Implement the tick event

This makes our tests less flaky, shorter, and more readable.

fixes #2988

AnyEvent-I3/lib/AnyEvent/I3.pm

@@ -99,11 +99,12 @@ use constant TYPE_GET_BAR_CONFIG => 6;
 use constant TYPE_GET_VERSION => 7;
 use constant TYPE_GET_BINDING_MODES => 8;
 use constant TYPE_GET_CONFIG => 9;
+use constant TYPE_SEND_TICK => 10;
 
 our %EXPORT_TAGS = ( 'all' => [
     qw(i3 TYPE_RUN_COMMAND TYPE_COMMAND TYPE_GET_WORKSPACES TYPE_SUBSCRIBE TYPE_GET_OUTPUTS
        TYPE_GET_TREE TYPE_GET_MARKS TYPE_GET_BAR_CONFIG TYPE_GET_VERSION
-       TYPE_GET_BINDING_MODES TYPE_GET_CONFIG)
+       TYPE_GET_BINDING_MODES TYPE_GET_CONFIG TYPE_SEND_TICK)
 ] );
 
 our @EXPORT_OK = ( @{ $EXPORT_TAGS{all} } );
@@ -120,6 +121,7 @@ my %events = (
     barconfig_update => ($event_mask | 4),
     binding => ($event_mask | 5),
     shutdown => ($event_mask | 6),
+    tick => ($event_mask | 7),
     _error => 0xFFFFFFFF,
 );
 
@@ -519,6 +521,18 @@ sub get_config {
     $self->message(TYPE_GET_CONFIG);
 }
 
+=head2 send_tick
+
+Sends a tick event. Requires i3 >= 4.15
+
+=cut
+sub send_tick {
+    my ($self, $payload) = @_;
+
+    $self->_ensure_connection;
+
+    $self->message(TYPE_SEND_TICK, $payload);
+}
 
 =head2 command($content)
 

docs/ipc

@@ -64,6 +64,7 @@ to do that).
 | 7 | +GET_VERSION+ | <<_version_reply,VERSION>> | Gets the i3 version.
 | 8 | +GET_BINDING_MODES+ | <<_binding_modes_reply,BINDING_MODES>> | Gets the names of all currently configured binding modes.
 | 9 | +GET_CONFIG+ | <<_config_reply,CONFIG>> | Returns the last loaded i3 config.
+| 10 | +SEND_TICK+ | <<_tick_reply,TICK>> | Sends a tick event with the specified payload.
 |======================================================
 
 So, a typical message could look like this:
@@ -126,6 +127,8 @@ BINDING_MODES (8)::
         Reply to the GET_BINDING_MODES message.
 GET_CONFIG (9)::
 	Reply to the GET_CONFIG message.
+TICK (10)::
+	Reply to the SEND_TICK message.
 
 [[_command_reply]]
 === COMMAND reply
@@ -637,6 +640,19 @@ which is a string containing the config file as loaded by i3 most recently.
 { "config": "font pango:monospace 8\nbindsym Mod4+q exit\n" }
 -------------------
 
+[[_tick_reply]]
+=== TICK reply
+
+The reply is a map containing the "success" member. After the reply was
+received, the tick event has been written to all IPC connections which subscribe
+to tick events. UNIX sockets are usually buffered, but you can be certain that
+once you receive the tick event you just triggered, you must have received all
+events generated prior to the +SEND_TICK+ message (happened-before relation).
+
+*Example:*
+-------------------
+{ "success": true }
+-------------------
 
 == Events
 
@@ -694,6 +710,10 @@ binding (5)::
 	mouse
 shutdown (6)::
 	Sent when the ipc shuts down because of a restart or exit by user command
+tick (7)::
+	Sent when the ipc client subscribes to the tick event (with +"first":
+	true+) or when any ipc client sends a SEND_TICK message (with +"first":
+	false+).
 
 *Example:*
 --------------------------------------------------------------------
@@ -866,6 +886,27 @@ because of a user action such as a +restart+ or +exit+ command. The +change
 }
 ---------------------------
 
+=== tick event
+
+This event is triggered by a subscription to tick events or by a +SEND_TICK+
+message.
+
+*Example (upon subscription):*
+--------------------------------------------------------------------------------
+{
+ "first": true,
+ "payload": ""
+}
+--------------------------------------------------------------------------------
+
+*Example (upon +SEND_TICK+ with a payload of +arbitrary string+):*
+--------------------------------------------------------------------------------
+{
+ "first": false,
+ "payload": "arbitrary string"
+}
+--------------------------------------------------------------------------------
+
 == See also (existing libraries)
 
 [[libraries]]

i3-msg/main.c

@@ -207,9 +207,11 @@ int main(int argc, char *argv[]) {
                 message_type = I3_IPC_MESSAGE_TYPE_GET_VERSION;
             } else if (strcasecmp(optarg, "get_config") == 0) {
                 message_type = I3_IPC_MESSAGE_TYPE_GET_CONFIG;
+            } else if (strcasecmp(optarg, "send_tick") == 0) {
+                message_type = I3_IPC_MESSAGE_TYPE_SEND_TICK;
             } else {
                 printf("Unknown message type\n");
-                printf("Known types: run_command, get_workspaces, get_outputs, get_tree, get_marks, get_bar_config, get_binding_modes, get_version, get_config\n");
+                printf("Known types: run_command, get_workspaces, get_outputs, get_tree, get_marks, get_bar_config, get_binding_modes, get_version, get_config, send_tick\n");
                 exit(EXIT_FAILURE);
             }
         } else if (o == 'q') {

include/i3/ipc.h

@@ -60,6 +60,9 @@ typedef struct i3_ipc_header {
 /** Request the raw last loaded i3 config. */
 #define I3_IPC_MESSAGE_TYPE_GET_CONFIG 9
 
+/** Send a tick event to all subscribers. */
+#define I3_IPC_MESSAGE_TYPE_SEND_TICK 10
+
 /*
  * Messages from i3 to clients
  *
@@ -74,6 +77,7 @@ typedef struct i3_ipc_header {
 #define I3_IPC_REPLY_TYPE_VERSION 7
 #define I3_IPC_REPLY_TYPE_BINDING_MODES 8
 #define I3_IPC_REPLY_TYPE_CONFIG 9
+#define I3_IPC_REPLY_TYPE_TICK 10
 
 /*
  * Events from i3 to clients. Events have the first bit set high.
@@ -101,3 +105,6 @@ typedef struct i3_ipc_header {
 
 /** The shutdown event will be triggered when the ipc shuts down */
 #define I3_IPC_EVENT_SHUTDOWN (I3_IPC_EVENT_MASK | 6)
+
+/** The tick event will be sent upon a tick IPC message */
+#define I3_IPC_EVENT_TICK (I3_IPC_EVENT_MASK | 7)

include/ipc.h

@@ -31,6 +31,10 @@ typedef struct ipc_client {
     int num_events;
     char **events;
 
+    /* For clients which subscribe to the tick event: whether the first tick
+     * event has been sent by i3. */
+    bool first_tick_sent;
+
     TAILQ_ENTRY(ipc_client)
     clients;
 } ipc_client;

src/ipc.c

@@ -1046,8 +1046,9 @@ static int add_subscription(void *extra, const unsigned char *s,
     memcpy(client->events[event], s, len);
 
     DLOG("client is now subscribed to:\n");
-    for (int i = 0; i < client->num_events; i++)
+    for (int i = 0; i < client->num_events; i++) {
         DLOG("event %s\n", client->events[i]);
+    }
     DLOG("(done)\n");
 
     return 1;
@@ -1099,6 +1100,25 @@ IPC_HANDLER(subscribe) {
     yajl_free(p);
     const char *reply = "{\"success\":true}";
     ipc_send_message(fd, strlen(reply), I3_IPC_REPLY_TYPE_SUBSCRIBE, (const uint8_t *)reply);
+
+    if (client->first_tick_sent) {
+        return;
+    }
+
+    bool is_tick = false;
+    for (int i = 0; i < client->num_events; i++) {
+        if (strcmp(client->events[i], "tick") == 0) {
+            is_tick = true;
+            break;
+        }
+    }
+    if (!is_tick) {
+        return;
+    }
+
+    client->first_tick_sent = true;
+    const char *payload = "{\"first\":true,\"payload\":\"\"}";
+    ipc_send_message(client->fd, strlen(payload), I3_IPC_EVENT_TICK, (const uint8_t *)payload);
 }
 
 /*
@@ -1122,9 +1142,35 @@ IPC_HANDLER(get_config) {
     y(free);
 }
 
+/*
+ * Sends the tick event from the message payload to subscribers. Establishes a
+ * synchronization point in event-related tests.
+ */
+IPC_HANDLER(send_tick) {
+    yajl_gen gen = ygenalloc();
+
+    y(map_open);
+
+    ystr("payload");
+    yajl_gen_string(gen, (unsigned char *)message, message_size);
+
+    y(map_close);
+
+    const unsigned char *payload;
+    ylength length;
+    y(get_buf, &payload, &length);
+
+    ipc_send_event("tick", I3_IPC_EVENT_TICK, (const char *)payload);
+    y(free);
+
+    const char *reply = "{\"success\":true}";
+    ipc_send_message(fd, strlen(reply), I3_IPC_REPLY_TYPE_TICK, (const uint8_t *)reply);
+    DLOG("Sent tick event\n");
+}
+
 /* The index of each callback function corresponds to the numeric
  * value of the message type (see include/i3/ipc.h) */
-handler_t handlers[10] = {
+handler_t handlers[11] = {
     handle_run_command,
     handle_get_workspaces,
     handle_subscribe,
@@ -1135,6 +1181,7 @@ handler_t handlers[10] = {
     handle_get_version,
     handle_get_binding_modes,
     handle_get_config,
+    handle_send_tick,
 };
 
 /*

testcases/lib/i3test.pm.in

@@ -47,6 +47,8 @@ our @EXPORT = qw(
     wait_for_unmap
     $x
     kill_all_windows
+    events_for
+    listen_for_binding
 );
 
 =head1 NAME
@@ -900,6 +902,86 @@ sub kill_all_windows {
     cmd '[title=".*"] kill';
 }
 
+=head2 events_for($subscribecb, [ $rettype ], [ $eventcbs ])
+
+Helper function which returns an array containing all events of type $rettype
+which were generated by i3 while $subscribecb was running.
+
+Set $eventcbs to subscribe to multiple event types and/or perform your own event
+aggregation.
+
+=cut
+sub events_for {
+    my ($subscribecb, $rettype, $eventcbs) = @_;
+
+    my @events;
+    $eventcbs //= {};
+    if (defined($rettype)) {
+	$eventcbs->{$rettype} = sub { push @events, shift };
+    }
+    my $subscribed = AnyEvent->condvar;
+    my $flushed = AnyEvent->condvar;
+    $eventcbs->{tick} = sub {
+	my ($event) = @_;
+	if ($event->{first}) {
+	    $subscribed->send($event);
+	} else {
+	    $flushed->send($event);
+	}
+    };
+    my $i3 = i3(get_socket_path(0));
+    $i3->connect->recv;
+    $i3->subscribe($eventcbs)->recv;
+    $subscribed->recv;
+    # Subscription established, run the callback.
+    $subscribecb->();
+    # Now generate a tick event, which we know we’ll receive (and at which point
+    # all other events have been received).
+    my $nonce = int(rand(255)) + 1;
+    $i3->send_tick($nonce);
+
+    my $tick = $flushed->recv;
+    $tester->is_eq($tick->{payload}, $nonce, 'tick nonce received');
+    return @events;
+}
+
+=head2 listen_for_binding($cb)
+
+Helper function to evaluate whether sending KeyPress/KeyRelease events via XTEST
+triggers an i3 key binding or not. Expects key bindings to be configured in the
+form “bindsym <binding> nop <binding>”, e.g.  “bindsym Mod4+Return nop
+Mod4+Return”.
+
+  is(listen_for_binding(
+      sub {
+          xtest_key_press(133); # Super_L
+          xtest_key_press(36); # Return
+          xtest_key_release(36); # Return
+          xtest_key_release(133); # Super_L
+          xtest_sync_with_i3;
+      },
+      ),
+     'Mod4+Return',
+     'triggered the "Mod4+Return" keybinding');
+
+=cut
+
+sub listen_for_binding {
+    my ($cb) = @_;
+    my $triggered = AnyEvent->condvar;
+    my @events = events_for(
+	$cb,
+	'binding');
+
+    $tester->is_eq(scalar @events, 1, 'Received precisely one event');
+    $tester->is_eq($events[0]->{change}, 'run', 'change is "run"');
+    # We look at the command (which is “nop <binding>”) because that is easier
+    # than re-assembling the string representation of $event->{binding}.
+    my $command = $events[0]->{binding}->{command};
+    $command =~ s/^nop //g;
+    return $command;
+}
+
 =head1 AUTHOR
 
 Michael Stapelberg <michael@i3wm.org>