Class file

Manages file-system based caching.

Metadata is stored at the beginning of each cache file with the following data fields. See $seekOffset to skip to the cache entry data:

Timestamp of last modification (32-bit unsigned integer, little-endian),
time to live in seconds (32-bit unsigned integer, little-endian),
MD5 hash of file contents (16 bytes).

Implementations should however not rely on the format of stream headers and use the access methods provided by this driver.

Core\Object implements Core\Chainable

Core\Set implements Core\Accessor

Core\Cache

Core\Cache\Driver\file

Namespace: Core\Cache\Driver
Package: Core\Cache
Since: 3.0
Requires: PHP 5.3
Version: 1.1
Located at Cache/Driver/file.inc.php

Methods summary

`public`	# `__construct( Core\URI\Driver\file $uri )` Parameters `$uri` Driver configuration URI. Since 3.0 Overrides `Core\Cache::__construct`
`public boolean`	# `exists( string $class, string $key )` Tests, whether a cache entry for a class item exists. Tests, whether a cache entry for a class item exists. Parameters `$class` Cache class of item to test for. `$key` The item key to test for. Returns boolean `true`, if a cache entry for the requested item exists, otherwise `false`. Since 3.0
`public string`	# `get( string $class, string $key )` Reads a cache entry and returns all binary data for the entry. Reads a cache entry and returns all binary data for the entry. Parameters `$class` Class of cache item. `$key` The key of the cache item. Returns string Binary data string of cache entry. Since 3.0 Overrides `Core\Cache::get`
`public string`	# `getHash( string $class, string $key )` Returns the hash for the requested cache entry. The hash type depends on the backend in use and defaults to 16-byte binary MD5. Returns the hash for the requested cache entry. The hash type depends on the backend in use and defaults to 16-byte binary MD5. Parameters `$class` Class of cache item. `$key` The key of the cache item. Returns string Binary hash of cache element. Since 3.1 Overrides `Core\Cache::getHash`
`public Core\Stream`	# `getStream( string $class, string $key )` Returns a reading stream instance for the requested cache entry. Returns a reading stream instance for the requested cache entry. Parameters `$class` Class of cache item. `$key` The key of the cache item. Returns `Core\Stream` Reading Stream instance for the requested cache entry. Remark Avoid absolute seek positions; the file cache backend stores metadata at the beginning of the stream (see $seekOffset). See $seekOffset Since 3.0
`public integer`	# `getTimestamp( string $class, string $key )` Returns a UNIX timestamp of the last cache entry modification. Returns a UNIX timestamp of the last cache entry modification. Parameters `$class` Class of cache item. `$key` The key of the cache item. Returns integer UNIX timestamp of last modification to the named cache entry. Since 3.1
`public`	# `put( string $class, string $key, string $binaryData, integer $ttl = Core\Cache\Driver\null )` Writes binary data to a specified cache entry. Writes binary data to a specified cache entry. Parameters `$class` Class of cache item. `$key` The key of the cache item. `$binaryData` Binary data string to write to the cache entry. `$ttl` Time to live for cache entry (in seconds). Set to `null` if entry does not timeout. Since 3.0 Overrides `Core\Cache::put`
`public Core\Stream`	# `putStream( string $class, string $key, integer $ttl = Core\Cache\Driver\null )` Returns a writing stream instance for the requested cache entry. Returns a writing stream instance for the requested cache entry. Parameters `$class` Class of cache item. `$key` The key of the cache item. `$ttl` Time to live for cache entry (in seconds). Set to `null` if entry does not timeout. Returns `Core\Stream` Writing Stream instance for the requested cache entry. Remark Avoid absolute seek positions; the file cache backend stores metadata at the beginning of the stream (see $seekOffset). See $seekOffset Since 3.0
`public`	# `remove( string $class, string $key )` Deletes a cache key entry. If the entry does not exist, no operation is performed. Deletes a cache key entry. If the entry does not exist, no operation is performed. Parameters `$class` Class of cache item. `$key` The key of the cache item. Since 3.1
`public string`	# `targetFile( string $class, string $key, boolean $initClassPath = false )` Computes the cache target file name. Computes the cache target file name. Parameters `$class` Class of cache entry. `$key` Key of cache entry. `$initClassPath` Automatically initialises subdirectories as required; should only be used if a cache file is created, not if existence is checked. Returns string Target file name string of given cache class and key name. Throws `Core\Exception\InvalidArgument` Failed to create cache subdirectory or directory is not writable. Since 3.0

Constants summary

`string`	`SubdirectoryCharactersParameter` Sets the number of key characters used for subdirectory levels. Only used if a subdirectory level >0 is defined. Default value is 2, maximum allowed value is 3 (minimum is 1). Sets the number of key characters used for subdirectory levels. Only used if a subdirectory level >0 is defined. Default value is 2, maximum allowed value is 3 (minimum is 1). The number of characters per subdirectory level controls the maximum number of subdirectories per level. Usually hexadecimal characters are used for cache keys, hence a subdirectory character length of 1 yields at most 16 subdirectories per level. A length of 2 yields 256 subdirectories per level, which is the default and for most file systems a sensible value. A length of 3 yields 4096 subdirectories per level and is recommended for high-performance file systems with high cache usage. Since 3.1	# `'sub-chars'`
`string`	`SubdirectoryLevelParameter` Controls the number of subdirectories created for cached items. Default value is 0 (no subdirectories are created). Maximum allowed value is 8. Controls the number of subdirectories created for cached items. Default value is 0 (no subdirectories are created). Maximum allowed value is 8. Several systems suffer from performance loss if directories contain too many files. Additionally, the maximum number of allowed files per directory is restricted by many file systems, e.g. NTFS only allows up to 65534 files per directory. A sensitive choice are 2 or 3 levels, depending on the amount of cached items and the underlying system. Since 3.1	# `'sub-level'`
`string`	`SubdirectoryModeParameter` Default directory mode used for subdirectories. Defaults to 0777. Default directory mode used for subdirectories. Defaults to 0777. Expects an octal value. This parameter is ignored on Windows. Since 3.1	# `'sub-mode'`

Constants inherited from Core\Cache

SharedClass

Constants inherited from Core\Object

AnyParameterType, AutochainParameterType, AutocreateParameterType, BooleanParameterType, CharParameterType, EnumParameterType, IntegerParameterType, RealParameterType, StringParameterType, UserParameterType

Properties summary

`protected array`	`$_v_parameters` File cache settings array. File cache settings array. Since 3.1	#
`protected string`	`$_v_path` Storage path root directory. Storage path root directory. Since 3.0	#
`protected integer`	`$_v_seekOffset` Size of file headers to add to seek to absolute positions in streams. Size of file headers to add to seek to absolute positions in streams. Since 3.1	# `24`

Properties inherited from Core\Cache

$_activeInstance, $_v_versionID

Magic properties

`public read-only array`	`$parameters` Driver configuration array.
`public read-only string`	`$path` Storage root for storing cache entries.
`public read-only integer`	`$seekOffset` Size of file header meta data of stored cache entries.

Magic properties inherited from Core\Cache

$versionID

Magic properties inherited from Core\Object

$hash, $uuid

Namespaces

Classes

Class file

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Methods inherited from Core\Cache

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Methods inherited from Core\Object

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Magic properties inherited from Core\Object