From c1e32b90576af11556c8a9178e43902f3394a4b0 Mon Sep 17 00:00:00 2001 From: Patrick Griffis Date: Mon, 29 Oct 2018 09:53:07 -0400 Subject: [PATCH] gsocketclient: Improve handling of slow initial connections Currently a new connection will not be attempted until the previous one has timed out and as the current API only exposes a single timeout value in practice it often means that it will wait 30 seconds (or forever with 0 (the default)) on each connection. This is unacceptable so we are now trying to follow the behavior RFC 8305 recommends by making multiple connection attempts if the connection takes longer than 250ms. The first connection to make it to completion then wins. --- gio/gsocketclient.c | 174 ++++++++++++++++++++++++++++++++++++++------ 1 file changed, 150 insertions(+), 24 deletions(-) diff --git a/gio/gsocketclient.c b/gio/gsocketclient.c index ddd149734..5c6513c3d 100644 --- a/gio/gsocketclient.c +++ b/gio/gsocketclient.c @@ -2,6 +2,7 @@ * * Copyright © 2008, 2009 codethink * Copyright © 2009 Red Hat, Inc + * Copyright © 2018 Igalia S.L. * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public @@ -49,6 +50,10 @@ #include #include "glibintl.h" +/* As recommended by RFC 8305 this is the time it waits + * on a connection before starting another concurrent attempt. + */ +#define HAPPY_EYEBALLS_CONNECTION_ATTEMPT_TIMEOUT_MS 250 /** * SECTION:gsocketclient @@ -1328,28 +1333,82 @@ typedef struct GSocketConnectable *connectable; GSocketAddressEnumerator *enumerator; GProxyAddress *proxy_addr; - GSocketAddress *current_addr; - GSocket *current_socket; + GSocket *socket; GIOStream *connection; + GSList *connection_attempts; GError *last_error; } GSocketClientAsyncConnectData; +static void connection_attempt_unref (gpointer attempt); + static void g_socket_client_async_connect_data_free (GSocketClientAsyncConnectData *data) { g_clear_object (&data->connectable); g_clear_object (&data->enumerator); g_clear_object (&data->proxy_addr); - g_clear_object (&data->current_addr); - g_clear_object (&data->current_socket); + g_clear_object (&data->socket); g_clear_object (&data->connection); + g_slist_free_full (data->connection_attempts, connection_attempt_unref); g_clear_error (&data->last_error); g_slice_free (GSocketClientAsyncConnectData, data); } +typedef struct +{ + GSocketAddress *address; + GSocket *socket; + GIOStream *connection; + GSocketClientAsyncConnectData *data; /* unowned */ + GSource *timeout_source; + GCancellable *cancellable; + grefcount ref; +} ConnectionAttempt; + +static ConnectionAttempt * +connection_attempt_new (void) +{ + ConnectionAttempt *attempt = g_new0 (ConnectionAttempt, 1); + g_ref_count_init (&attempt->ref); + return attempt; +} + +static ConnectionAttempt * +connection_attempt_ref (ConnectionAttempt *attempt) +{ + g_ref_count_inc (&attempt->ref); + return attempt; +} + +static void +connection_attempt_unref (gpointer pointer) +{ + ConnectionAttempt *attempt = pointer; + if (g_ref_count_dec (&attempt->ref)) + { + g_clear_object (&attempt->address); + g_clear_object (&attempt->socket); + g_clear_object (&attempt->connection); + g_clear_object (&attempt->cancellable); + if (attempt->timeout_source) + { + g_source_destroy (attempt->timeout_source); + g_source_unref (attempt->timeout_source); + } + g_free (attempt); + } +} + +static void +connection_attempt_remove (ConnectionAttempt *attempt) +{ + attempt->data->connection_attempts = g_slist_remove (attempt->data->connection_attempts, attempt); + connection_attempt_unref (attempt); +} + static void g_socket_client_async_connect_complete (GSocketClientAsyncConnectData *data) { @@ -1359,8 +1418,7 @@ g_socket_client_async_connect_complete (GSocketClientAsyncConnectData *data) { GSocketConnection *wrapper_connection; - wrapper_connection = g_tcp_wrapper_connection_new (data->connection, - data->current_socket); + wrapper_connection = g_tcp_wrapper_connection_new (data->connection, data->socket); g_object_unref (data->connection); data->connection = (GIOStream *)wrapper_connection; } @@ -1389,8 +1447,7 @@ static void enumerator_next_async (GSocketClientAsyncConnectData *data) { /* We need to cleanup the state */ - g_clear_object (&data->current_socket); - g_clear_object (&data->current_addr); + g_clear_object (&data->socket); g_clear_object (&data->proxy_addr); g_clear_object (&data->connection); @@ -1485,34 +1542,68 @@ g_socket_client_connected_callback (GObject *source, GAsyncResult *result, gpointer user_data) { - GSocketClientAsyncConnectData *data = user_data; + ConnectionAttempt *attempt = user_data; + GSocketClientAsyncConnectData *data = attempt->data; + GSList *l; GError *error = NULL; GProxy *proxy; const gchar *protocol; - if (g_task_return_error_if_cancelled (data->task)) + /* data is NULL once the task is completed */ + if (data && g_task_return_error_if_cancelled (data->task)) { g_object_unref (data->task); + connection_attempt_unref (attempt); return; } + if (attempt->timeout_source) + { + g_source_destroy (attempt->timeout_source); + g_clear_pointer (&attempt->timeout_source, g_source_unref); + } + if (!g_socket_connection_connect_finish (G_SOCKET_CONNECTION (source), result, &error)) { - clarify_connect_error (error, data->connectable, - data->current_addr); - set_last_error (data, error); + if (!g_cancellable_is_cancelled (attempt->cancellable)) + { + clarify_connect_error (error, data->connectable, attempt->address); + set_last_error (data, error); + } + else + g_clear_error (&error); + + if (data) + { + connection_attempt_remove (attempt); + enumerator_next_async (data); + } + else + connection_attempt_unref (attempt); - /* try next one */ - enumerator_next_async (data); return; } + data->socket = g_steal_pointer (&attempt->socket); + data->connection = g_steal_pointer (&attempt->connection); + + for (l = data->connection_attempts; l; l = g_slist_next (l)) + { + ConnectionAttempt *attempt_entry = l->data; + g_cancellable_cancel (attempt_entry->cancellable); + attempt_entry->data = NULL; + connection_attempt_unref (attempt_entry); + } + g_slist_free (data->connection_attempts); + data->connection_attempts = NULL; + connection_attempt_unref (attempt); + g_socket_connection_set_cached_remote_address ((GSocketConnection*)data->connection, NULL); g_socket_client_emit_event (data->client, G_SOCKET_CLIENT_CONNECTED, data->connectable, data->connection); /* wrong, but backward compatible */ - g_socket_set_blocking (data->current_socket, TRUE); + g_socket_set_blocking (data->socket, TRUE); if (!data->proxy_addr) { @@ -1565,6 +1656,26 @@ g_socket_client_connected_callback (GObject *source, } } +static gboolean +on_connection_attempt_timeout (gpointer data) +{ + ConnectionAttempt *attempt = data; + + enumerator_next_async (attempt->data); + + g_clear_pointer (&attempt->timeout_source, g_source_unref); + return G_SOURCE_REMOVE; +} + +static void +on_connection_cancelled (GCancellable *cancellable, + gpointer data) +{ + GCancellable *attempt_cancellable = data; + + g_cancellable_cancel (attempt_cancellable); +} + static void g_socket_client_enumerator_callback (GObject *object, GAsyncResult *result, @@ -1573,6 +1684,7 @@ g_socket_client_enumerator_callback (GObject *object, GSocketClientAsyncConnectData *data = user_data; GSocketAddress *address = NULL; GSocket *socket; + ConnectionAttempt *attempt; GError *error = NULL; if (g_task_return_error_if_cancelled (data->task)) @@ -1585,6 +1697,9 @@ g_socket_client_enumerator_callback (GObject *object, result, &error); if (address == NULL) { + if (data->connection_attempts) + return; + g_socket_client_emit_event (data->client, G_SOCKET_CLIENT_COMPLETE, data->connectable, NULL); if (!error) { @@ -1621,16 +1736,27 @@ g_socket_client_enumerator_callback (GObject *object, return; } - data->current_socket = socket; - data->current_addr = address; - data->connection = (GIOStream *) g_socket_connection_factory_create_connection (socket); + attempt = connection_attempt_new (); + attempt->data = data; + attempt->socket = socket; + attempt->address = address; + attempt->cancellable = g_cancellable_new (); + attempt->connection = (GIOStream *)g_socket_connection_factory_create_connection (socket); + attempt->timeout_source = g_timeout_source_new (HAPPY_EYEBALLS_CONNECTION_ATTEMPT_TIMEOUT_MS); + g_source_set_callback (attempt->timeout_source, on_connection_attempt_timeout, attempt, NULL); + g_source_attach (attempt->timeout_source, g_main_context_get_thread_default ()); + data->connection_attempts = g_slist_append (data->connection_attempts, attempt); - g_socket_connection_set_cached_remote_address ((GSocketConnection*)data->connection, address); - g_socket_client_emit_event (data->client, G_SOCKET_CLIENT_CONNECTING, data->connectable, data->connection); - g_socket_connection_connect_async (G_SOCKET_CONNECTION (data->connection), + if (g_task_get_cancellable (data->task)) + g_cancellable_connect (g_task_get_cancellable (data->task), G_CALLBACK (on_connection_cancelled), + g_object_ref (attempt->cancellable), g_object_unref); + + g_socket_connection_set_cached_remote_address ((GSocketConnection *)attempt->connection, address); + g_socket_client_emit_event (data->client, G_SOCKET_CLIENT_CONNECTING, data->connectable, attempt->connection); + g_socket_connection_connect_async (G_SOCKET_CONNECTION (attempt->connection), address, - g_task_get_cancellable (data->task), - g_socket_client_connected_callback, data); + attempt->cancellable, + g_socket_client_connected_callback, connection_attempt_ref (attempt)); } /**