git-reflog: gc.* configuration and documentation.

Signed-off-by: Junio C Hamano <junkio@cox.net>

Documentation/config.txt

@@ -192,6 +192,15 @@ format.headers::
 	Additional email headers to include in a patch to be submitted
 	by mail.  See gitlink:git-format-patch[1].
 
+gc.reflogexpire::
+	`git reflog expire` removes reflog entries older than
+	this time; defaults to 90 days.
+
+gc.reflogexpireunreachable::
+	`git reflog expire` removes reflog entries older than
+	this time and are not reachable from the current tip;
+	defaults to 30 days.
+
 gc.rerereresolved::
 	Records of conflicted merge you resolved earlier are
 	kept for this many days when `git rerere gc` is run.

Documentation/git-reflog.txt

@@ -0,0 +1,59 @@
+git-reflog(1)
+=============
+
+NAME
+----
+git-reflog - Manage reflog information
+
+
+SYNOPSIS
+--------
+[verse]
+'git-reflog' expire [--dry-run]
+	[--expire=<time>] [--expire-unreachable=<time>] [--all] <refs>...
+
+
+DESCRIPTION
+-----------
+
+Reflog is a mechanism to record when the tip of branches are
+updated.  This command is to manage the information recorded in it.
+
+The subcommand "expire" is used to prune older reflog entries.
+Entries older than `expire` time, or entries older than
+`expire-unreachable` time and are not reachable from the current
+tip, are removed from the reflog.  This is typically not used
+directly by the end users -- instead, see gitlink:git-gc[1].
+
+
+
+OPTIONS
+-------
+
+--expire=<time>::
+	Entries older than this time are pruned.  Without the
+	option it is taken from configuration `gc.reflogExpire`,
+	which in turn defaults to 90 days.
+
+--expire-unreachable=<time>::
+	Entries older than this time and are not reachable from
+	the current tip of the branch are pruned.  Without the
+	option it is taken from configuration
+	`gc.reflogExpireUnreachable`, which in turn defaults to
+	30 days.
+
+--all::
+	Instead of listing <refs> explicitly, prune all refs.
+
+Author
+------
+Written by Junio C Hamano <junkio@cox.net>
+
+Documentation
+--------------
+Documentation by Junio C Hamano and the git-list <git@vger.kernel.org>.
+
+GIT
+---
+Part of the gitlink:git[7] suite
+

Documentation/git.txt

@@ -224,6 +224,9 @@ gitlink:git-prune[1]::
 gitlink:git-quiltimport[1]::
 	Applies a quilt patchset onto the current branch.
 
+gitlink:git-reflog[1]::
+	Manage reflog information.
+
 gitlink:git-relink[1]::
 	Hardlink common objects in local repositories.
 

builtin-reflog.c

@@ -5,6 +5,9 @@
 #include "dir.h"
 #include "tree-walk.h"
 
+static unsigned long default_reflog_expire;
+static unsigned long default_reflog_expire_unreachable;
+
 struct expire_reflog_cb {
 	FILE *newlog;
 	const char *ref;
@@ -150,6 +153,17 @@ static int expire_reflog(const char *ref, const unsigned char *sha1, int unused,
 	return status;
 }
 
+static int reflog_expire_config(const char *var, const char *value)
+{
+	if (!strcmp(var, "gc.reflogexpire"))
+		default_reflog_expire = approxidate(value);
+	else if (!strcmp(var, "gc.reflogexpireunreachable"))
+		default_reflog_expire_unreachable = approxidate(value);
+	else
+		return git_default_config(var, value);
+	return 0;
+}
+
 static const char reflog_expire_usage[] =
 "git-reflog expire [--dry-run] [--expire=<time>] [--expire-unreachable=<time>] [--all] <refs>...";
 
@@ -159,11 +173,18 @@ static int cmd_reflog_expire(int argc, const char **argv, const char *prefix)
 	unsigned long now = time(NULL);
 	int i, status, do_all;
 
+	git_config(reflog_expire_config);
+
 	save_commit_buffer = 0;
 	do_all = status = 0;
 	memset(&cb, 0, sizeof(cb));
-	cb.expire_total = now - 90 * 24 * 3600;
-	cb.expire_unreachable = now - 30 * 24 * 3600;
+
+	if (!default_reflog_expire_unreachable)
+		default_reflog_expire_unreachable = now - 30 * 24 * 3600;
+	if (!default_reflog_expire)
+		default_reflog_expire = now - 90 * 24 * 3600;
+	cb.expire_total = default_reflog_expire;
+	cb.expire_unreachable = default_reflog_expire_unreachable;
 
 	for (i = 1; i < argc; i++) {
 		const char *arg = argv[i];