Reworked the DaemonCommand.

* Accepts options for PID and log file.
* Uses posix_kill whenever available.
* Checks that the daemon actually started or stopped.
* Try to terminate then kill the daemon.
* Uses the logger or output instead of "echo".

Added a ProcessControl interface and implementations.

Closed #908

PHPCI/ProcessControl/Factory.php

@@ -0,0 +1,63 @@
+<?php
+/**
+ * PHPCI - Continuous Integration for PHP
+ *
+ * @copyright    Copyright 2015, Block 8 Limited.
+ * @license      https://github.com/Block8/PHPCI/blob/master/LICENSE.md
+ * @link         https://www.phptesting.org/
+ */
+
+namespace PHPCI\ProcessControl;
+
+/**
+ * Construct an appropriate ProcessControl instance.
+ *
+ * @author Adirelle <adirelle@gmail.com>
+ */
+class Factory
+{
+    /**
+     * ProcessControl singleton.
+     *
+     * @var ProcessControlInterface
+     */
+    protected static $instance = null;
+
+    /**
+     * Returns the ProcessControl singleton.
+     *
+     * @return ProcessControlInterface
+     */
+    public static function getInstance()
+    {
+        if (static::$instance === null) {
+            static::$instance = static::createProcessControl();
+        }
+        return static::$instance;
+    }
+
+    /**
+     * Create a ProcessControl depending on available extensions and the underlying OS.
+     *
+     * Check PosixProcessControl, WindowsProcessControl and UnixProcessControl, in that order.
+     *
+     * @return ProcessControlInterface
+     *
+     * @internal
+     */
+    public static function createProcessControl()
+    {
+        switch(true) {
+            case PosixProcessControl::isAvailable():
+                return new PosixProcessControl();
+
+            case WindowsProcessControl::isAvailable():
+                return new WindowsProcessControl();
+
+            case UnixProcessControl::isAvailable():
+                return new UnixProcessControl();
+        }
+
+        throw new \Exception("No ProcessControl implementation available.");
+    }
+}