Fact.EventLedger (Fact v0.2.1)

This is the Judge Judy of the system, it manages the event ledger for a Fact database instance, handling all commits, enforcing optimistic concurrency control via append conditions.

Fact.EventLedger is a GenServer responsible for:

Writing event record files, and appending to the ledger
Ensuring events are enriched with metadata, ids, timestamps, and store positions
Publishing appended events via Fact.EventPublisher
Tracking the current ledger position and maintaining order

Summary

Types

commit_option()

Defines the options that can be specified when committing.

option()

Defines the options for starting a Fact.EventLedger.

Functions

child_spec(init_arg)

Returns a specification to start this module under a supervisor.

commit(database_id, events, append_condition \\ nil, options \\ [])

Commits an event or set of events.

start_link(opts)

Starts the event ledger process.

Types

commit_option()

(since 0.1.0)

@type commit_option() :: {:timeout, timeout()}

Defines the options that can be specified when committing.

:timeout (default: 5000) - specifies how long the caller should wait for the commit operation to complete in milliseconds

option()

(since 0.1.0)

@type option() :: {:database_id, Fact.database_id()}

Defines the options for starting a Fact.EventLedger.

Functions

child_spec(init_arg)

(since 0.1.0)

Returns a specification to start this module under a supervisor.

See Supervisor.

commit(database_id, events, append_condition \\ nil, options \\ [])

(since 0.2.0)

@spec commit(
  Fact.database_id(),
  Fact.event() | [Fact.event()],
  Fact.append_condition() | nil,
  [commit_option()]
) :: {:ok, Fact.event_position()} | {:error, term()}

Commits an event or set of events.

Each event is enriched with additional metadata, including a timestamp, and assigning a store position. Events are then written to the configured storage and a reference to the event is appended to the ledger file.

If the commit operation is successful, an {:appended, {record_id, event}} message will be published by the Fact.EventPublisher for each event that was written.

start_link(opts)

(since 0.1.0)

@spec start_link([option()]) :: {:ok, pid()} | {:error, term()}

Starts the event ledger process.