blobpath

Documentation

Overview

Package blobpath maps a blob's logical name to its driver-side path according to the Store's PathTopology. Pure functions, no I/O, no side effects.

Conventions encoded here are part of the on-disk format: changing them requires a migration. The canonical layouts:

Sharded:   blobs/<aa>/<bb>/<full-ref>
           where aa,bb are hex chars 4..6 of the blob's hash hex.
Flat:      blobs/<full-ref>
Native:    rejected — Native means BlobStorage: ExternalRef
           and skips the blob-path machinery entirely.

Chunk and pack paths use the same topology with different roots: "chunks/" and "packs/" instead of "blobs/". The BlobType argument selects the root.

DAG: blobpath imports only domain. It does not import core, driver, or any sibling helper.

Index

• func ArtifactIDFromManifestPath(p string) (domain.ArtifactID, error)
• func ManifestPath(id domain.ArtifactID) (string, error)
• func RefFromPath(p string) (string, error)
• func Resolve(topology domain.PathTopology, blobType domain.BlobType, ref string) (string, error)

Functions

func ArtifactIDFromManifestPath

func ArtifactIDFromManifestPath(p string) (domain.ArtifactID, error)

ArtifactIDFromManifestPath is the manifests-side counterpart of RefFromPath. Manifest paths follow the Sharded layout exclusively (see ManifestPath); the structural validation is identical.

func ManifestPath

func ManifestPath(id domain.ArtifactID) (string, error)

ManifestPath returns the driver-side path of a manifest file by ArtifactID. Manifests live under "manifests/" and follow the same shard rules as blobs — same fan-out concerns apply. There is no Flat manifest layout: even on object stores the manifest directory sees enough churn that two-level sharding pays off.

func RefFromPath

func RefFromPath(p string) (string, error)

RefFromPath extracts the blob ref ("<algo>-<hex>") from a driver-side blob path produced by Resolve. Both topologies are supported:

Sharded:  blobs/<aa>/<bb>/<algo>-<hex>  → "<algo>-<hex>"
Flat:     blobs/<algo>-<hex>            → "<algo>-<hex>"

The function performs only structural validation — last segment shape "<algo>-<hex>" with a non-empty algo and a hex tail at least four characters long (matching shardOf's lower bound). It does NOT cross-check the segment against the topology shards; callers that need that level of paranoia (e.g. distinguishing a real orphan from an unrelated stray file under blobs/) re-run Resolve on the result and compare paths.

Used by the bootstrap Orphan Scan to map a driver-listed file back to a StoreIndex.Resolve key.

func Resolve

func Resolve(topology domain.PathTopology, blobType domain.BlobType, ref string) (string, error)

Resolve returns the driver-side path for a blob with the given ref under the given topology and type. The result is forward- slash separated, root-relative — exactly what driver.Driver expects.

PathTopologyNative is rejected: blobs whose physical placement is "native" do not go through this resolver — they are referenced by ExternalRef URI instead, and the engine handles them through driver.Open rather than driver.Get/Put.