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[03/22] pack-bitmap-write.c: free existing bitmaps

Message ID 014c18b8965fda2c5feb4ec5c4fe9d82f213a744.1617991824.git.me@ttaylorr.com (mailing list archive)
State New
Headers show
Series multi-pack reachability bitmaps | expand

Commit Message

Taylor Blau April 9, 2021, 6:10 p.m. UTC
When writing a new bitmap, the bitmap writer code attempts to read the
existing bitmap (if one is present). This is done in order to quickly
permute the bits of any bitmaps for commits which appear in the existing
bitmap, and were also selected for the new bitmap.

But since this code was added in 341fa34887 (pack-bitmap-write: use
existing bitmaps, 2020-12-08), the resources associated with opening an
existing bitmap were never released.

It's fine to ignore this, but it's bad hygiene. It will also cause a
problem for the multi-pack-index builtin, which will be responsible not
only for writing bitmaps, but also for expiring any old multi-pack
bitmaps.

If an existing bitmap was reused here, it will also be expired. That
will cause a problem on platforms which require file resources to be
closed before unlinking them, like Windows. Avoid this by ensuring we
close reused bitmaps with free_bitmap_index() before removing them.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
---
 pack-bitmap-write.c | 1 +
 1 file changed, 1 insertion(+)
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Patch

diff --git a/pack-bitmap-write.c b/pack-bitmap-write.c
index e829c46649..f90e100e3e 100644
--- a/pack-bitmap-write.c
+++ b/pack-bitmap-write.c
@@ -520,6 +520,7 @@  int bitmap_writer_build(struct packing_data *to_pack)
 	clear_prio_queue(&queue);
 	clear_prio_queue(&tree_queue);
 	bitmap_builder_clear(&bb);
+	free_bitmap_index(old_bitmap);
 	free(mapping);
 
 	trace2_region_leave("pack-bitmap-write", "building_bitmaps_total",