[1.7] Add getSocketResource method to enhance socket management (#17)

* Add getSocketResource method to enhance socket management

This method is a prerequisite to eventually resolving chrome-php/chrome#606

* StyleCI

* public function waitForData

* remove getSocketResource

* StyleCI

* StyleCI

* error message

* oops use stream_select not socket_select

* error handling

src/Client.php

@@ -286,4 +286,31 @@ protected function configure(array $options): void
 
         parent::configure($options);
     }
+
+    /**
+     * Waits for data to become available on the socket.
+     *
+     * @param float $maxSeconds the maximum amount of time to wait for data, in seconds
+     *
+     * @return ?bool Returns true if data is available, false if the wait timed out, and null on error.
+     */
+    public function waitForData(float $maxSeconds): ?bool
+    {
+        $read = [$this->socket->getResource()];
+        $write = null;
+        $except = null;
+        $seconds = (int) \floor($maxSeconds);
+        $microseconds = (int) (($maxSeconds - $seconds) * 1e6);
+        $result = \stream_select($read, $write, $except, $seconds, $microseconds);
+        if (false === $result) {
+            // An error occurred. stream_select() probably triggered an error internally.
+            return null;
+        } elseif (0 === $result) {
+            // Timeout occurred, no data available
+            return false;
+        }
+
+        // Data is available
+        return true;
+    }
 }