Prevent blocking empty fread()

src/Socket/AbstractSocket.php

@@ -56,6 +56,13 @@ abstract class AbstractSocket extends Configurable implements ResourceInterface
      */
     protected $name;
 
+    /**
+     * Whether we have ran fread() on the socket at least once.
+     *
+     * @var bool
+     */
+    private $hasBeenFreadInitialized = false;
+
     /**
      * Gets the IP address of the socket.
      *
@@ -242,8 +249,22 @@ public function receive(int $length = self::DEFAULT_RECEIVE_LENGTH): string
 
                     return $buffer;
                 }
-
-                $result = \fread($this->socket, $length);
+                if (!$this->hasBeenFreadInitialized) {
+                    // stream_select() may erroneously return 0 before the first fread() (observed on PHP8.4.12 Ubuntu24.04 chrome-php/wrench1.8.0)
+                    $this->hasBeenFreadInitialized = true;
+                    $selectResult = 1;
+                } else {
+                    $readArray = [$this->socket];
+                    $writeArray = null;
+                    $exceptArray = null;
+                    $selectResult = \stream_select($readArray, $writeArray, $exceptArray, 0);
+                }
+                // 1 means there is data to read, false means we were unable to check if there is data to read
+                if (1 === $selectResult || false === $selectResult) {
+                    $result = \fread($this->socket, $length);
+                } else {
+                    $result = false;
+                }
 
                 if ($makeBlockingAfterRead) {
                     \stream_set_blocking($this->socket, true);

tests/ClientTest.php

@@ -116,7 +116,8 @@ public function testSend(): void
 
             $bytes = $instance->sendData('baz', Protocol::TYPE_TEXT);
             self::assertTrue($bytes >= 3, 'sent text frame');
-
+            self::assertSame([], $instance->receive(), 'Instantly recieve after send');
+            \usleep(500000);
             // test fix for issue #43
             $responses = $instance->receive();
             self::assertTrue(\is_array($responses));