, user_data, notify);
-
-    id = g_source_attach(source, NULL);
+    source = qio_channel_add_watch_full(ioc, condition, func,
+                                        user_data, notify, NULL);
+    id = g_source_get_id(source);
     g_source_unref(source);
 
     return id;
-- 
2.14.3