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/UnixProcessControl.php

@@ -0,0 +1,54 @@
+<?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;
+
+/**
+ * Control processes using the "ps" and "kill" commands.
+ *
+ * @author Adirelle <adirelle@gmail.com>
+ */
+class UnixProcessControl implements ProcessControlInterface
+{
+    /**
+     * Check process using the "ps" command.
+     *
+     * @param int $pid
+     * @return boolean
+     */
+    public function isRunning($pid)
+    {
+        $output = $exitCode = null;
+        exec(sprintf("ps %d", $pid), $output, $exitCode);
+        return $exitCode === 0;
+    }
+
+    /**
+     * Sends a signal using the "kill" command.
+     *
+     * @param int $pid
+     * @param bool $forcefully
+     */
+    public function kill($pid, $forcefully = false)
+    {
+        exec(sprintf("kill -%d %d", $forcefully ? 9 : 15, $pid));
+    }
+
+    /**
+     * Check whether the commands "ps" and "kill" are available.
+     *
+     * @return bool
+     *
+     * @internal
+     */
+    public static function isAvailable()
+    {
+        return DIRECTORY_SEPARATOR === '/' && exec("which ps") && exec("which kill");
+    }
+}