Teach Git to inspect a commit graph file to supply the contents of a
struct commit when calling parse_commit_gently(). This implementation
satisfies all post-conditions on the struct commit, including loading
parents, the root tree, and the commit date.
If core.commitGraph is false, then do not check graph files.
In test script t5318-commit-graph.sh, add output-matching conditions on
read-only graph operations.
By loading commits from the graph instead of parsing commit buffers, we
save a lot of time on long commit walks. Here are some performance
results for a copy of the Linux repository where 'master' has 664,185
reachable commits and is behind 'origin/master' by 60,191 commits.
| Command | Before | After | Rel % |
|----------------------------------|--------|--------|-------|
| log --oneline --topo-order -1000 | 6.56s | 0.66s | -89% |
| branch -vv | 1.35s | 0.32s | -76% |
| rev-list --all | 6.7s | 0.83s | -87% |
| rev-list --all --objects | 33.0s | 27.5s | -16% |
Signed-off-by: Derrick Stolee <dsto...@microsoft.com>
---
alloc.c | 1 +
commit-graph.c | 141 +++++++++++++++++++++++++++++++++++++++++++++++-
commit-graph.h | 12 +++++
commit.c | 3 ++
commit.h | 3 ++
t/t5318-commit-graph.sh | 47 +++++++++++++++-
6 files changed, 205 insertions(+), 2 deletions(-)
diff --git a/alloc.c b/alloc.c
index 12afadf..cf4f8b6 100644
--- a/alloc.c
+++ b/alloc.c
@@ -93,6 +93,7 @@ void *alloc_commit_node(void)
struct commit *c = alloc_node(&commit_state, sizeof(struct commit));
c->object.type = OBJ_COMMIT;
c->index = alloc_commit_index();
+ c->graph_pos = COMMIT_NOT_FROM_GRAPH;
return c;
}
diff --git a/commit-graph.c b/commit-graph.c
index 01aa23d..184b8da 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -38,7 +38,6 @@
#define GRAPH_MIN_SIZE (5 * GRAPH_CHUNKLOOKUP_WIDTH + GRAPH_FANOUT_SIZE + \
GRAPH_OID_LEN + 8)
-
char *get_commit_graph_filename(const char *obj_dir)
{
return xstrfmt("%s/info/commit-graph", obj_dir);
@@ -182,6 +181,145 @@ struct commit_graph *load_commit_graph_one(const char
*graph_file)
exit(1);
}
+/* global storage */
+struct commit_graph *commit_graph = NULL;
+
+static void prepare_commit_graph_one(const char *obj_dir)
+{
+ char *graph_name;
+
+ if (commit_graph)
+ return;
+
+ graph_name = get_commit_graph_filename(obj_dir);
+ commit_graph = load_commit_graph_one(graph_name);
+
+ FREE_AND_NULL(graph_name);
+}
+
+static int prepare_commit_graph_run_once = 0;
+static void prepare_commit_graph(void)
+{
+ struct alternate_object_database *alt;
+ char *obj_dir;
+
+ if (prepare_commit_graph_run_once)
+ return;
+ prepare_commit_graph_run_once = 1;
+
+ obj_dir = get_object_directory();
+ prepare_commit_graph_one(obj_dir);
+ prepare_alt_odb();
+ for (alt = alt_odb_list; !commit_graph && alt; alt = alt->next)
+ prepare_commit_graph_one(alt->path);
+}
+
+static void close_commit_graph(void)
+{
+ if (!commit_graph)
+ return;
+
+ if (commit_graph->graph_fd >= 0) {
+ munmap((void *)commit_graph->data, commit_graph->data_len);
+ commit_graph->data = NULL;
+ close(commit_graph->graph_fd);
+ }
+
+ FREE_AND_NULL(commit_graph);
+}
+
+static int bsearch_graph(struct commit_graph *g, struct object_id *oid,
uint32_t *pos)
+{
+ return bsearch_hash(oid->hash, g->chunk_oid_fanout,
+ g->chunk_oid_lookup, g->hash_len, pos);
+}
+
+static struct commit_list **insert_parent_or_die(struct commit_graph *g,
+ uint64_t pos,
+ struct commit_list **pptr)
+{
+ struct commit *c;
+ struct object_id oid;
+ hashcpy(oid.hash, g->chunk_oid_lookup + g->hash_len * pos);
+ c = lookup_commit(&oid);
+ if (!c)
+ die("could not find commit %s", oid_to_hex(&oid));
+ c->graph_pos = pos;
+ return &commit_list_insert(c, pptr)->next;
+}
+
+static int fill_commit_in_graph(struct commit *item, struct commit_graph *g,
uint32_t pos)
+{
+ struct object_id oid;
+ uint32_t edge_value;
+ 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;
+
+ item->object.parsed = 1;
+ item->graph_pos = pos;
+
+ hashcpy(oid.hash, commit_data);
+ item->tree = lookup_tree(&oid);
+
+ date_high = ntohl(*(uint32_t*)(commit_data + g->hash_len + 8)) & 0x3;
+ date_low = ntohl(*(uint32_t*)(commit_data + g->hash_len + 12));
+ item->date = (timestamp_t)((date_high << 32) | date_low);
+
+ pptr = &item->parents;
+
+ edge_value = ntohl(*(uint32_t*)(commit_data + g->hash_len));
+ if (edge_value == GRAPH_PARENT_NONE)
+ return 1;
+ pptr = insert_parent_or_die(g, edge_value, pptr);
+
+ edge_value = ntohl(*(uint32_t*)(commit_data + g->hash_len + 4));
+ if (edge_value == GRAPH_PARENT_NONE)
+ return 1;
+ if (!(edge_value & GRAPH_OCTOPUS_EDGES_NEEDED)) {
+ pptr = insert_parent_or_die(g, edge_value, pptr);
+ return 1;
+ }
+
+ parent_data_ptr = (uint32_t*)(g->chunk_large_edges +
+ 4 * (uint64_t)(edge_value & GRAPH_EDGE_LAST_MASK));
+ do {
+ edge_value = ntohl(*parent_data_ptr);
+ pptr = insert_parent_or_die(g,
+ edge_value & GRAPH_EDGE_LAST_MASK,
+ pptr);
+ parent_data_ptr++;
+ } while (!(edge_value & GRAPH_LAST_EDGE));
+
+ return 1;
+}
+
+int parse_commit_in_graph(struct commit *item)
+{
+ if (!core_commit_graph)
+ return 0;
+ if (item->object.parsed)
+ return 1;
+
+ prepare_commit_graph();
+ if (commit_graph) {
+ uint32_t pos;
+ int found;
+ if (item->graph_pos != COMMIT_NOT_FROM_GRAPH) {
+ pos = item->graph_pos;
+ found = 1;
+ } else {
+ found = bsearch_graph(commit_graph,
&(item->object.oid), &pos);
+ }
+
+ if (found)
+ return fill_commit_in_graph(item, commit_graph, pos);
+ }
+
+ return 0;
+}
+
static void write_graph_chunk_fanout(struct hashfile *f,
struct commit **commits,
int nr_commits)
@@ -511,6 +649,7 @@ void write_commit_graph(const char *obj_dir)
write_graph_chunk_data(f, GRAPH_OID_LEN, commits.list, commits.nr);
write_graph_chunk_large_edges(f, commits.list, commits.nr);
+ close_commit_graph();
hashclose(f, final_hash, CSUM_CLOSE | CSUM_FSYNC | CSUM_KEEP_OPEN);
commit_lock_file(&lk);
diff --git a/commit-graph.h b/commit-graph.h
index 8b4b0f9..b223b9b 100644
--- a/commit-graph.h
+++ b/commit-graph.h
@@ -5,6 +5,18 @@
char *get_commit_graph_filename(const char *obj_dir);
+/*
+ * Given a commit struct, try to fill the commit struct info, including:
+ * 1. tree object
+ * 2. date
+ * 3. parents.
+ *
+ * Returns 1 if and only if the commit was found in the packed graph.
+ *
+ * See parse_commit_buffer() for the fallback after this call.
+ */
+int parse_commit_in_graph(struct commit *item);
+
struct commit_graph {
int graph_fd;
diff --git a/commit.c b/commit.c
index e8a49b9..eb61729 100644
--- a/commit.c
+++ b/commit.c
@@ -1,6 +1,7 @@
#include "cache.h"
#include "tag.h"
#include "commit.h"
+#include "commit-graph.h"
#include "pkt-line.h"
#include "utf8.h"
#include "diff.h"
@@ -383,6 +384,8 @@ int parse_commit_gently(struct commit *item, int
quiet_on_missing)
return -1;
if (item->object.parsed)
return 0;
+ if (parse_commit_in_graph(item))
+ return 0;
buffer = read_sha1_file(item->object.oid.hash, &type, &size);
if (!buffer)
return quiet_on_missing ? -1 :
diff --git a/commit.h b/commit.h
index 0fb8271..e57ae4b 100644
--- a/commit.h
+++ b/commit.h
@@ -9,6 +9,8 @@
#include "string-list.h"
#include "pretty.h"
+#define COMMIT_NOT_FROM_GRAPH 0xFFFFFFFF
+
struct commit_list {
struct commit *item;
struct commit_list *next;
@@ -21,6 +23,7 @@ struct commit {
timestamp_t date;
struct commit_list *parents;
struct tree *tree;
+ uint32_t graph_pos;
};
extern int save_commit_buffer;
diff --git a/t/t5318-commit-graph.sh b/t/t5318-commit-graph.sh
index 0085e23..9a0cd71 100755
--- a/t/t5318-commit-graph.sh
+++ b/t/t5318-commit-graph.sh
@@ -7,6 +7,7 @@ test_expect_success 'setup full repo' '
mkdir full &&
cd "$TRASH_DIRECTORY/full" &&
git init &&
+ git config core.commitGraph true &&
objdir=".git/objects"
'
@@ -26,6 +27,29 @@ test_expect_success 'create commits and repack' '
git repack
'
+graph_git_two_modes() {
+ git -c core.graph=true $1 >output
+ git -c core.graph=false $1 >expect
+ test_cmp output expect
+}
+
+graph_git_behavior() {
+ MSG=$1
+ DIR=$2
+ BRANCH=$3
+ COMPARE=$4
+ test_expect_success "check normal git operations: $MSG" '
+ cd "$TRASH_DIRECTORY/$DIR" &&
+ graph_git_two_modes "log --oneline $BRANCH" &&
+ graph_git_two_modes "log --topo-order $BRANCH" &&
+ graph_git_two_modes "log --graph $COMPARE..$BRANCH" &&
+ graph_git_two_modes "branch -vv" &&
+ graph_git_two_modes "merge-base -a $BRANCH $COMPARE"
+ '
+}
+
+graph_git_behavior 'no graph' full commits/3 commits/1
+
graph_read_expect() {
OPTIONAL=""
NUM_CHUNKS=3
@@ -50,6 +74,8 @@ test_expect_success 'write graph' '
graph_read_expect "3"
'
+graph_git_behavior 'graph exists' full commits/3 commits/1
+
test_expect_success 'Add more commits' '
cd "$TRASH_DIRECTORY/full" &&
git reset --hard commits/1 &&
@@ -86,7 +112,6 @@ test_expect_success 'Add more commits' '
# |___/____/
# 1
-
test_expect_success 'write graph with merges' '
cd "$TRASH_DIRECTORY/full" &&
git commit-graph write &&
@@ -94,6 +119,10 @@ test_expect_success 'write graph with merges' '
graph_read_expect "10" "large_edges"
'
+graph_git_behavior 'merge 1 vs 2' full merge/1 merge/2
+graph_git_behavior 'merge 1 vs 3' full merge/1 merge/3
+graph_git_behavior 'merge 2 vs 3' full merge/2 merge/3
+
test_expect_success 'Add one more commit' '
cd "$TRASH_DIRECTORY/full" &&
test_commit 8 &&
@@ -115,6 +144,9 @@ test_expect_success 'Add one more commit' '
# |___/____/
# 1
+graph_git_behavior 'mixed mode, commit 8 vs merge 1' full commits/8 merge/1
+graph_git_behavior 'mixed mode, commit 8 vs merge 2' full commits/8 merge/2
+
test_expect_success 'write graph with new commit' '
cd "$TRASH_DIRECTORY/full" &&
git commit-graph write &&
@@ -122,6 +154,9 @@ test_expect_success 'write graph with new commit' '
graph_read_expect "11" "large_edges"
'
+graph_git_behavior 'full graph, commit 8 vs merge 1' full commits/8 merge/1
+graph_git_behavior 'full graph, commit 8 vs merge 2' full commits/8 merge/2
+
test_expect_success 'write graph with nothing new' '
cd "$TRASH_DIRECTORY/full" &&
git commit-graph write &&
@@ -129,13 +164,20 @@ test_expect_success 'write graph with nothing new' '
graph_read_expect "11" "large_edges"
'
+graph_git_behavior 'cleared graph, commit 8 vs merge 1' full commits/8 merge/1
+graph_git_behavior 'cleared graph, commit 8 vs merge 2' full commits/8 merge/2
+
test_expect_success 'setup bare repo' '
cd "$TRASH_DIRECTORY" &&
git clone --bare --no-local full bare &&
cd bare &&
+ git config core.commitGraph true &&
baredir="./objects"
'
+graph_git_behavior 'bare repo, commit 8 vs merge 1' bare commits/8 merge/1
+graph_git_behavior 'bare repo, commit 8 vs merge 2' bare commits/8 merge/2
+
test_expect_success 'write graph in bare repo' '
cd "$TRASH_DIRECTORY/bare" &&
git commit-graph write &&
@@ -143,5 +185,8 @@ test_expect_success 'write graph in bare repo' '
graph_read_expect "11" "large_edges"
'
+graph_git_behavior 'bare repo with graph, commit 8 vs merge 1' bare commits/8
merge/1
+graph_git_behavior 'bare repo with graph, commit 8 vs merge 2' bare commits/8
merge/2
+
test_done
--
2.7.4
