State snapshot at a given point in time.
Checkpoint()The version of the checkpoint format. Currently 1.
The ID of the checkpoint.
This is both unique and monotonically increasing, so can be used for sorting checkpoints from first to last.
The timestamp of the checkpoint in ISO 8601 format.
The values of the channels at the time of the checkpoint.
Mapping from channel name to deserialized channel snapshot value.
The versions of the channels at the time of the checkpoint.
The keys are channel names and the values are monotonically increasing version strings for each channel.
Map from node ID to map from channel name to version seen.
This keeps track of the versions of the channels that each node has seen. Used to determine which nodes to execute next.
The channels that were updated in this checkpoint.