From be463fdea686360fe57d877b851c46957f2751a1 Mon Sep 17 00:00:00 2001
From: Won-Kyu Park <wkpark@gmail.com>
Date: Wed, 8 Jul 2015 09:46:51 +0900
Subject: [PATCH] Context::setCacheControl() method added etc.

 * make cache friendly
 * make cache-control public/private conditionally
 * use session_start() conditionally
---
 classes/context/Context.class.php        | 36 ++++++++++++++++++++++--
 classes/display/DisplayHandler.class.php | 15 ----------
 2 files changed, 34 insertions(+), 17 deletions(-)

diff --git a/classes/context/Context.class.php b/classes/context/Context.class.php
index 09f7d09a1..492ca2443 100644
--- a/classes/context/Context.class.php
+++ b/classes/context/Context.class.php
@@ -333,8 +333,20 @@ class Context
 			);
 		}
 
-		if($sess = $_POST[session_name()]) session_id($sess);
-		session_start();
+		$sessid = session_name();
+		if($sess = $_POST[$sessid]) session_id($sess);
+		else $sess = $_COOKIE[$sessid];
+
+		session_cache_limiter(''); // to control the cache-control header manually
+		if(!empty($sess))
+		{
+			Context::setCacheControl('private', true);
+			session_start();
+		}
+		else
+		{
+			Context::setCacheControl();
+		}
 
 		// set authentication information in Context and session
 		if(self::isInstalled())
@@ -430,6 +442,26 @@ class Context
 		session_write_close();
 	}
 
+	/**
+	 * set Cache-Control header
+	 *
+	 * @return void
+	 */
+	function setCacheControl($public = 'public', $nocache = false)
+	{
+		is_a($this, 'Context') ? $self = $this : $self = self::getInstance();
+
+		$public = !empty($public) ? $public.', ' : '';
+		header("Cache-Control: ".$public."must-revalidate, post-check=0, pre-check=0");
+		if ($nocache)
+		{
+			header("Cache-Control: no-store, no-cache, must-revalidate", false);
+			header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");
+			header("Expires: Mon, 26 Jul 1997 05:00:00 GMT");
+			header("Pragma: no-cache");
+		}
+	}
+
 	/**
 	 * Load the database information
 	 *
diff --git a/classes/display/DisplayHandler.class.php b/classes/display/DisplayHandler.class.php
index deb8d8326..6b9f91e58 100644
--- a/classes/display/DisplayHandler.class.php
+++ b/classes/display/DisplayHandler.class.php
@@ -321,11 +321,6 @@ class DisplayHandler extends Handler
 	function _printXMLHeader()
 	{
 		header("Content-Type: text/xml; charset=UTF-8");
-		header("Expires: Mon, 26 Jul 1997 05:00:00 GMT");
-		header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");
-		header("Cache-Control: no-store, no-cache, must-revalidate");
-		header("Cache-Control: post-check=0, pre-check=0", false);
-		header("Pragma: no-cache");
 	}
 
 	/**
@@ -335,11 +330,6 @@ class DisplayHandler extends Handler
 	function _printHTMLHeader()
 	{
 		header("Content-Type: text/html; charset=UTF-8");
-		header("Expires: Mon, 26 Jul 1997 05:00:00 GMT");
-		header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");
-		header("Cache-Control: no-store, no-cache, must-revalidate");
-		header("Cache-Control: post-check=0, pre-check=0", false);
-		header("Pragma: no-cache");
 	}
 
 	/**
@@ -349,11 +339,6 @@ class DisplayHandler extends Handler
 	function _printJSONHeader()
 	{
 		header("Content-Type: text/html; charset=UTF-8");
-		header("Expires: Mon, 26 Jul 1997 05:00:00 GMT");
-		header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");
-		header("Cache-Control: no-store, no-cache, must-revalidate");
-		header("Cache-Control: post-check=0, pre-check=0", false);
-		header("Pragma: no-cache");
 	}
 
 	/**