\Drupal\strata\Capture\Classifier KeyspaceSourceInterface

Somewhere ephemeral keys can be enumerated from.

What holds the keyspace differs per site - Redis when strata_redis is installed, the cache and key-value tables otherwise, something else entirely on a site with a custom backend - so discovery asks sources rather than knowing about backends. A submodule contributes one by tagging a service.

Two rules bind every implementation:

It must be bounded. A source over a Redis holding ten million keys has to stop at the limit it is given rather than reading all of them into a discovery pass. Sampling is fine and is expected; the pattern totals are used to rank what needs a decision, not to bill anyone.
It must not block on a backend that is down. A source whose backend is unreachable raises, and discovery reports that source as unread and carries on with the others.

Summary

Methods

Constants

id()
isAvailable()
keys()

No public constants found

File: src/Capture/Classifier/KeyspaceSourceInterface.php
Package: \Application
See also

Methods

id()

id() : string

A short identifier, used to name this source in a problem report.

Returns

string —

For example "redis" or "database".

isAvailable()

isAvailable() : bool

Whether this source can be read right now.

Returns

bool —

FALSE when the backend it reads is absent or unreachable, so discovery can skip it without treating that as a fault.

keys()

keys(int  $limit) : \Traversable<string,int>

The keys this source holds, with their sizes.

Parameters

int

$limit

Most keys to return.

Throws

\RuntimeException: When the backend cannot be read at all.

Returns

\Traversable —

Key name keyed to its size in bytes. A source that cannot measure a size yields zero rather than guessing, and the byte totals are then understood to be a lower bound.