1 files changed, 194 insertions, 0 deletions
diff --git a/includes/objectcache/DBABagOStuff.php b/includes/objectcache/DBABagOStuff.php
new file mode 100644
index 00000000..783cd22b
--- /dev/null
+++ b/includes/objectcache/DBABagOStuff.php
@@ -0,0 +1,194 @@
+<?php
+
+/**
+ * Cache that uses DBA as a backend.
+ * Slow due to the need to constantly open and close the file to avoid holding
+ * writer locks. Intended for development use only,  as a memcached workalike
+ * for systems that don't have it.
+ *
+ * @ingroup Cache
+ */
+class DBABagOStuff extends BagOStuff {
+	var $mHandler, $mFile, $mReader, $mWriter, $mDisabled;
+
+	public function __construct( $dir = false ) {
+		global $wgDBAhandler;
+
+		if ( $dir === false ) {
+			global $wgTmpDirectory;
+			$dir = $wgTmpDirectory;
+		}
+
+		$this->mFile = "$dir/mw-cache-" . wfWikiID();
+		$this->mFile .= '.db';
+		wfDebug( __CLASS__ . ": using cache file {$this->mFile}\n" );
+		$this->mHandler = $wgDBAhandler;
+	}
+
+	/**
+	 * Encode value and expiry for storage
+	 * @param $value
+	 * @param $expiry
+	 *
+	 * @return string
+	 */
+	function encode( $value, $expiry ) {
+		# Convert to absolute time
+		$expiry = $this->convertExpiry( $expiry );
+
+		return sprintf( '%010u', intval( $expiry ) ) . ' ' . serialize( $value );
+	}
+
+	/**
+	 * @return array list containing value first and expiry second
+	 */
+	function decode( $blob ) {
+		if ( !is_string( $blob ) ) {
+			return array( null, 0 );
+		} else {
+			return array(
+				unserialize( substr( $blob, 11 ) ),
+				intval( substr( $blob, 0, 10 ) )
+			);
+		}
+	}
+
+	function getReader() {
+		if ( file_exists( $this->mFile ) ) {
+			$handle = dba_open( $this->mFile, 'rl', $this->mHandler );
+		} else {
+			$handle = $this->getWriter();
+		}
+
+		if ( !$handle ) {
+			wfDebug( "Unable to open DBA cache file {$this->mFile}\n" );
+		}
+
+		return $handle;
+	}
+
+	function getWriter() {
+		$handle = dba_open( $this->mFile, 'cl', $this->mHandler );
+
+		if ( !$handle ) {
+			wfDebug( "Unable to open DBA cache file {$this->mFile}\n" );
+		}
+
+		return $handle;
+	}
+
+	function get( $key ) {
+		wfProfileIn( __METHOD__ );
+		wfDebug( __METHOD__ . "($key)\n" );
+
+		$handle = $this->getReader();
+		if ( !$handle ) {
+			wfProfileOut( __METHOD__ );
+			return null;
+		}
+
+		$val = dba_fetch( $key, $handle );
+		list( $val, $expiry ) = $this->decode( $val );
+
+		# Must close ASAP because locks are held
+		dba_close( $handle );
+
+		if ( !is_null( $val ) && $expiry && $expiry < time() ) {
+			# Key is expired, delete it
+			$handle = $this->getWriter();
+			dba_delete( $key, $handle );
+			dba_close( $handle );
+			wfDebug( __METHOD__ . ": $key expired\n" );
+			$val = null;
+		}
+
+		wfProfileOut( __METHOD__ );
+		return $val;
+	}
+
+	function set( $key, $value, $exptime = 0 ) {
+		wfProfileIn( __METHOD__ );
+		wfDebug( __METHOD__ . "($key)\n" );
+
+		$blob = $this->encode( $value, $exptime );
+
+		$handle = $this->getWriter();
+		if ( !$handle ) {
+			wfProfileOut( __METHOD__ );
+			return false;
+		}
+
+		$ret = dba_replace( $key, $blob, $handle );
+		dba_close( $handle );
+
+		wfProfileOut( __METHOD__ );
+		return $ret;
+	}
+
+	function delete( $key, $time = 0 ) {
+		wfProfileIn( __METHOD__ );
+		wfDebug( __METHOD__ . "($key)\n" );
+
+		$handle = $this->getWriter();
+		if ( !$handle ) {
+			wfProfileOut( __METHOD__ );
+			return false;
+		}
+
+		$ret = dba_delete( $key, $handle );
+		dba_close( $handle );
+
+		wfProfileOut( __METHOD__ );
+		return $ret;
+	}
+
+	function add( $key, $value, $exptime = 0 ) {
+		wfProfileIn( __METHOD__ );
+
+		$blob = $this->encode( $value, $exptime );
+
+		$handle = $this->getWriter();
+
+		if ( !$handle ) {
+			wfProfileOut( __METHOD__ );
+			return false;
+		}
+
+		$ret = dba_insert( $key, $blob, $handle );
+
+		# Insert failed, check to see if it failed due to an expired key
+		if ( !$ret ) {
+			list( $value, $expiry ) = $this->decode( dba_fetch( $key, $handle ) );
+
+			if ( $expiry < time() ) {
+				# Yes expired, delete and try again
+				dba_delete( $key, $handle );
+				$ret = dba_insert( $key, $blob, $handle );
+				# This time if it failed then it will be handled by the caller like any other race
+			}
+		}
+
+		dba_close( $handle );
+
+		wfProfileOut( __METHOD__ );
+		return $ret;
+	}
+
+	function keys() {
+		$reader = $this->getReader();
+		$k1 = dba_firstkey( $reader );
+
+		if ( !$k1 ) {
+			return array();
+		}
+
+		$result[] = $k1;
+
+		while ( $key = dba_nextkey( $reader ) ) {
+			$result[] = $key;
+		}
+
+		return $result;
+	}
+}
+