Allow PHP binary to be specified

This change allows a binary path to be given to the Process context, which in turn can be specified when constructing a WorkerProcess. The default worker factory now looks for an environment variable or constant named AMP_PHP_BINARY and, if found, uses the value for the PHP binary. Fixes #26 and supersedes #28.

lib/Context/Process.php

@@ -26,10 +26,11 @@ class Process implements Context {
     /**
      * @param string|array $script Path to PHP script or array with first element as path and following elements options
      *     to the PHP script (e.g.: ['bin/worker', '-eOptionValue', '-nOptionValue'].
+     * @param string $binary Path to PHP binary. Defaults to \PHP_BINARY.
      * @param string $cwd Working directory.
      * @param mixed[] $env Array of environment variables.
      */
-    public function __construct($script, string $cwd = "", array $env = []) {
+    public function __construct($script, string $binary = \PHP_BINARY, string $cwd = "", array $env = []) {
         $options = [
             "html_errors" => "0",
             "display_errors" => "0",
@@ -44,7 +45,7 @@ public function __construct($script, string $cwd = "", array $env = []) {
 
         $options = (\PHP_SAPI === "phpdbg" ? " -b -qrr " : " ") . $this->formatOptions($options);
         $separator = \PHP_SAPI === "phpdbg" ? " -- " : " ";
-        $command = \escapeshellarg(\PHP_BINARY) . $options . $separator . $script;
+        $command = \escapeshellarg($binary) . $options . $separator . $script;
 
         $processOptions = [];
 

lib/Worker/DefaultWorkerFactory.php

@@ -22,6 +22,11 @@ public function create(): Worker {
             return new WorkerThread;
         }
 
-        return new WorkerProcess;
+        $binary = \getenv("AMP_PHP_BINARY");
+        if (!$binary && \defined("AMP_PHP_BINARY")) {
+            $binary = \AMP_PHP_BINARY;
+        }
+
+        return new WorkerProcess($binary ?: \PHP_BINARY);
     }
 }

lib/Worker/WorkerProcess.php

@@ -9,17 +9,18 @@
  */
 class WorkerProcess extends AbstractWorker {
     /**
+     * @param string $binaryPath Path to PHP Binary. Defaults to value of \PHP_BINARY.
      * @param string $envClassName Name of class implementing \Amp\Parallel\Worker\Environment to instigate.
      *     Defaults to \Amp\Parallel\Worker\BasicEnvironment.
      * @param mixed[] $env Array of environment variables to pass to the worker. Empty array inherits from the current
      *     PHP process. See the $env parameter of \Amp\Process\Process::__construct().
      */
-    public function __construct(string $envClassName = BasicEnvironment::class, array $env = []) {
+    public function __construct(string $binaryPath = \PHP_BINARY, string $envClassName = BasicEnvironment::class, array $env = []) {
         $dir = \dirname(__DIR__, 2) . '/bin';
         $script = [
             $dir . "/worker",
             "-e" . $envClassName,
         ];
-        parent::__construct(new Process($script, $dir, $env));
+        parent::__construct(new Process($script, $binaryPath, $dir, $env));
     }
 }