midx-write.c: reduce argument count for `get_sorted_entries()`

The function `midx-write.c::get_sorted_entries()` is responsible for
constructing the array of OIDs from a given list of packs which will
comprise the MIDX being written.

The singular call-site for this function looks something like:

    ctx.entries = get_sorted_entries(ctx.m, ctx.info, ctx.nr,
                                     &ctx.entries_nr,
                                     ctx.preferred_pack_idx);

This function has five formal arguments, all of which are members of the
shared `struct write_midx_context` used to track various pieces of
information about the MIDX being written.

The function `get_sorted_entries()` dates back to fe1ed56f5e4 (midx:
sort and deduplicate objects from packfiles, 2018-07-12), which came
shortly after 396f257018a (multi-pack-index: read packfile list,
2018-07-12). The latter patch introduced the `pack_list` structure,
which was a precursor to the structure we now know as
`write_midx_context` (c.f. 577dc49696a (midx: rename pack_info to
write_midx_context, 2021-02-18)).

At the time, `get_sorted_entries()` likely could have used the pack_list
structure introduced earlier in 396f257018a, but understandably did not
since the structure only contained three fields (only two of which were
relevant to `get_sorted_entries()`) at the time.

Simplify the declaration of this function by taking a single pointer to
the whole `struct write_midx_context` instead of various members within
it. Since this function is now computing the entire result (populating
both `ctx->entries`, and `ctx->entries_nr`), rename it to something that
doesn't start with "get_" to make clear that this function has a
side-effect.

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

diff --git a/midx-write.c b/midx-write.c
index fface1e93a8f1d733e2bd423fb329d7ec77b94f4..f1d3cbed57005ff1c5dc7e215a484f1f85a3fb61 100644 (file)
--- a/midx-write.c
+++ b/midx-write.c
@@ -299,21 +299,16 @@ 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 multi_pack_index *m,
-                                                 struct pack_info *info,
-                                                 uint32_t nr_packs,
-                                                 size_t *nr_objects,
-                                                 int preferred_pack)
+static void compute_sorted_entries(struct write_midx_context *ctx)
 {
        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 = m ? m->num_packs : 0;
+       uint32_t start_pack = ctx->m ? ctx->m->num_packs : 0;
 
-       for (cur_pack = start_pack; cur_pack < nr_packs; cur_pack++)
+       for (cur_pack = start_pack; cur_pack < ctx->nr; cur_pack++)
                total_objects = st_add(total_objects,
-                                      info[cur_pack].p->num_objects);
+                                      ctx->info[cur_pack].p->num_objects);
 
        /*
         * As we de-duplicate by fanout value, we expect the fanout
@@ -323,26 +318,26 @@ static struct pack_midx_entry *get_sorted_entries(struct multi_pack_index *m,
        alloc_objects = fanout.alloc = total_objects > 3200 ? total_objects / 200 : 16;
 
        ALLOC_ARRAY(fanout.entries, fanout.alloc);
-       ALLOC_ARRAY(deduplicated_entries, alloc_objects);
-       *nr_objects = 0;
+       ALLOC_ARRAY(ctx->entries, alloc_objects);
+       ctx->entries_nr = 0;
 
        for (cur_fanout = 0; cur_fanout < 256; cur_fanout++) {
                fanout.nr = 0;
 
-               if (m)
-                       midx_fanout_add_midx_fanout(&fanout, m, cur_fanout,
-                                                   preferred_pack);
+               if (ctx->m)
+                       midx_fanout_add_midx_fanout(&fanout, ctx->m, cur_fanout,
+                                                   ctx->preferred_pack_idx);
 
-               for (cur_pack = start_pack; cur_pack < nr_packs; cur_pack++) {
-                       int preferred = cur_pack == preferred_pack;
+               for (cur_pack = start_pack; cur_pack < ctx->nr; cur_pack++) {
+                       int preferred = cur_pack == ctx->preferred_pack_idx;
                        midx_fanout_add_pack_fanout(&fanout,
-                                                   info, cur_pack,
+                                                   ctx->info, cur_pack,
                                                    preferred, cur_fanout);
                }
 
-               if (-1 < preferred_pack && preferred_pack < start_pack)
-                       midx_fanout_add_pack_fanout(&fanout, info,
-                                                   preferred_pack, 1,
+               if (-1 < ctx->preferred_pack_idx && ctx->preferred_pack_idx < start_pack)
+                       midx_fanout_add_pack_fanout(&fanout, ctx->info,
+                                                   ctx->preferred_pack_idx, 1,
                                                    cur_fanout);
 
                midx_fanout_sort(&fanout);
@@ -356,17 +351,16 @@ static struct pack_midx_entry *get_sorted_entries(struct multi_pack_index *m,
                                                &fanout.entries[cur_object].oid))
                                continue;
 
-                       ALLOC_GROW(deduplicated_entries, st_add(*nr_objects, 1),
+                       ALLOC_GROW(ctx->entries, st_add(ctx->entries_nr, 1),
                                   alloc_objects);
-                       memcpy(&deduplicated_entries[*nr_objects],
+                       memcpy(&ctx->entries[ctx->entries_nr],
                               &fanout.entries[cur_object],
                               sizeof(struct pack_midx_entry));
-                       (*nr_objects)++;
+                       ctx->entries_nr++;
                }
        }
 
        free(fanout.entries);
-       return deduplicated_entries;
 }
 
 static int write_midx_pack_names(struct hashfile *f, void *data)
@@ -1054,8 +1048,7 @@ static int write_midx_internal(const char *object_dir,
                }
        }
 
-       ctx.entries = get_sorted_entries(ctx.m, ctx.info, ctx.nr, &ctx.entries_nr,
-                                        ctx.preferred_pack_idx);
+       compute_sorted_entries(&ctx);
 
        ctx.large_offsets_needed = 0;
        for (i = 0; i < ctx.entries_nr; i++) {