Raft v0.2.1 Raft.Log

The Log module provides an api for all log operations. Since the log process is the only process that can access the underlying log store we cache several values in the log process state.

Link to this section Summary

Functions

Appends new entries to the log and returns the latest index

Deletes all logs in the range inclusivesly

Gets the current configuration

Gets the entry at the given index

Gets the current metadata for the server

Gets the current term

Invoked when the server is started. start_link/3 or start/3 will block until it returns

Returns the last entry in the log. If there are no entries then it returns an :error

Returns the index of the last entry in the log

Returns the term of the last entry in the log. If the log is empty returns 0

Link to this section Types

Link to this type candidate()
candidate() :: atom() | :none
Link to this type log_term()
log_term() :: non_neg_integer()
Link to this type metadata()
metadata() :: %{term: non_neg_integer(), voted_for: atom() | nil}

Link to this section Functions

Link to this function append(name, entries)
append(atom(), [Raft.Log.Entry.t()]) :: {:ok, index()} | {:error, term()}

Appends new entries to the log and returns the latest index.

Link to this function delete_range(name, a, b)

Deletes all logs in the range inclusivesly

Link to this function get_configuration(name)

Gets the current configuration.

Link to this function get_entry(name, index)
get_entry(atom(), index()) :: {:ok, Raft.Log.Entry.t()} | {:error, :not_found}

Gets the entry at the given index.

Link to this function get_metadata(name)
get_metadata(atom()) :: metadata()

Gets the current metadata for the server.

Link to this function get_term(name)
get_term(atom()) :: log_term()

Gets the current term.

Invoked when the server is started. start_link/3 or start/3 will block until it returns.

args is the argument term (second argument) passed to start_link/3.

Returning {:ok, state} will cause start_link/3 to return {:ok, pid} and the process to enter its loop.

Returning {:ok, state, timeout} is similar to {:ok, state} except handle_info(:timeout, state) will be called after timeout milliseconds if no messages are received within the timeout.

Returning {:ok, state, :hibernate} is similar to {:ok, state} except the process is hibernated before entering the loop. See c:handle_call/3 for more information on hibernation.

Returning :ignore will cause start_link/3 to return :ignore and the process will exit normally without entering the loop or calling c:terminate/2. If used when part of a supervision tree the parent supervisor will not fail to start nor immediately try to restart the GenServer. The remainder of the supervision tree will be (re)started and so the GenServer should not be required by other processes. It can be started later with Supervisor.restart_child/2 as the child specification is saved in the parent supervisor. The main use cases for this are:

  • The GenServer is disabled by configuration but might be enabled later.
  • An error occurred and it will be handled by a different mechanism than the Supervisor. Likely this approach involves calling Supervisor.restart_child/2 after a delay to attempt a restart.

Returning {:stop, reason} will cause start_link/3 to return {:error, reason} and the process to exit with reason reason without entering the loop or calling c:terminate/2.

Callback implementation for GenServer.init/1.

Link to this function last_entry(name)
last_entry(atom()) :: {:ok, Raft.Log.Entry.t()} | :empty

Returns the last entry in the log. If there are no entries then it returns an :error.

Link to this function last_index(name)
last_index(atom()) :: non_neg_integer()

Returns the index of the last entry in the log.

Link to this function last_term(name)
last_term(atom()) :: non_neg_integer()

Returns the term of the last entry in the log. If the log is empty returns 0.

Link to this function set_metadata(name, candidate, term)
set_metadata(atom(), candidate(), log_term()) :: :ok

Sets metadata.

Link to this function start_link(list)