make object_directory.loose_objects_subdir_seen a bitmap
There's no point in using 8 bits per-directory when 1 bit will do. This saves us 224 bytes per object directory, which ends up being 22MB when dealing with 100K alternates. Signed-off-by: Eric Wong <e@80x24.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Eric Wong committed
Jul 7, 2021 at 23:10 UTC
33f379eee63a0529f85079857598ac6325d3aec5
2 files changed
+9
-4
object-file.c
+8
-3
@@ -2461,12 +2461,17 @@ struct oid_array *odb_loose_cache(struct object_directory *odb,
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{
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int subdir_nr = oid->hash[0];
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struct strbuf buf = STRBUF_INIT;
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+ size_t word_bits = bitsizeof(odb->loose_objects_subdir_seen[0]);
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+ size_t word_index = subdir_nr / word_bits;
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+ size_t mask = 1 << (subdir_nr % word_bits);
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+ uint32_t *bitmap;
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if (subdir_nr < 0 ||
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- subdir_nr >= ARRAY_SIZE(odb->loose_objects_subdir_seen))
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+ subdir_nr >= bitsizeof(odb->loose_objects_subdir_seen))
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BUG("subdir_nr out of range");
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- if (odb->loose_objects_subdir_seen[subdir_nr])
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+ bitmap = &odb->loose_objects_subdir_seen[word_index];
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+ if (*bitmap & mask)
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return &odb->loose_objects_cache[subdir_nr];
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strbuf_addstr(&buf, odb->path);
@@ -2474,7 +2479,7 @@ struct oid_array *odb_loose_cache(struct object_directory *odb,
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append_loose_object,
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NULL, NULL,
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&odb->loose_objects_cache[subdir_nr]);
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- odb->loose_objects_subdir_seen[subdir_nr] = 1;
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+ *bitmap |= mask;
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strbuf_release(&buf);
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return &odb->loose_objects_cache[subdir_nr];
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}
object-store.h
+1
-1
@@ -22,7 +22,7 @@ struct object_directory {
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*
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* Be sure to call odb_load_loose_cache() before using.
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*/
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- char loose_objects_subdir_seen[256];
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+ uint32_t loose_objects_subdir_seen[8]; /* 256 bits */
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struct oid_array loose_objects_cache[256];
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/*