Create 'git gc' to perform common maintenance operations.

Junio asked for a 'git gc' utility which users can execute on a
regular basis to perform basic repository actions such as:

 * pack-refs --prune
 * reflog expire
 * repack -a -d
 * prune
 * rerere gc

So here is a command which does exactly that.  The parameters fed
to reflog's expire subcommand can be chosen by the user by setting
configuration options in .git/config (or ~/.gitconfig), as users may
want different expiration windows for each repository but shouldn't
be bothered to remember what they are all of the time.
Signed-off-by: NShawn O. Pearce <spearce@spearce.org>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

.gitignore

@@ -42,6 +42,7 @@ git-fmt-merge-msg
 git-for-each-ref
 git-format-patch
 git-fsck-objects
+git-gc
 git-get-tar-commit-id
 git-grep
 git-hash-object

Documentation/git-gc.txt

+git-gc(1)
+=========
+
+NAME
+----
+git-gc - Cleanup unnecessary files and optimize the local repository
+
+
+SYNOPSIS
+--------
+'git-gc'
+
+DESCRIPTION
+-----------
+Runs a number of housekeeping tasks within the current repository,
+such as compressing file revisions (to reduce disk space and increase
+performance) and removing unreachable objects which may have been
+created from prior invocations of gitlink:git-add[1].
+
+Users are encouraged to run this task on a regular basis within
+each repository to maintain good disk space utilization and good
+operating performance.
+
+Configuration
+-------------
+
+The optional configuration variable 'gc.reflogExpire' can be
+set to indicate how long historical entries within each branch's
+reflog should remain available in this repository.  The setting is
+expressed as a length of time, for example '90 days' or '3 months'.
+It defaults to '90 days'.
+
+The optional configuration variable 'gc.reflogExpireUnreachable'
+can be set to indicate how long historical reflog entries which
+are not part of the current branch should remain available in
+this repository.  These types of entries are generally created as
+a result of using `git commit \--amend` or `git rebase` and are the
+commits prior to the amend or rebase occuring.  Since these changes
+are not part of the current project most users will want to expire
+them sooner.  This option defaults to '30 days'.
+
+The optional configuration variable 'gc.rerereresolved' indicates
+how long records of conflicted merge you resolved earlier are
+kept.  This defaults to 60 days.
+
+The optional configuration variable 'gc.rerereunresolved' indicates
+how long records of conflicted merge you have not resolved are
+kept.  This defaults to 15 days.
+
+
+See Also
+--------
+gitlink:git-prune[1]
+gitlink:git-reflog[1]
+gitlink:git-repack[1]
+gitlink:git-rerere[1]
+
+Author
+------
+Written by Shawn O. Pearce <spearce@spearce.org>
+
+GIT
+---
+Part of the gitlink:git[7] suite

Documentation/git.txt

@@ -212,6 +212,9 @@ gitlink:git-cvsexportcommit[1]::
 gitlink:git-cvsserver[1]::
 	A CVS server emulator for git.
 
+gitlink:git-gc[1]::
+	Cleanup unnecessary files and optimize the local repository.
+
 gitlink:git-lost-found[1]::
 	Recover lost refs that luckily have not yet been pruned.
 

Makefile

@@ -157,7 +157,7 @@ BASIC_LDFLAGS =
 SCRIPT_SH = \
 	git-bisect.sh git-checkout.sh \
 	git-clean.sh git-clone.sh git-commit.sh \
-	git-fetch.sh \
+	git-fetch.sh git-gc.sh \
 	git-ls-remote.sh \
 	git-merge-one-file.sh git-parse-remote.sh \
 	git-pull.sh git-rebase.sh \

git-gc.sh

+#!/bin/sh
+#
+# Copyright (c) 2006, Shawn O. Pearce
+#
+# Cleanup unreachable files and optimize the repository.
+
+USAGE=''
+SUBDIRECTORY_OK=Yes
+. git-sh-setup
+
+git-pack-refs --prune &&
+git-reflog expire --all &&
+git-repack -a -d &&
+git-prune &&
+git-rerere gc || exit