[PATCH v4 0/6] commit-graph: remove reliance on global state

[Patrick Steinhardt <ps@pks.im>]

Hi,

this patch series is another step on our long road towards not having
global state. In addition to that, as commit-graphs are part of the
object database layer, this is also another step towards pluggable
object databases.

Changes in v2:
  - Use `unsigned` instead of `size_t` to count number of Bloom filters.
  - Use `uint32_t` instead of `size_t` for number of commit graphs,
    as this type is also used to iterate through this count already.
  - Refactor `parse_commit_graph()` to take a repository instead of both
    repo settings and a hash algo.
  - Link to v1: https://lore.kernel.org/r/20250804-b4-pks-commit-graph-wo-the-repository-v1-0-850d626eb2e8@pks.im

Changes in v3:
  - Use `unsigned` for commit-graph options instead of `size_t`.
  - Link to v2: https://lore.kernel.org/r/20250806-b4-pks-commit-graph-wo-the-repository-v2-0-911bae638e61@pks.im

Changes in v4:
  - Drop the patches that fix `-Wsign-compare` warnings.
  - Link to v3: https://lore.kernel.org/r/20250807-b4-pks-commit-graph-wo-the-repository-v3-0-82edef830a1e@pks.im

Thanks!

Patrick

---
Patrick Steinhardt (6):
      commit-graph: stop using `the_hash_algo` via macros
      commit-graph: store the hash algorithm instead of its length
      commit-graph: refactor `parse_commit_graph()` to take a repository
      commit-graph: stop using `the_hash_algo`
      commit-graph: stop using `the_repository`
      commit-graph: stop passing in redundant repository

 builtin/commit-graph.c       |   9 +-
 builtin/commit.c             |   2 +-
 builtin/merge.c              |   2 +-
 commit-graph.c               | 283 +++++++++++++++++++++----------------------
 commit-graph.h               |  21 ++--
 oss-fuzz/fuzz-commit-graph.c |   6 +-
 t/helper/test-read-graph.c   |   2 +-
 7 files changed, 157 insertions(+), 168 deletions(-)

Range-diff versus v3:

 1:  26daf74e02 <  -:  ---------- trace2: introduce function to trace unsigned integers
 2:  646805924e <  -:  ---------- commit-graph: stop using signed integers to count Bloom filters
 3:  01e38f39cf <  -:  ---------- commit-graph: fix type for some write options
 4:  a362f63472 <  -:  ---------- commit-graph: fix sign comparison warnings
 5:  041d9c07a0 =  1:  f7083b7e3b commit-graph: stop using `the_hash_algo` via macros
 6:  6c1fa6be4f =  2:  336e35e93b commit-graph: store the hash algorithm instead of its length
 7:  ed04f7b787 =  3:  1446e1d66f commit-graph: refactor `parse_commit_graph()` to take a repository
 8:  1eb6316e8d !  4:  368e5ada3e commit-graph: stop using `the_hash_algo`
    @@ commit-graph.c: int open_commit_graph_chain(const char *chain_file,
      		close(*fd);
      		return 0;
      	}
    --	if (st->st_size < (ssize_t) the_hash_algo->hexsz) {
    -+	if (st->st_size < (ssize_t) hash_algo->hexsz) {
    +-	if (st->st_size < the_hash_algo->hexsz) {
    ++	if (st->st_size < hash_algo->hexsz) {
      		close(*fd);
      		if (!st->st_size) {
      			/* treat empty files the same as missing */
     @@ commit-graph.c: struct commit_graph *load_commit_graph_chain_fd_st(struct repository *r,
    + 	int i = 0, valid = 1, count;
      	FILE *fp = xfdopen(fd, "r");
    - 	size_t count;
      
     -	count = st->st_size / (the_hash_algo->hexsz + 1);
     +	count = st->st_size / (r->hash_algo->hexsz + 1);
    @@ commit-graph.c: static struct tree *load_tree_for_commit(struct repository *r,
      
      	oidread(&oid, commit_data, the_repository->hash_algo);
     @@ commit-graph.c: static int write_graph_chunk_oids(struct hashfile *f,
    - 
    + 	int count;
      	for (count = 0; count < ctx->commits.nr; count++, list++) {
      		display_progress(ctx->progress, ++ctx->progress_cnt);
     -		hashwrite(f, (*list)->object.oid.hash, the_hash_algo->rawsz);
    @@ commit-graph.c: static int write_graph_chunk_data(struct hashfile *f,
      
      		parent = (*list)->parents;
      
    -@@ commit-graph.c: static size_t write_graph_chunk_base_1(struct hashfile *f,
    +@@ commit-graph.c: static int write_graph_chunk_base_1(struct hashfile *f,
      		return 0;
      
      	num = write_graph_chunk_base_1(f, g->base_graph);
 9:  8d599f5a37 !  5:  a51cccec0d commit-graph: stop using `the_repository`
    @@ builtin/merge.c: int cmd_merge(int argc,
      ## commit-graph.c ##
     @@
     -#define USE_THE_REPOSITORY_VARIABLE
    --
    + #define DISABLE_SIGN_COMPARE_WARNINGS
    + 
      #include "git-compat-util.h"
    - #include "config.h"
    - #include "csum-file.h"
     @@
      #include "tree.h"
      #include "chunk-format.h"
10:  41ccdd6da1 !  6:  841d280105 commit-graph: stop passing in redundant repository
    @@ commit-graph.c: int open_commit_graph_chain(const char *chain_file,
      						   int *incomplete_chain)
      {
     @@ commit-graph.c: struct commit_graph *load_commit_graph_chain_fd_st(struct repository *r,
    + 	int i = 0, valid = 1, count;
      	FILE *fp = xfdopen(fd, "r");
    - 	size_t count;
      
     -	count = st->st_size / (r->hash_algo->hexsz + 1);
     +	count = st->st_size / (odb->repo->hash_algo->hexsz + 1);
    @@ commit-graph.c: struct commit_graph *load_commit_graph_chain_fd_st(struct reposi
     -	odb_prepare_alternates(r->objects);
     +	odb_prepare_alternates(odb);
      
    - 	for (size_t i = 0; i < count; i++) {
    + 	for (i = 0; i < count; i++) {
      		struct odb_source *source;
     @@ commit-graph.c: struct commit_graph *load_commit_graph_chain_fd_st(struct repository *r,
      		if (strbuf_getline_lf(&line, fp) == EOF)

---
base-commit: e813a0200a7121b97fec535f0d0b460b0a33356c
change-id: 20250717-b4-pks-commit-graph-wo-the-repository-1dc2cacbc8e3