From ec002cdf8a903f2b7ca3894529940778248bafd8 Mon Sep 17 00:00:00 2001
From: Aaron Schulz <aschulz@wikimedia.org>
Date: Wed, 23 May 2012 15:28:12 -0700
Subject: [PATCH] [FileBackend] Worked around Akamai CDN purge limits.

* Added swiftCDNTTL to let the cache TTL be configurable
* Also added swiftCDNPurgable option to disable purges

Change-Id: Ic8e779c20f7501a5a55f4a49fc612923d0dc268c
---
 .../filerepo/backend/SwiftFileBackend.php     | 21 ++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/includes/filerepo/backend/SwiftFileBackend.php b/includes/filerepo/backend/SwiftFileBackend.php
index 36d4334e7f..dc6cd44458 100644
--- a/includes/filerepo/backend/SwiftFileBackend.php
+++ b/includes/filerepo/backend/SwiftFileBackend.php
@@ -42,6 +42,9 @@ class SwiftFileBackend extends FileBackendStore {
 	protected $authTTL; // integer seconds
 	protected $swiftAnonUser; // string; username to handle unauthenticated requests
 	protected $swiftUseCDN; // boolean; whether CloudFiles CDN is enabled
+	protected $swiftCDNExpiry; // integer; how long to cache things in the CDN
+	protected $swiftCDNPurgable; // boolean; whether object CDN purging is enabled
+
 	protected $maxContCacheSize = 300; // integer; max containers with entries
 
 	/** @var CF_Connection */
@@ -59,6 +62,11 @@ class SwiftFileBackend extends FileBackendStore {
 	 *    swiftAuthTTL       : Swift authentication TTL (seconds)
 	 *    swiftAnonUser      : Swift user used for end-user requests (account:username)
 	 *    swiftUseCDN        : Whether a Cloud Files Content Delivery Network is set up
+	 *    swiftCDNExpiry     : How long (in seconds) to store content in the CDN.
+	 *                         If files may likely change, this should probably not exceed
+	 *                         a few days. For example, deletions may take this long to apply.
+	 *                         If object purging is enabled, however, this is not an issue.
+	 *    swiftCDNPurgable   : Whether object purge requests are allowed by the CDN.
 	 *    shardViaHashLevels : Map of container names to sharding config with:
 	 *                         'base'   : base of hash characters, 16 or 36
 	 *                         'levels' : the number of hash levels (and digits)
@@ -90,6 +98,12 @@ class SwiftFileBackend extends FileBackendStore {
 		$this->swiftUseCDN = isset( $config['swiftUseCDN'] )
 			? $config['swiftUseCDN']
 			: false;
+		$this->swiftCDNExpiry = isset( $config['swiftCDNExpiry'] )
+			? $config['swiftCDNExpiry']
+			: 3600; // hour
+		$this->swiftCDNPurgable = isset( $config['swiftCDNPurgable'] )
+			? $config['swiftCDNPurgable']
+			: true;
 		// Cache container info to mask latency
 		$this->memCache = wfGetMainCache();
 	}
@@ -519,7 +533,7 @@ class SwiftFileBackend extends FileBackendStore {
 				) );
 			}
 			if ( $this->swiftUseCDN ) { // Rackspace style CDN
-				$contObj->make_public();
+				$contObj->make_public( $this->swiftCDNExpiry );
 			}
 		} catch ( CDNNotEnabledException $e ) {
 			// CDN not enabled; nothing to see here
@@ -1018,13 +1032,14 @@ class SwiftFileBackend extends FileBackendStore {
 	}
 
 	/**
-	 * Purge the CDN cache of affected objects if CDN caching is enabled
+	 * Purge the CDN cache of affected objects if CDN caching is enabled.
+	 * This is for Rackspace/Akamai CDNs.
 	 *
 	 * @param $objects Array List of CF_Object items
 	 * @return void
 	 */
 	public function purgeCDNCache( array $objects ) {
-		if ( $this->swiftUseCDN ) { // Rackspace style CDN
+		if ( $this->swiftUseCDN && $this->swiftCDNPurgable ) {
 			foreach ( $objects as $object ) {
 				try {
 					$object->purge_from_cdn();
-- 
2.20.1