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[PATCH 3/8] midx-write.c: pass `start_pack` to `get_sorted_entries()`

From
Taylor Blau <me@ttaylorr.com>
Date
May 23, 2024, 16:38 UTC
Message-ID
<7acf4557dcb2240cb43eadebfd21b5c37515ba7f.1716482279.git.me@ttaylorr.com>
In-Reply-To
<cover.1716482279.git.me@ttaylorr.com>

The function `get_sorted_entries()` is broadly responsible for building an array of the objects to be written into a MIDX based on the provided list of packs.

If we have loaded an existing MIDX, however, we may not use all of its packs, despite loading them into the ctx->info array.

The existing implementation simply skips past the first ctx->m->num_packs (if ctx->m is non-NULL, indicating that we loaded an existing MIDX). Future changes (outside the scope of this patch series) to the MIDX code will require us to skip *at most* that number[^1].

We could tag each pack with a bit that indicates the pack's contents should be included in the MIDX. But we can just as easily determine the number of packs to skip by passing in the number of packs we learned about after processing an existing MIDX.

[^1]: Kind of. The real number will be bounded by the number of packs in
  a MIDX layer, and the number of packs in its base layer(s), but that
  concept hasn't been fully defined yet.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
---
 midx-write.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/midx-write.c b/midx-write.c
index ad32e8953d..cf7e391b6e 100644
--- a/midx-write.c
+++ b/midx-write.c
@@ -299,13 +299,13 @@ static void midx_fanout_add_pack_fanout(struct midx_fanout *fanout,
  * Copy only the de-duplicated entries (selected by most-recent modified time
  * of a packfile containing the object).
  */
-static struct pack_midx_entry *get_sorted_entries(struct write_midx_context *ctx)
+static struct pack_midx_entry *get_sorted_entries(struct write_midx_context *ctx,
+						  uint32_t start_pack)
 {
 	uint32_t cur_fanout, cur_pack, cur_object;
 	size_t alloc_objects, total_objects = 0;
 	struct midx_fanout fanout = { 0 };
 	struct pack_midx_entry *deduplicated_entries = NULL;
-	uint32_t start_pack = ctx->m ? ctx->m->num_packs : 0;
 
 	for (cur_pack = start_pack; cur_pack < ctx->nr; cur_pack++)
 		total_objects = st_add(total_objects,
@@ -886,7 +886,7 @@ static int write_midx_internal(const char *object_dir,
 {
 	struct strbuf midx_name = STRBUF_INIT;
 	unsigned char midx_hash[GIT_MAX_RAWSZ];
-	uint32_t i;
+	uint32_t i, start_pack;
 	struct hashfile *f = NULL;
 	struct lock_file lk;
 	struct write_midx_context ctx = { 0 };
@@ -954,6 +954,8 @@ static int write_midx_internal(const char *object_dir,
 		}
 	}
 
+	start_pack = ctx.nr;
+
 	ctx.pack_paths_checked = 0;
 	if (flags & MIDX_PROGRESS)
 		ctx.progress = start_delayed_progress(_("Adding packfiles to multi-pack-index"), 0);
@@ -1051,7 +1053,7 @@ static int write_midx_internal(const char *object_dir,
 		}
 	}
 
-	ctx.entries = get_sorted_entries(&ctx);
+	ctx.entries = get_sorted_entries(&ctx, start_pack);
 
 	ctx.large_offsets_needed = 0;
 	for (i = 0; i < ctx.entries_nr; i++) {
-- 
2.45.1.217.g9bb58e2bf5a.dirty
Previous: Taylor BlauNext: Patrick Steinhardt
Message 8 of 34 in “midx-write: miscellaneous clean-ups for incremental MIDXs”
  1. 0/8 midx-write: miscellaneous clean-ups for incremental MIDXsTaylor Blau, May 23, 2024
  2. 1/8 midx-write.c: tolerate `--preferred-pack` without bitmapsTaylor Blau, May 23, 2024
  3. Patrick SteinhardtMay 29, 2024
  4. Taylor BlauMay 29, 2024
  5. 2/8 midx-write.c: reduce argument count for `get_sorted_entries()`Taylor Blau, May 23, 2024
  6. Patrick SteinhardtMay 29, 2024
  7. Taylor BlauMay 29, 2024
  8. 3/8 midx-write.c: pass `start_pack` to `get_sorted_entries()`Taylor Blau, May 23, 2024
  9. Patrick SteinhardtMay 29, 2024
  10. Taylor BlauMay 29, 2024
  11. 4/8 midx-write.c: extract `should_include_pack()`Taylor Blau, May 23, 2024
  12. Patrick SteinhardtMay 29, 2024
  13. Taylor BlauMay 29, 2024
  14. 5/8 midx-write.c: extract `fill_packs_from_midx()`Taylor Blau, May 23, 2024
  15. 6/8 midx-write.c: support reading an existing MIDX with `packs_to_include`Taylor Blau, May 23, 2024
  16. Patrick SteinhardtMay 29, 2024
  17. Taylor BlauMay 29, 2024
  18. 7/8 midx: replace `get_midx_rev_filename()` with a generic helperTaylor Blau, May 23, 2024
  19. 8/8 pack-bitmap.c: reimplement `midx_bitmap_filename()` with helperTaylor Blau, May 23, 2024
  20. 0/8 midx-write: miscellaneous clean-ups for incremental MIDXsTaylor Blau, May 29, 2024
  21. 1/8 midx-write.c: tolerate `--preferred-pack` without bitmapsTaylor Blau, May 29, 2024
  22. 2/8 midx-write.c: reduce argument count for `get_sorted_entries()`Taylor Blau, May 29, 2024
  23. 3/8 midx-write.c: pass `start_pack` to `compute_sorted_entries()`Taylor Blau, May 29, 2024
  24. Jeff KingMay 30, 2024
  25. 4/8 midx-write.c: extract `should_include_pack()`Taylor Blau, May 29, 2024
  26. 5/8 midx-write.c: extract `fill_packs_from_midx()`Taylor Blau, May 29, 2024
  27. 6/8 midx-write.c: support reading an existing MIDX with `packs_to_include`Taylor Blau, May 29, 2024
  28. Jeff KingMay 30, 2024
  29. 7/8 midx: replace `get_midx_rev_filename()` with a generic helperTaylor Blau, May 29, 2024
  30. Jeff KingMay 30, 2024
  31. 8/8 pack-bitmap.c: reimplement `midx_bitmap_filename()` with helperTaylor Blau, May 29, 2024
  32. Jeff KingMay 30, 2024
  33. Taylor BlauMay 30, 2024
  34. Patrick SteinhardtMay 31, 2024

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