Merge branch 'ds/commit-graph-generation-config'

A new configuration variable has been introduced to allow choosing
which version of the generation number gets used in the
commit-graph file.

* ds/commit-graph-generation-config:
  commit-graph: use config to specify generation type
  commit-graph: create local repository pointer

Author: gitster

Documentation/config/commitgraph.txt

@@ -1,3 +1,9 @@
+commitGraph.generationVersion::
+	Specifies the type of generation number version to use when writing
+	or reading the commit-graph file. If version 1 is specified, then
+	the corrected commit dates will not be written or read. Defaults to
+	2.
+
 commitGraph.maxNewFilters::
 	Specifies the default value for the `--max-new-filters` option of `git
 	commit-graph write` (c.f., linkgit:git-commit-graph[1]).

commit-graph.c

@@ -96,6 +96,13 @@ define_commit_slab(commit_graph_data_slab, struct commit_graph_data);
 static struct commit_graph_data_slab commit_graph_data_slab =
 	COMMIT_SLAB_INIT(1, commit_graph_data_slab);
 
+static int get_configured_generation_version(struct repository *r)
+{
+	int version = 2;
+	repo_config_get_int(r, "commitgraph.generationversion", &version);
+	return version;
+}
+
 uint32_t commit_graph_position(const struct commit *c)
 {
 	struct commit_graph_data *data =
@@ -394,10 +401,13 @@ struct commit_graph *parse_commit_graph(struct repository *r,
 	pair_chunk(cf, GRAPH_CHUNKID_DATA, &graph->chunk_commit_data);
 	pair_chunk(cf, GRAPH_CHUNKID_EXTRAEDGES, &graph->chunk_extra_edges);
 	pair_chunk(cf, GRAPH_CHUNKID_BASE, &graph->chunk_base_graphs);
-	pair_chunk(cf, GRAPH_CHUNKID_GENERATION_DATA,
-		   &graph->chunk_generation_data);
-	pair_chunk(cf, GRAPH_CHUNKID_GENERATION_DATA_OVERFLOW,
-		   &graph->chunk_generation_data_overflow);
+
+	if (get_configured_generation_version(r) >= 2) {
+		pair_chunk(cf, GRAPH_CHUNKID_GENERATION_DATA,
+			&graph->chunk_generation_data);
+		pair_chunk(cf, GRAPH_CHUNKID_GENERATION_DATA_OVERFLOW,
+			&graph->chunk_generation_data_overflow);
+	}
 
 	if (r->settings.commit_graph_read_changed_paths) {
 		pair_chunk(cf, GRAPH_CHUNKID_BLOOMINDEXES,
@@ -1839,8 +1849,6 @@ static int write_commit_graph_file(struct write_commit_graph_context *ctx)
 	add_chunk(cf, GRAPH_CHUNKID_DATA, (hashsz + 16) * ctx->commits.nr,
 		  write_graph_chunk_data);
 
-	if (git_env_bool(GIT_TEST_COMMIT_GRAPH_NO_GDAT, 0))
-		ctx->write_generation_data = 0;
 	if (ctx->write_generation_data)
 		add_chunk(cf, GRAPH_CHUNKID_GENERATION_DATA,
 			  sizeof(uint32_t) * ctx->commits.nr,
@@ -2223,30 +2231,31 @@ int write_commit_graph(struct object_directory *odb,
 		       enum commit_graph_write_flags flags,
 		       const struct commit_graph_opts *opts)
 {
+	struct repository *r = the_repository;
 	struct write_commit_graph_context *ctx;
 	uint32_t i;
 	int res = 0;
 	int replace = 0;
 	struct bloom_filter_settings bloom_settings = DEFAULT_BLOOM_FILTER_SETTINGS;
 	struct topo_level_slab topo_levels;
 
-	prepare_repo_settings(the_repository);
-	if (!the_repository->settings.core_commit_graph) {
+	prepare_repo_settings(r);
+	if (!r->settings.core_commit_graph) {
 		warning(_("attempting to write a commit-graph, but 'core.commitGraph' is disabled"));
 		return 0;
 	}
-	if (!commit_graph_compatible(the_repository))
+	if (!commit_graph_compatible(r))
 		return 0;
 
 	CALLOC_ARRAY(ctx, 1);
-	ctx->r = the_repository;
+	ctx->r = r;
 	ctx->odb = odb;
 	ctx->append = flags & COMMIT_GRAPH_WRITE_APPEND ? 1 : 0;
 	ctx->report_progress = flags & COMMIT_GRAPH_WRITE_PROGRESS ? 1 : 0;
 	ctx->split = flags & COMMIT_GRAPH_WRITE_SPLIT ? 1 : 0;
 	ctx->opts = opts;
 	ctx->total_bloom_filter_data_size = 0;
-	ctx->write_generation_data = 1;
+	ctx->write_generation_data = (get_configured_generation_version(r) == 2);
 	ctx->num_generation_data_overflows = 0;
 
 	bloom_settings.bits_per_entry = git_env_ulong("GIT_TEST_BLOOM_SETTINGS_BITS_PER_ENTRY",

commit-graph.h

@@ -6,7 +6,6 @@
 #include "oidset.h"
 
 #define GIT_TEST_COMMIT_GRAPH "GIT_TEST_COMMIT_GRAPH"
-#define GIT_TEST_COMMIT_GRAPH_NO_GDAT "GIT_TEST_COMMIT_GRAPH_NO_GDAT"
 #define GIT_TEST_COMMIT_GRAPH_DIE_ON_PARSE "GIT_TEST_COMMIT_GRAPH_DIE_ON_PARSE"
 #define GIT_TEST_COMMIT_GRAPH_CHANGED_PATHS "GIT_TEST_COMMIT_GRAPH_CHANGED_PATHS"
 

t/README

@@ -387,9 +387,6 @@ GIT_TEST_COMMIT_GRAPH=<boolean>, when true, forces the commit-graph to
 be written after every 'git commit' command, and overrides the
 'core.commitGraph' setting to true.
 
-GIT_TEST_COMMIT_GRAPH_NO_GDAT=<boolean>, when true, forces the
-commit-graph to be written without generation data chunk.
-
 GIT_TEST_COMMIT_GRAPH_CHANGED_PATHS=<boolean>, when true, forces
 commit-graph write to compute and write changed path Bloom filters for
 every 'git commit-graph write', as if the `--changed-paths` option was

t/t5318-commit-graph.sh

@@ -475,7 +475,7 @@ test_expect_success 'lower layers have overflow chunk' '
 
 test_expect_success 'git commit-graph verify' '
 	cd "$TRASH_DIRECTORY/full" &&
-	git rev-parse commits/8 | GIT_TEST_COMMIT_GRAPH_NO_GDAT=1 git commit-graph write --stdin-commits &&
+	git rev-parse commits/8 | git -c commitGraph.generationVersion=1 commit-graph write --stdin-commits &&
 	git commit-graph verify >output &&
 	graph_read_expect 9 extra_edges
 '

t/t5324-split-commit-graph.sh

@@ -489,15 +489,15 @@ test_expect_success 'setup repo for mixed generation commit-graph-chain' '
 			test_commit $i &&
 			git branch commits/$i || return 1
 		done &&
-		git commit-graph write --reachable --split &&
+		git -c commitGraph.generationVersion=2 commit-graph write --reachable --split &&
 		graph_read_expect $NUM_FIRST_LAYER_COMMITS &&
 		test_line_count = 1 $graphdir/commit-graph-chain &&
 		for i in $(test_seq $SECOND_LAYER_SEQUENCE_START $SECOND_LAYER_SEQUENCE_END)
 		do
 			test_commit $i &&
 			git branch commits/$i || return 1
 		done &&
-		GIT_TEST_COMMIT_GRAPH_NO_GDAT=1 git commit-graph write --reachable --split=no-merge &&
+		git -c commitGraph.generationVersion=1 commit-graph write --reachable --split=no-merge &&
 		test_line_count = 2 $graphdir/commit-graph-chain &&
 		test-tool read-graph >output &&
 		cat >expect <<-EOF &&

t/t6600-test-reach.sh

@@ -55,7 +55,7 @@ test_expect_success 'setup' '
 	git show-ref -s commit-5-5 | git commit-graph write --stdin-commits &&
 	mv .git/objects/info/commit-graph commit-graph-half &&
 	chmod u+w commit-graph-half &&
-	GIT_TEST_COMMIT_GRAPH_NO_GDAT=1 git commit-graph write --reachable &&
+	git -c commitGraph.generationVersion=1 commit-graph write --reachable &&
 	mv .git/objects/info/commit-graph commit-graph-no-gdat &&
 	chmod u+w commit-graph-no-gdat &&
 	git config core.commitGraph true