simplefilecache.php

<?php
/*  Copyright 2009  Carson McDonald  (carson@ioncannon.net)

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 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 General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
*/

require_once( dirname( __FILE__ ) . '/aux-lib.php' );

class SimpleFileCache {
	function canCache() {
		global $wp_version;
		if ( version_compare( $wp_version, '2.8', '>=' ) ) {
			return true;
		} else {
			$lh       = SimpleFileCache::lock();
			$filename = sys_get_temp_dir() . '/gad_cache_' . md5( 'cachetest' ) . '.dat';
			if ( $f = @fopen( $filename, "w" ) ) {
				fclose( $f );
				SimpleFileCache::unlock( $lh );

				return true;
			} else {
				return false;
			}
		}
	}

	function isExpired( $key, $expire ) {
		global $wp_version;
		if ( version_compare( $wp_version, '2.8', '>=' ) ) {
			$trans_id = get_option( 'gad_trans_id' );
			if ( $trans_id === false ) {
				$trans_id = 0;
			}
			if ( false === get_transient( 'gad_cache_' . $trans_id . '_' . md5( $key ) ) ) {
				return true;
			} else {
				return false;
			}
		} else {
			$filename = sys_get_temp_dir() . '/gad_cache_' . md5( $key ) . '.dat';
			if ( file_exists( $filename ) ) {
				return time() - filemtime( $filename ) > $expire;
			} else {
				return true;
			}
		}
	}

	function clearCache() {
		global $wp_version;
		if ( version_compare( $wp_version, '2.8', '>=' ) ) {
			$trans_id = get_option( 'gad_trans_id' );
			if ( $trans_id === false ) {
				$trans_id = 0;
			}
			update_option( 'gad_trans_id', $trans_id + 1 );
		} else {
			$lh = SimpleFileCache::lock();
			foreach ( glob( sys_get_temp_dir() . '/gad_cache_*.dat' ) as $filename ) {
				@unlink( $filename );
			}
			SimpleFileCache::unlock( $lh );
		}
	}

	function cachePut( $key, $value, $timeout ) {
		global $wp_version;
		if ( version_compare( $wp_version, '2.8', '>=' ) ) {
			$trans_id = get_option( 'gad_trans_id' );
			if ( $trans_id === false ) {
				$trans_id = 0;
			}
			set_transient( 'gad_cache_' . $trans_id . '_' . md5( $key ), $value, $timeout );
		} else {
			$lh       = SimpleFileCache::lock();
			$filename = sys_get_temp_dir() . '/gad_cache_' . md5( $key ) . '.dat';
			if ( $f = @fopen( $filename, "w" ) ) {
				fwrite( $f, serialize( $value ) );
				fclose( $f );
			}
			SimpleFileCache::unlock( $lh );
		}
	}

	function cacheGet( $key ) {
		global $wp_version;
		if ( version_compare( $wp_version, '2.8', '>=' ) ) {
			$trans_id = get_option( 'gad_trans_id' );
			if ( $trans_id === false ) {
				$trans_id = 0;
			}

			return get_transient( 'gad_cache_' . $trans_id . '_' . md5( $key ) );
		} else {
			$lh       = SimpleFileCache::lock();
			$filename = sys_get_temp_dir() . '/gad_cache_' . md5( $key ) . '.dat';
			$result   = '';
			if ( $f = @fopen( $filename, "r" ) ) {
				$data   = fread( $f, filesize( $filename ) );
				$result = unserialize( $data );
				fclose( $f );
			}
			SimpleFileCache::unlock( $lh );

			return $result;
		}
	}

	function lock() {
		$filename = sys_get_temp_dir() . '/gad_lock.dat';
		if ( file_exists( $filename ) ) {
			$file_size = filesize( $filename );
			$fp        = @fopen( $filename, "r+" );
		} else {
			$file_size = 0;
			$fp        = @fopen( $filename, "w+" );
		}
		if ( @flock( $fp, LOCK_EX ) ) {
			$last_ts = $file_size == 0 ? time() : fread( $fp, $file_size );
			fseek( $fp, 0 );
			if ( $last_ts + 360 < time() ) {
				foreach ( glob( sys_get_temp_dir() . '/gad_cache_*.dat' ) as $filename ) {
					if ( time() - filemtime( $filename ) > 360 ) {
						@unlink( $filename );
					}
				}
				fwrite( $fp, time() );
			} else {
				if ( $file_size == 0 ) {
					fwrite( $fp, $last_ts );
				}
			}
		}

		return $fp;
	}

	function unlock( $fp ) {
		@flock( $fp, LOCK_UN );
	}
}