abstract class Raft::Log

• Raft::Log
• Reference
• Object

Overview

Abstract base class for the Raft replicated log.

The log stores an ordered sequence of entries, persistent metadata (current term and voted-for), and snapshots. Entries are 1-indexed — index 0 means "no entry" (empty log).

Two implementations are provided:

• Log::InMemory — all data held in memory, suitable for testing
• Log::File — on-disk persistence with crash recovery

log = Raft::Log::InMemory.new      # for testing
log = Raft::Log::File.new("/data") # for production

Direct Known Subclasses

• Raft::Log::File
• Raft::Log::InMemory

Defined in:

raft/log.cr
raft/log/entry.cr

Instance Method Summary

• #append(entries : Array(Entry)) : Nil

  Appends entries to the log with conflict detection.

• #close : Nil

  Releases any resources held by the log (e.g., file handles).

• #get(index : UInt64) : Entry | Nil

  Returns the entry at the given 1-based index, or nil if not present.

• #last_index : UInt64

  Returns the index of the last entry, or 0 if the log is empty.

• #last_term : UInt64

  Returns the term of the last entry, or 0 if the log is empty.

• #load_metadata : Metadata

  Loads the persisted metadata, or returns defaults (term 0, no vote).

• #load_snapshot : Tuple(UInt64, UInt64, Bytes) | Nil

  Loads the most recent snapshot, or returns nil if none exists.

• #save_metadata(meta : Metadata) : Nil

  Persists the node's current term and voted-for state.

• #save_snapshot(last_index : UInt64, last_term : UInt64, data : Bytes) : Nil

  Saves a snapshot and compacts the log up to last_index.

• #slice(from : UInt64, to : UInt64) : Array(Entry)

  Returns entries in the inclusive range [from, to].

• #term_at(index : UInt64) : UInt64 | Nil

  Returns the term of the entry at index, or nil if not present.

• #truncate_from(index : UInt64) : Nil

  Removes all entries at index and beyond (inclusive).

Instance Method Detail