The struct commit is used in many contexts. However, members
`generation` and `graph_pos` are only used for commit-graph related
operations and otherwise waste memory.
As they are often accessed together, let's introduce struct
commit_graph_data and move them to a commit_graph_data slab.
Signed-off-by: Abhishek Kumar <abhishekkumar8222@xxxxxxxxx>
---
commit-graph.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
commit-graph.h | 10 ++++++++++
2 files changed, 59 insertions(+)
diff --git a/commit-graph.c b/commit-graph.c
index e3420ddcbf..7d887a6a2c 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -87,6 +87,55 @@ static int commit_pos_cmp(const void *va, const void *vb)
commit_pos_at(&commit_pos, b);
}
+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);
+
+uint32_t commit_graph_position(const struct commit *c)
+{
+ struct commit_graph_data *data =
+ commit_graph_data_slab_peek(&commit_graph_data_slab, c);
+
+ return data ? data->graph_pos : COMMIT_NOT_FROM_GRAPH;
+}
+
+uint32_t commit_graph_generation(const struct commit *c)
+{
+ struct commit_graph_data *data =
+ commit_graph_data_slab_peek(&commit_graph_data_slab, c);
+
+ if (!data)
+ return GENERATION_NUMBER_INFINITY;
+ if (data->graph_pos == COMMIT_NOT_FROM_GRAPH)
+ return GENERATION_NUMBER_INFINITY;
+
+ return data->generation;
+}
+
+static struct commit_graph_data *commit_graph_data_at(const struct commit *c)
+{
+ uint32_t i = commit_graph_data_slab.slab_count, j;
+ uint32_t slab_size = commit_graph_data_slab.slab_size;
+ struct commit_graph_data *data =
+ commit_graph_data_slab_at(&commit_graph_data_slab, c);
+
+ /*
+ * commit-slab initializes elements with zero, overwrite this with
+ * COMMIT_NOT_FROM_GRAPH for graph_pos.
+ *
+ * We avoid the cost of initializing `generation` as generation
+ * number would be GENERATION_NUMBER_INFINITY if graph position
+ * is COMMIT_NOT_FROM_GRAPH.
+ */
+ for (; i < commit_graph_data_slab.slab_count; i++) {
+ for (j = 0; j < slab_size; j++) {
+ commit_graph_data_slab.slab[i][j].graph_pos = COMMIT_NOT_FROM_GRAPH;
+ }
+ }
+
+ return data;
+}
+
static int commit_gen_cmp(const void *va, const void *vb)
{
const struct commit *a = *(const struct commit **)va;
diff --git a/commit-graph.h b/commit-graph.h
index 4212766a4f..9d22f98f44 100644
--- a/commit-graph.h
+++ b/commit-graph.h
@@ -137,4 +137,14 @@ void free_commit_graph(struct commit_graph *);
*/
void disable_commit_graph(struct repository *r);
+struct commit_graph_data {
+ uint32_t graph_pos;
+ uint32_t generation;
+};
+
+/*
+ * Commits should be parsed before accessing generation, graph positions.
+ */
+uint32_t commit_graph_generation(const struct commit *);
+uint32_t commit_graph_position(const struct commit *);
#endif
--
2.27.0
