PHP 緩衝實現代碼及詳細注釋

複製代碼 代碼如下:class CacheException extends Exception {}
/**
* 緩衝抽象類別
*/
abstract class Cache_Abstract {
/**
* 讀緩衝變數
*
* @param string $key 緩衝下標
* @return mixed
*/
abstract public function fetch($key);

/**
* 緩衝變數
*
* @param string $key 緩衝變數下標
* @param string $value 緩衝變數的值
* @return bool
*/
abstract public function store($key, $value);

/**
* 刪除緩衝變數
*
* @param string $key 緩衝下標
* @return Cache_Abstract
*/
abstract public function delete($key);

/**
* 清(刪)除所有緩衝
*
* @return Cache_Abstract
*/
abstract public function clear();

/**
* 鎖定緩衝變數
*
* @param string $key 緩衝下標
* @return Cache_Abstract
*/
abstract public function lock($key);
/**
* 緩衝變數解鎖
*
* @param string $key 緩衝下標
* @return Cache_Abstract
*/
abstract public function unlock($key);
/**
* 取得緩衝變數是否被鎖定
*
* @param string $key 緩衝下標
* @return bool
*/
abstract public function isLocked($key);
/**
* 確保不是鎖定狀態
* 最多做$tries次睡眠等待解鎖，逾時則跳過並解鎖
*
* @param string $key 緩衝下標
*/
public function checkLock($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，逾時則跳過並解鎖
$this->isLocked($key) && $this->unlock($key);

return $this;
}
}

/**
* APC擴充緩衝實現
*
*
* @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 版本號碼 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');
}
}

/**
* 儲存緩衝變數
*
* @param string $key
* @param mixed $value
* @return bool
*/
public function store($key, $value) {
return apc_store($this->_storageKey($key), $value);
}

/**
* 讀取緩衝
*
* @param string $key
* @return mixed
*/
public function fetch($key) {
return apc_fetch($this->_storageKey($key));
}

/**
* 清除緩衝
*
* @return Cache_Apc
*/
public function clear() {
apc_clear_cache();
return $this;
}

/**
* 刪除緩衝單元
*
* @return Cache_Apc
*/
public function delete($key) {
apc_delete($this->_storageKey($key));
return $this;
}

/**
* 緩衝單元是否被鎖定
*
* @param string $key
* @return bool
*/
public function isLocked($key) {
if ((apc_fetch($this->_storageKey($key) . '.lock')) === false) {
return false;
}

return true;
}

/**
* 鎖定緩衝單元
*
* @param string $key
* @return Cache_Apc
*/
public function lock($key) {
apc_store($this->_storageKey($key) . '.lock', '', 5);
return $this;
}

/**
* 緩衝單元解鎖
*
* @param string $key
* @return Cache_Apc
*/
public function unlock($key) {
apc_delete($this->_storageKey($key) . '.lock');
return $this;
}

/**
* 完整緩衝名
*
* @param string $key
* @return string
*/
private function _storageKey($key) {
return $this->_prefix . '_' . $key;
}
}
/**
* 檔案快取實現
*
*
* @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 版本號碼 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');
}
}

/**
* 擷取快取檔案
*
* @param string $key
* @return string
*/
protected function _getCacheFile($key) {
return $this->_cachesDir . '/' . substr($key, 0, 2) . '/' . $key . '.php';
}
/**
* 讀取緩衝變數
* 為防止資訊泄露，快取檔案格式為php檔案，並以"<?php exit;?>"開頭
*
* @param string $key 緩衝下標
* @return mixed
*/
public function fetch($key) {
$cacheFile = self::_getCacheFile($key);
if (file_exists($cacheFile) && is_readable($cacheFile)) {
return unserialize(@file_get_contents($cacheFile, false, NULL, 13));
}
return false;
}
/**
* 緩衝變數
* 為防止資訊泄露，快取檔案格式為php檔案，並以"<?php exit;?>"開頭
*
* @param string $key 緩衝變數下標
* @param string $value 緩衝變數的值
* @return bool
*/
public function store($key, $value) {
$cacheFile = self::_getCacheFile($key);
$cacheDir = dirname($cacheFile);
if(!is_dir($cacheDir)) {
if(mkdir($cacheDir" target="_blank">!@mkdir($cacheDir, 0755, true)) {
throw new CacheException("Could not make cache directory");
}
}
return @file_put_contents($cacheFile, '<?php exit;?>' . serialize($value));
}
/**
* 刪除緩衝變數
*
* @param string $key 緩衝下標
* @return Cache_File
*/
public function delete($key) {
if(emptyempty($key)) {
throw new CacheException("Missing argument 1 for Cache_File::delete()");
}

$cacheFile = self::_getCacheFile($key);
if($cacheFile" target="_blank">!@unlink($cacheFile)) {
throw new CacheException("Cache file could not be deleted");
}
return $this;
}
/**
* 緩衝單元是否已經鎖定
*
* @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" target="_blank">!@mkdir($cacheDir, 0755, true)) {
if(!is_dir($cacheDir)) {
throw new CacheException("Could not make cache directory");
}
}
}
// 設定緩衝鎖檔案的訪問和修改時間
@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;
}
/**
* 設定檔案快取目錄
* @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;
}

/**
* 清空所有緩衝
*
* @return Cache_File
*/
public function clear() {
// 遍曆目錄清除緩衝
$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)) {
// 快取檔案夾有兩級
$d2 = dir($cacheEntry);
while(false !== ($entry = $d2->read())) {
if('.' == $entry[0]) {
continue;
}

$cacheEntry .= '/' . $entry;
if(is_file($cacheEntry)) {
@unlink($cacheEntry);
}
}
$d2->close();
}
}
$d->close();

return $this;
}
}
/**
* 緩衝單元的資料結構
* array(
* 'time' => time(), // 緩衝寫入時的時間戳記
* 'expire' => $expire, // 緩衝到期時間
* 'valid' => true, // 緩衝是否有效
* 'data' => $value // 緩衝的值
* );
*/
final class Cache {
/**
* 緩衝到期時間長度(s)
*
* @var int
*/
private $_expire = 3600;
/**
* 緩衝處理類
*
* @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();
}
/**
* 設定緩衝
*
* @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;
}
}
/**
* 讀取緩衝
*
* @param string $key
* @return mixed
*/
public function get($key) {
$data = $this->fetch($key);
if ($data && $data['valid'] && !$data['isExpired']) {
return $data['data'];
}

return false;
}
/**
* 讀緩衝，包括到期的和無效的，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;
}
/**
* 刪除緩衝
*
* @param string $key
*/
public function delete($key) {
$this->_storage->checkLock($key)
->lock($key)
->delete($key)
->unlock($key);
}

public function clear() {
$this->_storage->clear();
}
/**
* 把緩衝設為無效
*
* @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;
}
}

/**
* 設定緩衝到期時間（s）
*
* @param int $expire
*/
public function setExpire($expire) {
$this->_expire = (int) $expire;
return $this;
}
}