From b381e54d992e8ffa5800a4b3c3fc9728a42bda3a Mon Sep 17 00:00:00 2001
From: Karsten Heiken <karsten@disposed.de>
Date: Fri, 22 Apr 2011 02:49:53 +0200
Subject: [PATCH] Implement a simple rpc system

Servers can transmit their workload and jobstatus updates.
---
 application/controllers/statusrpc.php | 49 +++++++++++++++++++++++++++
 application/models/job.php            | 23 +++++++++++++
 application/models/server.php         | 40 ++++++++++++++++++++++
 3 files changed, 112 insertions(+)
 create mode 100644 application/controllers/statusrpc.php
 create mode 100644 application/models/job.php
 create mode 100644 application/models/server.php

diff --git a/application/controllers/statusrpc.php b/application/controllers/statusrpc.php
new file mode 100644
index 0000000..3696f0b
--- /dev/null
+++ b/application/controllers/statusrpc.php
@@ -0,0 +1,49 @@
+<?php
+
+/**
+ * Simple RPC class to handle requests from calculation servers.
+ *
+ * @author Karsten Heiken, karsten@disposed.de
+ */
+class Statusrpc extends CI_Controller {
+	
+	/**
+	 * Update the state of a given job.
+	 * 
+	 * Because we do not want any access from servers we do not trust,
+	 * we need a special secret to authenticate the servers.
+	 * 
+	 * @param type $secret The secret to authenticate the server.
+	 * @param type $job_id The job id that is running on the server.
+	 * @param type $state The state of the job.
+	 */
+	public function update_job($secret, $job_id, $progress) {
+		$this->load->model('job');
+
+		$query = $this->db->get_where('servers', array('secret' => $secret));
+
+		// if we are in production mode, we do not want to tell the evil hacker
+		// that he used a wrong secret. That just encourages him.
+		if($query->num_rows() < 1 && ENVIRONMENT != 'production') {
+			die("Unauthorized access.");
+		}
+
+		$this->job->update($job_id, $progress);
+	}
+
+	/**
+	 * Update the workload of the server.
+	 */
+	public function update_workload($secret, $workload) {
+		$this->load->model('server');
+		$query = $this->db->get_where('servers', array('secret' => $secret));
+
+		// if we are in production mode, we do not want to tell the evil hacker
+		// that he used a wrong secret. That just encourages him.
+		if($query->num_rows() < 1 && ENVIRONMENT != 'production') {
+			die("Unauthorized access.");
+		}
+
+		$this->server->update_workload($secret, $workload);
+	}
+}
\ No newline at end of file
diff --git a/application/models/job.php b/application/models/job.php
new file mode 100644
index 0000000..de6d45e
--- /dev/null
+++ b/application/models/job.php
@@ -0,0 +1,23 @@
+<?php
+
+/**
+ * @author Karsten Heiken, karsten@disposed.de
+ */
+class Job extends CI_Model {
+
+	/**
+	 * Update the progress of a given job.
+	 *
+	 * @param string $job_id The job's id you want to update.
+	 * @param integer $progress The progress of the job.
+	 */
+	public function update($job_id, $progress) {
+		$finished_at = "";
+		if($progress == 100)
+			$finished_at = ", `finished_at`=NOW()";
+
+		$this->db->query("UPDATE `jobs` SET `progress`=".
+				$this->db->escape($progress).$finished_at. " WHERE `id`=".
+				$this->db->escape($job_id));
+	}
+}
diff --git a/application/models/server.php b/application/models/server.php
new file mode 100644
index 0000000..b4d8570
--- /dev/null
+++ b/application/models/server.php
@@ -0,0 +1,40 @@
+<?php
+
+/**
+ * @author Karsten Heiken, karsten@disposed.de
+ */
+class Server extends CI_Model {
+
+	/**
+	 * Get a list of all available servers.
+	 *
+	 * @return array List of all available servers.
+	 */
+	public function get_all() {
+		return $this->db->get('servers')->result_array();
+	}
+
+	/**
+	 * Get a list of servers that could handle another job.
+	 *
+	 * @return array List of servers that could handle another job.
+	 */
+	public function get_idle() {
+		return $this->db->get_where('servers', 'workload <= 2')->result_array();
+	}
+
+	/**
+	 * Set a server's workload.
+	 *
+	 * In order to check if a server can handle another job we need to know
+	 * the workload of every server.
+	 *
+	 * @param type $secret The server's secret for basic authentication.
+	 * @param type $workload The server's workload.
+	 */
+	public function update_workload($secret, $workload) {
+		$this->db->query("UPDATE `servers` SET `workload`=".$this->db->escape($workload)
+				. ", `last_update`=NOW()"
+				. " WHERE `secret`=".$this->db->escape($secret));
+	}
+}