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, fallback)

Bases: buildgrid.server.cas.storage.storage_abc.StorageABC

has_blob(digest)

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

get_blob(digest)

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.

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

delete_blob(digest)

Delete the blob from storage if it’s present.

bulk_delete(digests)

Delete a list of blobs from storage.

begin_write(digest)

Return a file-like object to which a blob’s contents could be written.

commit_write(digest, write_session)

Commit the write operation. write_session must be an object returned by begin_write.

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(blobs)

Return a container containing the blobs not present in CAS.

bulk_update_blobs(blobs)

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)

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

is_cleanup_enabled()