commit-graph: prepare for commit-graph chains
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 position 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. While here, change insert_parent_or_die() to take a uint32_t position, as that is the type used by its only caller and that makes more sense with the limits in the commit-graph format. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Derrick Stolee committed
Jun 18, 2019 at 11:14 UTC
d4f4d60f6da8b93f768b2b4958c04cc1b3cea443
2 files changed
+81
-11
commit-graph.c
+78
-11
@@ -359,9 +359,18 @@ int generation_numbers_enabled(struct repository *r)
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return !!first_generation;
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}
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+static void close_commit_graph_one(struct commit_graph *g)
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+{
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+ if (!g)
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+ return;
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+
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+ close_commit_graph_one(g->base_graph);
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+ free_commit_graph(g);
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+}
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+
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void close_commit_graph(struct raw_object_store *o)
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{
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- free_commit_graph(o->commit_graph);
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+ close_commit_graph_one(o->commit_graph);
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o->commit_graph = NULL;
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}
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@@ -371,18 +380,38 @@ static int bsearch_graph(struct commit_graph *g, struct object_id *oid, uint32_t
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g->chunk_oid_lookup, g->hash_len, pos);
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}
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+static void load_oid_from_graph(struct commit_graph *g,
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+ uint32_t pos,
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+ struct object_id *oid)
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+{
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+ uint32_t lex_index;
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+
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+ while (g && pos < g->num_commits_in_base)
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+ g = g->base_graph;
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+
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+ if (!g)
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+ BUG("NULL commit-graph");
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+
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+ if (pos >= g->num_commits + g->num_commits_in_base)
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+ die(_("invalid commit position. commit-graph is likely corrupt"));
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+
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+ lex_index = pos - g->num_commits_in_base;
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+
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+ hashcpy(oid->hash, g->chunk_oid_lookup + g->hash_len * lex_index);
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+}
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+
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static struct commit_list **insert_parent_or_die(struct repository *r,
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struct commit_graph *g,
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- uint64_t pos,
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+ uint32_t pos,
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struct commit_list **pptr)
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{
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struct commit *c;
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struct object_id oid;
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- if (pos >= g->num_commits)
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- die("invalid parent position %"PRIu64, pos);
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+ if (pos >= g->num_commits + g->num_commits_in_base)
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+ die("invalid parent position %"PRIu32, pos);
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- hashcpy(oid.hash, g->chunk_oid_lookup + g->hash_len * pos);
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+ load_oid_from_graph(g, pos, &oid);
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c = lookup_commit(r, &oid);
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if (!c)
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die(_("could not find commit %s"), oid_to_hex(&oid));
@@ -392,7 +421,14 @@ static struct commit_list **insert_parent_or_die(struct repository *r,
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static void fill_commit_graph_info(struct commit *item, struct commit_graph *g, uint32_t pos)
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{
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- const unsigned char *commit_data = g->chunk_commit_data + GRAPH_DATA_WIDTH * pos;
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+ const unsigned char *commit_data;
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+ uint32_t lex_index;
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+
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+ while (pos < g->num_commits_in_base)
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+ g = g->base_graph;
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+
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+ lex_index = pos - g->num_commits_in_base;
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+ commit_data = g->chunk_commit_data + GRAPH_DATA_WIDTH * lex_index;
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item->graph_pos = pos;
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item->generation = get_be32(commit_data + g->hash_len + 8) >> 2;
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}
@@ -405,10 +441,25 @@ static int fill_commit_in_graph(struct repository *r,
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uint32_t *parent_data_ptr;
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uint64_t date_low, date_high;
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struct commit_list **pptr;
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- const unsigned char *commit_data = g->chunk_commit_data + (g->hash_len + 16) * pos;
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+ const unsigned char *commit_data;
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+ uint32_t lex_index;
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- item->object.parsed = 1;
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+ while (pos < g->num_commits_in_base)
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+ g = g->base_graph;
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+
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+ if (pos >= g->num_commits + g->num_commits_in_base)
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+ die(_("invalid commit position. commit-graph is likely corrupt"));
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+
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+ /*
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+ * Store the "full" position, but then use the
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+ * "local" position for the rest of the calculation.
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+ */
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item->graph_pos = pos;
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+ lex_index = pos - g->num_commits_in_base;
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+
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+ commit_data = g->chunk_commit_data + (g->hash_len + 16) * lex_index;
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+
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+ item->object.parsed = 1;
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item->maybe_tree = NULL;
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@@ -452,7 +503,18 @@ static int find_commit_in_graph(struct commit *item, struct commit_graph *g, uin
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*pos = item->graph_pos;
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return 1;
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} else {
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- return bsearch_graph(g, &(item->object.oid), pos);
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+ struct commit_graph *cur_g = g;
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+ uint32_t lex_index;
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+
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+ while (cur_g && !bsearch_graph(cur_g, &(item->object.oid), &lex_index))
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+ cur_g = cur_g->base_graph;
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+
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+ if (cur_g) {
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+ *pos = lex_index + cur_g->num_commits_in_base;
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+ return 1;
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+ }
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+
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+ return 0;
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}
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}
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@@ -492,8 +554,13 @@ static struct tree *load_tree_for_commit(struct repository *r,
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struct commit *c)
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{
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struct object_id oid;
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- const unsigned char *commit_data = g->chunk_commit_data +
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- GRAPH_DATA_WIDTH * (c->graph_pos);
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+ const unsigned char *commit_data;
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+
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+ while (c->graph_pos < g->num_commits_in_base)
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+ g = g->base_graph;
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+
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+ commit_data = g->chunk_commit_data +
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+ GRAPH_DATA_WIDTH * (c->graph_pos - g->num_commits_in_base);
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hashcpy(oid.hash, commit_data);
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c->maybe_tree = lookup_tree(r, &oid);
commit-graph.h
+3
@@ -48,6 +48,9 @@ struct commit_graph {
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uint32_t num_commits;
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struct object_id oid;
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+ uint32_t num_commits_in_base;
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+ struct commit_graph *base_graph;
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+
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const uint32_t *chunk_oid_fanout;
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const unsigned char *chunk_oid_lookup;
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const unsigned char *chunk_commit_data;