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gerrit / jgit / 0e3d4a273f3d5b79c55205a25f21d688b6f131fc
commit0e3d4a273f3d5b79c55205a25f21d688b6f131fc[log] [tgz]
authorHan-Wen Nienhuys <hanwen@google.com>Sat Aug 31 21:33:58 2019 +0200
committerMatthias Sohn <matthias.sohn@sap.com>Tue Sep 03 10:37:30 2019 +0200
treeaff2fa6e991a32c7a2528849b994eb9f577ed211
parent400342bbc1cff644ee9d7fd1076e62be89bb54f4 [diff]
BatchRefUpdate: repro racy atomic update, and fix it

PackedBatchRefUpdate was creating a new packed-refs list that was
potentially unsorted. This would be papered over when the list was
read back from disk in parsePackedRef, which detects unsorted ref
lists on reading, and sorts them. However, the BatchRefUpdate also
installed the new (unsorted) list in-memory in
RefDirectory#packedRefs.

With the timestamp granularity code committed to stable-5.1, we can
more often accurately decide that the packed-refs file is clean, and
will return the erroneous unsorted data more often. Unluckily timed
delays also cause the file to be clean, hence this problem was
exacerbated under load.

The symptom is that refs added by a BatchRefUpdate would stop being
visible directly after they were added. In particular, the Gerrit
integration tests uses BatchRefUpdate in its setup for creating the
Admin group, and then tries to read it out directly afterward.

The tests recreates one failure case. A better approach would be to
revise RefList.Builder, so it detects out-of-order lists and
automatically sorts them.

Fixes https://bugs.eclipse.org/bugs/show_bug.cgi?id=548716 and
https://bugs.chromium.org/p/gerrit/issues/detail?id=11373.

Bug: 548716
Change-Id: I613c8059964513ce2370543620725b540b3cb6d1
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
2 files changed
tree: aff2fa6e991a32c7a2528849b994eb9f577ed211
  1. .mvn/
  2. Documentation/
  3. lib/
  4. org.eclipse.jgit/
  5. org.eclipse.jgit.ant/
  6. org.eclipse.jgit.ant.test/
  7. org.eclipse.jgit.archive/
  8. org.eclipse.jgit.http.apache/
  9. org.eclipse.jgit.http.server/
  10. org.eclipse.jgit.http.test/
  11. org.eclipse.jgit.junit/
  12. org.eclipse.jgit.junit.http/
  13. org.eclipse.jgit.lfs/
  14. org.eclipse.jgit.lfs.server/
  15. org.eclipse.jgit.lfs.server.test/
  16. org.eclipse.jgit.lfs.test/
  17. org.eclipse.jgit.packaging/
  18. org.eclipse.jgit.pgm/
  19. org.eclipse.jgit.pgm.test/
  20. org.eclipse.jgit.test/
  21. org.eclipse.jgit.ui/
  22. tools/
  23. .gitattributes
  24. .gitignore
  25. .mailmap
  26. BUILD
  27. CONTRIBUTING.md
  28. LICENSE
  29. pom.xml
  30. README.md
  31. WORKSPACE
README.md

Java Git

An implementation of the Git version control system in pure Java.

This package is licensed under the EDL (Eclipse Distribution License).

JGit can be imported straight into Eclipse, built and tested from there, but the automated builds use Maven.

  • org.eclipse.jgit

    A pure Java library capable of being run standalone, with no additional support libraries. It provides classes to read and write a Git repository and operate on a working directory.

    All portions of JGit are covered by the EDL. Absolutely no GPL, LGPL or EPL contributions are accepted within this package.

  • org.eclipse.jgit.ant

    Ant tasks based on JGit.

  • org.eclipse.jgit.archive

    Support for exporting to various archive formats (zip etc).

  • org.eclipse.jgit.http.apache

    Apache httpclient support

  • org.eclipse.jgit.http.server

    Server for the smart and dumb Git HTTP protocol.

  • org.eclipse.jgit.pgm

    Command-line interface Git commands implemented using JGit (“pgm” stands for program).

  • org.eclipse.jgit.packaging

    Production of Eclipse features and p2 repository for JGit. See the JGit Wiki on why and how to use this module.

Tests

  • org.eclipse.jgit.junit

    Helpers for unit testing

  • org.eclipse.jgit.test

    Unit tests for org.eclipse.jgit

  • org.eclipse.jgit.ant.test

  • org.eclipse.jgit.pgm.test

  • org.eclipse.jgit.http.test

  • org.eclipse.jgit.junit.test

    No further description needed

Warnings/Caveats

  • Native smbolic links are supported, provided the file system supports them. For Windows you must have Windows Vista/Windows 2008 or newer, use a non-administrator account and have the SeCreateSymbolicLinkPrivilege.

  • Only the timestamp of the index is used by jgit if the index is dirty.

  • JGit requires at least a Java 8 JDK.

  • CRLF conversion is performed depending on the core.autocrlf setting, however Git for Windows by default stores that setting during installation in the “system wide” configuration file. If Git is not installed, use the global or repository configuration for the core.autocrlf setting.

  • The system wide configuration file is located relative to where C Git is installed. Make sure Git can be found via the PATH environment variable. When installing Git for Windows check the “Run Git from the Windows Command Prompt” option. There are other options like Eclipse settings that can be used for pointing out where C Git is installed. Modifying PATH is the recommended option if C Git is installed.

  • We try to use the same notation of $HOME as C Git does. On Windows this is often not the same value as the user.home system property.

Package Features

  • org.eclipse.jgit/

    • Read loose and packed commits, trees, blobs, including deltafied objects.

    • Read objects from shared repositories

    • Write loose commits, trees, blobs.

    • Write blobs from local files or Java InputStreams.

    • Read blobs as Java InputStreams.

    • Copy trees to local directory, or local directory to a tree.

    • Lazily loads objects as necessary.

    • Read and write .git/config files.

    • Create a new repository.

    • Read and write refs, including walking through symrefs.

    • Read, update and write the Git index.

    • Checkout in dirty working directory if trivial.

    • Walk the history from a given set of commits looking for commits introducing changes in files under a specified path.

    • Object transport Fetch via ssh, git, http, Amazon S3 and bundles. Push via ssh, git and Amazon S3. JGit does not yet deltify the pushed packs so they may be a lot larger than C Git packs.

    • Garbage collection

    • Merge

    • Rebase

    • And much more

  • org.eclipse.jgit.pgm/

    • Assorted set of command line utilities. Mostly for ad-hoc testing of jgit log, glog, fetch etc.

  • org.eclipse.jgit.ant/

    • Ant tasks

  • org.eclipse.jgit.archive/

    • Support for Zip/Tar and other formats

  • org.eclipse.http.*/

    • HTTP client and server support

Missing Features

There are some missing features:

  • gitattributes support

Support

Post question, comments or patches to the jgit-dev@eclipse.org mailing list. You need to be subscribed to post, see here:

https://dev.eclipse.org/mailman/listinfo/jgit-dev

Contributing

See the EGit Contributor Guide:

http://wiki.eclipse.org/EGit/Contributor_Guide

About Git

More information about Git, its repository format, and the canonical C based implementation can be obtained from the Git website:

http://git-scm.com/