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- [X] Tests added - [X] Branch rebased on top of current main (`git pull --rebase origin main`) - [X] Changes squashed to a single commit (described [here](http://gitready.com/advanced/2009/02/10/squashing-commits-with-rebase.html)) - [x] Build is green in Travis CI - [X] You have certified that the contribution is your original work and that you license the work to the project under the [Apache 2 license](https://github.com/nats-io/nats-server/blob/main/LICENSE) ### Changes proposed in this pull request: Fixes a race condition in some leader failover scenarios leading to messages being potentially sourced more than once. In some failure scenarios where the current leader of a stream sourcing from other stream(s) gets shutdown while publications are happening on the stream(s) being sourced leads to `setLeader(true)` being called on the new leader for the sourcing stream before all the messages having been sourced by the previous leader are completely processed such that when the new leader does it's reverse scan from the last message in it's view of the stream in order to know what sequence number to start the consumer for the stream being sourced from, such that the last message(s) sourced by the previous leader get sourced again, leading to some messages being sourced more than once. The existing `TestNoRaceJetStreamSuperClusterSources` test would sidestep the issue by relying on the deduplication window in the sourcing stream. Without deduplication the test is a flapper. This avoid the race condition by adding a small delay before scanning for the last message(s) having been sourced and starting the sources' consumer(s). Now the test (without using the deduplication window) never fails because more messages than expected have been received in the sourcing stream. (Also adds a guard to give up if `setupSourceConsumers()` is called and we are no longer the leader for the stream (that check was already present in `setupMirrorConsumer()` so assuming it was forgotten for `setupSourceConsumers()`)
NATS is a simple, secure and performant communications system for digital systems, services and devices. NATS is part of the Cloud Native Computing Foundation (CNCF). NATS has over 40 client language implementations, and its server can run on-premise, in the cloud, at the edge, and even on a Raspberry Pi. NATS can secure and simplify design and operation of modern distributed systems.
Documentation
- Official Website
- Official Documentation
- FAQ
- Watch a video overview of NATS.
- Watch this video from SCALE 13x to learn more about its origin story and design philosophy.
Contact
- Twitter: Follow us on Twitter!
- Google Groups: Where you can ask questions
- Slack: Click here to join. You can ask question to our maintainers and to the rich and active community.
Contributing
If you are interested in contributing to NATS, read about our...
Roadmap
The NATS product roadmap can be found here.
Security
Security Audit
A third party security audit was performed by Cure53, you can see the full report here.
Reporting Security Vulnerabilities
If you've found a vulnerability or a potential vulnerability in the NATS server, please let us know at nats-security.
License
Unless otherwise noted, the NATS source files are distributed under the Apache Version 2.0 license found in the LICENSE file.