In commit 07e7dbf0d (gc: default aggressive depth to 50, 2016-08-11),
the default aggressive depth of git-gc has been changed to 50. While
git-config(1) has been updated to represent the new default value,
git-gc(1) still mentions the old value. This patch fixes it.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Doc update.

* mm/gc-safety-doc:
  git-gc.txt: expand discussion of races with other processes

In general, "git gc" may delete objects that another concurrent process
is using but hasn't created a reference to.  Git has some mitigations,
but they fall short of a complete solution.  Document this in the
git-gc(1) man page and add a reference from the documentation of the
gc.pruneExpire config variable.

Based on a write-up by Jeff King:

http://marc.info/?l=git&m=147922960131779&w=2

Signed-off-by: Matt McCutchen <matt@mattmccutchen.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

This change configuration variables that where in italic style
to monospace font according to the guideline. It was obtained with

	grep '[[:alpha:]]*\.[[:alpha:]]*::$' config.txt | \
	sed -e 's/::$//' -e 's/\./\\\\./' | \
	xargs -iP perl -pi -e "s/\'P\'/\`P\`/g" ./*.txt

Signed-off-by: Tom Russello <tom.russello@grenoble-inp.org>
Signed-off-by: Erwan Mathoniere <erwan.mathoniere@grenoble-inp.org>
Signed-off-by: Samuel Groot <samuel.groot@grenoble-inp.org>
Signed-off-by: Matthieu Moy <matthieu.moy@grenoble-inp.fr>
Reviewed-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

"git gc" is safe to run anytime only because it has the built-in
grace period to protect young objects.  In order to run with no
grace period, the user must make sure that the repository is
quiescent.

* jc/doc-gc-prune-now:
  Documentation/gc: warn against --prune=<now>

"git gc" is safe to run anytime only because it has the built-in
grace period to protect objects that are created by other processes
that are waiting for ref updates to anchor them to the history.  In
order to run with no grace period, the user must make sure that the
repository is quiescent.

Reviewed-by: Matthieu Moy <Matthieu.Moy@grenoble-inp.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

This should improve readability. Compare "thislongname" and
"thisLongName". The following keys are left in unchanged. We can
decide what to do with them later.

 - am.keepcr
 - core.autocrlf .safecrlf .trustctime
 - diff.dirstat .noprefix
 - gitcvs.usecrlfattr
 - gui.blamehistoryctx .trustmtime
 - pull.twohead
 - receive.autogc
 - sendemail.signedoffbycc .smtpsslcertpath .suppresscc

Helped-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

When 1c192f3 (gc --aggressive: make it really aggressive - 2007-12-06)
made --depth=250 the default value, it didn't really explain the
reason behind, especially the pros and cons of --depth=250.

An old mail from Linus below explains it at length. Long story short,
--depth=250 is a disk saver and a performance killer. Not everybody
agrees on that aggressiveness. Let the user configure it.

    From: Linus Torvalds <torvalds@linux-foundation.org>
    Subject: Re: [PATCH] gc --aggressive: make it really aggressive
    Date: Thu, 6 Dec 2007 08:19:24 -0800 (PST)
    Message-ID: <alpine.LFD.0.9999.0712060803430.13796@woody.linux-foundation.org>
    Gmane-URL: http://article.gmane.org/gmane.comp.gcc.devel/94637

    On Thu, 6 Dec 2007, Harvey Harrison wrote:
    >
    > 7:41:25elapsed 86%CPU

    Heh. And this is why you want to do it exactly *once*, and then just
    export the end result for others ;)

    > -r--r--r-- 1 hharrison hharrison 324094684 2007-12-06 07:26 pack-1d46...pack

    But yeah, especially if you allow longer delta chains, the end result can
    be much smaller (and what makes the one-time repack more expensive is the
    window size, not the delta chain - you could make the delta chains longer
    with no cost overhead at packing time)

    HOWEVER.

    The longer delta chains do make it potentially much more expensive to then
    use old history. So there's a trade-off. And quite frankly, a delta depth
    of 250 is likely going to cause overflows in the delta cache (which is
    only 256 entries in size *and* it's a hash, so it's going to start having
    hash conflicts long before hitting the 250 depth limit).

    So when I said "--depth=250 --window=250", I chose those numbers more as
    an example of extremely aggressive packing, and I'm not at all sure that
    the end result is necessarily wonderfully usable. It's going to save disk
    space (and network bandwidth - the delta's will be re-used for the network
    protocol too!), but there are definitely downsides too, and using long
    delta chains may simply not be worth it in practice.

    (And some of it might just want to have git tuning, ie if people think
    that long deltas are worth it, we could easily just expand on the delta
    hash, at the cost of some more memory used!)

    That said, the good news is that working with *new* history will not be
    affected negatively, and if you want to be _really_ sneaky, there are ways
    to say "create a pack that contains the history up to a version one year
    ago, and be very aggressive about those old versions that we still want to
    have around, but do a separate pack for newer stuff using less aggressive
    parameters"

    So this is something that can be tweaked, although we don't really have
    any really nice interfaces for stuff like that (ie the git delta cache
    size is hardcoded in the sources and cannot be set in the config file, and
    the "pack old history more aggressively" involves some manual scripting
    and knowing how "git pack-objects" works rather than any nice simple
    command line switch).

    So the thing to take away from this is:
     - git is certainly flexible as hell
     - .. but to get the full power you may need to tweak things
     - .. happily you really only need to have one person to do the tweaking,
       and the tweaked end results will be available to others that do not
       need to know/care.

    And whether the difference between 320MB and 500MB is worth any really
    involved tweaking (considering the potential downsides), I really don't
    know. Only testing will tell.

			    Linus

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

* nd/gc-lock-against-each-other:
  gc: reject if another gc is running, unless --force is given

This may happen when `git gc --auto` is run automatically, then the
user, to avoid wait time, switches to a new terminal, keeps working
and `git gc --auto` is started again because the first gc instance has
not clean up the repository.

This patch tries to avoid multiple gc running, especially in --auto
mode. In the worst case, gc may be delayed 12 hours if a daemon reuses
the pid stored in gc.pid.

kill(pid, 0) support is added to MinGW port so it should work on
Windows too.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>