diff --git a/commit-graph.c b/commit-graph.c
index 9bc110b4bd..7034a14e5c 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -614,6 +614,21 @@ static struct commit_graph *load_commit_graph_chain(struct repository *r,
return graph_chain;
}
+static void validate_mixed_generation_chain(struct commit_graph *g)
+{
+ int read_generation_data;
+
+ if (!g)
+ return;
+
+ read_generation_data = !!g->chunk_generation_data;
+
+ while (g) {
+ g->read_generation_data = read_generation_data;
+ g = g->base_graph;
+ }
+}
+
struct commit_graph *read_commit_graph_one(struct repository *r,
struct object_directory *odb)
{
@@ -622,6 +637,8 @@ struct commit_graph *read_commit_graph_one(struct repository *r,
if (!g)
g = load_commit_graph_chain(r, odb);
+ validate_mixed_generation_chain(g);
+
return g;
}
@@ -791,7 +808,7 @@ static void fill_commit_graph_info(struct commit *item, struct commit_graph *g,
date_low = get_be32(commit_data + g->hash_len + 12);
item->date = (timestamp_t)((date_high << 32) | date_low);
- if (g->chunk_generation_data) {
+ if (g->read_generation_data) {
offset = (timestamp_t)get_be32(g->chunk_generation_data + sizeof(uint32_t) * lex_index);
if (offset & CORRECTED_COMMIT_DATE_OFFSET_OVERFLOW) {
@@ -2019,6 +2036,13 @@ static void split_graph_merge_strategy(struct write_commit_graph_context *ctx)
if (i < ctx->num_commit_graphs_after)
ctx->commit_graph_hash_after[i] = xstrdup(oid_to_hex(&g->oid));
+ /*
+ * If the topmost remaining layer has generation data chunk, the
+ * resultant layer also has generation data chunk.
+ */
+ if (i == ctx->num_commit_graphs_after - 2)
+ ctx->write_generation_data = !!g->chunk_generation_data;
+
i--;
g = g->base_graph;
}
@@ -2343,6 +2367,8 @@ int write_commit_graph(struct object_directory *odb,
} else
ctx->num_commit_graphs_after = 1;
+ validate_mixed_generation_chain(ctx->r->objects->commit_graph);
+
compute_generation_numbers(ctx);
if (ctx->changed_paths)
@@ -2541,7 +2567,7 @@ int verify_commit_graph(struct repository *r, struct commit_graph *g, int flags)
* also GENERATION_NUMBER_V1_MAX. Decrement to avoid extra logic
* in the following condition.
*/
- if (!g->chunk_generation_data && max_generation == GENERATION_NUMBER_V1_MAX)
+ if (!g->read_generation_data && max_generation == GENERATION_NUMBER_V1_MAX)
max_generation--;
generation = commit_graph_generation(graph_commit);
diff --git a/commit-graph.h b/commit-graph.h
index 19a02001fd..ad52130883 100644
--- a/commit-graph.h
+++ b/commit-graph.h
@@ -64,6 +64,7 @@ struct commit_graph {
struct object_directory *odb;
uint32_t num_commits_in_base;
+ unsigned int read_generation_data;
struct commit_graph *base_graph;
const uint32_t *chunk_oid_fanout;
diff --git a/t/t5324-split-commit-graph.sh b/t/t5324-split-commit-graph.sh
index 587757b62d..8e90f3423b 100755
--- a/t/t5324-split-commit-graph.sh
+++ b/t/t5324-split-commit-graph.sh
@@ -453,4 +453,185 @@ test_expect_success 'prevent regression for duplicate commits across layers' '
git -C dup commit-graph verify
'
+NUM_FIRST_LAYER_COMMITS=64
+NUM_SECOND_LAYER_COMMITS=16
+NUM_THIRD_LAYER_COMMITS=7
+NUM_FOURTH_LAYER_COMMITS=8
+NUM_FIFTH_LAYER_COMMITS=16
+SECOND_LAYER_SEQUENCE_START=$(($NUM_FIRST_LAYER_COMMITS + 1))
+SECOND_LAYER_SEQUENCE_END=$(($SECOND_LAYER_SEQUENCE_START + $NUM_SECOND_LAYER_COMMITS - 1))
+THIRD_LAYER_SEQUENCE_START=$(($SECOND_LAYER_SEQUENCE_END + 1))
+THIRD_LAYER_SEQUENCE_END=$(($THIRD_LAYER_SEQUENCE_START + $NUM_THIRD_LAYER_COMMITS - 1))
+FOURTH_LAYER_SEQUENCE_START=$(($THIRD_LAYER_SEQUENCE_END + 1))
+FOURTH_LAYER_SEQUENCE_END=$(($FOURTH_LAYER_SEQUENCE_START + $NUM_FOURTH_LAYER_COMMITS - 1))
+FIFTH_LAYER_SEQUENCE_START=$(($FOURTH_LAYER_SEQUENCE_END + 1))
+FIFTH_LAYER_SEQUENCE_END=$(($FIFTH_LAYER_SEQUENCE_START + $NUM_FIFTH_LAYER_COMMITS - 1))
+
+# Current split graph chain:
+#
+# 16 commits (No GDAT)
+# ------------------------
+# 64 commits (GDAT)
+#
+test_expect_success 'setup repo for mixed generation commit-graph-chain' '
+ graphdir=".git/objects/info/commit-graphs" &&
+ test_oid_cache <<-EOF &&
+ oid_version sha1:1
+ oid_version sha256:2
+ EOF
+ git init mixed &&
+ (
+ cd mixed &&
+ git config core.commitGraph true &&
+ git config gc.writeCommitGraph false &&
+ for i in $(test_seq $NUM_FIRST_LAYER_COMMITS)
+ do
+ test_commit $i &&
+ git branch commits/$i || return 1
+ done &&
+ git 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 &&
+ test_line_count = 2 $graphdir/commit-graph-chain &&
+ test-tool read-graph >output &&
+ cat >expect <<-EOF &&
+ header: 43475048 1 $(test_oid oid_version) 4 1
+ num_commits: $NUM_SECOND_LAYER_COMMITS
+ chunks: oid_fanout oid_lookup commit_metadata
+ EOF
+ test_cmp expect output &&
+ git commit-graph verify &&
+ cat $graphdir/commit-graph-chain
+ )
+'
+
+# The new layer will be added without generation data chunk as it was not
+# present on the layer underneath it.
+#
+# 7 commits (No GDAT)
+# ------------------------
+# 16 commits (No GDAT)
+# ------------------------
+# 64 commits (GDAT)
+#
+test_expect_success 'do not write generation data chunk if not present on existing tip' '
+ git clone mixed mixed-no-gdat &&
+ (
+ cd mixed-no-gdat &&
+ for i in $(test_seq $THIRD_LAYER_SEQUENCE_START $THIRD_LAYER_SEQUENCE_END)
+ do
+ test_commit $i &&
+ git branch commits/$i || return 1
+ done &&
+ git commit-graph write --reachable --split=no-merge &&
+ test_line_count = 3 $graphdir/commit-graph-chain &&
+ test-tool read-graph >output &&
+ cat >expect <<-EOF &&
+ header: 43475048 1 $(test_oid oid_version) 4 2
+ num_commits: $NUM_THIRD_LAYER_COMMITS
+ chunks: oid_fanout oid_lookup commit_metadata
+ EOF
+ test_cmp expect output &&
+ git commit-graph verify
+ )
+'
+
+# Number of commits in each layer of the split-commit graph before merge:
+#
+# 8 commits (No GDAT)
+# ------------------------
+# 7 commits (No GDAT)
+# ------------------------
+# 16 commits (No GDAT)
+# ------------------------
+# 64 commits (GDAT)
+#
+# The top two layers are merged and do not have generation data chunk as layer below them does
+# not have generation data chunk.
+#
+# 15 commits (No GDAT)
+# ------------------------
+# 16 commits (No GDAT)
+# ------------------------
+# 64 commits (GDAT)
+#
+test_expect_success 'do not write generation data chunk if the topmost remaining layer does not have generation data chunk' '
+ git clone mixed-no-gdat mixed-merge-no-gdat &&
+ (
+ cd mixed-merge-no-gdat &&
+ for i in $(test_seq $FOURTH_LAYER_SEQUENCE_START $FOURTH_LAYER_SEQUENCE_END)
+ do
+ test_commit $i &&
+ git branch commits/$i || return 1
+ done &&
+ git commit-graph write --reachable --split --size-multiple 1 &&
+ test_line_count = 3 $graphdir/commit-graph-chain &&
+ test-tool read-graph >output &&
+ cat >expect <<-EOF &&
+ header: 43475048 1 $(test_oid oid_version) 4 2
+ num_commits: $(($NUM_THIRD_LAYER_COMMITS + $NUM_FOURTH_LAYER_COMMITS))
+ chunks: oid_fanout oid_lookup commit_metadata
+ EOF
+ test_cmp expect output &&
+ git commit-graph verify
+ )
+'
+
+# Number of commits in each layer of the split-commit graph before merge:
+#
+# 16 commits (No GDAT)
+# ------------------------
+# 15 commits (No GDAT)
+# ------------------------
+# 16 commits (No GDAT)
+# ------------------------
+# 64 commits (GDAT)
+#
+# The top three layers are merged and has generation data chunk as the topmost remaining layer
+# has generation data chunk.
+#
+# 47 commits (GDAT)
+# ------------------------
+# 64 commits (GDAT)
+#
+test_expect_success 'write generation data chunk if topmost remaining layer has generation data chunk' '
+ git clone mixed-merge-no-gdat mixed-merge-gdat &&
+ (
+ cd mixed-merge-gdat &&
+ for i in $(test_seq $FIFTH_LAYER_SEQUENCE_START $FIFTH_LAYER_SEQUENCE_END)
+ do
+ test_commit $i &&
+ git branch commits/$i || return 1
+ done &&
+ git commit-graph write --reachable --split --size-multiple 1 &&
+ test_line_count = 2 $graphdir/commit-graph-chain &&
+ test-tool read-graph >output &&
+ cat >expect <<-EOF &&
+ header: 43475048 1 $(test_oid oid_version) 5 1
+ num_commits: $(($NUM_SECOND_LAYER_COMMITS + $NUM_THIRD_LAYER_COMMITS + $NUM_FOURTH_LAYER_COMMITS + $NUM_FIFTH_LAYER_COMMITS))
+ chunks: oid_fanout oid_lookup commit_metadata generation_data
+ EOF
+ test_cmp expect output
+ )
+'
+
+test_expect_success 'write generation data chunk when commit-graph chain is replaced' '
+ git clone mixed mixed-replace &&
+ (
+ cd mixed-replace &&
+ git commit-graph write --reachable --split=replace &&
+ test_path_is_file $graphdir/commit-graph-chain &&
+ test_line_count = 1 $graphdir/commit-graph-chain &&
+ verify_chain_files_exist $graphdir &&
+ graph_read_expect $(($NUM_FIRST_LAYER_COMMITS + $NUM_SECOND_LAYER_COMMITS)) &&
+ git commit-graph verify
+ )
+'
+
test_done