Merge branch 'tb/geometric-repack'

"git repack" so far has been only capable of repacking everything
under the sun into a single pack (or split by size).  A cleverer
strategy to reduce the cost of repacking a repository has been
introduced.

* tb/geometric-repack:
  builtin/pack-objects.c: ignore missing links with --stdin-packs
  builtin/repack.c: reword comment around pack-objects flags
  builtin/repack.c: be more conservative with unsigned overflows
  builtin/repack.c: assign pack split later
  t7703: test --geometric repack with loose objects
  builtin/repack.c: do not repack single packs with --geometric
  builtin/repack.c: add '--geometric' option
  packfile: add kept-pack cache for find_kept_pack_entry()
  builtin/pack-objects.c: rewrite honor-pack-keep logic
  p5303: measure time to repack with keep
  p5303: add missing &&-chains
  builtin/pack-objects.c: add '--stdin-packs' option
  revision: learn '--no-kept-objects'
  packfile: introduce 'find_kept_pack_entry()'

Documentation/git-pack-objects.txt

@@ -85,6 +85,16 @@ base-name::
 	reference was included in the resulting packfile.  This
 	can be useful to send new tags to native Git clients.
 
+--stdin-packs::
+	Read the basenames of packfiles (e.g., `pack-1234abcd.pack`)
+	from the standard input, instead of object names or revision
+	arguments. The resulting pack contains all objects listed in the
+	included packs (those not beginning with `^`), excluding any
+	objects listed in the excluded packs (beginning with `^`).
++
+Incompatible with `--revs`, or options that imply `--revs` (such as
+`--all`), with the exception of `--unpacked`, which is compatible.
+
 --window=<n>::
 --depth=<n>::
 	These two options affect how the objects contained in

Documentation/git-repack.txt

@@ -165,6 +165,29 @@ depth is 4095.
 	Pass the `--delta-islands` option to `git-pack-objects`, see
 	linkgit:git-pack-objects[1].
 
+-g=<factor>::
+--geometric=<factor>::
+	Arrange resulting pack structure so that each successive pack
+	contains at least `<factor>` times the number of objects as the
+	next-largest pack.
++
+`git repack` ensures this by determining a "cut" of packfiles that need
+to be repacked into one in order to ensure a geometric progression. It
+picks the smallest set of packfiles such that as many of the larger
+packfiles (by count of objects contained in that pack) may be left
+intact.
++
+Unlike other repack modes, the set of objects to pack is determined
+uniquely by the set of packs being "rolled-up"; in other words, the
+packs determined to need to be combined in order to restore a geometric
+progression.
++
+When `--unpacked` is specified, loose objects are implicitly included in
+this "roll-up", without respect to their reachability. This is subject
+to change in the future. This option (implying a drastically different
+repack mode) is not guaranteed to work with all other combinations of
+option to `git repack`).
+
 CONFIGURATION
 -------------