An extension of https://github.com/arkency/aggregate_root with support for concurrent writers.
Snapshots are created automatically as required by the #store method. Implementations of this class must implement
2 methods.
#build_snapshot#apply_snapshot(snapshot)
Optionally Implementations may also override
#snapshot_threshold- Override how often snapshots are taken#requires_snapshot?- Provide a custom implementation for when snapshots a required
In order to be safe for current writes snapshot aggregate root exposes a #with_write_context(stream_name, event_store:) method. This method loads the aggregate, applies the block, then stores the events within a mutex so that only one concurrent writer can execute the block. Event handlers are triggered after the command is complete
The entire command handler for a snapshot aggregate root should be executed within this block eg.
def apply_command(command)
SomeAggregate.new.with_write_context(command.aggregate_id) do |aggregate|
aggregate.do_command(command)
end
end