>
> The current approach with OutputQueue in webdav has several problems:
>
> * if the connection is slow, webdav keeps reading from phodav
> and pushing messages to the internal channel xmit_queue.
> This way, the queue can grow very quickly and the whole file
> that is being transferred using webdav essentially gets loaded into memory.
>
> * spice channel first flushes all messages in the xmit_queue and
> then proceeds to reading. If webdav floods the xmit_queue with
> a ton of messages, spice channel does not leave iterate_write until
> the queue gets empty. This way, reading from the channel is blocked
> till the whole file is transferred.
>
> * OutputQueue uses g_output_stream_flush_async() on SpiceVmcOutputStream
> that does not implement flush
>
> To solve these issues, don't read from phodav until the last message
> for a given client is written out to the socket.
> (main channel currently uses the same approach when transferring files)
>
> OutputQueue used an idle function to schedule the write and then
> called mux_pushed_cb which started reading from phodav with priority
> G_PRIORITY_DEFAULT.
> Since this new approach does not utilize the idle scheduling,
> lower the priority in client_start_read() to G_PRIORITY_DEFAULT_IDLE
> to make sure other sources with lower priority get dispatched as well
> (e.g. signals from coroutines, redrawing and resizing operations).
>
> Also implement spice_webdav_channel_reset(). This is necessary because
> spice_vmc_write_async() references the channel. If the channel is to be
> disconnected, the write operations need to be cancelled so that
> the references to the channel are released asap. Otherwise,
> spice session would be stuck waiting for the channel to finalize.
>
> Signed-off-by: Jakub Janků <jjanku@xxxxxxxxxx>
Acked
> ---
> Changes since v1:
> * updated commit log and comment
> ---
> src/channel-webdav.c | 43 ++++++++++++++++++++++++++++++++-----------
> 1 file changed, 32 insertions(+), 11 deletions(-)
>
> diff --git a/src/channel-webdav.c b/src/channel-webdav.c
> index 0fa0d69..14d4e05 100644
> --- a/src/channel-webdav.c
> +++ b/src/channel-webdav.c
> @@ -45,13 +45,12 @@
> * Since: 0.24
> */
>
> -typedef struct _OutputQueue OutputQueue;
> +/* typedef struct _OutputQueue OutputQueue; */
>
> struct _SpiceWebdavChannelPrivate {
> SpiceVmcStream *stream;
> GCancellable *cancellable;
> GHashTable *clients;
> - OutputQueue *queue;
>
> gboolean demuxing;
> struct _demux {
> @@ -65,6 +64,7 @@ G_DEFINE_TYPE_WITH_PRIVATE(SpiceWebdavChannel,
> spice_webdav_channel, SPICE_TYPE_
>
> static void spice_webdav_handle_msg(SpiceChannel *channel, SpiceMsgIn *msg);
>
> +#if 0
> struct _OutputQueue {
> GOutputStream *output;
> gboolean flushing;
> @@ -178,6 +178,7 @@ static void output_queue_push(OutputQueue *q, const
> guint8 *buf, gsize size,
> if (!q->idle_id && !q->flushing)
> q->idle_id = g_idle_add(output_queue_idle, q);
> }
> +#endif
>
> #define MAX_MUX_SIZE G_MAXUINT16
>
> @@ -227,11 +228,15 @@ static void remove_client(Client *client)
> g_hash_table_remove(client->self->priv->clients, &client->id);
> }
>
> -static void mux_pushed_cb(OutputQueue *q, gpointer user_data)
> +static void
> +mux_msg_flushed_cb(GObject *source_object,
> + GAsyncResult *result,
> + gpointer user_data)
> {
> Client *client = user_data;
>
> - if (client->mux.size == 0 ||
> + if (!g_output_stream_write_all_finish(G_OUTPUT_STREAM(source_object),
> result, NULL, NULL) ||
> + client->mux.size == 0 ||
> !client_start_read(client)) {
> remove_client(client);
> }
> @@ -245,6 +250,7 @@ static void server_reply_cb(GObject *source_object,
> {
> Client *client = user_data;
> SpiceWebdavChannelPrivate *c = client->self->priv;
> + GOutputStream *mux_out;
> GError *err = NULL;
> gssize size;
>
> @@ -256,8 +262,12 @@ static void server_reply_cb(GObject *source_object,
> g_return_if_fail(size >= 0);
> client->mux.size = GUINT16_TO_LE(size);
>
> - output_queue_push(c->queue, (guint8 *)&client->mux, sizeof(gint64) +
> sizeof(guint16) + size,
> - (GFunc)mux_pushed_cb, client);
> + mux_out = g_io_stream_get_output_stream(G_IO_STREAM(c->stream));
> +
> + /* this internally uses spice_vmc_write_async(), priority is ignored;
> + * the callback is invoked once the msg is written out to the socket */
> + g_output_stream_write_all_async(mux_out, (guint8 *)&client->mux,
> sizeof(gint64) + sizeof(guint16) + size,
> + G_PRIORITY_DEFAULT, client->cancellable, mux_msg_flushed_cb,
> client);
>
> return;
>
> @@ -280,8 +290,10 @@ static bool client_start_read(Client *client)
> if (g_input_stream_is_closed(input)) {
> return false;
> }
> + /* use G_PRIORITY_DEFAULT_IDLE to make sure
> + * other low-priority sources get dispatched as well */
> g_input_stream_read_async(input, client->mux.buf, MAX_MUX_SIZE,
> - G_PRIORITY_DEFAULT, client->cancellable,
> server_reply_cb,
> + G_PRIORITY_DEFAULT_IDLE, client->cancellable,
> server_reply_cb,
> client_ref(client));
> return true;
> }
> @@ -535,9 +547,6 @@ static void spice_webdav_channel_init(SpiceWebdavChannel
> *channel)
> c->clients = g_hash_table_new_full(g_int64_hash, g_int64_equal,
> NULL, client_remove_unref);
> c->demux.buf = g_malloc0(MAX_MUX_SIZE);
> -
> - GOutputStream *ostream =
> g_io_stream_get_output_stream(G_IO_STREAM(c->stream));
> - c->queue = output_queue_new(ostream);
> }
>
> static void spice_webdav_channel_finalize(GObject *object)
> @@ -555,7 +564,6 @@ static void spice_webdav_channel_dispose(GObject *object)
>
> g_cancellable_cancel(c->cancellable);
> g_clear_object(&c->cancellable);
> - g_clear_pointer(&c->queue, output_queue_free);
> g_clear_object(&c->stream);
> g_hash_table_unref(c->clients);
>
> @@ -567,6 +575,18 @@ static void spice_webdav_channel_up(SpiceChannel
> *channel)
> CHANNEL_DEBUG(channel, "up");
> }
>
> +static void spice_webdav_channel_reset(SpiceChannel *channel, gboolean
> migrating)
> +{
> + SpiceWebdavChannelPrivate *c;
> + c =
> spice_webdav_channel_get_instance_private(SPICE_WEBDAV_CHANNEL(channel));
> +
> + g_cancellable_cancel(c->cancellable);
> + c->demuxing = FALSE;
> + g_hash_table_remove_all(c->clients);
> +
> +
> SPICE_CHANNEL_CLASS(spice_webdav_channel_parent_class)->channel_reset(channel,
> migrating);
> +}
> +
> static void spice_webdav_channel_class_init(SpiceWebdavChannelClass *klass)
> {
> GObjectClass *gobject_class = G_OBJECT_CLASS(klass);
> @@ -576,6 +596,7 @@ static void
> spice_webdav_channel_class_init(SpiceWebdavChannelClass *klass)
> gobject_class->finalize = spice_webdav_channel_finalize;
> channel_class->handle_msg = spice_webdav_handle_msg;
> channel_class->channel_up = spice_webdav_channel_up;
> + channel_class->channel_reset = spice_webdav_channel_reset;
>
> g_signal_override_class_handler("port-event",
> SPICE_TYPE_WEBDAV_CHANNEL,
Frediano
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