From: Derrick Stolee <derrickstolee@xxxxxxxxxx>
Tests already cover that we will start reading these prefixes.
TODO: discuss time and space savings over typical approach.
Signed-off-by: Derrick Stolee <derrickstolee@xxxxxxxxxx>
---
refs/packed-format-v2.c | 103 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 103 insertions(+)
diff --git a/refs/packed-format-v2.c b/refs/packed-format-v2.c
index 0ab277f7ad4..2cd45a5987a 100644
--- a/refs/packed-format-v2.c
+++ b/refs/packed-format-v2.c
@@ -398,6 +398,18 @@ struct write_packed_refs_v2_context {
uint64_t *offsets;
size_t nr;
size_t offsets_alloc;
+
+ int write_prefixes;
+ const char *cur_prefix;
+ size_t cur_prefix_len;
+
+ char **prefixes;
+ uint32_t *prefix_offsets;
+ uint32_t *prefix_rows;
+ size_t prefix_nr;
+ size_t prefixes_alloc;
+ size_t prefix_offsets_alloc;
+ size_t prefix_rows_alloc;
};
struct write_packed_refs_v2_context *create_v2_context(struct packed_ref_store *refs,
@@ -434,6 +446,56 @@ static int write_packed_entry_v2(const char *refname,
ALLOC_GROW(ctx->offsets, i + 1, ctx->offsets_alloc);
+ if (ctx->write_prefixes) {
+ if (ctx->cur_prefix && starts_with(refname, ctx->cur_prefix)) {
+ /* skip ahead! */
+ refname += ctx->cur_prefix_len;
+ reflen -= ctx->cur_prefix_len;
+ } else {
+ size_t len;
+ const char *slash, *slashslash = NULL;
+ if (ctx->prefix_nr) {
+ /* close out the old prefix. */
+ ctx->prefix_rows[ctx->prefix_nr - 1] = ctx->nr;
+ }
+
+ /* Find the new prefix. */
+ slash = strchr(refname, '/');
+ if (slash)
+ slashslash = strchr(slash + 1, '/');
+ /* If there are two slashes, use that. */
+ slash = slashslash ? slashslash : slash;
+ /*
+ * If there is at least one slash, use that,
+ * and include the slash in the string.
+ * Otherwise, use the end of the ref.
+ */
+ slash = slash ? slash + 1 : refname + strlen(refname);
+
+ len = slash - refname;
+ ALLOC_GROW(ctx->prefixes, ctx->prefix_nr + 1, ctx->prefixes_alloc);
+ ALLOC_GROW(ctx->prefix_offsets, ctx->prefix_nr + 1, ctx->prefix_offsets_alloc);
+ ALLOC_GROW(ctx->prefix_rows, ctx->prefix_nr + 1, ctx->prefix_rows_alloc);
+
+ if (ctx->prefix_nr)
+ ctx->prefix_offsets[ctx->prefix_nr] = ctx->prefix_offsets[ctx->prefix_nr - 1] + len + 1;
+ else
+ ctx->prefix_offsets[ctx->prefix_nr] = len + 1;
+
+ ctx->prefixes[ctx->prefix_nr] = xstrndup(refname, len);
+ ctx->cur_prefix = ctx->prefixes[ctx->prefix_nr];
+ ctx->prefix_nr++;
+
+ refname += len;
+ reflen -= len;
+ ctx->cur_prefix_len = len;
+ }
+
+ /* Update the last row continually. */
+ ctx->prefix_rows[ctx->prefix_nr - 1] = i + 1;
+ }
+
+
/* Write entire ref, including null terminator. */
hashwrite(ctx->f, refname, reflen);
hashwrite(ctx->f, oid->hash, the_hash_algo->rawsz);
@@ -483,13 +545,54 @@ static int write_refs_chunk_offsets(struct hashfile *f,
return 0;
}
+static int write_refs_chunk_prefix_data(struct hashfile *f,
+ void *data)
+{
+ struct write_packed_refs_v2_context *ctx = data;
+ size_t i;
+
+ trace2_region_enter("refs", "prefix-data", the_repository);
+ for (i = 0; i < ctx->prefix_nr; i++) {
+ size_t len = strlen(ctx->prefixes[i]) + 1;
+ hashwrite(f, ctx->prefixes[i], len);
+
+ /* TODO: assert the prefix lengths match the stored offsets? */
+ }
+
+ trace2_region_leave("refs", "prefix-data", the_repository);
+ return 0;
+}
+
+static int write_refs_chunk_prefix_offsets(struct hashfile *f,
+ void *data)
+{
+ struct write_packed_refs_v2_context *ctx = data;
+ size_t i;
+
+ trace2_region_enter("refs", "prefix-offsets", the_repository);
+ for (i = 0; i < ctx->prefix_nr; i++) {
+ hashwrite_be32(f, ctx->prefix_offsets[i]);
+ hashwrite_be32(f, ctx->prefix_rows[i]);
+ }
+
+ trace2_region_leave("refs", "prefix-offsets", the_repository);
+ return 0;
+}
+
int write_packed_refs_v2(struct write_packed_refs_v2_context *ctx)
{
unsigned char file_hash[GIT_MAX_RAWSZ];
+ ctx->write_prefixes = git_env_bool("GIT_TEST_WRITE_PACKED_REFS_PREFIXES", 1);
+
add_chunk(ctx->cf, CHREFS_CHUNKID_REFS, 0, write_refs_chunk_refs);
add_chunk(ctx->cf, CHREFS_CHUNKID_OFFSETS, 0, write_refs_chunk_offsets);
+ if (ctx->write_prefixes) {
+ add_chunk(ctx->cf, CHREFS_CHUNKID_PREFIX_DATA, 0, write_refs_chunk_prefix_data);
+ add_chunk(ctx->cf, CHREFS_CHUNKID_PREFIX_OFFSETS, 0, write_refs_chunk_prefix_offsets);
+ }
+
hashwrite_be32(ctx->f, PACKED_REFS_SIGNATURE);
hashwrite_be32(ctx->f, 2);
hashwrite_be32(ctx->f, the_hash_algo->format_id);
--
gitgitgadget
