Backend

Abstract base class for cache backend implementations.

class Backend implements \Hazaar\Cache\BackendInterface

Provides shared option/state handling and capability registration used by concrete cache backends (file, shm, sqlite, etc.). The frontend cache adapter queries backend capabilities via {@see self::can()} to determine behavior such as object serialization strategy and array export support.

Subclasses are responsible for implementing storage operations defined by {@see BackendInterface}, while this class supplies common defaults for optional behaviors like locking and connection closing.

Properties

options

The backend options.

public array $options

weight

Backend preference/priority weight used when selecting among candidates.

protected int $weight = 10

namespace

public string $namespace

capabilities

The backends list of capabilities.

private array $capabilities

Standard capabilities are:

• store_objects - Backend can directly store & return objects. Whether the backend itself really can (like APCu) or the backend class takes care of this.
• compress - Can compress objects being stored. If the backend can do this, then we don't want the frontend to ever do it.
• array - Can return all elements in the cache as an associative array
• expire_ns - Backend supports storage TTLs on the namespace as a whole.
• expire_val - Backend supports storage TTLs on individual values stored within the namespace
• keepalive - When a value is accessed it's TTL can be reset to keep it alive in cache.

Methods

__construct

public __construct(array $options, string $namespace): void

Parameters

Parameter	Type	Description
$options	array
$namespace	string

close

Closes backend resources, if applicable.

public close(): bool

Default implementation is a no-op.

can

Checks whether a backend capability is supported.

public can(string $key): bool

Parameters

Parameter	Type	Description
$key	string	capability name

getWeight

Returns backend selection weight.

public getWeight(): int

setOption

Sets or overrides a backend option.

public setOption(string $key, mixed $value): void

Parameters

Parameter	Type	Description
$key	string	option key
$value	mixed	option value

lock

Attempts to acquire a lock for a cache key.

public lock(string $key): bool

Default implementation indicates unsupported locking.

Parameters

Parameter	Type	Description
$key	string	lock key

unlock

Attempts to release a lock for a cache key.

public unlock(string $key): bool

Default implementation indicates unsupported locking.

Parameters

Parameter	Type	Description
$key	string	lock key

addCapabilities

Registers one or more backend capabilities.

protected addCapabilities(string $args): void

Parameters

Parameter	Type	Description
$args	string

configure

protected configure(array $options): void

Parameters

Parameter	Type	Description
$options	array

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