Ankusa.Codec behaviour (ankusa v0.7.0)

Copy Markdown View Source

Segment record framing. encode/1 packs many records into one immutable segment binary and returns a per-record index (byte offset + length within the segment). A single range GET on the blob store then reads exactly one record, which decode_record/1 validates and unframes.

Ankusa.Storage.Segment wraps what encode/1 returns in the segment header and sha256 trailer, and shifts the offsets past the header; a codec only frames records. It may export id/0, the one-byte id the header records for it (1 is Ankusa.Codec.Raw); without one the header says 0 and the catalogue row names the module.

Summary

Types

index_entry()
segment_record()

Callbacks

decode_record(binary)
encode(list)
id()

Types

index_entry()

@type index_entry() :: %{
  key: String.t(),
  offset: non_neg_integer(),
  length: pos_integer()
}

segment_record()

@type segment_record() :: %{key: String.t(), payload: binary()}

Callbacks

decode_record(binary)

@callback decode_record(binary()) :: {:ok, binary()} | {:error, term()}

encode(list)

@callback encode([segment_record()]) :: {segment :: binary(), index :: [index_entry()]}

id()

(optional) 
@callback id() :: 1..255