[IGNITE-19888] Java client: Track observable timestamp

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.0.0-beta1
• Fix Version/s: 3.0
• Component/s: platforms, thin client
• Labels: ignite-3
• Epic Link: RO transaction in past
• Ignite Flags: Release Notes Required
• Assignee: Pavel Tupitsyn
• Reporter: Vladislav Pyatkov
• Reviewer: Vladislav Pyatkov
• Created: 29/Jun/23 17:42
• Updated: 04/Sep/24 16:10
• Resolved: 01/Aug/23 11:14

Description

Motivation
The read timestamp for a RO transaction is supposed to be determined by a client timestamp to linearize transactions.

Implementation notes

• The request which starts RO transaction (IGNITE-19887) has to provide a timestamp.
• Requests which start SQL, also provide a specific timestamp (if they start RO internally) (IGNITE-19898 here the concrete method to retrieve timestamp will be implemented).
• The current server timestamp (clock.now()) should be added to (except in the cases above) the transaction response.
• If a server response does not have the timestamp or timestamp is less than the client already has, do nothing.
• If the time is grater than the client has, the client timestamp should be updated.
• The timestamp is used to start RO transaction (IGNITE-19887)

Definition of done
The timestamp is passed from the server-side to a client. The client just save the timestamp and send it in each request to server-side.
All client-side created RO transactions should execute in past with timestamp has been determining by client timestamp.

Issue Links

• blocks: IGNITE-20056 .NET: Thin 3.0: Track observable timestamp
• blocks: IGNITE-20057 C++ client: Track observable timestamp
• is blocked by: IGNITE-19886 Retrive commit timestamp [DISCUSSION NEEDED] We may use clock.now() instead of retrieving actual commit timestamp
• is blocked by: IGNITE-19887 Transfer observable timestamp to read-only transaction
• is blocked by: IGNITE-19898 SQL implicit RO transaction should used observation timestamp
• links to: GitHub Pull Request #2371