The approximate timestamp

This is either the last observed sequencer timestamp OR the effective timestamp after we observed the time difference of (effective - sequencer = epsilon)

Finds the transaction with maximum effective time that has been sequenced before or at sequencedTime and yields the sequenced / effective time of that transaction. Potentially waits for sequencedTime to be observed.

Returns an optional future which will complete when the sequenced timestamp has been observed

If the timestamp is already observed, returns None.

Waits until a snapshot is available

The snapshot returned by this method should be used for validating transaction and reassignment requests (Phase 2 - 7). Use the request timestamp as parameter for this method. Do not use a response or result timestamp, because all validation steps must use the same topology snapshot.

Returns an optional future which will complete when the effective timestamp has been observed

If the timestamp is already observed, returns None.

Our current snapshot approximation

As topology transactions are future dated (to prevent sequential bottlenecks), we do have to "guess" the current state, as time is defined by the sequencer after we've sent the transaction. Therefore, this function will return the best snapshot approximation known.

The snapshot returned by this method should be used when preparing a transaction or reassignment request (Phase 1). It must not be used when validating a request (Phase 2 - 7); instead, use one of the snapshot methods with the request timestamp.

Returns the topology information at a certain point in time

Use this method if you are sure to be synchronized with the topology state updates. The method will block & wait for an update, but emit a warning if it is not available

The snapshot returned by this method should be used for validating transaction and reassignment requests (Phase 2 - 7). Use the request timestamp as parameter for this method. Do not use a response or result timestamp, because all validation steps must use the same topology snapshot.

The most recently observed effective timestamp

The effective timestamp is sequencer_time + epsilon(sequencer_time), where epsilon is given by the topology change delay time, defined using the synchronizer parameters.

This is the highest timestamp for which we can serve snapshots

Returns the topology information at a certain point in time

Fails with an exception if the state is not yet known.

The snapshot returned by this method should be used for validating transaction and reassignment requests (Phase 2 - 7). Use the request timestamp as parameter for this method. Do not use a response or result timestamp, because all validation steps must use the same topology snapshot.

Possibly future dated head snapshot

As we future date topology transactions, the head snapshot is our latest knowledge of the topology state, but as it can be still future dated, we need to be careful when actually using it: the state might not yet be active, as the topology transactions are future dated. Therefore, do not act towards the sequencer using this snapshot, but use the currentSnapshotApproximation instead.