buildgrid.server.cas.storage.with_cache module

WithCacheStorage

A storage provider that first checks a cache, then tries a slower fallback provider.

To ensure clients can reliably store blobs in CAS, only get_blob calls are cached – has_blob and missing_blobs will always query the fallback.

class buildgrid.server.cas.storage.with_cache.WithCacheStorage(cache: StorageABC, fallback: StorageABC, defer_fallback_writes: bool = False, fallback_writer_threads: int = 20)

Bases: StorageABC

TYPE: str = 'WithCache'

start() → None

stop() → None

has_blob(digest: Digest) → bool

Return True if the blob with the given instance/digest exists.

get_blob(digest: Digest) → IO[bytes] | None

Return a file-like object containing the blob. Most implementations will read the entire file into memory and return a BytesIO object. Eventually this should be corrected to handle files which cannot fit into memory.

The file-like object must be readable and seekable.

If the blob isn’t present in storage, return None.

delete_blob(digest: Digest) → None

Delete the blob from storage if it’s present.

bulk_delete(digests: List[Digest]) → List[str]

Delete a list of blobs from storage.

commit_write(digest: Digest, write_session: IO[bytes]) → None

Store the contents for a digest.

The storage object is not responsible for verifying that the data written to the write_session actually matches the digest. The caller must do that.

missing_blobs(digests: List[Digest]) → List[Digest]

Return a container containing the blobs not present in CAS.

bulk_update_blobs(blobs: List[Tuple[Digest, bytes]]) → List[Status]

Given a container of (digest, value) tuples, add all the blobs to CAS. Return a list of Status objects corresponding to the result of uploading each of the blobs.

Unlike in commit_write, the storage object will verify that each of the digests matches the provided data.

bulk_read_blobs(digests: List[Digest]) → Dict[str, bytes]

Given an iterable container of digests, return a {hash: file-like object} dictionary corresponding to the blobs represented by the input digests.

Each file-like object must be readable and seekable.