Tracks which frames the store already holds.
Deduplication is the whole reason this exists: before a frame is compressed, sealed and uploaded, the index is asked whether its content address is already present. A hit costs one local lookup and skips the entire pipeline plus a network round trip.
It also holds the reference counts a prune depends on. A frame is collectable only when nothing points at it, and the three things that can point at one - a segment, a tree and a file map - are counted the same way.
The index is derived state. Everything in it can be rebuilt from the objects in the bucket by
strata:reindex, which is what makes it safe for a module uninstall to drop the tables.
record(\Drupal\strata\Cas\FrameRecord $record) : \Drupal\strata\Cas\FrameRecord
Records a newly stored frame, or increments an existing one.
Recording a frame the index already holds adds a reference rather than replacing the record, because the stored bytes are identical by construction and the location is already correct.
| \Drupal\strata\Cas\FrameRecord | $record | The record. |
The stored record, with its resulting reference count.
relocate(\Drupal\strata\Cas\FrameRecord $record) : \Drupal\strata\Cas\FrameRecord
Replaces where a frame lives and how it is encoded, keeping its reference count.
What compaction needs. Recompressing a frame changes its object, its offset, its codec and its stored size, and changes nothing about its content address or who points at it - the address is the digest of the decoded bytes, so it survives a change of encoding by construction.
Distinct from FrameIndexInterface::record(), which treats a frame it already holds as a second reference to the same bytes in the same place and must not move it.
| \Drupal\strata\Cas\FrameRecord | $record | The record's new location and encoding. Its reference count is ignored in favour of the one already stored. |
The stored record, with the reference count it kept.
dereference(string $hash, int $count = 1) : int
Removes references from a frame.
The record is kept at zero references rather than deleted, so a prune can find it, report what it is about to remove, and be told not to.
| string | $hash | Content address of the decoded frame. |
| int | $count | How many references to remove. |
The resulting reference count, never below zero.
page(int $limit = 1000, int $offset = 0) : list<\Drupal\strata\Cas\FrameRecord>
One page of every frame the index holds, referenced or not, oldest first.
A pass that has to touch the whole store rather than a reachable part of it needs this:
orphans() answers what is collectable and a tree walk answers what is reachable, and a key
rotation is neither. Ordered by creation and then by address, so paging is stable while frames
are being added.
| int | $limit | Most records to return. |
| int | $offset | Records to skip. |
The page, empty once the offset is past the end.
dependents(string $hash, int $limit = 100) : list<\Drupal\strata\Cas\FrameRecord>
Frames that decode against a given frame.
The upward half of delta-chain reachability: a frame nothing references directly is still not collectable while something that IS referenced decodes against it.
| string | $hash | Content address of the candidate parent. |
| int | $limit | Most records to return, so the query stays bounded on a frame with many children. |
Records naming this frame as their delta parent.
deepestChains(int $minimum, int $limit = 100) : list<\Drupal\strata\Cas\FrameRecord>
Frames whose delta chains are at least a given depth, deepest first.
What a re-anchoring pass works from. Ordered deepest first because re-anchoring the deepest link shortens every chain hanging off it, so one rewrite can bring several chains back inside the cap.
| int | $minimum | Fewest links a chain must have to be returned. Zero returns every delta frame. |
| int | $limit | Most records to return, so a pass over a store with many long chains stays bounded. |
The records, deepest chain first.
statistics() : array{frames: int, rawBytes: int, storedBytes: int, orphans: int, ratio: float}
What the store holds, for the settings form and the storage explorer.
Frame count, decoded and stored byte totals, how many frames are collectable, and the overall compression ratio.