[Spice-devel] [PATCH spice-server 3/4] red_channel: add option to monitor whether a channel client is alive
Yonit Halperin
yhalperi at redhat.com
Wed Aug 14 08:26:03 PDT 2013
rhbz#994175
When a client connection is closed surprisingly (i.e., without a FIN
segment), we cannot identify it by a socket error (which is the only
way by which we identified disconnections so far).
This patch allows a channel client to periodically check the state of
the connection and identify surprise disconnections.
---
server/red_channel.c | 119 ++++++++++++++++++++++++++++++++++++++++++++++++++-
server/red_channel.h | 14 ++++++
2 files changed, 132 insertions(+), 1 deletion(-)
diff --git a/server/red_channel.c b/server/red_channel.c
index bcf5a60..715ed3e 100644
--- a/server/red_channel.c
+++ b/server/red_channel.c
@@ -64,6 +64,13 @@ enum QosPingState {
PING_STATE_LATENCY,
};
+enum ConnectivityState {
+ CONNECTIVITY_STATE_CONNECTED,
+ CONNECTIVITY_STATE_BLOCKED,
+ CONNECTIVITY_STATE_WAIT_PONG,
+ CONNECTIVITY_STATE_DISCONNECTED,
+};
+
static void red_channel_client_start_ping_timer(RedChannelClient *rcc, uint32_t timeout);
static void red_channel_client_cancel_ping_timer(RedChannelClient *rcc);
static void red_channel_client_restart_ping_timer(RedChannelClient *rcc);
@@ -73,6 +80,7 @@ static void red_client_add_channel(RedClient *client, RedChannelClient *rcc);
static void red_client_remove_channel(RedChannelClient *rcc);
static RedChannelClient *red_client_get_channel(RedClient *client, int type, int id);
static void red_channel_client_restore_main_sender(RedChannelClient *rcc);
+static inline int red_channel_client_waiting_for_ack(RedChannelClient *rcc);
/*
* Lifetime of RedChannel, RedChannelClient and RedClient:
@@ -388,12 +396,18 @@ static void red_peer_handle_outgoing(RedsStream *stream, OutgoingHandler *handle
static void red_channel_client_on_output(void *opaque, int n)
{
RedChannelClient *rcc = opaque;
-
+ if (rcc->connectivity_monitor.timer) {
+ rcc->connectivity_monitor.out_bytes += n;
+ }
stat_inc_counter(rcc->channel->out_bytes_counter, n);
}
static void red_channel_client_on_input(void *opaque, int n)
{
+ RedChannelClient *rcc = opaque;
+ if (rcc->connectivity_monitor.timer) {
+ rcc->connectivity_monitor.in_bytes += n;
+ }
}
static void red_channel_client_default_peer_on_error(RedChannelClient *rcc)
@@ -759,6 +773,97 @@ static void red_channel_client_ping_timer(void *opaque)
#endif /* ifdef HAVE_LINUX_SOCKIOS_H */
}
+/*
+ * When a connection is not alive (and we can't detect it via a socket error), we
+ * reach one of these 2 states:
+ * (1) Sending msgs is blocked: either writes return EGAIN
+ * or we are missing MSGC_ACK from the client.
+ * (2) MSG_PING was sent without receiving a MSGC_PONG in reply.
+ *
+ * The connectivity_timer callback tests if the channel's state matches one of the above.
+ * In case it does, on the next time the timer is called, it checks if the connection has
+ * been idle during the time that passed since the previous timer call. If the connection
+ * has been idle, we consider the client as disconnected.
+ */
+static void red_channel_client_connectivity_timer(void *opaque)
+{
+ RedChannelClient *rcc = opaque;
+ RedChannelClientConnectivityMonitor *monitor = &rcc->connectivity_monitor;
+ int is_alive = TRUE;
+
+ if (monitor->state == CONNECTIVITY_STATE_BLOCKED) {
+ if (monitor->in_bytes == 0 && monitor->out_bytes == 0) {
+ if (!rcc->send_data.blocked && !red_channel_client_waiting_for_ack(rcc)) {
+ spice_warning("mismatch between rcc-state and connectivity-state");
+ }
+ spice_debug("rcc is blocked; connection is idle");
+ is_alive = FALSE;
+ }
+ } else if (monitor->state == CONNECTIVITY_STATE_WAIT_PONG) {
+ if (monitor->in_bytes == 0) {
+ if (rcc->latency_monitor.state != PING_STATE_WARMUP &&
+ rcc->latency_monitor.state != PING_STATE_LATENCY) {
+ spice_warning("mismatch between rcc-state and connectivity-state");
+ }
+ spice_debug("rcc waits for pong; connection is idle");
+ is_alive = FALSE;
+ }
+ }
+
+ if (is_alive) {
+ monitor->in_bytes = 0;
+ monitor->out_bytes = 0;
+ if (rcc->send_data.blocked || red_channel_client_waiting_for_ack(rcc)) {
+ monitor->state = CONNECTIVITY_STATE_BLOCKED;
+ } else if (rcc->latency_monitor.state == PING_STATE_WARMUP ||
+ rcc->latency_monitor.state == PING_STATE_LATENCY) {
+ monitor->state = CONNECTIVITY_STATE_WAIT_PONG;
+ } else {
+ monitor->state = CONNECTIVITY_STATE_CONNECTED;
+ }
+ rcc->channel->core->timer_start(rcc->connectivity_monitor.timer,
+ rcc->connectivity_monitor.timeout);
+ } else {
+ monitor->state = CONNECTIVITY_STATE_DISCONNECTED;
+ spice_debug("rcc %p has not been responsive for more than %u ms, disconnecting",
+ rcc, monitor->timeout);
+ red_channel_client_disconnect(rcc);
+ }
+}
+
+void red_channel_client_start_connectivity_monitoring(RedChannelClient *rcc, uint32_t timeout_ms)
+{
+ if (!red_channel_client_is_connected(rcc)) {
+ return;
+ }
+ spice_debug(NULL);
+ spice_assert(timeout_ms > 0);
+ /*
+ * If latency_monitor is not active, we activate it in order to enable
+ * periodic ping messages so that we will be be able to identify a disconnected
+ * channel-client even if there are no ongoing channel specific messages
+ * on this channel.
+ */
+ if (rcc->latency_monitor.timer == NULL) {
+ rcc->latency_monitor.timer = rcc->channel->core->timer_add(
+ red_channel_client_ping_timer, rcc);
+ if (!rcc->client->during_target_migrate) {
+ red_channel_client_start_ping_timer(rcc, PING_TEST_IDLE_NET_TIMEOUT_MS);
+ }
+ rcc->latency_monitor.roundtrip = -1;
+ }
+ if (rcc->connectivity_monitor.timer == NULL) {
+ rcc->connectivity_monitor.state = CONNECTIVITY_STATE_CONNECTED;
+ rcc->connectivity_monitor.timer = rcc->channel->core->timer_add(
+ red_channel_client_connectivity_timer, rcc);
+ rcc->connectivity_monitor.timeout = timeout_ms;
+ if (!rcc->client->during_target_migrate) {
+ rcc->channel->core->timer_start(rcc->connectivity_monitor.timer,
+ rcc->connectivity_monitor.timeout);
+ }
+ }
+}
+
RedChannelClient *red_channel_client_create(int size, RedChannel *channel, RedClient *client,
RedsStream *stream,
int monitor_latency,
@@ -859,6 +964,10 @@ static void red_channel_client_seamless_migration_done(RedChannelClient *rcc)
if (rcc->latency_monitor.timer) {
red_channel_client_start_ping_timer(rcc, PING_TEST_IDLE_NET_TIMEOUT_MS);
}
+ if (rcc->connectivity_monitor.timer) {
+ rcc->channel->core->timer_start(rcc->connectivity_monitor.timer,
+ rcc->connectivity_monitor.timeout);
+ }
}
pthread_mutex_unlock(&rcc->client->lock);
}
@@ -905,6 +1014,10 @@ void red_channel_client_default_migrate(RedChannelClient *rcc)
rcc->channel->core->timer_remove(rcc->latency_monitor.timer);
rcc->latency_monitor.timer = NULL;
}
+ if (rcc->connectivity_monitor.timer) {
+ rcc->channel->core->timer_remove(rcc->connectivity_monitor.timer);
+ rcc->connectivity_monitor.timer = NULL;
+ }
red_channel_client_pipe_add_type(rcc, PIPE_ITEM_TYPE_MIGRATE);
}
@@ -1752,6 +1865,10 @@ void red_channel_client_disconnect(RedChannelClient *rcc)
rcc->channel->core->timer_remove(rcc->latency_monitor.timer);
rcc->latency_monitor.timer = NULL;
}
+ if (rcc->connectivity_monitor.timer) {
+ rcc->channel->core->timer_remove(rcc->connectivity_monitor.timer);
+ rcc->connectivity_monitor.timer = NULL;
+ }
red_channel_remove_client(rcc);
rcc->channel->channel_cbs.on_disconnect(rcc);
}
diff --git a/server/red_channel.h b/server/red_channel.h
index 1592896..676e1ef 100644
--- a/server/red_channel.h
+++ b/server/red_channel.h
@@ -236,6 +236,14 @@ typedef struct RedChannelClientLatencyMonitor {
int64_t roundtrip;
} RedChannelClientLatencyMonitor;
+typedef struct RedChannelClientConnectivityMonitor {
+ int state;
+ uint32_t out_bytes;
+ uint32_t in_bytes;
+ uint32_t timeout;
+ SpiceTimer *timer;
+} RedChannelClientConnectivityMonitor;
+
struct RedChannelClient {
RingItem channel_link;
RingItem client_link;
@@ -289,6 +297,7 @@ struct RedChannelClient {
int wait_migrate_flush_mark;
RedChannelClientLatencyMonitor latency_monitor;
+ RedChannelClientConnectivityMonitor connectivity_monitor;
};
struct RedChannel {
@@ -448,6 +457,11 @@ SpiceMarshaller *red_channel_client_switch_to_urgent_sender(RedChannelClient *rc
/* returns -1 if we don't have an estimation */
int red_channel_client_get_roundtrip_ms(RedChannelClient *rcc);
+/*
+ * Checks periodically if the connection is still alive
+ */
+void red_channel_client_start_connectivity_monitoring(RedChannelClient *rcc, uint32_t timeout_ms);
+
void red_channel_pipe_item_init(RedChannel *channel, PipeItem *item, int type);
// TODO: add back the channel_pipe_add functionality - by adding reference counting
--
1.8.1.4
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