This patch series is upstreaming work made by GitHub and available in: https://github.com/peff/git/commits/jk/delta-islands
The above work has been already described in the following article: https://githubengineering.com/counting-objects/ The above branch contains only one patch. In this patch series the patch has been split into 4 patches (1/7, 3/7, 4/7 and 5/7) with their own commit message, and on top of that 3 new patches (2/7, 6/7 and 7/7) have been added. The new patches implement things that have been requested on the mailing list. I kept Peff as the author of the original 4 patches and took the liberty to add his Signed-off-by to them. As explained in details in the "Counting Objects" article referenced above, the goal of the delta island mechanism is for a hosting provider to make it possible to have the "forks" of a repository share as much storage as possible while preventing object packs to contain deltas between different forks. If deltas between different forks are not prevented, when users clone or fetch a fork, preparing the pack that should be sent to them can be very costly CPU wise, as objects from a different fork should not be sent, which means that a lot of deltas might need to be computed again (instead of reusing existing deltas). The following changes have been made since the previous iteration: * suggested by Ramsay: fix typo in "deltified" in commit message in patch 1/7 * suggested by Ramsay and Peff: use FLEX_ARRAY when defining 'struct island_bitmap' in delta-islands.c in patch 1/7 The diff against v4 is: ======= diff --git a/delta-islands.c b/delta-islands.c index 2ced34d99c..8e5018e406 100644 --- a/delta-islands.c +++ b/delta-islands.c @@ -35,7 +35,7 @@ struct remote_island { struct island_bitmap { uint32_t refcount; - uint32_t bits[]; + uint32_t bits[FLEX_ARRAY]; }; static uint32_t island_bitmap_size; ======= This patch series is also available on GitHub in: https://github.com/chriscool/git/commits/delta-islands The previous versions are available there: V4: https://github.com/chriscool/git/commits/delta-islands32 V3: https://github.com/chriscool/git/commits/delta-islands29 V2: https://github.com/chriscool/git/commits/delta-islands19 V1: https://github.com/chriscool/git/commits/delta-islands6 V4: https://public-inbox.org/git/20180812051151.6425-1-chrisc...@tuxfamily.org/ V3: https://public-inbox.org/git/20180809155532.26151-1-chrisc...@tuxfamily.org/ V2: https://public-inbox.org/git/20180805172525.15278-1-chrisc...@tuxfamily.org/ V1: https://public-inbox.org/git/20180722054836.28935-1-chrisc...@tuxfamily.org/ Christian Couder (3): pack-objects: refactor code into compute_layer_order() pack-objects: move tree_depth into 'struct packing_data' pack-objects: move 'layer' into 'struct packing_data' Jeff King (4): Add delta-islands.{c,h} pack-objects: add delta-islands support repack: add delta-islands support t: add t5319-delta-islands.sh Documentation/config.txt | 19 ++ Documentation/git-pack-objects.txt | 97 ++++++ Documentation/git-repack.txt | 5 + Makefile | 1 + builtin/pack-objects.c | 137 +++++--- builtin/repack.c | 9 + delta-islands.c | 502 +++++++++++++++++++++++++++++ delta-islands.h | 11 + pack-objects.c | 12 + pack-objects.h | 39 +++ t/t5319-delta-islands.sh | 143 ++++++++ 11 files changed, 932 insertions(+), 43 deletions(-) create mode 100644 delta-islands.c create mode 100644 delta-islands.h create mode 100755 t/t5319-delta-islands.sh -- 2.18.0.673.gcd86e60100
