From ea0024deb9faa5474673a3db8f4f98812b48f44d Mon Sep 17 00:00:00 2001 From: Taylor Blau Date: Tue, 25 Jun 2024 13:39:50 -0400 Subject: [PATCH] repo-settings: introduce commitgraph.changedPathsVersion A subsequent commit will introduce another version of the changed-path filter in the commit graph file. In order to control which version to write (and read), a config variable is needed. Therefore, introduce this config variable. For forwards compatibility, teach Git to not read commit graphs when the config variable is set to an unsupported version. Because we teach Git this, commitgraph.readChangedPaths is now redundant, so deprecate it and define its behavior in terms of the config variable we introduce. This commit does not change the behavior of writing (Git writes changed path filters when explicitly instructed regardless of any config variable), but a subsequent commit will restrict Git such that it will only write when commitgraph.changedPathsVersion is a recognized value. Signed-off-by: Jonathan Tan Signed-off-by: Junio C Hamano Signed-off-by: Taylor Blau Signed-off-by: Junio C Hamano --- Documentation/config/commitgraph.txt | 26 +++++++++++++++++++++++--- commit-graph.c | 5 +++-- oss-fuzz/fuzz-commit-graph.c | 2 +- repo-settings.c | 6 +++++- repository.h | 2 +- 5 files changed, 33 insertions(+), 8 deletions(-) diff --git a/Documentation/config/commitgraph.txt b/Documentation/config/commitgraph.txt index 30604e4a4c..e68cdededa 100644 --- a/Documentation/config/commitgraph.txt +++ b/Documentation/config/commitgraph.txt @@ -9,6 +9,26 @@ commitGraph.maxNewFilters:: commit-graph write` (c.f., linkgit:git-commit-graph[1]). commitGraph.readChangedPaths:: - If true, then git will use the changed-path Bloom filters in the - commit-graph file (if it exists, and they are present). Defaults to - true. See linkgit:git-commit-graph[1] for more information. + Deprecated. Equivalent to commitGraph.changedPathsVersion=-1 if true, and + commitGraph.changedPathsVersion=0 if false. (If commitGraph.changedPathVersion + is also set, commitGraph.changedPathsVersion takes precedence.) + +commitGraph.changedPathsVersion:: + Specifies the version of the changed-path Bloom filters that Git will read and + write. May be -1, 0 or 1. Note that values greater than 1 may be + incompatible with older versions of Git which do not yet understand + those versions. Use caution when operating in a mixed-version + environment. ++ +Defaults to -1. ++ +If -1, Git will use the version of the changed-path Bloom filters in the +repository, defaulting to 1 if there are none. ++ +If 0, Git will not read any Bloom filters, and will write version 1 Bloom +filters when instructed to write. ++ +If 1, Git will only read version 1 Bloom filters, and will write version 1 +Bloom filters. ++ +See linkgit:git-commit-graph[1] for more information. diff --git a/commit-graph.c b/commit-graph.c index 00113b0f62..91c98ebc6c 100644 --- a/commit-graph.c +++ b/commit-graph.c @@ -459,7 +459,7 @@ struct commit_graph *parse_commit_graph(struct repo_settings *s, graph->read_generation_data = 1; } - if (s->commit_graph_read_changed_paths) { + if (s->commit_graph_changed_paths_version) { read_chunk(cf, GRAPH_CHUNKID_BLOOMINDEXES, graph_read_bloom_index, graph); read_chunk(cf, GRAPH_CHUNKID_BLOOMDATA, @@ -555,7 +555,8 @@ static void validate_mixed_bloom_settings(struct commit_graph *g) } if (g->bloom_filter_settings->bits_per_entry != settings->bits_per_entry || - g->bloom_filter_settings->num_hashes != settings->num_hashes) { + g->bloom_filter_settings->num_hashes != settings->num_hashes || + g->bloom_filter_settings->hash_version != settings->hash_version) { g->chunk_bloom_indexes = NULL; g->chunk_bloom_data = NULL; FREE_AND_NULL(g->bloom_filter_settings); diff --git a/oss-fuzz/fuzz-commit-graph.c b/oss-fuzz/fuzz-commit-graph.c index 2992079dd9..325c0b991a 100644 --- a/oss-fuzz/fuzz-commit-graph.c +++ b/oss-fuzz/fuzz-commit-graph.c @@ -19,7 +19,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) * possible. */ the_repository->settings.commit_graph_generation_version = 2; - the_repository->settings.commit_graph_read_changed_paths = 1; + the_repository->settings.commit_graph_changed_paths_version = 1; g = parse_commit_graph(&the_repository->settings, (void *)data, size); repo_clear(the_repository); free_commit_graph(g); diff --git a/repo-settings.c b/repo-settings.c index 30cd478762..c821583fe5 100644 --- a/repo-settings.c +++ b/repo-settings.c @@ -23,6 +23,7 @@ void prepare_repo_settings(struct repository *r) int value; const char *strval; int manyfiles; + int read_changed_paths; if (!r->gitdir) BUG("Cannot add settings for uninitialized repository"); @@ -53,7 +54,10 @@ void prepare_repo_settings(struct repository *r) /* Commit graph config or default, does not cascade (simple) */ repo_cfg_bool(r, "core.commitgraph", &r->settings.core_commit_graph, 1); repo_cfg_int(r, "commitgraph.generationversion", &r->settings.commit_graph_generation_version, 2); - repo_cfg_bool(r, "commitgraph.readchangedpaths", &r->settings.commit_graph_read_changed_paths, 1); + repo_cfg_bool(r, "commitgraph.readchangedpaths", &read_changed_paths, 1); + repo_cfg_int(r, "commitgraph.changedpathsversion", + &r->settings.commit_graph_changed_paths_version, + read_changed_paths ? -1 : 0); repo_cfg_bool(r, "gc.writecommitgraph", &r->settings.gc_write_commit_graph, 1); repo_cfg_bool(r, "fetch.writecommitgraph", &r->settings.fetch_write_commit_graph, 0); diff --git a/repository.h b/repository.h index 5f18486f64..f71154e12c 100644 --- a/repository.h +++ b/repository.h @@ -29,7 +29,7 @@ struct repo_settings { int core_commit_graph; int commit_graph_generation_version; - int commit_graph_read_changed_paths; + int commit_graph_changed_paths_version; int gc_write_commit_graph; int fetch_write_commit_graph; int command_requires_full_index;