PHP緩存實現

<?php
class CacheException extends Exception {}
/**
* 緩存抽象類
*/
abstract class Cache_Abstract {
/**
* 讀緩存變量
*
* @param string $key 緩存下標
* @return mixed
*/
abstract public function fetch( $key );
/**
* 緩存變量
*
* @param string $key 緩存變量下標
* @param string $value 緩存變量的值
* @return bool
*/
abstract public function store( $key , $value );
/**
* 刪除緩存變量
*
* @param string $key 緩存下標
* @return Cache_Abstract
*/
abstract public function delete ( $key );
/**
* 清(刪)除所有緩存
*
* @return Cache_Abstract
*/
abstract public function clear();
/**
* 鎖定緩存變量
*
* @param string $key 緩存下標
* @return Cache_Abstract
*/
abstract public function lock( $key );
/**
* 緩存變量解鎖
*
* @param string $key 緩存下標
* @return Cache_Abstract
*/
abstract public function unlock( $key );
/**
* 取得緩存變量是否被鎖定
*
* @param string $key 緩存下標
* @return bool
*/
abstract public function isLocked( $key );
/**
* 確保不是鎖定狀態
* 最多做$tries次睡眠等待解鎖，超時則跳過並解鎖
*
* @param string $key 緩存下標
*/
public function checkLock( $key ) {
if (! $this ->isLocked( $key )) {
return $this ;
}
$tries = 10;
$count = 0;
do {
usleep(200);
$count ++;
} while ( $count <= $tries && $this ->isLocked( $key )); // 最多做十次睡眠等待解鎖，超時則跳過並解鎖
$this ->isLocked( $key ) && $this ->unlock( $key );
return $this ;
}
}
/**
* APC擴展緩存實現
*
*
* @category Mjie
* @package Cache
* @author 流水孟春
* @copyright Copyright (c) 2008- <cmpan(at)qq.com>
* @license New BSD License
* @version $Id: Cache/Apc.php 版本號 2010-04-18 23:02 cmpan $
*/
class Cache_Apc extends Cache_Abstract {
protected $_prefix = 'cache.mjie.net' ;
public function __construct() {
if (!function_exists( 'apc_cache_info' )) {
throw new CacheException( 'apc extension didn/'t installed' );
}
}
/**
* 保存緩存變量
*
* @param string $key
* @param mixed $value
* @return bool
*/
public function store( $key , $value ) {
return apc_store( $this ->_storageKey( $key ), $value );
}
/**
* 讀取緩存
*
* @param string $key
* @return mixed
*/
public function fetch( $key ) {
return apc_fetch( $this ->_storageKey( $key ));
}
/**
* 清除緩存
*
* @return Cache_Apc
*/
public function clear() {
apc_clear_cache();
return $this ;
}
/**
* 刪除緩存單元
*
* @return Cache_Apc
*/
public function delete ( $key ) {
apc_delete($this ->_storageKey( $key ));
return $this ;
}
/**
* 緩存單元是否被鎖定
*
* @param string $key
* @return bool
*/
public function isLocked( $key ) {
if ((apc_fetch( $this ->_storageKey( $key ) . '.lock' )) === false) {
return false;
}
return true;
}
/**
* 鎖定緩存單元
*
* @param string $key
* @return Cache_Apc
*/
public function lock( $key ) {
apc_store($this ->_storageKey( $key ) . '.lock' , '' , 5);
return $this ;
}
/**
* 緩存單元解鎖
*
* @param string $key
* @return Cache_Apc
*/
public function unlock( $key ) {
apc_delete($this ->_storageKey( $key ) . '.lock' );
return $this ;
}
/**
* 完整緩存名
*
* @param string $key
* @return string
*/
private function _storageKey( $key ) {
return $this ->_prefix . '_' . $key ;
}
}
/**
* 文件緩存實現
*
*
* @category Mjie
* @package Cache
* @author 流水孟春
* @copyright Copyright (c) 2008- <cmpan(at)qq.com>
* @license New BSD License
* @version $Id: Cache/File.php 版本號 2010-04-18 16:46 cmpan $
*/
class Cache_File extends Cache_Abstract {
protected $_cachesDir = 'cache' ;
public function __construct() {
if (defined( 'DATA_DIR' )) {
$this ->_setCacheDir(DATA_DIR . '/cache' );
}
}
/**
* 獲取緩存文件
*
* @param string $key
* @return string
*/
protected function _getCacheFile( $key ) {
return $this ->_cachesDir . '/' . substr ( $key , 0, 2) . '/' . $key . '.php' ;
}
/**
* 讀取緩存變量
* 爲防止信息泄露，緩存文件格式爲php文件，並以"<?php exit;?>"開頭
*
* @param string $key 緩存下標
* @return mixed
*/
public function fetch( $key ) {
$cacheFile = self::_getCacheFile( $key );
if ( file_exists ( $cacheFile ) && is_readable ( $cacheFile )) {
return unserialize(@ file_get_contents ( $cacheFile , false, NULL, 13));
}
return false;
}
/**
* 緩存變量
* 爲防止信息泄露，緩存文件格式爲php文件，並以"<?php exit;?>"開頭
*
* @param string $key 緩存變量下標
* @param string $value 緩存變量的值
* @return bool
*/
public function store( $key , $value ) {
$cacheFile = self::_getCacheFile( $key );
$cacheDir = dirname( $cacheFile );
if (! is_dir ( $cacheDir )) {
if (!@ mkdir ( $cacheDir , 0755, true)) {
throw new CacheException( "Could not make cache directory" );
}
}
return @ file_put_contents ( $cacheFile , '<?php exit;?>' . serialize( $value ));
}
/**
* 刪除緩存變量
*
* @param string $key 緩存下標
* @return Cache_File
*/
public function delete ( $key ) {
if ( empty empty ( $key )) {
throw new CacheException( "Missing argument 1 for Cache_File::delete()" );
}
$cacheFile = self::_getCacheFile( $key );
if (!@unlink( $cacheFile )) {
throw new CacheException( "Cache file could not be deleted" );
}
return $this ;
}
/**
* 緩存單元是否已經鎖定
*
* @param string $key
* @return bool
*/
public function isLocked( $key ) {
$cacheFile = self::_getCacheFile( $key );
clearstatcache();
return file_exists ( $cacheFile . '.lock' );
}
/**
* 鎖定
*
* @param string $key
* @return Cache_File
*/
public function lock( $key ) {
$cacheFile = self::_getCacheFile( $key );
$cacheDir = dirname( $cacheFile );
if (! is_dir ( $cacheDir )) {
if (!@ mkdir ( $cacheDir , 0755, true)) {
if (! is_dir ( $cacheDir )) {
throw new CacheException( "Could not make cache directory" );
}
}
}
// 設定緩存鎖文件的訪問和修改時間
@touch($cacheFile . '.lock' );
return $this ;
}
/**
* 解鎖
*
* @param string $key
* @return Cache_File
*/
public function unlock( $key ) {
$cacheFile = self::_getCacheFile( $key );
@unlink($cacheFile . '.lock' );
return $this ;
}
/**
* 設置文件緩存目錄
* @param string $dir
* @return Cache_File
*/
protected function _setCacheDir( $dir ) {
$this ->_cachesDir = rtrim( str_replace ( '//', ' / ', trim($dir)), ' /');
clearstatcache();
if (! is_dir ( $this ->_cachesDir)) {
mkdir ( $this ->_cachesDir, 0755, true);
}
//
return $this ;
}
/**
* 清空所有緩存
*
* @return Cache_File
*/
public function clear() {
// 遍歷目錄清除緩存
$cacheDir = $this ->_cachesDir;
$d = dir( $cacheDir );
while (false !== ( $entry = $d ->read())) {
if ( '.' == $entry [0]) {
continue ;
}
$cacheEntry = $cacheDir . '/' . $entry ;
if ( is_file ( $cacheEntry )) {
@unlink($cacheEntry );
} elseif ( is_dir ( $cacheEntry )) {
// 緩存文件夾有兩級
$d2 = dir( $cacheEntry );
while (false !== ( $entry = $d2 ->read())) {
if ( '.' == $entry [0]) {
continue ;
}
$cacheEntry .= '/' . $entry ;
if ( is_file ( $cacheEntry )) {
@unlink($cacheEntry );
}
}
$d2 ->close();
}
}
$d ->close();
return $this ;
}
}
/**
* 緩存單元的數據結構
* array(
* 'time' => time(), // 緩存寫入時的時間戳
* 'expire' => $expire, // 緩存過期時間
* 'valid' => true, // 緩存是否有效
* 'data' => $value // 緩存的值
* );
*/
final class Cache {
/**
* 緩存過期時間長度(s)
*
* @var int
*/
private $_expire = 3600;
/**
* 緩存處理類
*
* @var Cache_Abstract
*/
private $_storage = null;
/**
* @return Cache
*/
static public function createCache( $cacheClass = 'Cache_File' ) {
return new self( $cacheClass );
}
private function __construct( $cacheClass ) {
$this ->_storage = new $cacheClass ();
}
/**
* 設置緩存
*
* @param string $key
* @param mixed $value
* @param int $expire
*/
public function set( $key , $value , $expire = false) {
if (! $expire ) {
$expire = $this ->_expire;
}
$this ->_storage->checkLock( $key );
$data = array ( 'time' => time(), 'expire' => $expire , 'valid' => true, 'data' => $value );
$this ->_storage->lock( $key );
try {
$this ->_storage->store( $key , $data );
$this ->_storage->unlock( $key );
} catch (CacheException $e ) {
$this ->_storage->unlock( $key );
throw $e ;
}
}
/**
* 讀取緩存
*
* @param string $key
* @return mixed
*/
public function get( $key ) {
$data = $this ->fetch( $key );
if ( $data && $data [ 'valid' ] && ! $data [ 'isExpired' ]) {
return $data [ 'data' ];
}
return false;
}
/**
* 讀緩存，包括過期的和無效的，取得完整的存貯結構
*
* @param string $key
*/
public function fetch( $key ) {
$this ->_storage->checkLock( $key );
$data = $this ->_storage->fetch( $key );
if ( $data ) {
$data [ 'isExpired' ] = (time() - $data [ 'time' ]) > $data [ 'expire' ] ? true : false;
return $data ;
}
return false;
}
/**
* 刪除緩存
*
* @param string $key
*/
public function delete ( $key ) {
$this ->_storage->checkLock( $key )
->lock($key )
->delete ( $key )
->unlock($key );
}
public function clear() {
$this ->_storage->clear();
}
/**
* 把緩存設爲無效
*
* @param string $key
*/
public function setInvalidate( $key ) {
$this ->_storage->checkLock( $key )
->lock($key );
try {
$data = $this ->_storage->fetch( $key );
if ( $data ) {
$data [ 'valid' ] = false;
$this ->_storage->store( $key , $data );
}
$this ->_storage->unlock( $key );
} catch (CacheException $e ) {
$this ->_storage->unlock( $key );
throw $e ;
}
}
/**
* 設置緩存過期時間（s）
*
* @param int $expire
*/
public function setExpire( $expire ) {
$this ->_expire = (int) $expire ;
return $this ;
}
}

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