Change log

v0.3.3 - 2026.05.27

Fixed:

• Election correctness during :global merge. candidate_nodes/0 now queries every connected node live (parallel erpc:multicall) instead of reading the asynchronously-populated candidate cache. The cache-driven path could race with candidate_status propagation when a node joined an existing cluster — the joining node's commission self-elected against a single-node view, broadcast set_leader(self), and the wrong leader stuck because no re-election fired after the :global name conflict resolved. Live queries return the full candidate set on every election, eliminating the race.

Added:

• elector_strategy_behaviour:is_local_candidate/0 — exported for the live cross-node candidate query.
• elector_merge_race_SUITE — regression suite that boots two isolated peers, lets each pre-merge-elect, connects them, and asserts both converge on the strategy's choice over the full candidate set.

v0.3.2 - 2025.09.28

Major architectural improvement with distributed candidate caching system.

Added:

• New elector_candidate_cache process for distributed candidate state management
• New candidate_cache_refresh_interval configuration (default: 0 = disabled, event-based only)
• Automatic node monitoring and cache synchronization across cluster
• Event-driven candidate status updates on node join/leave events
• Smart fallback mechanism if cache is unavailable

Fixed:

• Completely eliminated :undef errors with smart distributed candidate caching system
• Fixed :undef errors in election strategies - replaced anonymous functions with MFA tuples in elector_time_strategy_base
• Zero remote calls during elections - uses local cache with node join/leave event updates
• Implemented intelligent candidate node broadcasting on startup and cluster events
• Respects candidate_node configuration while eliminating network dependencies
• Fixed compilation warning for unused candidate_cache() type

Improved:

• Dramatically improved performance - elections now use O(1) local cache lookups instead of O(n) remote calls
• Enhanced resilience for distributed test environments with frequent node restarts
• Eliminated network timeouts and erpc serialization issues during elections

v0.3.1 - 2025.09.28

Minor updates and fixes.

Changed:

• hooks_execution - Default value changed from global to local. This means that by default, the pre and post election hooks will now be executed only on the node that initiates the election process. This change aims to reduce unnecessary execution of hooks on all nodes, which can be particularly beneficial in larger clusters where such operations might lead to increased load and potential performance issues.
• Migrated from edoc to hex docs.

Fixed:

• Completely eliminated :undef errors with smart distributed candidate caching system
• Zero remote calls during elections - uses local cache with node join/leave event updates
• Implemented intelligent candidate node broadcasting on startup and cluster events
• Added graceful fallback to local-only checking if cache is unavailable
• Respects candidate_node configuration while eliminating network dependencies

Added:

• New elector_candidate_cache process for distributed candidate state management
• New candidate_cache_refresh_interval configuration (default: 0 = disabled, event-based only)
• Automatic node monitoring and cache synchronization across cluster
• Event-driven candidate status updates on node join/leave

Improved:

• Migrated documentation from edoc to hex docs for better user experience
• Enhanced module and function documentation with better examples and formatting
• Updated build system to use rebar3 ex_doc instead of rebar3 edoc
• Dramatically improved performance - elections now use O(1) local cache lookups instead of O(n) remote calls

v0.3.0 - 2023.07.28

The existing API functions did not change but the overall architecture did change meaning it is recommended to restart the elector application on all nodes after upgrading to this version.

Update rebar.config deps list:

{deps, [{elector, "0.3.0"}]}.

Changed:

• The previous implementation started the election process on all nodes. The new version utilizes a global process(singleton) named 'commission' which will initiate the election and gathers information from the cluster. Based on this information, the 'commission' process will determine the leader node. The selected node information will then be propagated to all other nodes in the cluster. This significant change grants us better control over the election process and helps reduce bandwidth usage.
• Default election strategy is now elector_ut_high_strategy which selects the node with the highest uptime as the leader.

Added

• candidate_node configuration option which will allow us to leave the node out of the election process. Default value is true.
• hooks_execution - configuration option which defines if the hooks should be executed on all nodes or only on the commission node. Default value is global.
• automatic_elections configuration option which will allow us to disable the automatic election process started by the commission when node joins or leaves the cluster. Default value is true.
• elector_config_handler:add_pre_election_hook/3 - function to add new pre election hook.
• elector_config_handler:add_post_election_hook/3 - function to add new post election hook.
• elector_config_handler:rem_pre_election_hook/3 - function to remove pre election hook.
• elector_config_handler:rem_post_election_hook/3 - function to remove post election hook.
• 2 new strategies that are based on node uptime.

Removed

• startup_hooks_enabled configuration option

v0.2.2 - 2023.04.02

Update rebar.config deps list:

{deps, [{elector, "0.2.2"}]}.

Changed:

• Calling manually elect functions will trigger the election globally on all nodes
• Doc directory to git
• Test logs directory to git
• Updated documentation and readme file

Added

• New API function clear_leader/0 with test suite
• Added more assertions for elector:elect and elector:elect_sync functions

Fixed

• Fixed typo on the elect cast function gen_server's name.

v0.2.1 - 2023.03.19

Update rebar.config deps list:

{deps, [{elector, "0.2.1"}]}.

Changed:

• Made post and pre election hooks synchronous
• Updated github CI settings
• Updated documentation

Fixed:

• Renamed modules to avoid collisions with other applications
• Post election hooks were not running after the election fix

v0.2.0 - 2023.03.16

Update rebar.config deps list:

{deps, [{elector, "0.2.0"}]}.

Added:

• New configuration option quorum_size to set the minimum number of nodes that should be available in the cluster before the election process is started.

Changed:

• Updated Erlang version inside the docker-compose.yml
• Set the user and group for the docker container to 1000:1000 to match the host user and group.
• Updated documentation
• Enabled all features for the BEAM using the ERL_AFLAGS=-enable-feature all inside the docker-compose.yml file.

Fixed:

• Fixed running the ct_run command inside the docker container
• Removed duplicate project_plugins from the rebar.config file

v0.1.1 - 2023.01.29

Updated edocs overview section.