Fix presence channel state management and event firing

Author: stayallive

src/HttpApi/Controllers/FetchUsersController.php

@@ -22,8 +22,8 @@ public function __invoke(Request $request)
         }
 
         return [
-            'users' => Collection::make($channel->getUsers())->map(function ($user) {
-                return ['id' => $user->user_id];
+            'users' => Collection::make($channel->getUsers())->keys()->map(function ($userId) {
+                return ['id' => $userId];
             })->values(),
         ];
     }

src/WebSockets/Channels/PresenceChannel.php

@@ -5,26 +5,44 @@
 use Ratchet\ConnectionInterface;
 use stdClass;
 
+/**
+ * @link https://pusher.com/docs/pusher_protocol#presence-channel-events
+ */
 class PresenceChannel extends Channel
 {
+    /**
+     * List of users in the channel keyed by their user ID with their info as value.
+     *
+     * @var array<string, array>
+     */
     protected $users = [];
 
-    public function getUsers(): array
-    {
-        return $this->users;
-    }
-
-    /*
-     * @link https://pusher.com/docs/pusher_protocol#presence-channel-events
+    /**
+     * List of sockets keyed by their ID with the value pointing to a user ID.
+     *
+     * @var array<string, string>
      */
+    protected $sockets = [];
+
     public function subscribe(ConnectionInterface $connection, stdClass $payload)
     {
         $this->verifySignature($connection, $payload);
 
         $this->saveConnection($connection);
 
-        $channelData = json_decode($payload->channel_data);
-        $this->users[$connection->socketId] = $channelData;
+        $channelData = json_decode($payload->channel_data, true);
+
+        // The ID of the user connecting
+        $userId = (string) $channelData['user_id'];
+
+        // Check if the user was already connected to the channel before storing the connection in the state
+        $userFirstConnection = ! isset($this->users[$userId]);
+
+        // Add or replace the user info in the state
+        $this->users[$userId] = $channelData['user_info'] ?? [];
+
+        // Add the socket ID to user ID map in the state
+        $this->sockets[$connection->socketId] = $userId;
 
         // Send the success event
         $connection->send(json_encode([
@@ -33,72 +51,74 @@ public function subscribe(ConnectionInterface $connection, stdClass $payload)
             'data' => json_encode($this->getChannelData()),
         ]));
 
-        $this->broadcastToOthers($connection, [
-            'event' => 'pusher_internal:member_added',
-            'channel' => $this->channelName,
-            'data' => json_encode($channelData),
-        ]);
+        // The `pusher_internal:member_added` event is triggered when a user joins a channel.
+        // It's quite possible that a user can have multiple connections to the same channel
+        // (for example by having multiple browser tabs open)
+        // and in this case the events will only be triggered when the first tab is opened.
+        if ($userFirstConnection) {
+            $this->broadcastToOthers($connection, [
+                'event' => 'pusher_internal:member_added',
+                'channel' => $this->channelName,
+                'data' => json_encode($channelData),
+            ]);
+        }
     }
 
     public function unsubscribe(ConnectionInterface $connection)
     {
         parent::unsubscribe($connection);
 
-        if (! isset($this->users[$connection->socketId])) {
+        if (! isset($this->sockets[$connection->socketId])) {
             return;
         }
 
-        $this->broadcastToOthers($connection, [
-            'event' => 'pusher_internal:member_removed',
-            'channel' => $this->channelName,
-            'data' => json_encode([
-                'user_id' => $this->users[$connection->socketId]->user_id,
-            ]),
-        ]);
-
-        unset($this->users[$connection->socketId]);
+        // Find the user ID belonging to this socket
+        $userId = $this->sockets[$connection->socketId];
+
+        // Remove the socket from the state
+        unset($this->sockets[$connection->socketId]);
+
+        // Test if the user still has open sockets to this channel
+        $userHasOpenConnections = (array_flip($this->sockets)[$userId] ?? null) !== null;
+
+        // The `pusher_internal:member_removed` is triggered when a user leaves a channel.
+        // It's quite possible that a user can have multiple connections to the same channel
+        // (for example by having multiple browser tabs open)
+        // and in this case the events will only be triggered when the last one is closed.
+        if (! $userHasOpenConnections) {
+            $this->broadcastToOthers($connection, [
+                'event' => 'pusher_internal:member_removed',
+                'channel' => $this->channelName,
+                'data' => json_encode([
+                    'user_id' => $userId,
+                ]),
+            ]);
+
+            // Remove the user info from the state
+            unset($this->users[$userId]);
+        }
     }
 
     protected function getChannelData(): array
     {
         return [
             'presence' => [
-                'ids' => $userIds = $this->getUserIds(),
-                'hash' => $this->getHash(),
-                'count' => count($userIds),
+                'ids' => array_keys($this->users),
+                'hash' => $this->users,
+                'count' => count($this->users),
             ],
         ];
     }
 
-    public function toArray(): array
-    {
-        return array_merge(parent::toArray(), [
-            'user_count' => count($this->getUserIds()),
-        ]);
-    }
-
-    protected function getUserIds(): array
+    public function getUsers(): array
     {
-        $userIds = array_map(function ($channelData) {
-            return (string) $channelData->user_id;
-        }, $this->users);
-
-        return array_values(array_unique($userIds));
+        return $this->users;
     }
 
-    /**
-     * Compute the hash for the presence channel integrity.
-     *
-     * @return array
-     */
-    protected function getHash(): array
+    public function toArray(): array
     {
-        $hash = [];
-
-        foreach ($this->users as $socketId => $channelData) {
-            $hash[$channelData->user_id] = $channelData->user_info ?? [];
-        }
-
-        return $hash;
+        return array_merge(parent::toArray(), [
+            'user_count' => count($this->users),
+        ]);
     }
 }

tests/Channels/PresenceChannelTest.php

@@ -43,7 +43,7 @@ public function clients_with_valid_auth_signatures_can_join_presence_channels()
             ],
         ];
 
-        $message = $this->getSignedMessage($connection, 'presence-channel', $channelData);
+        $message = $this->getSignedSubscribeMessage($connection, 'presence-channel', $channelData);
 
         $this->pusherServer->onMessage($connection, $message);
 
@@ -63,7 +63,7 @@ public function clients_with_no_user_info_can_join_presence_channels()
             'user_id' => 1,
         ];
 
-        $message = $this->getSignedMessage($connection, 'presence-channel', $channelData);
+        $message = $this->getSignedSubscribeMessage($connection, 'presence-channel', $channelData);
 
         $this->pusherServer->onMessage($connection, $message);
 
@@ -80,27 +80,64 @@ public function multiple_clients_with_same_user_id_are_counted_once()
 
         $channelName = 'presence-channel';
         $channelData = [
-            'user_id' => $userId = 1,
+            'user_id' => $userId = 'user:1',
         ];
 
-        $this->pusherServer->onMessage($connection, $this->getSignedMessage($connection, $channelName, $channelData));
-        $this->pusherServer->onMessage($connection2, $this->getSignedMessage($connection2, $channelName, $channelData));
+        $this->pusherServer->onMessage($connection, $this->getSignedSubscribeMessage($connection, $channelName, $channelData));
+        $this->pusherServer->onMessage($connection2, $this->getSignedSubscribeMessage($connection2, $channelName, $channelData));
 
         $connection2->assertSentEvent('pusher_internal:subscription_succeeded', [
             'channel' => $channelName,
             'data' => json_encode([
                 'presence' => [
-                    'ids' => [(string) $userId],
+                    'ids' => [$userId],
                     'hash' => [
-                        (string) $userId => [],
+                        $userId => [],
                     ],
                     'count' => 1,
                 ],
             ]),
         ]);
     }
 
-    private function getSignedMessage(Connection $connection, string $channelName, array $channelData): Message
+    /** @test */
+    public function multiple_clients_with_same_user_id_trigger_member_added_and_removed_event_only_on_first_and_last_socket_connection()
+    {
+        $channelName = 'presence-channel';
+
+        // Connect the `observer` user to the server
+        $this->pusherServer->onOpen($observerConnection = $this->getWebSocketConnection());
+        $this->pusherServer->onMessage($observerConnection, $this->getSignedSubscribeMessage($observerConnection, $channelName, ['user_id' => 'observer']));
+
+        // Connect the first socket for user `user:1` to the server
+        $this->pusherServer->onOpen($firstConnection = $this->getWebSocketConnection());
+        $this->pusherServer->onMessage($firstConnection, $this->getSignedSubscribeMessage($firstConnection, $channelName, ['user_id' => 'user:1']));
+
+        // Make sure the observer sees a `member_added` event for `user:1`
+        $observerConnection->assertSentEvent('pusher_internal:member_added');
+        $observerConnection->resetEvents();
+
+        // Connect the second socket for user `user:1` to the server
+        $this->pusherServer->onOpen($secondConnection = $this->getWebSocketConnection());
+        $this->pusherServer->onMessage($secondConnection, $this->getSignedSubscribeMessage($secondConnection, $channelName, ['user_id' => 'user:1']));
+
+        // Make sure the observer was not notified of a `member_added` event (user was already connected)
+        $observerConnection->assertNotSentEvent('pusher_internal:member_added');
+
+        // Disconnect the first socket for user `user:1` on the server
+        $this->pusherServer->onClose($firstConnection);
+
+        // Make sure the observer was not notified of a `member_removed` event (user still connected on another socket)
+        $observerConnection->assertNotSentEvent('pusher_internal:member_removed');
+
+        // Disconnect the second (and last) socket for user `user:1` on the server
+        $this->pusherServer->onClose($secondConnection);
+
+        // Make sure the observer was notified of a `member_removed` event (last socket for user was disconnected)
+        $observerConnection->assertSentEvent('pusher_internal:member_removed');
+    }
+
+    private function getSignedSubscribeMessage(Connection $connection, string $channelName, array $channelData): Message
     {
         $signature = "{$connection->socketId}:{$channelName}:".json_encode($channelData);
 

tests/HttpApi/FetchChannelTest.php

@@ -75,7 +75,7 @@ public function it_returns_the_channel_information_for_presence_channel()
 
         $connection = new Connection();
 
-        $requestPath = "/apps/1234/channel/presence-global";
+        $requestPath = '/apps/1234/channel/presence-global';
         $routeParams = [
             'appId' => '1234',
             'channelName' => 'presence-global',

tests/HttpApi/FetchChannelsTest.php

@@ -103,10 +103,10 @@ public function it_returns_the_channel_information_for_prefix()
     /** @test */
     public function it_returns_the_channel_information_for_prefix_with_user_count()
     {
-        $this->joinPresenceChannel('presence-global.1');
-        $this->joinPresenceChannel('presence-global.1');
-        $this->joinPresenceChannel('presence-global.2');
-        $this->joinPresenceChannel('presence-notglobal.2');
+        $this->joinPresenceChannel('presence-global.1', 'user:1');
+        $this->joinPresenceChannel('presence-global.1', 'user:2');
+        $this->joinPresenceChannel('presence-global.2', 'user:3');
+        $this->joinPresenceChannel('presence-notglobal.2', 'user:4');
 
         $connection = new Connection();
 

tests/Mocks/Connection.php

@@ -28,6 +28,12 @@ public function close()
         $this->closed = true;
     }
 
+    public function resetEvents()
+    {
+        $this->sentData = [];
+        $this->sentRawData = [];
+    }
+
     public function assertSentEvent(string $name, array $additionalParameters = [])
     {
         $event = collect($this->sentData)->firstWhere('event', '=', $name);