Simple cache system in php

simple_chace.php

<?php

function write_file( $path, $data, $mode = 'wb') {
        if ( ! $fp = @fopen( $path, $mode ) ) return FALSE;

        flock( $fp, LOCK_EX );

        for ( $result = $written = 0, $length = strlen( $data ); $written < $length; $written += $result ) {
                if ( ( $result = fwrite( $fp, substr( $data, $written ) ) ) === FALSE ) break;
        }

        flock( $fp, LOCK_UN );
        fclose( $fp );

        return is_int( $result );
}

function read_file( $file ) {
        return @file_get_contents( $file );
}

function delete_files( $path, $del_dir = FALSE, $htdocs = FALSE, $_level = 0 ) {
        $path = rtrim($path, '/\\');

        if ( ! $current_dir = @opendir( $path ) ) return FALSE;

        while ( FALSE !== ( $filename = @readdir( $current_dir ) ) ) {
                if ( $filename !== '.' && $filename !== '..' ) {
                        $filepath = $path.DIRECTORY_SEPARATOR.$filename;

                        if ( is_dir( $filepath ) && $filename[0] !== '.' && ! is_link( $filepath ) ) {
                                delete_files( $filepath, $del_dir, $htdocs, $_level + 1 );
                        }elseif ($htdocs !== TRUE OR ! preg_match( '/^(\.htaccess|index\.(html|htm|php)|web\.config)$/i', $filename ) ) {
                                @unlink( $filepath );
                        }
                }
        }

        closedir( $current_dir );

        return ( $del_dir === TRUE && $_level > 0 )
                ? @rmdir($path)
                : TRUE;
}

function cache_get($id=NULL, $expire = FALSE ) {
        if ( empty($id) ) return FALSE;
        $path = cache_path( $id );
        if (file_exists( $path )){
                if ( !$expire ) $expire = 300;
                if (time() - filemtime($path) < $expire ) return read_file( $path );

                @unlink( $path );
        }

        return FALSE;
}
   
function cache_save($id, $data) {
        if ( empty($id) ) return FALSE;
        if (write_file( cache_path( $id ), $data ) ) {
                chmod( cache_path( $id ), 0640 );
                return TRUE;
        }

        return FALSE;
}

function cache_delete($id) {
        $path = cache_path( $id );
        return is_file( cache_path( $id ) ) ? unlink( $path ) : FALSE;
}

function clear_cache() {
        return delete_files( cache_path(), FALSE, TRUE );
}
     
function cache_path( $file='' ) {
        $path = config_item( 'cache', 'path');
        $path = ( $path === '' ) ? '/tmp/' : $path;
        return ( $file === '' ) ? $path : $path.$file.'.cache';
}

if ( ! $foo = cache_get('foo', 60)) {
        $foo = 'bar';
        cache_save('foo', $foo);
}

echo $foo;