meta

Documentation

Overview

Package meta loads a RecordMetaData from one of the two supported sources declared in a Context's MetadataSource field:

• FileSource: a serialized RecordMetaDataProto.MetaData on disk
• FDBStoreSource: an FDBMetaDataStore at a given keyspace path

Both produce the same *recordlayer.RecordMetaData and callers never need to know which source produced it. See cmd/frl/docs/operator-guide.md for the app-side wiring (Go + Java) for each path.

Index

• Variables
• type FDBStoreSource
  • func (s *FDBStoreSource) Load(ctx context.Context) (*recordlayer.RecordMetaData, error)
  • func (s *FDBStoreSource) Name() string
• type FileSource
  • func (s *FileSource) Load(_ context.Context) (*recordlayer.RecordMetaData, error)
  • func (s *FileSource) Name() string
• type Source
  • func FromContext(ctx *configv1.Context, db *recordlayer.FDBDatabase, ...) (Source, error)

Variables

var ErrFDBStoreNotAvailable = errors.New("this command does not support fdb_store metadata sources — configure `meta_file` in the context or pass --meta-file")

ErrFDBStoreNotAvailable is returned by FromContext when the context is wired for an FDBMetaDataStore source but the caller passed a nil db handle or keyspaceResolver — i.e. the command explicitly opted out of FDB-store support. Callers that want to surface a friendlier "this command doesn't support fdb_store sources" message detect this with errors.Is().

The message starts with "this command" (rather than "fdb_store …") so fang's auto-capitalized error banner reads as a sentence — "fdb_store" gets up-cased to "Fdb_store" which looks like a typo.

var ErrMissingSource = errors.New("context has no metadata source; add metadata.meta_file or metadata.meta_store_keyspace to the context")

ErrMissingSource is returned by FromContext when the context has no metadata source configured and one is required by the caller.

Types

type FDBStoreSource

type FDBStoreSource struct {
	DB           *recordlayer.FDBDatabase
	Subspace     subspace.Subspace
	KeyspacePath string // retained for Name() / error context
}

FDBStoreSource reads the current RecordMetaData from an FDBMetaDataStore at the configured subspace. Loads are performed in a new read transaction for each call.

func (*FDBStoreSource) Load

func (s *FDBStoreSource) Load(ctx context.Context) (*recordlayer.RecordMetaData, error)

func (*FDBStoreSource) Name

func (s *FDBStoreSource) Name() string

type FileSource

type FileSource struct {
	Path string
}

FileSource reads a serialized com.apple.foundationdb.record.RecordMetaDataProto.MetaData message from disk. Typically produced by an app's build/deploy tooling using recordlayer.WriteRecordMetaData (or Java's meta.toProto().writeTo()).

func (*FileSource) Load

func (s *FileSource) Load(_ context.Context) (*recordlayer.RecordMetaData, error)

func (*FileSource) Name

func (s *FileSource) Name() string

type Source

type Source interface {
	// Name is a short human-readable identifier used in errors and logs,
	// e.g. "file:/etc/myapp/meta.pb" or "fdb_store:/myapp/_meta".
	Name() string

	// Load resolves the source into a RecordMetaData. Errors wrap the
	// underlying cause (file IO, FDB transaction, proto unmarshal, or
	// metadata build) and are safe to surface directly to the operator.
	Load(ctx context.Context) (*recordlayer.RecordMetaData, error)
}

Source abstracts where a RecordMetaData comes from. Implementations are expected to be cheap to construct; Load is where the actual IO happens.

func FromContext

func FromContext(
	ctx *configv1.Context,
	db *recordlayer.FDBDatabase,
	keyspaceResolver func(string) (subspace.Subspace, error),
) (Source, error)

FromContext builds a Source from a Context's metadata field. Returns ErrMissingSource if neither meta_file nor meta_store_keyspace is set (commands that can tolerate missing metadata — like `store info` — should check errors.Is(err, ErrMissingSource) and skip loading).

keyspaceResolver is the hook used by FDBStoreSource to turn a string keyspace path into an FDB subspace. Callers inject this so the meta package doesn't duplicate parse-path logic living in internal/cmd.