add receivedTimestamp to message

src/Queue/Message.php

@@ -8,6 +8,7 @@ class Message
     protected string $queue;
     protected int $timestamp;
     protected array $payload;
+    protected float $receivedTimestamp;
 
     public function __construct(array $array = [])
     {
@@ -19,6 +20,7 @@ public function __construct(array $array = [])
         $this->queue = $array['queue'];
         $this->timestamp = $array['timestamp'];
         $this->payload = $array['payload'] ?? [];
+        $this->receivedTimestamp = (float)$array['receivedTimestamp'] ?? 0.;
     }
 
     public function setPid(string $pid): self
@@ -69,6 +71,17 @@ public function getPayload(): array
         return $this->payload;
     }
 
+    /**
+     * Timestamp recorded when this message was received by the server.
+     * The delta between `$receivedTimestamp` and `$timestamp` is the amount of time the message was waiting in the queue.
+     *
+     * @return float
+     */
+    public function getReceivedTimestamp(): float
+    {
+        return $this->receivedTimestamp;
+    }
+
     public function asArray(): array
     {
         return [

src/Queue/Server.php

@@ -204,6 +204,7 @@ public function start(): self
                     }
 
                     $nextMessage['timestamp'] = (int)$nextMessage['timestamp'];
+                    $nextMessage['receivedTimestamp'] = microtime(true);
 
                     $message = new Message($nextMessage);