commit | b4c66104fb7502f133989291a4a5595f965771d3 | [log] [tgz] |
---|---|---|
author | Luca Milanesio <luca.milanesio@gmail.com> | Mon Jun 13 23:09:55 2022 +0100 |
committer | Matthias Sohn <matthias.sohn@sap.com> | Fri Jan 19 01:28:04 2024 +0100 |
tree | ce76680b90ddd2fa117bff7974c3009d4e118719 | |
parent | 2d52df15465b85c5f90a0e2052bcf35ef9b58e39 [diff] |
Introduce a PriorityQueue sorting RevCommits by commit timestamp The DateRevQueue uses a tailor-made algorithm to keep RevCommits sorted by reversed commit timestamp, which has a O(n*n/2) complexity and caused the explosion of the Git fetch times to tens of seconds. The standard Java PriorityQueue provides a O(n*log(n)) complexity and scales much better with the increase of the number of RevCommits. Introduce a new implementation DateRevPriorityQueue of the DateRevQueue based on PriorityQueue. Enable usage of the new DateRevPriorityQueue implementation by setting the system property REVWALK_USE_PRIORITY_QUEUE=true. By default the old implementation DateRevQueue is used. Benchmark results: ``` (numCommits) (usePriorityQueue) Mode Cnt Score Error Units 5 true avgt 10 39,4 ± 6,1 ns/op 5 false avgt 10 14,1 ± 2,2 ns/op 10 true avgt 10 29,7 ± 3,5 ns/op 10 false avgt 10 13,2 ± 2,0 ns/op 50 true avgt 10 50,4 ± 5,3 ns/op 50 false avgt 10 18,6 ± 0,2 ns/op 100 true avgt 10 58,3 ± 5,0 ns/op 100 false avgt 10 20,5 ± 0,8 ns/op 500 true avgt 10 51,7 ± 2,6 ns/op 500 false avgt 10 43,3 ± 0,5 ns/op 1000 true avgt 10 49,2 ± 2,4 ns/op 1000 false avgt 10 62,7 ± 0,2 ns/op 5000 true avgt 10 48,8 ± 1,5 ns/op 5000 false avgt 10 228,3 ± 0,5 ns/op 10000 true avgt 10 44,2 ± 0,9 ns/op 10000 false avgt 10 377,6 ± 2,7 ns/op 50000 true avgt 10 50,3 ± 1,6 ns/op 50000 false avgt 10 637,0 ± 111,8 ns/op 100000 true avgt 10 61,8 ± 4,4 ns/op 100000 false avgt 10 965,1 ± 268,0 ns/op 500000 true avgt 10 127,2 ± 7,9 ns/op 500000 false avgt 10 9610,2 ± 184,8 ns/op ``` Memory allocation results: ``` Number of commits loaded: 850 000 Custom implementation: 378 245 120 Bytes Priority queue implementation: 340 495 616 Bytes ``` Bug: 580137 Change-Id: I8b33df6e9ee88933098ecc81ce32bdb189715041 Signed-off-by: Luca Milanesio <luca.milanesio@gmail.com>
An implementation of the Git version control system in pure Java.
This project is licensed under the EDL (Eclipse Distribution License).
JGit can be imported straight into Eclipse and built and tested from there. It can be built from the command line using Maven or Bazel. The CI builds use Maven and run on Jenkins.
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.lfs
Support for LFS (Large File Storage).
org.eclipse.jgit.lfs.server
Basic LFS server support.
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.
org.eclipse.jgit.pgm
Command-line interface Git commands implemented using JGit (“pgm” stands for program).
org.eclipse.jgit.ssh.apache
Client support for the SSH protocol based on Apache Mina sshd.
org.eclipse.jgit.ssh.apache.agent
Optional support for SSH agents for org.eclipse.jgit.ssh.apache.
org.eclipse.jgit.ui
Simple UI for displaying git log.
Native symbolic links are supported, provided the file system supports them. For Windows you must 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 6.0 and newer requires at least Java 11. Older versions require at least Java 1.8.
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.
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, http, 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
org.eclipse.jgit.ant
org.eclipse.jgit.archive
org.eclipse.http
There are some missing features:
Post questions, comments or discussions to the jgit-dev@eclipse.org mailing list. You need to be subscribed to post. File bugs and enhancement requests in Bugzilla.
See the EGit Contributor Guide.
More information about Git, its repository format, and the canonical C based implementation can be obtained from the Git website.