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commit-graph: rearrange chunk count logic

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The number of chunks in a commit-graph file can change depending on
whether we need the Extra Edges Chunk. We are going to add more optional
chunks, and it will be helpful to rearrange this logic around the chunk
count before doing so.

Specifically, we need to finalize the number of chunks before writing
the commit-graph header. Further, we also need to fill out the chunk
lookup table dynamically and using "num_chunks" as we add optional
chunks is useful for adding optional chunks in the future.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Derrick Stolee 2019-06-18 11:14:27 -07:00 committed by Junio C Hamano
parent 118bd57002
commit 144354b054
1 changed files with 21 additions and 14 deletions
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35
commit-graph.c
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@ -1213,7 +1213,7 @@ static int write_commit_graph_file(struct write_commit_graph_context *ctx)
uint64_t chunk_offsets[5];
const unsigned hashsz = the_hash_algo->rawsz;
struct strbuf progress_title = STRBUF_INIT;
int num_chunks = ctx->num_extra_edges ? 4 : 3;
int num_chunks = 3;
ctx->graph_name = get_commit_graph_filename(ctx->obj_dir);
if (safe_create_leading_directories(ctx->graph_name)) {
@ -1226,27 +1226,34 @@ static int write_commit_graph_file(struct write_commit_graph_context *ctx)
hold_lock_file_for_update(&lk, ctx->graph_name, LOCK_DIE_ON_ERROR);
f = hashfd(lk.tempfile->fd, lk.tempfile->filename.buf);
hashwrite_be32(f, GRAPH_SIGNATURE);
hashwrite_u8(f, GRAPH_VERSION);
hashwrite_u8(f, oid_version());
hashwrite_u8(f, num_chunks);
hashwrite_u8(f, 0); /* unused padding byte */
chunk_ids[0] = GRAPH_CHUNKID_OIDFANOUT;
chunk_ids[1] = GRAPH_CHUNKID_OIDLOOKUP;
chunk_ids[2] = GRAPH_CHUNKID_DATA;
if (ctx->num_extra_edges)
chunk_ids[3] = GRAPH_CHUNKID_EXTRAEDGES;
else
chunk_ids[3] = 0;
chunk_ids[4] = 0;
if (ctx->num_extra_edges) {
chunk_ids[num_chunks] = GRAPH_CHUNKID_EXTRAEDGES;
num_chunks++;
}
chunk_ids[num_chunks] = 0;
chunk_offsets[0] = 8 + (num_chunks + 1) * GRAPH_CHUNKLOOKUP_WIDTH;
chunk_offsets[1] = chunk_offsets[0] + GRAPH_FANOUT_SIZE;
chunk_offsets[2] = chunk_offsets[1] + hashsz * ctx->commits.nr;
chunk_offsets[3] = chunk_offsets[2] + (hashsz + 16) * ctx->commits.nr;
chunk_offsets[4] = chunk_offsets[3] + 4 * ctx->num_extra_edges;
num_chunks = 3;
if (ctx->num_extra_edges) {
chunk_offsets[num_chunks + 1] = chunk_offsets[num_chunks] +
4 * ctx->num_extra_edges;
num_chunks++;
}
hashwrite_be32(f, GRAPH_SIGNATURE);
hashwrite_u8(f, GRAPH_VERSION);
hashwrite_u8(f, oid_version());
hashwrite_u8(f, num_chunks);
hashwrite_u8(f, 0);
for (i = 0; i <= num_chunks; i++) {
uint32_t chunk_write[3];