midx.c: respect 'pack.writeBitmapHashcache' when writing bitmaps

In the previous commit, the bitmap writing code learned to propagate
values from an existing hash-cache extension into the bitmap that it is
writing.

Now that that functionality exists, let's expose it by teaching the 'git
multi-pack-index' builtin to respect the `pack.writeBitmapHashCache`
option so that the hash-cache may be written at all.

Two minor points worth noting here:

  - The 'git multi-pack-index write' sub-command didn't previously read
    any configuration (instead this is handled in the base command). A
    separate handler is added here to respect this write-specific
    config option.

  - I briefly considered adding a 'bitmap_flags' field to the static
    options struct, but decided against it since it would require
    plumbing through a new parameter to the write_midx_file() function.

    Instead, a new MIDX-specific flag is added, which is translated to
    the corresponding bitmap one.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/midx.c b/midx.c
index 864034a6ad..38c8600458 100644
--- a/midx.c
+++ b/midx.c
@@ -1008,9 +1008,13 @@ static int write_midx_bitmap(char *midx_name, unsigned char *midx_hash,
 	struct pack_idx_entry **index;
 	struct commit **commits = NULL;
 	uint32_t i, commits_nr;
+	uint16_t options = 0;
 	char *bitmap_name = xstrfmt("%s-%s.bitmap", midx_name, hash_to_hex(midx_hash));
 	int ret;
 
+	if (flags & MIDX_WRITE_BITMAP_HASH_CACHE)
+		options |= BITMAP_OPT_HASH_CACHE;
+
 	prepare_midx_packing_data(&pdata, ctx);
 
 	commits = find_commits_for_midx_bitmap(&commits_nr, ctx);
@@ -1049,7 +1053,7 @@ static int write_midx_bitmap(char *midx_name, unsigned char *midx_hash,
 		goto cleanup;
 
 	bitmap_writer_set_checksum(midx_hash);
-	bitmap_writer_finish(index, pdata.nr_objects, bitmap_name, 0);
+	bitmap_writer_finish(index, pdata.nr_objects, bitmap_name, options);
 
 cleanup:
 	free(index);