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apache / bookkeeper / a6e3747d65025b53c09f016d81cf824da7fcbb3a
commita6e3747d65025b53c09f016d81cf824da7fcbb3a[log] [tgz]
authorIvan Kelly <ivank@apache.org>Tue Mar 05 08:49:23 2019 +0100
committerIvan Kelly <ivank@apache.org>Tue Mar 05 08:50:31 2019 +0100
tree50014b8acedad2d1aa78d0a5f796b46027c6c3e1
parent2f507b0b4103e2272d1361a2bf12a018b23fd4a9 [diff]
[DLOG] Avoid double read in readahead

There was a bug in the ReadAheadReader whereby, if it was in a paused
state and the last segment it had read had been closed, then when a
writer started writing new segments, the ReadAheadReader would issue a
double read. This would end up triggering an error when it got to the
end of the segment as the issued one of the issued reads would then be
cancelled when the segment was closed.

This fix adds an explicit state machine to the reader and moves all
state transitions to run on the ordered executor, so only one read can
ever be issued at a time.

Reviewers: Enrico Olivelli <eolivelli@gmail.com>, Sijie Guo <sijie@apache.org>

This closes #1973 from ivankelly/dlog-reader-crash-master
(cherry picked from commit db5d7e7cf30d58c9c463ce29c7d7900115717206)

Signed-off-by: Ivan Kelly <ivank@apache.org>
2 files changed
tree: 50014b8acedad2d1aa78d0a5f796b46027c6c3e1
  1. .github/
  2. .test-infra/
  3. .travis_scripts/
  4. bin/
  5. bookkeeper-benchmark/
  6. bookkeeper-common/
  7. bookkeeper-dist/
  8. bookkeeper-http/
  9. bookkeeper-proto/
  10. bookkeeper-server/
  11. bookkeeper-stats/
  12. bookkeeper-stats-providers/
  13. buildtools/
  14. circe-checksum/
  15. conf/
  16. deploy/
  17. dev/
  18. docker/
  19. microbenchmarks/
  20. shaded/
  21. site/
  22. stream/
  23. tests/
  24. tools/
  25. .gitignore
  26. .travis.yml
  27. LICENSE
  28. NOTICE
  29. pom.xml
  30. README.md
README.md

Build Status Build Status Coverage Status Maven Central

Apache BookKeeper

Apache BookKeeper is a scalable, fault tolerant and low latency storage service optimized for append-only workloads.

It is suitable for being used in following scenarios:

  • WAL (Write-Ahead-Logging), e.g. HDFS NameNode.
  • Message Store, e.g. Apache Pulsar.
  • Offset/Cursor Store, e.g. Apache Pulsar.
  • Object/Blob Store, e.g. storing state machine snapshots.

Get Started

  • Concepts: Start with the basic concepts of Apache BookKeeper. This will help you to fully understand the other parts of the documentation.
  • Getting Started to setup BookKeeper to write logs.

Documentation

Developers

You can also read Turning Ledgers into Logs to learn how to turn ledgers into continuous log streams. If you are looking for a high level log stream API, you can checkout DistributedLog.

Administrators

Contributors

Get In Touch

Report a Bug

For filing bugs, suggesting improvements, or requesting new features, help us out by opening a Github issue or opening an Apache jira.

Need Help?

Subscribe or mail the user@bookkeeper.apache.org list - Ask questions, find answers, and also help other users.

Subscribe or mail the dev@bookkeeper.apache.org list - Join development discussions, propose new ideas and connect with contributors.

Join us on Slack - This is the most immediate way to connect with Apache BookKeeper committers and contributors.

Contributing

We feel that a welcoming open community is important and welcome contributions.

Contributing Code

  1. See Developer Setup to get your local environment setup.

  2. Take a look at our open issues: JIRA Issues Github Issues.

  3. Review our coding style and follow our pull requests to learn about our conventions.

  4. Make your changes according to our contribution guide.

Improving Website and Documentation

  1. See Building the website and documentation on how to build the website and documentation.