2 files changed, 116 insertions, 0 deletions
diff --git a/lib/processmanager.php b/lib/processmanager.php
new file mode 100644
index 000000000..6032bfc5c
--- /dev/null
+++ b/lib/processmanager.php
@@ -0,0 +1,84 @@
+<?php
+/**
+ * StatusNet, the distributed open-source microblogging tool
+ *
+ * i/o manager to watch for a dead parent process
+ *
+ * PHP version 5
+ *
+ * LICENCE: This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * @category  QueueManager
+ * @package   StatusNet
+ * @author    Brion Vibber <brion@status.net>
+ * @copyright 2010 StatusNet, Inc.
+ * @license   http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
+ * @link      http://status.net/
+ */
+
+class ProcessManager extends IoManager
+{
+    protected $socket;
+
+    public static function get()
+    {
+        throw new Exception("Must pass ProcessManager per-instance");
+    }
+
+    public function __construct($socket)
+    {
+        $this->socket = $socket;
+    }
+
+    /**
+     * Tell the i/o queue master if and how we can handle multi-site
+     * processes.
+     *
+     * Return one of:
+     *   IoManager::SINGLE_ONLY
+     *   IoManager::INSTANCE_PER_SITE
+     *   IoManager::INSTANCE_PER_PROCESS
+     */
+    public static function multiSite()
+    {
+        return IoManager::INSTANCE_PER_PROCESS;
+    }
+
+    /**
+     * We won't get any input on it, but if it's broken we'll
+     * know something's gone horribly awry.
+     *
+     * @return array of resources
+     */
+    function getSockets()
+    {
+        return array($this->socket);
+    }
+
+    /**
+     * See if the parent died and request a shutdown...
+     *
+     * @param resource $socket
+     * @return boolean success
+     */
+    function handleInput($socket)
+    {
+        if (feof($socket)) {
+            common_log(LOG_INFO, "Parent process exited; shutting down child.");
+            $this->master->requestShutdown();
+        }
+        return true;
+    }
+}
+
diff --git a/lib/spawningdaemon.php b/lib/spawningdaemon.php
index fd9ae4355..2f9f6e32e 100644
--- a/lib/spawningdaemon.php
+++ b/lib/spawningdaemon.php
@@ -71,6 +71,8 @@ abstract class SpawningDaemon extends Daemon
      */
     function run()
     {
+        $this->initPipes();
+
         $children = array();
         for ($i = 1; $i <= $this->threads; $i++) {
             $pid = pcntl_fork();
@@ -129,6 +131,34 @@ abstract class SpawningDaemon extends Daemon
     }
 
     /**
+     * Create an IPC socket pair which child processes can use to detect
+     * if the parent process has been killed.
+     */
+    function initPipes()
+    {
+        $sockets = stream_socket_pair(STREAM_PF_UNIX, STREAM_SOCK_STREAM, 0);
+        if ($sockets) {
+            $this->parentWriter = $sockets[0];
+            $this->parentReader = $sockets[1];
+        } else {
+            $this->log(LOG_ERROR, "Couldn't create inter-process sockets");
+            exit(1);
+        }
+    }
+
+    /**
+     * Build an IOManager that simply ensures that we have a connection
+     * to the parent process open. If it breaks, the child process will
+     * die.
+     *
+     * @return ProcessManager
+     */
+    public function processManager()
+    {
+        return new ProcessManager($this->parentReader);
+    }
+
+    /**
      * Determine whether to respawn an exited subprocess based on its exit code.
      * Otherwise we'll respawn all exits by default.
      *
@@ -152,6 +182,8 @@ abstract class SpawningDaemon extends Daemon
      */
     protected function initAndRunChild($thread)
     {
+        // Close the writer end of our parent<->children pipe.
+        fclose($this->parentWriter);
         $this->set_id($this->get_id() . "." . $thread);
         $this->resetDb();
         $exitCode = $this->runThread();