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Yii原始碼分析之FileCache

FileCache使用檔案實現快取元件。

對於要快取的每個資料值,FileCache會將其儲存在單獨的檔案中。快取檔案位於$ cachePath下。 FileCache將自動執行垃圾收集以刪除過期的快取檔案。

有關FileCache支援的常見快取操作,請參閱yii \ caching \ Cache。

其原始碼如下:

<?php
/**
 * @link http://www.yiiframework.com/
 * @copyright Copyright (c) 2008 Yii Software LLC
 * @license http://www.yiiframework.com/license/
 */

namespace yii\caching;

use Yii;
use yii\helpers\FileHelper;

/**
 * FileCache implements a cache component using files.
 *
 * For each data value being cached, FileCache will store it in a separate file.
 * The cache files are placed under [[cachePath]]. FileCache will perform garbage collection
 * automatically to remove expired cache files.
 *
 * Please refer to [[Cache]] for common cache operations that are supported by FileCache.
 *
 * For more details and usage information on Cache, see the [guide article on caching](guide:caching-overview).
 *
 * @author Qiang Xue <
[email protected]
> * @since 2.0 */ class FileCache extends Cache { /** * @var string a string prefixed to every cache key. This is needed when you store * cache data under the same [[cachePath]] for different applications to avoid * conflict. * * To ensure interoperability, only alphanumeric characters should be used. */ public $keyPrefix = ''; /** * @var string the directory to store cache files. You may use [path alias](guide:concept-aliases) here. * If not set, it will use the "cache" subdirectory under the application runtime path. */ public $cachePath = '@runtime/cache'; /** * @var string cache file suffix. Defaults to '.bin'. */ public $cacheFileSuffix = '.bin'; /** * @var int the level of sub-directories to store cache files. Defaults to 1. * If the system has huge number of cache files (e.g. one million), you may use a bigger value * (usually no bigger than 3). Using sub-directories is mainly to ensure the file system * is not over burdened with a single directory having too many files. */ public $directoryLevel = 1; /** * @var int the probability (parts per million) that garbage collection (GC) should be performed * when storing a piece of data in the cache. Defaults to 10, meaning 0.001% chance. * This number should be between 0 and 1000000. A value 0 means no GC will be performed at all. */ public $gcProbability = 10; /** * @var int the permission to be set for newly created cache files. * This value will be used by PHP chmod() function. No umask will be applied. * If not set, the permission will be determined by the current environment. */ public $fileMode; /** * @var int the permission to be set for newly created directories. * This value will be used by PHP chmod() function. No umask will be applied. * Defaults to 0775, meaning the directory is read-writable by owner and group, * but read-only for other users. */ public $dirMode = 0775; /** * Initializes this component by ensuring the existence of the cache path. */ public function init() { parent::init(); $this->cachePath = Yii::getAlias($this->cachePath); if (!is_dir($this->cachePath)) { FileHelper::createDirectory($this->cachePath, $this->dirMode, true); } } /** * Checks whether a specified key exists in the cache. * This can be faster than getting the value from the cache if the data is big. * Note that this method does not check whether the dependency associated * with the cached data, if there is any, has changed. So a call to [[get]] * may return false while exists returns true. * @param mixed $key a key identifying the cached value. This can be a simple string or * a complex data structure consisting of factors representing the key. * @return bool true if a value exists in cache, false if the value is not in the cache or expired. */ public function exists($key) { $cacheFile = $this->getCacheFile($this->buildKey($key)); return @filemtime($cacheFile) > time(); } /** * Retrieves a value from cache with a specified key. * This is the implementation of the method declared in the parent class. * @param string $key a unique key identifying the cached value * @return string|false the value stored in cache, false if the value is not in the cache or expired. */ protected function getValue($key) { $cacheFile = $this->getCacheFile($key); if (@filemtime($cacheFile) > time()) { $fp = @fopen($cacheFile, 'r'); if ($fp !== false) { @flock($fp, LOCK_SH); $cacheValue = @stream_get_contents($fp); @flock($fp, LOCK_UN); @fclose($fp); return $cacheValue; } } return false; } /** * Stores a value identified by a key in cache. * This is the implementation of the method declared in the parent class. * * @param string $key the key identifying the value to be cached * @param string $value the value to be cached. Other types (If you have disabled [[serializer]]) unable to get is * correct in [[getValue()]]. * @param int $duration the number of seconds in which the cached value will expire. 0 means never expire. * @return bool true if the value is successfully stored into cache, false otherwise */ protected function setValue($key, $value, $duration) { $this->gc(); $cacheFile = $this->getCacheFile($key); if ($this->directoryLevel > 0) { @FileHelper::createDirectory(dirname($cacheFile), $this->dirMode, true); } // If ownership differs the touch call will fail, so we try to // rebuild the file from scratch by deleting it first // https://github.com/yiisoft/yii2/pull/16120 if (is_file($cacheFile) && function_exists('posix_geteuid') && fileowner($cacheFile) !== posix_geteuid()) { @unlink($cacheFile); } if (@file_put_contents($cacheFile, $value, LOCK_EX) !== false) { if ($this->fileMode !== null) { @chmod($cacheFile, $this->fileMode); } if ($duration <= 0) { $duration = 31536000; // 1 year } return @touch($cacheFile, $duration + time()); } $error = error_get_last(); Yii::warning("Unable to write cache file '{$cacheFile}': {$error['message']}", __METHOD__); return false; } /** * Stores a value identified by a key into cache if the cache does not contain this key. * This is the implementation of the method declared in the parent class. * * @param string $key the key identifying the value to be cached * @param string $value the value to be cached. Other types (if you have disabled [[serializer]]) unable to get is * correct in [[getValue()]]. * @param int $duration the number of seconds in which the cached value will expire. 0 means never expire. * @return bool true if the value is successfully stored into cache, false otherwise */ protected function addValue($key, $value, $duration) { $cacheFile = $this->getCacheFile($key); if (@filemtime($cacheFile) > time()) { return false; } return $this->setValue($key, $value, $duration); } /** * Deletes a value with the specified key from cache * This is the implementation of the method declared in the parent class. * @param string $key the key of the value to be deleted * @return bool if no error happens during deletion */ protected function deleteValue($key) { $cacheFile = $this->getCacheFile($key); return @unlink($cacheFile); } /** * Returns the cache file path given the cache key. * @param string $key cache key * @return string the cache file path */ protected function getCacheFile($key) { if ($this->directoryLevel > 0) { $base = $this->cachePath; for ($i = 0; $i < $this->directoryLevel; ++$i) { if (($prefix = substr($key, $i + $i, 2)) !== false) { $base .= DIRECTORY_SEPARATOR . $prefix; } } return $base . DIRECTORY_SEPARATOR . $key . $this->cacheFileSuffix; } return $this->cachePath . DIRECTORY_SEPARATOR . $key . $this->cacheFileSuffix; } /** * Deletes all values from cache. * This is the implementation of the method declared in the parent class. * @return bool whether the flush operation was successful. */ protected function flushValues() { $this->gc(true, false); return true; } /** * Removes expired cache files. * @param bool $force whether to enforce the garbage collection regardless of [[gcProbability]]. * Defaults to false, meaning the actual deletion happens with the probability as specified by [[gcProbability]]. * @param bool $expiredOnly whether to removed expired cache files only. * If false, all cache files under [[cachePath]] will be removed. */ public function gc($force = false, $expiredOnly = true) { if ($force || mt_rand(0, 1000000) < $this->gcProbability) { $this->gcRecursive($this->cachePath, $expiredOnly); } } /** * Recursively removing expired cache files under a directory. * This method is mainly used by [[gc()]]. * @param string $path the directory under which expired cache files are removed. * @param bool $expiredOnly whether to only remove expired cache files. If false, all files * under `$path` will be removed. */ protected function gcRecursive($path, $expiredOnly) { if (($handle = opendir($path)) !== false) { while (($file = readdir($handle)) !== false) { if ($file[0] === '.') { continue; } $fullPath = $path . DIRECTORY_SEPARATOR . $file; if (is_dir($fullPath)) { $this->gcRecursive($fullPath, $expiredOnly); if (!$expiredOnly) { if (
[email protected]
($fullPath)) { $error = error_get_last(); Yii::warning("Unable to remove directory '{$fullPath}': {$error['message']}", __METHOD__); } } } elseif (!$expiredOnly || $expiredOnly && @filemtime($fullPath) < time()) { if (
[email protected]
($fullPath)) { $error = error_get_last(); Yii::warning("Unable to remove file '{$fullPath}': {$error['message']}", __METHOD__); } } } closedir($handle); } } }