[PATCH v2 00/19] WIP object filtering for partial clone

From: Jeff Hostetler <jeffhost@microsoft.com>

This WIP is a follow up to my earlier patch series to teach pack-objects to omit large blobs from packfiles. [1]

Like the previous version, this version builds upon a suggestion from Peff [2] to use the traverse_commit_list() machinery to allow custom object filtering using a filter callback. This hides the filtering logic in list-objects.c and list-objects-filters.c and minimizes the changes to actual commands, such as pack-objects.

This version adds that same filtering capability to rev-list allowing filtering to be demonstrated without building a packfile. Filtered blobs are printed with a leading "~" (along with their sizes).

    $ ./git rev-list --objects HEAD~1..HEAD
    74f806c70507317b8bdbcf3b08459c7c83906bee
    818617707aac81ae4620239182b514f65638e37e 
    d21329bffeb9801682d8d6d6acedc2958d17f4e0 builtin
    306c16551e548ace12c709a332bfea22adcc395f builtin/fetch.c

    $ ./git rev-list --objects --filter-omit-all-blobs --filter-print-manifest HEAD~1..HEAD
    74f806c70507317b8bdbcf3b08459c7c83906bee
    818617707aac81ae4620239182b514f65638e37e 
    d21329bffeb9801682d8d6d6acedc2958d17f4e0 builtin
    ~306c16551e548ace12c709a332bfea22adcc395f 40732

    $ ./git rev-list --objects --filter-omit-all-blobs --filter-print-manifest --quiet HEAD~1..HEAD
    ~306c16551e548ace12c709a332bfea22adcc395f 40732

This version contains 3 filters:
1. filter-omit-all-blobs to exclude all blobs (trees and commits only).

2. filter-omit-large-blobs=<n>[kmg] to exclude blobs larger than <n>
   (but always including ".git*" special files).

3. filter-use-sparse=<blob-ish> to exclude blobs not needed by the
   corresponding sparse-checkout.

Sparse-checkout filtering is currently limited to filtering unneeded blobs. A later enhancement should be able to also filter unneeded tree objects.

This version updates clone, fetch, fetch-pack, and upload-pack commands to pass the additional object-filter parameters.

As a (possibly) temporary measure, some commands have been updated to relax missing blob errors during consistency checks. Maintining info on missing blobs is currently being discussed in [3].

TODO
1. Incorporate with a patch series like [4] to dynamically fetch a
   missing blob from the server in read_object on demand.
2. Resolve missing blob consistency check issue.
3. Store filter options from clone in config or .git/info and default
   to them in subsequent fetches.
4. fsck, gc, and assorted commands.
5. testing.

[1] https://public-inbox.org/git/20170622203615.34135-1-git@jeffhostetler.com/ [2] https://public-inbox.org/git/20170309073117.g3br5btsfwntcdpe@sigill.intra.peff.net/ [3] https://public-inbox.org/git/cover.1499800530.git.jonathantanmy@google.com/ [4] https://public-inbox.org/git/20170505152802.6724-1-benpeart@microsoft.com/

Jeff Hostetler (19):
  dir: refactor add_excludes()
  oidset2: create oidset subclass with object length and pathname
  list-objects: filter objects in traverse_commit_list
  list-objects-filters: add omit-all-blobs filter
  list-objects-filters: add omit-large-blobs filter
  list-objects-filters: add use-sparse-checkout filter
  object-filter: common declarations for object filtering
  rev-list: add object filtering support
  rev-list: add filtering help text
  t6112: rev-list object filtering test
  pack-objects: add object filtering support
  pack-objects: add filtering help text
  upload-pack: add filter-objects to protocol documentation
  upload-pack: add object filtering
  fetch-pack: add object filtering support
  connected: add filter_allow_omitted option to API
  clone: add filter arguments
  index-pack: relax consistency checks for omitted objects
  fetch: add object filtering to fetch

 Documentation/git-pack-objects.txt                |  14 +
 Documentation/git-rev-list.txt                    |   7 +-
 Documentation/rev-list-options.txt                |  26 ++
 Documentation/technical/pack-protocol.txt         |  16 +
 Documentation/technical/protocol-capabilities.txt |   7 +
 Makefile                                          |   3 +
 builtin/clone.c                                   |  28 ++
 builtin/fetch-pack.c                              |   3 +
 builtin/fetch.c                                   |  27 +-
 builtin/index-pack.c                              |  15 +
 builtin/pack-objects.c                            |  33 +-
 builtin/rev-list.c                                |  58 +++-
 connected.c                                       |   3 +
 connected.h                                       |   6 +
 dir.c                                             |  53 +++-
 dir.h                                             |   4 +
 fetch-pack.c                                      |  28 ++
 fetch-pack.h                                      |   2 +
 list-objects-filters.c                            | 361 ++++++++++++++++++++++
 list-objects-filters.h                            |  45 +++
 list-objects.c                                    |  66 +++-
 list-objects.h                                    |  30 ++
 object-filter.c                                   | 201 ++++++++++++
 object-filter.h                                   | 145 +++++++++
 oidset2.c                                         | 101 ++++++
 oidset2.h                                         |  56 ++++
 t/t6112-rev-list-filters-objects.sh               |  37 +++
 transport.c                                       |  27 ++
 transport.h                                       |   8 +
 upload-pack.c                                     |  39 ++-
 30 files changed, 1425 insertions(+), 24 deletions(-)
 create mode 100644 list-objects-filters.c
 create mode 100644 list-objects-filters.h
 create mode 100644 object-filter.c
 create mode 100644 object-filter.h
 create mode 100644 oidset2.c
 create mode 100644 oidset2.h
 create mode 100644 t/t6112-rev-list-filters-objects.sh