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gerrit / jgit / 16760c3e9a242f21538c2f4da1aad96953cafc37
commit16760c3e9a242f21538c2f4da1aad96953cafc37[log] [tgz]
authorMatthias Sohn <matthias.sohn@sap.com>Fri Jun 21 18:12:14 2019 +0200
committerMatthias Sohn <matthias.sohn@sap.com>Wed Jul 17 09:42:14 2019 +0200
tree15146bff31bd9b3f27662baf04bdc5726944e4f2
parent0966731cad37fab239d458735c14be012cc70958 [diff]
Persist filesystem timestamp resolution and allow manual configuration

To enable persisting filesystem timestamp resolution per FileStore add a
new config section to the user global git configuration:

- Config section is "filesystem"
- Config subsection is concatenation of
  - Java vendor (system property "java.vm.vendor")
  - runtime version (system property "java.vm.version")
  - FileStore's name
  - separated by '|'
  e.g.
    "AdoptOpenJDK|1.8.0_212-b03|/dev/disk1s1"
  The prefix is needed since some Java versions do not expose the full
  timestamp resolution of the underlying filesystem. This may also
  depend on the underlying operating system hence concrete key values
  may not be portable.
- Config key for timestamp resolution is "timestampResolution" as a time
  value, supported time units are those supported by
  DefaultTypedConfigGetter#getTimeUnit

If timestamp resolution is already configured for a given FileStore
the configured value is used instead of measuring the resolution.

When timestamp resolution was measured it is persisted in the user
global git configuration.

Example:

[filesystem "AdoptOpenJDK|1.8.0_212-b03|/dev/disk1s1"]
	timestampResolution = 1 seconds

If locking the git config file fails retry saving the resolution up to 5
times in order to workaround races with another thread.

In order to avoid stack overflow use the fallback filesystem timestamp
resolution when loading FileBasedConfig which creates itself a
FileSnapshot to help checking if the config changed.

Note:
- on some OSes Java 8,9 truncate to milliseconds or seconds, see
https://bugs.openjdk.java.net/browse/JDK-8177809, fixed in Java 10
- UnixFileAttributes up to Java 12 truncates timestamp resolution to
microseconds when converting the internal representation to FileTime
exposed in the API, see https://bugs.openjdk.java.net/browse/JDK-8181493
- WindowsFileAttributes also provides only microsecond resolution up to
Java 12

Hence do not attempt to manually configure a higher timestamp resolution
than supported by the Java version being used at runtime.

Bug: 546891
Bug: 548188
Change-Id: Iff91b8f9e6e5e2295e1463f87c8e95edf4abbcf8
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
8 files changed
tree: 15146bff31bd9b3f27662baf04bdc5726944e4f2
  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/