Behaviour for acquiring and releasing locks around transform execution.

Pollard uses a lock to prevent concurrent transform runs across nodes in a cluster. The lock strategy is configurable via the :lock option on Pollard.Runner.run/3.

Built-in implementations

• Pollard.Lock.Postgres - Uses Postgres advisory locks. Recommended for Postgres-backed applications.
• Pollard.Lock.None - No-op lock. Use for single-node deployments or databases where concurrent deploys are not a concern (e.g. SQLite).

Custom implementations

defmodule MyApp.Lock.Redis do
  @behaviour Pollard.Lock

  @impl true
  def acquire(repo, opts) do
    # acquire a distributed lock
    :ok
  end

  @impl true
  def release(repo, opts) do
    :ok
  end
end

Then pass it as an option:

Pollard.Runner.run(MyApp.Repo, path, lock: MyApp.Lock.Redis)