From: Derrick Stolee <dstolee@xxxxxxxxxxxxx>
To prepare for a chain of commit-graph files, augment the
commit_graph struct to point to a base commit_graph. As we load
commits from the graph, we may actually want to read from a base
file according to the graph position.
The "graph position" of a commit is given by concatenating the
lexicographic commit orders from each of the commit-graph files in
the chain. This means that we must distinguish two values:
* lexicographic index : the position within the lexicographic
order in a single commit-graph file.
* graph position: the posiiton within the concatenated order
of multiple commit-graph files
Given the lexicographic index of a commit in a graph, we can
compute the graph position by adding the number of commits in
the lower-level graphs. To find the lexicographic index of
a commit, we subtract the number of commits in lower-level graphs.
Signed-off-by: Derrick Stolee <dstolee@xxxxxxxxxxxxx>
---
commit-graph.c | 74 ++++++++++++++++++++++++++++++++++++++++++++------
commit-graph.h | 3 ++
2 files changed, 69 insertions(+), 8 deletions(-)
diff --git a/commit-graph.c b/commit-graph.c
index 7723156964..3afedcd7f5 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -371,6 +371,25 @@ static int bsearch_graph(struct commit_graph *g, struct object_id *oid, uint32_t
g->chunk_oid_lookup, g->hash_len, pos);
}
+static void load_oid_from_graph(struct commit_graph *g, int pos, struct object_id *oid)
+{
+ uint32_t lex_index;
+
+ if (!g)
+ BUG("NULL commit-graph");
+
+ while (pos < g->num_commits_in_base)
+ g = g->base_graph;
+
+ if (pos >= g->num_commits + g->num_commits_in_base)
+ BUG("position %d is beyond the scope of this commit-graph (%d local + %d base commits)",
+ pos, g->num_commits, g->num_commits_in_base);
+
+ lex_index = pos - g->num_commits_in_base;
+
+ hashcpy(oid->hash, g->chunk_oid_lookup + g->hash_len * lex_index);
+}
+
static struct commit_list **insert_parent_or_die(struct repository *r,
struct commit_graph *g,
uint64_t pos,
@@ -379,10 +398,10 @@ static struct commit_list **insert_parent_or_die(struct repository *r,
struct commit *c;
struct object_id oid;
- if (pos >= g->num_commits)
+ if (pos >= g->num_commits + g->num_commits_in_base)
die("invalid parent position %"PRIu64, pos);
- hashcpy(oid.hash, g->chunk_oid_lookup + g->hash_len * pos);
+ load_oid_from_graph(g, pos, &oid);
c = lookup_commit(r, &oid);
if (!c)
die(_("could not find commit %s"), oid_to_hex(&oid));
@@ -392,7 +411,14 @@ static struct commit_list **insert_parent_or_die(struct repository *r,
static void fill_commit_graph_info(struct commit *item, struct commit_graph *g, uint32_t pos)
{
- const unsigned char *commit_data = g->chunk_commit_data + GRAPH_DATA_WIDTH * pos;
+ const unsigned char *commit_data;
+ uint32_t lex_index;
+
+ while (pos < g->num_commits_in_base)
+ g = g->base_graph;
+
+ lex_index = pos - g->num_commits_in_base;
+ commit_data = g->chunk_commit_data + GRAPH_DATA_WIDTH * lex_index;
item->graph_pos = pos;
item->generation = get_be32(commit_data + g->hash_len + 8) >> 2;
}
@@ -405,10 +431,26 @@ static int fill_commit_in_graph(struct repository *r,
uint32_t *parent_data_ptr;
uint64_t date_low, date_high;
struct commit_list **pptr;
- const unsigned char *commit_data = g->chunk_commit_data + (g->hash_len + 16) * pos;
+ const unsigned char *commit_data;
+ uint32_t lex_index;
- item->object.parsed = 1;
+ while (pos < g->num_commits_in_base)
+ g = g->base_graph;
+
+ if (pos >= g->num_commits + g->num_commits_in_base)
+ BUG("position %d is beyond the scope of this commit-graph (%d local + %d base commits)",
+ pos, g->num_commits, g->num_commits_in_base);
+
+ /*
+ * Store the "full" position, but then use the
+ * "local" position for the rest of the calculation.
+ */
item->graph_pos = pos;
+ lex_index = pos - g->num_commits_in_base;
+
+ commit_data = g->chunk_commit_data + (g->hash_len + 16) * lex_index;
+
+ item->object.parsed = 1;
item->maybe_tree = NULL;
@@ -452,7 +494,18 @@ static int find_commit_in_graph(struct commit *item, struct commit_graph *g, uin
*pos = item->graph_pos;
return 1;
} else {
- return bsearch_graph(g, &(item->object.oid), pos);
+ struct commit_graph *cur_g = g;
+ uint32_t lex_index;
+
+ while (cur_g && !bsearch_graph(cur_g, &(item->object.oid), &lex_index))
+ cur_g = cur_g->base_graph;
+
+ if (cur_g) {
+ *pos = lex_index + cur_g->num_commits_in_base;
+ return 1;
+ }
+
+ return 0;
}
}
@@ -492,8 +545,13 @@ static struct tree *load_tree_for_commit(struct repository *r,
struct commit *c)
{
struct object_id oid;
- const unsigned char *commit_data = g->chunk_commit_data +
- GRAPH_DATA_WIDTH * (c->graph_pos);
+ const unsigned char *commit_data;
+
+ while (c->graph_pos < g->num_commits_in_base)
+ g = g->base_graph;
+
+ commit_data = g->chunk_commit_data +
+ GRAPH_DATA_WIDTH * (c->graph_pos - g->num_commits_in_base);
hashcpy(oid.hash, commit_data);
c->maybe_tree = lookup_tree(r, &oid);
diff --git a/commit-graph.h b/commit-graph.h
index 70f4caf0c7..f9fe32ebe3 100644
--- a/commit-graph.h
+++ b/commit-graph.h
@@ -48,6 +48,9 @@ struct commit_graph {
uint32_t num_commits;
struct object_id oid;
+ uint32_t num_commits_in_base;
+ struct commit_graph *base_graph;
+
const uint32_t *chunk_oid_fanout;
const unsigned char *chunk_oid_lookup;
const unsigned char *chunk_commit_data;
--
gitgitgadget
