helpful for these clones, anyway. The commit-graph will not be read or
written when shallow commits are present.
+Commit Graphs Chains
+--------------------
+
+Typically, repos grow with near-constant velocity (commits per day). Over time,
+the number of commits added by a fetch operation is much smaller than the
+number of commits in the full history. By creating a "chain" of commit-graphs,
+we enable fast writes of new commit data without rewriting the entire commit
+history -- at least, most of the time.
+
+## File Layout
+
+A commit-graph chain uses multiple files, and we use a fixed naming convention
+to organize these files. Each commit-graph file has a name
+`$OBJDIR/info/commit-graphs/graph-{hash}.graph` where `{hash}` is the hex-
+valued hash stored in the footer of that file (which is a hash of the file's
+contents before that hash). For a chain of commit-graph files, a plain-text
+file at `$OBJDIR/info/commit-graphs/commit-graph-chain` contains the
+hashes for the files in order from "lowest" to "highest".
+
+For example, if the `commit-graph-chain` file contains the lines
+
+```
+ {hash0}
+ {hash1}
+ {hash2}
+```
+
+then the commit-graph chain looks like the following diagram:
+
+ +-----------------------+
+ | graph-{hash2}.graph |
+ +-----------------------+
+ |
+ +-----------------------+
+ | |
+ | graph-{hash1}.graph |
+ | |
+ +-----------------------+
+ |
+ +-----------------------+
+ | |
+ | |
+ | |
+ | graph-{hash0}.graph |
+ | |
+ | |
+ | |
+ +-----------------------+
+
+Let X0 be the number of commits in `graph-{hash0}.graph`, X1 be the number of
+commits in `graph-{hash1}.graph`, and X2 be the number of commits in
+`graph-{hash2}.graph`. If a commit appears in position i in `graph-{hash2}.graph`,
+then we interpret this as being the commit in position (X0 + X1 + i), and that
+will be used as its "graph position". The commits in `graph-{hash2}.graph` use these
+positions to refer to their parents, which may be in `graph-{hash1}.graph` or
+`graph-{hash0}.graph`. We can navigate to an arbitrary commit in position j by checking
+its containment in the intervals [0, X0), [X0, X0 + X1), [X0 + X1, X0 + X1 +
+X2).
+
+Each commit-graph file (except the base, `graph-{hash0}.graph`) contains data
+specifying the hashes of all files in the lower layers. In the above example,
+`graph-{hash1}.graph` contains `{hash0}` while `graph-{hash2}.graph` contains
+`{hash0}` and `{hash1}`.
+
+## Merging commit-graph files
+
+If we only added a new commit-graph file on every write, we would run into a
+linear search problem through many commit-graph files. Instead, we use a merge
+strategy to decide when the stack should collapse some number of levels.
+
+The diagram below shows such a collapse. As a set of new commits are added, it
+is determined by the merge strategy that the files should collapse to
+`graph-{hash1}`. Thus, the new commits, the commits in `graph-{hash2}` and
+the commits in `graph-{hash1}` should be combined into a new `graph-{hash3}`
+file.
+
+ +---------------------+
+ | |
+ | (new commits) |
+ | |
+ +---------------------+
+ | |
+ +-----------------------+ +---------------------+
+ | graph-{hash2} |->| |
+ +-----------------------+ +---------------------+
+ | | |
+ +-----------------------+ +---------------------+
+ | | | |
+ | graph-{hash1} |->| |
+ | | | |
+ +-----------------------+ +---------------------+
+ | tmp_graphXXX
+ +-----------------------+
+ | |
+ | |
+ | |
+ | graph-{hash0} |
+ | |
+ | |
+ | |
+ +-----------------------+
+
+During this process, the commits to write are combined, sorted and we write the
+contents to a temporary file, all while holding a `commit-graph-chain.lock`
+lock-file. When the file is flushed, we rename it to `graph-{hash3}`
+according to the computed `{hash3}`. Finally, we write the new chain data to
+`commit-graph-chain.lock`:
+
+```
+ {hash3}
+ {hash0}
+```
+
+We then close the lock-file.
+
+## Merge Strategy
+
+When writing a set of commits that do not exist in the commit-graph stack of
+height N, we default to creating a new file at level N + 1. We then decide to
+merge with the Nth level if one of two conditions hold:
+
+ 1. `--size-multiple=<X>` is specified or X = 2, and the number of commits in
+ level N is less than X times the number of commits in level N + 1.
+
+ 2. `--max-commits=<C>` is specified with non-zero C and the number of commits
+ in level N + 1 is more than C commits.
+
+This decision cascades down the levels: when we merge a level we create a new
+set of commits that then compares to the next level.
+
+The first condition bounds the number of levels to be logarithmic in the total
+number of commits. The second condition bounds the total number of commits in
+a `graph-{hashN}` file and not in the `commit-graph` file, preventing
+significant performance issues when the stack merges and another process only
+partially reads the previous stack.
+
+The merge strategy values (2 for the size multiple, 64,000 for the maximum
+number of commits) could be extracted into config settings for full
+flexibility.
+
+## Deleting graph-{hash} files
+
+After a new tip file is written, some `graph-{hash}` files may no longer
+be part of a chain. It is important to remove these files from disk, eventually.
+The main reason to delay removal is that another process could read the
+`commit-graph-chain` file before it is rewritten, but then look for the
+`graph-{hash}` files after they are deleted.
+
+To allow holding old split commit-graphs for a while after they are unreferenced,
+we update the modified times of the files when they become unreferenced. Then,
+we scan the `$OBJDIR/info/commit-graphs/` directory for `graph-{hash}`
+files whose modified times are older than a given expiry window. This window
+defaults to zero, but can be changed using command-line arguments or a config
+setting.
+
+## Chains across multiple object directories
+
+In a repo with alternates, we look for the `commit-graph-chain` file starting
+in the local object directory and then in each alternate. The first file that
+exists defines our chain. As we look for the `graph-{hash}` files for
+each `{hash}` in the chain file, we follow the same pattern for the host
+directories.
+
+This allows commit-graphs to be split across multiple forks in a fork network.
+The typical case is a large "base" repo with many smaller forks.
+
+As the base repo advances, it will likely update and merge its commit-graph
+chain more frequently than the forks. If a fork updates their commit-graph after
+the base repo, then it should "reparent" the commit-graph chain onto the new
+chain in the base repo. When reading each `graph-{hash}` file, we track
+the object directory containing it. During a write of a new commit-graph file,
+we check for any changes in the source object directory and read the
+`commit-graph-chain` file for that source and create a new file based on those
+files. During this "reparent" operation, we necessarily need to collapse all
+levels in the fork, as all of the files are invalid against the new base file.
+
+It is crucial to be careful when cleaning up "unreferenced" `graph-{hash}.graph`
+files in this scenario. It falls to the user to define the proper settings for
+their custom environment:
+
+ 1. When merging levels in the base repo, the unreferenced files may still be
+ referenced by chains from fork repos.
+
+ 2. The expiry time should be set to a length of time such that every fork has
+ time to recompute their commit-graph chain to "reparent" onto the new base
+ file(s).
+
+ 3. If the commit-graph chain is updated in the base, the fork will not have
+ access to the new chain until its chain is updated to reference those files.
+ (This may change in the future [5].)
+
Related Links
-------------
[0] https://bugs.chromium.org/p/git/issues/detail?id=8
[4] https://public-inbox.org/git/20180108154822.54829-1-git@jeffhostetler.com/T/#u
A patch to remove the ahead-behind calculation from 'status'.
+
+[5] https://public-inbox.org/git/f27db281-abad-5043-6d71-cbb083b1c877@gmail.com/
+ A discussion of a "two-dimensional graph position" that can allow reading
+ multiple commit-graph chains at the same time.
#define GRAPH_CHUNKID_OIDLOOKUP 0x4f49444c /* "OIDL" */
#define GRAPH_CHUNKID_DATA 0x43444154 /* "CDAT" */
#define GRAPH_CHUNKID_EXTRAEDGES 0x45444745 /* "EDGE" */
+#define GRAPH_CHUNKID_BASE 0x42415345 /* "BASE" */
#define GRAPH_DATA_WIDTH (the_hash_algo->rawsz + 16)
char *get_commit_graph_filename(const char *obj_dir)
{
- return xstrfmt("%s/info/commit-graph", obj_dir);
+ char *filename = xstrfmt("%s/info/commit-graph", obj_dir);
+ char *normalized = xmalloc(strlen(filename) + 1);
+ normalize_path_copy(normalized, filename);
+ free(filename);
+ return normalized;
+}
+
+static char *get_split_graph_filename(const char *obj_dir,
+ const char *oid_hex)
+{
+ char *filename = xstrfmt("%s/info/commit-graphs/graph-%s.graph",
+ obj_dir,
+ oid_hex);
+ char *normalized = xmalloc(strlen(filename) + 1);
+ normalize_path_copy(normalized, filename);
+ free(filename);
+ return normalized;
+}
+
+static char *get_chain_filename(const char *obj_dir)
+{
+ return xstrfmt("%s/info/commit-graphs/commit-graph-chain", obj_dir);
}
static uint8_t oid_version(void)
else
graph->chunk_extra_edges = data + chunk_offset;
break;
+
+ case GRAPH_CHUNKID_BASE:
+ if (graph->chunk_base_graphs)
+ chunk_repeated = 1;
+ else
+ graph->chunk_base_graphs = data + chunk_offset;
}
if (chunk_repeated) {
last_chunk_offset = chunk_offset;
}
+ hashcpy(graph->oid.hash, graph->data + graph->data_len - graph->hash_len);
+
if (verify_commit_graph_lite(graph)) {
free(graph);
return NULL;
struct stat st;
int fd;
+ struct commit_graph *g;
int open_ok = open_commit_graph(graph_file, &fd, &st);
if (!open_ok)
return NULL;
- return load_commit_graph_one_fd_st(fd, &st);
+ g = load_commit_graph_one_fd_st(fd, &st);
+
+ if (g)
+ g->filename = xstrdup(graph_file);
+
+ return g;
+}
+
+static struct commit_graph *load_commit_graph_v1(struct repository *r, const char *obj_dir)
+{
+ char *graph_name = get_commit_graph_filename(obj_dir);
+ struct commit_graph *g = load_commit_graph_one(graph_name);
+ free(graph_name);
+
+ if (g)
+ g->obj_dir = obj_dir;
+
+ return g;
+}
+
+static int add_graph_to_chain(struct commit_graph *g,
+ struct commit_graph *chain,
+ struct object_id *oids,
+ int n)
+{
+ struct commit_graph *cur_g = chain;
+
+ if (n && !g->chunk_base_graphs) {
+ warning(_("commit-graph has no base graphs chunk"));
+ return 0;
+ }
+
+ while (n) {
+ n--;
+
+ if (!cur_g ||
+ !oideq(&oids[n], &cur_g->oid) ||
+ !hasheq(oids[n].hash, g->chunk_base_graphs + g->hash_len * n)) {
+ warning(_("commit-graph chain does not match"));
+ return 0;
+ }
+
+ cur_g = cur_g->base_graph;
+ }
+
+ g->base_graph = chain;
+
+ if (chain)
+ g->num_commits_in_base = chain->num_commits + chain->num_commits_in_base;
+
+ return 1;
+}
+
+static struct commit_graph *load_commit_graph_chain(struct repository *r, const char *obj_dir)
+{
+ struct commit_graph *graph_chain = NULL;
+ struct strbuf line = STRBUF_INIT;
+ struct stat st;
+ struct object_id *oids;
+ int i = 0, valid = 1, count;
+ char *chain_name = get_chain_filename(obj_dir);
+ FILE *fp;
+ int stat_res;
+
+ fp = fopen(chain_name, "r");
+ stat_res = stat(chain_name, &st);
+ free(chain_name);
+
+ if (!fp ||
+ stat_res ||
+ st.st_size <= the_hash_algo->hexsz)
+ return NULL;
+
+ count = st.st_size / (the_hash_algo->hexsz + 1);
+ oids = xcalloc(count, sizeof(struct object_id));
+
+ prepare_alt_odb(r);
+
+ for (i = 0; i < count; i++) {
+ struct object_directory *odb;
+
+ if (strbuf_getline_lf(&line, fp) == EOF)
+ break;
+
+ if (get_oid_hex(line.buf, &oids[i])) {
+ warning(_("invalid commit-graph chain: line '%s' not a hash"),
+ line.buf);
+ valid = 0;
+ break;
+ }
+
+ valid = 0;
+ for (odb = r->objects->odb; odb; odb = odb->next) {
+ char *graph_name = get_split_graph_filename(odb->path, line.buf);
+ struct commit_graph *g = load_commit_graph_one(graph_name);
+
+ free(graph_name);
+
+ if (g) {
+ g->obj_dir = odb->path;
+
+ if (add_graph_to_chain(g, graph_chain, oids, i)) {
+ graph_chain = g;
+ valid = 1;
+ }
+
+ break;
+ }
+ }
+
+ if (!valid) {
+ warning(_("unable to find all commit-graph files"));
+ break;
+ }
+ }
+
+ free(oids);
+ fclose(fp);
+
+ return graph_chain;
+}
+
+struct commit_graph *read_commit_graph_one(struct repository *r, const char *obj_dir)
+{
+ struct commit_graph *g = load_commit_graph_v1(r, obj_dir);
+
+ if (!g)
+ g = load_commit_graph_chain(r, obj_dir);
+
+ return g;
}
static void prepare_commit_graph_one(struct repository *r, const char *obj_dir)
{
- char *graph_name;
if (r->objects->commit_graph)
return;
- graph_name = get_commit_graph_filename(obj_dir);
- r->objects->commit_graph =
- load_commit_graph_one(graph_name);
-
- FREE_AND_NULL(graph_name);
+ r->objects->commit_graph = read_commit_graph_one(r, obj_dir);
}
/*
return !!first_generation;
}
+static void close_commit_graph_one(struct commit_graph *g)
+{
+ if (!g)
+ return;
+
+ close_commit_graph_one(g->base_graph);
+ free_commit_graph(g);
+}
+
void close_commit_graph(struct raw_object_store *o)
{
- free_commit_graph(o->commit_graph);
+ close_commit_graph_one(o->commit_graph);
o->commit_graph = NULL;
}
g->chunk_oid_lookup, g->hash_len, pos);
}
+static void load_oid_from_graph(struct commit_graph *g,
+ uint32_t pos,
+ struct object_id *oid)
+{
+ uint32_t lex_index;
+
+ while (g && pos < g->num_commits_in_base)
+ g = g->base_graph;
+
+ if (!g)
+ BUG("NULL commit-graph");
+
+ if (pos >= g->num_commits + g->num_commits_in_base)
+ die(_("invalid commit position. commit-graph is likely corrupt"));
+
+ 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,
+ uint32_t pos,
struct commit_list **pptr)
{
struct commit *c;
struct object_id oid;
- if (pos >= g->num_commits)
- die("invalid parent position %"PRIu64, pos);
+ if (pos >= g->num_commits + g->num_commits_in_base)
+ die("invalid parent position %"PRIu32, 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));
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;
}
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)
+ die(_("invalid commit position. commit-graph is likely corrupt"));
+
+ /*
+ * 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;
set_commit_tree(item, NULL);
*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;
}
}
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);
set_commit_tree(c, lookup_tree(r, &oid));
struct write_commit_graph_context {
struct repository *r;
- const char *obj_dir;
+ char *obj_dir;
char *graph_name;
struct packed_oid_list oids;
struct packed_commit_list commits;
struct progress *progress;
int progress_done;
uint64_t progress_cnt;
+
+ char *base_graph_name;
+ int num_commit_graphs_before;
+ int num_commit_graphs_after;
+ char **commit_graph_filenames_before;
+ char **commit_graph_filenames_after;
+ char **commit_graph_hash_after;
+ uint32_t new_num_commits_in_base;
+ struct commit_graph *new_base_graph;
+
unsigned append:1,
- report_progress:1;
+ report_progress:1,
+ split:1;
+
+ const struct split_commit_graph_opts *split_opts;
};
static void write_graph_chunk_fanout(struct hashfile *f,
ctx->commits.nr,
commit_to_sha1);
+ if (edge_value >= 0)
+ edge_value += ctx->new_num_commits_in_base;
+ else {
+ uint32_t pos;
+ if (find_commit_in_graph(parent->item,
+ ctx->new_base_graph,
+ &pos))
+ edge_value = pos;
+ }
+
if (edge_value < 0)
BUG("missing parent %s for commit %s",
oid_to_hex(&parent->item->object.oid),
ctx->commits.list,
ctx->commits.nr,
commit_to_sha1);
+
+ if (edge_value >= 0)
+ edge_value += ctx->new_num_commits_in_base;
+ else {
+ uint32_t pos;
+ if (find_commit_in_graph(parent->item,
+ ctx->new_base_graph,
+ &pos))
+ edge_value = pos;
+ }
+
if (edge_value < 0)
BUG("missing parent %s for commit %s",
oid_to_hex(&parent->item->object.oid),
ctx->commits.nr,
commit_to_sha1);
+ if (edge_value >= 0)
+ edge_value += ctx->new_num_commits_in_base;
+ else {
+ uint32_t pos;
+ if (find_commit_in_graph(parent->item,
+ ctx->new_base_graph,
+ &pos))
+ edge_value = pos;
+ }
+
if (edge_value < 0)
BUG("missing parent %s for commit %s",
oid_to_hex(&parent->item->object.oid),
}
}
-static int commit_compare(const void *_a, const void *_b)
+static int oid_compare(const void *_a, const void *_b)
{
const struct object_id *a = (const struct object_id *)_a;
const struct object_id *b = (const struct object_id *)_b;
display_progress(ctx->progress, i + 1);
commit = lookup_commit(ctx->r, &ctx->oids.list[i]);
- if (commit && !parse_commit_no_graph(commit))
+ if (!commit)
+ continue;
+ if (ctx->split) {
+ if (!parse_commit(commit) &&
+ commit->graph_pos == COMMIT_NOT_FROM_GRAPH)
+ add_missing_parents(ctx, commit);
+ } else if (!parse_commit_no_graph(commit))
add_missing_parents(ctx, commit);
}
stop_progress(&ctx->progress);
return 0;
}
-int write_commit_graph_reachable(const char *obj_dir, unsigned int flags)
+int write_commit_graph_reachable(const char *obj_dir, unsigned int flags,
+ const struct split_commit_graph_opts *split_opts)
{
struct string_list list = STRING_LIST_INIT_DUP;
int result;
for_each_ref(add_ref_to_list, &list);
result = write_commit_graph(obj_dir, NULL, &list,
- flags);
+ flags, split_opts);
string_list_clear(&list, 0);
return result;
_("Counting distinct commits in commit graph"),
ctx->oids.nr);
display_progress(ctx->progress, 0); /* TODO: Measure QSORT() progress */
- QSORT(ctx->oids.list, ctx->oids.nr, commit_compare);
+ QSORT(ctx->oids.list, ctx->oids.nr, oid_compare);
for (i = 1; i < ctx->oids.nr; i++) {
display_progress(ctx->progress, i + 1);
- if (!oideq(&ctx->oids.list[i - 1], &ctx->oids.list[i]))
+ if (!oideq(&ctx->oids.list[i - 1], &ctx->oids.list[i])) {
+ if (ctx->split) {
+ struct commit *c = lookup_commit(ctx->r, &ctx->oids.list[i]);
+
+ if (!c || c->graph_pos != COMMIT_NOT_FROM_GRAPH)
+ continue;
+ }
+
count_distinct++;
+ }
}
stop_progress(&ctx->progress);
if (i > 0 && oideq(&ctx->oids.list[i - 1], &ctx->oids.list[i]))
continue;
+ ALLOC_GROW(ctx->commits.list, ctx->commits.nr + 1, ctx->commits.alloc);
ctx->commits.list[ctx->commits.nr] = lookup_commit(ctx->r, &ctx->oids.list[i]);
+
+ if (ctx->split &&
+ ctx->commits.list[ctx->commits.nr]->graph_pos != COMMIT_NOT_FROM_GRAPH)
+ continue;
+
parse_commit_no_graph(ctx->commits.list[ctx->commits.nr]);
for (parent = ctx->commits.list[ctx->commits.nr]->parents;
stop_progress(&ctx->progress);
}
+static int write_graph_chunk_base_1(struct hashfile *f,
+ struct commit_graph *g)
+{
+ int num = 0;
+
+ if (!g)
+ return 0;
+
+ num = write_graph_chunk_base_1(f, g->base_graph);
+ hashwrite(f, g->oid.hash, the_hash_algo->rawsz);
+ return num + 1;
+}
+
+static int write_graph_chunk_base(struct hashfile *f,
+ struct write_commit_graph_context *ctx)
+{
+ int num = write_graph_chunk_base_1(f, ctx->new_base_graph);
+
+ if (num != ctx->num_commit_graphs_after - 1) {
+ error(_("failed to write correct number of base graph ids"));
+ return -1;
+ }
+
+ return 0;
+}
+
static int write_commit_graph_file(struct write_commit_graph_context *ctx)
{
uint32_t i;
+ int fd;
struct hashfile *f;
struct lock_file lk = LOCK_INIT;
- uint32_t chunk_ids[5];
- uint64_t chunk_offsets[5];
+ uint32_t chunk_ids[6];
+ uint64_t chunk_offsets[6];
const unsigned hashsz = the_hash_algo->rawsz;
struct strbuf progress_title = STRBUF_INIT;
- int num_chunks = ctx->num_extra_edges ? 4 : 3;
+ int num_chunks = 3;
+ struct object_id file_hash;
+
+ if (ctx->split) {
+ struct strbuf tmp_file = STRBUF_INIT;
+
+ strbuf_addf(&tmp_file,
+ "%s/info/commit-graphs/tmp_graph_XXXXXX",
+ ctx->obj_dir);
+ ctx->graph_name = strbuf_detach(&tmp_file, NULL);
+ } else {
+ ctx->graph_name = get_commit_graph_filename(ctx->obj_dir);
+ }
- ctx->graph_name = get_commit_graph_filename(ctx->obj_dir);
if (safe_create_leading_directories(ctx->graph_name)) {
UNLEAK(ctx->graph_name);
error(_("unable to create leading directories of %s"),
return -1;
}
- hold_lock_file_for_update(&lk, ctx->graph_name, LOCK_DIE_ON_ERROR);
- f = hashfd(lk.tempfile->fd, lk.tempfile->filename.buf);
+ if (ctx->split) {
+ char *lock_name = get_chain_filename(ctx->obj_dir);
- hashwrite_be32(f, GRAPH_SIGNATURE);
+ hold_lock_file_for_update(&lk, lock_name, LOCK_DIE_ON_ERROR);
- hashwrite_u8(f, GRAPH_VERSION);
- hashwrite_u8(f, oid_version());
- hashwrite_u8(f, num_chunks);
- hashwrite_u8(f, 0); /* unused padding byte */
+ fd = git_mkstemp_mode(ctx->graph_name, 0444);
+ if (fd < 0) {
+ error(_("unable to create '%s'"), ctx->graph_name);
+ return -1;
+ }
+
+ f = hashfd(fd, ctx->graph_name);
+ } else {
+ hold_lock_file_for_update(&lk, ctx->graph_name, LOCK_DIE_ON_ERROR);
+ fd = lk.tempfile->fd;
+ f = hashfd(lk.tempfile->fd, lk.tempfile->filename.buf);
+ }
chunk_ids[0] = GRAPH_CHUNKID_OIDFANOUT;
chunk_ids[1] = GRAPH_CHUNKID_OIDLOOKUP;
chunk_ids[2] = GRAPH_CHUNKID_DATA;
- if (ctx->num_extra_edges)
- chunk_ids[3] = GRAPH_CHUNKID_EXTRAEDGES;
- else
- chunk_ids[3] = 0;
- chunk_ids[4] = 0;
+ if (ctx->num_extra_edges) {
+ chunk_ids[num_chunks] = GRAPH_CHUNKID_EXTRAEDGES;
+ num_chunks++;
+ }
+ if (ctx->num_commit_graphs_after > 1) {
+ chunk_ids[num_chunks] = GRAPH_CHUNKID_BASE;
+ num_chunks++;
+ }
+
+ chunk_ids[num_chunks] = 0;
chunk_offsets[0] = 8 + (num_chunks + 1) * GRAPH_CHUNKLOOKUP_WIDTH;
chunk_offsets[1] = chunk_offsets[0] + GRAPH_FANOUT_SIZE;
chunk_offsets[2] = chunk_offsets[1] + hashsz * ctx->commits.nr;
chunk_offsets[3] = chunk_offsets[2] + (hashsz + 16) * ctx->commits.nr;
- chunk_offsets[4] = chunk_offsets[3] + 4 * ctx->num_extra_edges;
+
+ num_chunks = 3;
+ if (ctx->num_extra_edges) {
+ chunk_offsets[num_chunks + 1] = chunk_offsets[num_chunks] +
+ 4 * ctx->num_extra_edges;
+ num_chunks++;
+ }
+ if (ctx->num_commit_graphs_after > 1) {
+ chunk_offsets[num_chunks + 1] = chunk_offsets[num_chunks] +
+ hashsz * (ctx->num_commit_graphs_after - 1);
+ num_chunks++;
+ }
+
+ hashwrite_be32(f, GRAPH_SIGNATURE);
+
+ hashwrite_u8(f, GRAPH_VERSION);
+ hashwrite_u8(f, oid_version());
+ hashwrite_u8(f, num_chunks);
+ hashwrite_u8(f, ctx->num_commit_graphs_after - 1);
for (i = 0; i <= num_chunks; i++) {
uint32_t chunk_write[3];
write_graph_chunk_data(f, hashsz, ctx);
if (ctx->num_extra_edges)
write_graph_chunk_extra_edges(f, ctx);
+ if (ctx->num_commit_graphs_after > 1 &&
+ write_graph_chunk_base(f, ctx)) {
+ return -1;
+ }
stop_progress(&ctx->progress);
strbuf_release(&progress_title);
+ if (ctx->split && ctx->base_graph_name && ctx->num_commit_graphs_after > 1) {
+ char *new_base_hash = xstrdup(oid_to_hex(&ctx->new_base_graph->oid));
+ char *new_base_name = get_split_graph_filename(ctx->new_base_graph->obj_dir, new_base_hash);
+
+ free(ctx->commit_graph_filenames_after[ctx->num_commit_graphs_after - 2]);
+ free(ctx->commit_graph_hash_after[ctx->num_commit_graphs_after - 2]);
+ ctx->commit_graph_filenames_after[ctx->num_commit_graphs_after - 2] = new_base_name;
+ ctx->commit_graph_hash_after[ctx->num_commit_graphs_after - 2] = new_base_hash;
+ }
+
close_commit_graph(ctx->r->objects);
- finalize_hashfile(f, NULL, CSUM_HASH_IN_STREAM | CSUM_FSYNC);
+ finalize_hashfile(f, file_hash.hash, CSUM_HASH_IN_STREAM | CSUM_FSYNC);
+
+ if (ctx->split) {
+ FILE *chainf = fdopen_lock_file(&lk, "w");
+ char *final_graph_name;
+ int result;
+
+ close(fd);
+
+ if (!chainf) {
+ error(_("unable to open commit-graph chain file"));
+ return -1;
+ }
+
+ if (ctx->base_graph_name) {
+ const char *dest = ctx->commit_graph_filenames_after[
+ ctx->num_commit_graphs_after - 2];
+
+ if (strcmp(ctx->base_graph_name, dest)) {
+ result = rename(ctx->base_graph_name, dest);
+
+ if (result) {
+ error(_("failed to rename base commit-graph file"));
+ return -1;
+ }
+ }
+ } else {
+ char *graph_name = get_commit_graph_filename(ctx->obj_dir);
+ unlink(graph_name);
+ }
+
+ ctx->commit_graph_hash_after[ctx->num_commit_graphs_after - 1] = xstrdup(oid_to_hex(&file_hash));
+ final_graph_name = get_split_graph_filename(ctx->obj_dir,
+ ctx->commit_graph_hash_after[ctx->num_commit_graphs_after - 1]);
+ ctx->commit_graph_filenames_after[ctx->num_commit_graphs_after - 1] = final_graph_name;
+
+ result = rename(ctx->graph_name, final_graph_name);
+
+ for (i = 0; i < ctx->num_commit_graphs_after; i++)
+ fprintf(lk.tempfile->fp, "%s\n", ctx->commit_graph_hash_after[i]);
+
+ if (result) {
+ error(_("failed to rename temporary commit-graph file"));
+ return -1;
+ }
+ }
+
commit_lock_file(&lk);
return 0;
}
+static void split_graph_merge_strategy(struct write_commit_graph_context *ctx)
+{
+ struct commit_graph *g = ctx->r->objects->commit_graph;
+ uint32_t num_commits = ctx->commits.nr;
+ uint32_t i;
+
+ int max_commits = 0;
+ int size_mult = 2;
+
+ if (ctx->split_opts) {
+ max_commits = ctx->split_opts->max_commits;
+ size_mult = ctx->split_opts->size_multiple;
+ }
+
+ g = ctx->r->objects->commit_graph;
+ ctx->num_commit_graphs_after = ctx->num_commit_graphs_before + 1;
+
+ while (g && (g->num_commits <= size_mult * num_commits ||
+ (max_commits && num_commits > max_commits))) {
+ if (strcmp(g->obj_dir, ctx->obj_dir))
+ break;
+
+ num_commits += g->num_commits;
+ g = g->base_graph;
+
+ ctx->num_commit_graphs_after--;
+ }
+
+ ctx->new_base_graph = g;
+
+ if (ctx->num_commit_graphs_after == 2) {
+ char *old_graph_name = get_commit_graph_filename(g->obj_dir);
+
+ if (!strcmp(g->filename, old_graph_name) &&
+ strcmp(g->obj_dir, ctx->obj_dir)) {
+ ctx->num_commit_graphs_after = 1;
+ ctx->new_base_graph = NULL;
+ }
+
+ free(old_graph_name);
+ }
+
+ ALLOC_ARRAY(ctx->commit_graph_filenames_after, ctx->num_commit_graphs_after);
+ ALLOC_ARRAY(ctx->commit_graph_hash_after, ctx->num_commit_graphs_after);
+
+ for (i = 0; i < ctx->num_commit_graphs_after &&
+ i < ctx->num_commit_graphs_before; i++)
+ ctx->commit_graph_filenames_after[i] = xstrdup(ctx->commit_graph_filenames_before[i]);
+
+ i = ctx->num_commit_graphs_before - 1;
+ g = ctx->r->objects->commit_graph;
+
+ while (g) {
+ if (i < ctx->num_commit_graphs_after)
+ ctx->commit_graph_hash_after[i] = xstrdup(oid_to_hex(&g->oid));
+
+ i--;
+ g = g->base_graph;
+ }
+}
+
+static void merge_commit_graph(struct write_commit_graph_context *ctx,
+ struct commit_graph *g)
+{
+ uint32_t i;
+ uint32_t offset = g->num_commits_in_base;
+
+ ALLOC_GROW(ctx->commits.list, ctx->commits.nr + g->num_commits, ctx->commits.alloc);
+
+ for (i = 0; i < g->num_commits; i++) {
+ struct object_id oid;
+ struct commit *result;
+
+ display_progress(ctx->progress, i + 1);
+
+ load_oid_from_graph(g, i + offset, &oid);
+
+ /* only add commits if they still exist in the repo */
+ result = lookup_commit_reference_gently(ctx->r, &oid, 1);
+
+ if (result) {
+ ctx->commits.list[ctx->commits.nr] = result;
+ ctx->commits.nr++;
+ }
+ }
+}
+
+static int commit_compare(const void *_a, const void *_b)
+{
+ const struct commit *a = *(const struct commit **)_a;
+ const struct commit *b = *(const struct commit **)_b;
+ return oidcmp(&a->object.oid, &b->object.oid);
+}
+
+static void sort_and_scan_merged_commits(struct write_commit_graph_context *ctx)
+{
+ uint32_t i, num_parents;
+ struct commit_list *parent;
+
+ if (ctx->report_progress)
+ ctx->progress = start_delayed_progress(
+ _("Scanning merged commits"),
+ ctx->commits.nr);
+
+ QSORT(ctx->commits.list, ctx->commits.nr, commit_compare);
+
+ ctx->num_extra_edges = 0;
+ for (i = 0; i < ctx->commits.nr; i++) {
+ display_progress(ctx->progress, i);
+
+ if (i && oideq(&ctx->commits.list[i - 1]->object.oid,
+ &ctx->commits.list[i]->object.oid)) {
+ die(_("unexpected duplicate commit id %s"),
+ oid_to_hex(&ctx->commits.list[i]->object.oid));
+ } else {
+ num_parents = 0;
+ for (parent = ctx->commits.list[i]->parents; parent; parent = parent->next)
+ num_parents++;
+
+ if (num_parents > 2)
+ ctx->num_extra_edges += num_parents - 2;
+ }
+ }
+
+ stop_progress(&ctx->progress);
+}
+
+static void merge_commit_graphs(struct write_commit_graph_context *ctx)
+{
+ struct commit_graph *g = ctx->r->objects->commit_graph;
+ uint32_t current_graph_number = ctx->num_commit_graphs_before;
+ struct strbuf progress_title = STRBUF_INIT;
+
+ while (g && current_graph_number >= ctx->num_commit_graphs_after) {
+ current_graph_number--;
+
+ if (ctx->report_progress) {
+ strbuf_addstr(&progress_title, _("Merging commit-graph"));
+ ctx->progress = start_delayed_progress(progress_title.buf, 0);
+ }
+
+ merge_commit_graph(ctx, g);
+ stop_progress(&ctx->progress);
+ strbuf_release(&progress_title);
+
+ g = g->base_graph;
+ }
+
+ if (g) {
+ ctx->new_base_graph = g;
+ ctx->new_num_commits_in_base = g->num_commits + g->num_commits_in_base;
+ }
+
+ if (ctx->new_base_graph)
+ ctx->base_graph_name = xstrdup(ctx->new_base_graph->filename);
+
+ sort_and_scan_merged_commits(ctx);
+}
+
+static void mark_commit_graphs(struct write_commit_graph_context *ctx)
+{
+ uint32_t i;
+ time_t now = time(NULL);
+
+ for (i = ctx->num_commit_graphs_after - 1; i < ctx->num_commit_graphs_before; i++) {
+ struct stat st;
+ struct utimbuf updated_time;
+
+ stat(ctx->commit_graph_filenames_before[i], &st);
+
+ updated_time.actime = st.st_atime;
+ updated_time.modtime = now;
+ utime(ctx->commit_graph_filenames_before[i], &updated_time);
+ }
+}
+
+static void expire_commit_graphs(struct write_commit_graph_context *ctx)
+{
+ struct strbuf path = STRBUF_INIT;
+ DIR *dir;
+ struct dirent *de;
+ size_t dirnamelen;
+ timestamp_t expire_time = time(NULL);
+
+ if (ctx->split_opts && ctx->split_opts->expire_time)
+ expire_time -= ctx->split_opts->expire_time;
+ if (!ctx->split) {
+ char *chain_file_name = get_chain_filename(ctx->obj_dir);
+ unlink(chain_file_name);
+ free(chain_file_name);
+ ctx->num_commit_graphs_after = 0;
+ }
+
+ strbuf_addstr(&path, ctx->obj_dir);
+ strbuf_addstr(&path, "/info/commit-graphs");
+ dir = opendir(path.buf);
+
+ if (!dir) {
+ strbuf_release(&path);
+ return;
+ }
+
+ strbuf_addch(&path, '/');
+ dirnamelen = path.len;
+ while ((de = readdir(dir)) != NULL) {
+ struct stat st;
+ uint32_t i, found = 0;
+
+ strbuf_setlen(&path, dirnamelen);
+ strbuf_addstr(&path, de->d_name);
+
+ stat(path.buf, &st);
+
+ if (st.st_mtime > expire_time)
+ continue;
+ if (path.len < 6 || strcmp(path.buf + path.len - 6, ".graph"))
+ continue;
+
+ for (i = 0; i < ctx->num_commit_graphs_after; i++) {
+ if (!strcmp(ctx->commit_graph_filenames_after[i],
+ path.buf)) {
+ found = 1;
+ break;
+ }
+ }
+
+ if (!found)
+ unlink(path.buf);
+ }
+}
+
int write_commit_graph(const char *obj_dir,
struct string_list *pack_indexes,
struct string_list *commit_hex,
- unsigned int flags)
+ unsigned int flags,
+ const struct split_commit_graph_opts *split_opts)
{
struct write_commit_graph_context *ctx;
uint32_t i, count_distinct = 0;
+ size_t len;
int res = 0;
if (!commit_graph_compatible(the_repository))
ctx = xcalloc(1, sizeof(struct write_commit_graph_context));
ctx->r = the_repository;
- ctx->obj_dir = obj_dir;
+
+ /* normalize object dir with no trailing slash */
+ ctx->obj_dir = xmallocz(strlen(obj_dir) + 1);
+ normalize_path_copy(ctx->obj_dir, obj_dir);
+ len = strlen(ctx->obj_dir);
+ if (len && ctx->obj_dir[len - 1] == '/')
+ ctx->obj_dir[len - 1] = 0;
+
ctx->append = flags & COMMIT_GRAPH_APPEND ? 1 : 0;
ctx->report_progress = flags & COMMIT_GRAPH_PROGRESS ? 1 : 0;
+ ctx->split = flags & COMMIT_GRAPH_SPLIT ? 1 : 0;
+ ctx->split_opts = split_opts;
+
+ if (ctx->split) {
+ struct commit_graph *g;
+ prepare_commit_graph(ctx->r);
+
+ g = ctx->r->objects->commit_graph;
+
+ while (g) {
+ ctx->num_commit_graphs_before++;
+ g = g->base_graph;
+ }
+
+ if (ctx->num_commit_graphs_before) {
+ ALLOC_ARRAY(ctx->commit_graph_filenames_before, ctx->num_commit_graphs_before);
+ i = ctx->num_commit_graphs_before;
+ g = ctx->r->objects->commit_graph;
+
+ while (g) {
+ ctx->commit_graph_filenames_before[--i] = xstrdup(g->filename);
+ g = g->base_graph;
+ }
+ }
+ }
ctx->approx_nr_objects = approximate_object_count();
ctx->oids.alloc = ctx->approx_nr_objects / 32;
+ if (ctx->split && split_opts && ctx->oids.alloc > split_opts->max_commits)
+ ctx->oids.alloc = split_opts->max_commits;
+
if (ctx->append) {
prepare_commit_graph_one(ctx->r, ctx->obj_dir);
if (ctx->r->objects->commit_graph)
goto cleanup;
}
+ if (!ctx->commits.nr)
+ goto cleanup;
+
+ if (ctx->split) {
+ split_graph_merge_strategy(ctx);
+
+ merge_commit_graphs(ctx);
+ } else
+ ctx->num_commit_graphs_after = 1;
+
compute_generation_numbers(ctx);
res = write_commit_graph_file(ctx);
+ if (ctx->split)
+ mark_commit_graphs(ctx);
+
+ expire_commit_graphs(ctx);
+
cleanup:
free(ctx->graph_name);
free(ctx->commits.list);
free(ctx->oids.list);
+ free(ctx->obj_dir);
+
+ if (ctx->commit_graph_filenames_after) {
+ for (i = 0; i < ctx->num_commit_graphs_after; i++) {
+ free(ctx->commit_graph_filenames_after[i]);
+ free(ctx->commit_graph_hash_after[i]);
+ }
+
+ for (i = 0; i < ctx->num_commit_graphs_before; i++)
+ free(ctx->commit_graph_filenames_before[i]);
+
+ free(ctx->commit_graph_filenames_after);
+ free(ctx->commit_graph_filenames_before);
+ free(ctx->commit_graph_hash_after);
+ }
+
free(ctx);
return res;
#define GENERATION_ZERO_EXISTS 1
#define GENERATION_NUMBER_EXISTS 2
-int verify_commit_graph(struct repository *r, struct commit_graph *g)
+int verify_commit_graph(struct repository *r, struct commit_graph *g, int flags)
{
uint32_t i, cur_fanout_pos = 0;
struct object_id prev_oid, cur_oid, checksum;
struct hashfile *f;
int devnull;
struct progress *progress = NULL;
+ int local_error = 0;
if (!g) {
graph_report("no commit-graph file loaded");
break;
}
+ /* parse parent in case it is in a base graph */
+ parse_commit_in_graph_one(r, g, graph_parents->item);
+
if (!oideq(&graph_parents->item->object.oid, &odb_parents->item->object.oid))
graph_report(_("commit-graph parent for %s is %s != %s"),
oid_to_hex(&cur_oid),
}
stop_progress(&progress);
- return verify_commit_graph_error;
+ local_error = verify_commit_graph_error;
+
+ if (!(flags & COMMIT_GRAPH_VERIFY_SHALLOW) && g->base_graph)
+ local_error |= verify_commit_graph(r, g->base_graph, flags);
+
+ return local_error;
}
void free_commit_graph(struct commit_graph *g)
g->data = NULL;
close(g->graph_fd);
}
+ free(g->filename);
free(g);
}
--- /dev/null
+#!/bin/sh
+
+test_description='split commit graph'
+. ./test-lib.sh
+
+GIT_TEST_COMMIT_GRAPH=0
+
+test_expect_success 'setup repo' '
+ git init &&
+ git config core.commitGraph true &&
+ infodir=".git/objects/info" &&
+ graphdir="$infodir/commit-graphs" &&
+ test_oid_init
+'
+
+graph_read_expect() {
+ NUM_BASE=0
+ if test ! -z $2
+ then
+ NUM_BASE=$2
+ fi
+ cat >expect <<- EOF
+ header: 43475048 1 1 3 $NUM_BASE
+ num_commits: $1
+ chunks: oid_fanout oid_lookup commit_metadata
+ EOF
+ git commit-graph read >output &&
+ test_cmp expect output
+}
+
+test_expect_success 'create commits and write commit-graph' '
+ for i in $(test_seq 3)
+ do
+ test_commit $i &&
+ git branch commits/$i || return 1
+ done &&
+ git commit-graph write --reachable &&
+ test_path_is_file $infodir/commit-graph &&
+ graph_read_expect 3
+'
+
+graph_git_two_modes() {
+ git -c core.commitGraph=true $1 >output
+ git -c core.commitGraph=false $1 >expect
+ test_cmp expect output
+}
+
+graph_git_behavior() {
+ MSG=$1
+ BRANCH=$2
+ COMPARE=$3
+ test_expect_success "check normal git operations: $MSG" '
+ 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 'graph exists' commits/3 commits/1
+
+verify_chain_files_exist() {
+ for hash in $(cat $1/commit-graph-chain)
+ do
+ test_path_is_file $1/graph-$hash.graph || return 1
+ done
+}
+
+test_expect_success 'add more commits, and write a new base graph' '
+ git reset --hard commits/1 &&
+ for i in $(test_seq 4 5)
+ do
+ test_commit $i &&
+ git branch commits/$i || return 1
+ done &&
+ git reset --hard commits/2 &&
+ for i in $(test_seq 6 10)
+ do
+ test_commit $i &&
+ git branch commits/$i || return 1
+ done &&
+ git reset --hard commits/2 &&
+ git merge commits/4 &&
+ git branch merge/1 &&
+ git reset --hard commits/4 &&
+ git merge commits/6 &&
+ git branch merge/2 &&
+ git commit-graph write --reachable &&
+ graph_read_expect 12
+'
+
+test_expect_success 'fork and fail to base a chain on a commit-graph file' '
+ test_when_finished rm -rf fork &&
+ git clone . fork &&
+ (
+ cd fork &&
+ rm .git/objects/info/commit-graph &&
+ echo "$(pwd)/../.git/objects" >.git/objects/info/alternates &&
+ test_commit new-commit &&
+ git commit-graph write --reachable --split &&
+ test_path_is_file $graphdir/commit-graph-chain &&
+ test_line_count = 1 $graphdir/commit-graph-chain &&
+ verify_chain_files_exist $graphdir
+ )
+'
+
+test_expect_success 'add three more commits, write a tip graph' '
+ git reset --hard commits/3 &&
+ git merge merge/1 &&
+ git merge commits/5 &&
+ git merge merge/2 &&
+ git branch merge/3 &&
+ git commit-graph write --reachable --split &&
+ test_path_is_missing $infodir/commit-graph &&
+ test_path_is_file $graphdir/commit-graph-chain &&
+ ls $graphdir/graph-*.graph >graph-files &&
+ test_line_count = 2 graph-files &&
+ verify_chain_files_exist $graphdir
+'
+
+graph_git_behavior 'split commit-graph: merge 3 vs 2' merge/3 merge/2
+
+test_expect_success 'add one commit, write a tip graph' '
+ test_commit 11 &&
+ git branch commits/11 &&
+ git commit-graph write --reachable --split &&
+ test_path_is_missing $infodir/commit-graph &&
+ test_path_is_file $graphdir/commit-graph-chain &&
+ ls $graphdir/graph-*.graph >graph-files &&
+ test_line_count = 3 graph-files &&
+ verify_chain_files_exist $graphdir
+'
+
+graph_git_behavior 'three-layer commit-graph: commit 11 vs 6' commits/11 commits/6
+
+test_expect_success 'add one commit, write a merged graph' '
+ test_commit 12 &&
+ git branch commits/12 &&
+ git commit-graph write --reachable --split &&
+ test_path_is_file $graphdir/commit-graph-chain &&
+ test_line_count = 2 $graphdir/commit-graph-chain &&
+ ls $graphdir/graph-*.graph >graph-files &&
+ test_line_count = 2 graph-files &&
+ verify_chain_files_exist $graphdir
+'
+
+graph_git_behavior 'merged commit-graph: commit 12 vs 6' commits/12 commits/6
+
+test_expect_success 'create fork and chain across alternate' '
+ git clone . fork &&
+ (
+ cd fork &&
+ git config core.commitGraph true &&
+ rm -rf $graphdir &&
+ echo "$(pwd)/../.git/objects" >.git/objects/info/alternates &&
+ test_commit 13 &&
+ git branch commits/13 &&
+ git commit-graph write --reachable --split &&
+ test_path_is_file $graphdir/commit-graph-chain &&
+ test_line_count = 3 $graphdir/commit-graph-chain &&
+ ls $graphdir/graph-*.graph >graph-files &&
+ test_line_count = 1 graph-files &&
+ git -c core.commitGraph=true rev-list HEAD >expect &&
+ git -c core.commitGraph=false rev-list HEAD >actual &&
+ test_cmp expect actual &&
+ test_commit 14 &&
+ git commit-graph write --reachable --split --object-dir=.git/objects/ &&
+ test_line_count = 3 $graphdir/commit-graph-chain &&
+ ls $graphdir/graph-*.graph >graph-files &&
+ test_line_count = 1 graph-files
+ )
+'
+
+graph_git_behavior 'alternate: commit 13 vs 6' commits/13 commits/6
+
+test_expect_success 'test merge stragety constants' '
+ git clone . merge-2 &&
+ (
+ cd merge-2 &&
+ git config core.commitGraph true &&
+ test_line_count = 2 $graphdir/commit-graph-chain &&
+ test_commit 14 &&
+ git commit-graph write --reachable --split --size-multiple=2 &&
+ test_line_count = 3 $graphdir/commit-graph-chain
+
+ ) &&
+ git clone . merge-10 &&
+ (
+ cd merge-10 &&
+ git config core.commitGraph true &&
+ test_line_count = 2 $graphdir/commit-graph-chain &&
+ test_commit 14 &&
+ git commit-graph write --reachable --split --size-multiple=10 &&
+ test_line_count = 1 $graphdir/commit-graph-chain &&
+ ls $graphdir/graph-*.graph >graph-files &&
+ test_line_count = 1 graph-files
+ ) &&
+ git clone . merge-10-expire &&
+ (
+ cd merge-10-expire &&
+ git config core.commitGraph true &&
+ test_line_count = 2 $graphdir/commit-graph-chain &&
+ test_commit 15 &&
+ git commit-graph write --reachable --split --size-multiple=10 --expire-time=1980-01-01 &&
+ test_line_count = 1 $graphdir/commit-graph-chain &&
+ ls $graphdir/graph-*.graph >graph-files &&
+ test_line_count = 3 graph-files
+ ) &&
+ git clone --no-hardlinks . max-commits &&
+ (
+ cd max-commits &&
+ git config core.commitGraph true &&
+ test_line_count = 2 $graphdir/commit-graph-chain &&
+ test_commit 16 &&
+ test_commit 17 &&
+ git commit-graph write --reachable --split --max-commits=1 &&
+ test_line_count = 1 $graphdir/commit-graph-chain &&
+ ls $graphdir/graph-*.graph >graph-files &&
+ test_line_count = 1 graph-files
+ )
+'
+
+test_expect_success 'remove commit-graph-chain file after flattening' '
+ git clone . flatten &&
+ (
+ cd flatten &&
+ test_line_count = 2 $graphdir/commit-graph-chain &&
+ git commit-graph write --reachable &&
+ test_path_is_missing $graphdir/commit-graph-chain &&
+ ls $graphdir >graph-files &&
+ test_line_count = 0 graph-files
+ )
+'
+
+corrupt_file() {
+ file=$1
+ pos=$2
+ data="${3:-\0}"
+ chmod a+w "$file" &&
+ printf "$data" | dd of="$file" bs=1 seek="$pos" conv=notrunc
+}
+
+test_expect_success 'verify hashes along chain, even in shallow' '
+ git clone --no-hardlinks . verify &&
+ (
+ cd verify &&
+ git commit-graph verify &&
+ base_file=$graphdir/graph-$(head -n 1 $graphdir/commit-graph-chain).graph &&
+ corrupt_file "$base_file" 1760 "\01" &&
+ test_must_fail git commit-graph verify --shallow 2>test_err &&
+ grep -v "^+" test_err >err &&
+ test_i18ngrep "incorrect checksum" err
+ )
+'
+
+test_expect_success 'verify --shallow does not check base contents' '
+ git clone --no-hardlinks . verify-shallow &&
+ (
+ cd verify-shallow &&
+ git commit-graph verify &&
+ base_file=$graphdir/graph-$(head -n 1 $graphdir/commit-graph-chain).graph &&
+ corrupt_file "$base_file" 1000 "\01" &&
+ git commit-graph verify --shallow &&
+ test_must_fail git commit-graph verify 2>test_err &&
+ grep -v "^+" test_err >err &&
+ test_i18ngrep "incorrect checksum" err
+ )
+'
+
+test_expect_success 'warn on base graph chunk incorrect' '
+ git clone --no-hardlinks . base-chunk &&
+ (
+ cd base-chunk &&
+ git commit-graph verify &&
+ base_file=$graphdir/graph-$(tail -n 1 $graphdir/commit-graph-chain).graph &&
+ corrupt_file "$base_file" 1376 "\01" &&
+ git commit-graph verify --shallow 2>test_err &&
+ grep -v "^+" test_err >err &&
+ test_i18ngrep "commit-graph chain does not match" err
+ )
+'
+
+test_expect_success 'verify after commit-graph-chain corruption' '
+ git clone --no-hardlinks . verify-chain &&
+ (
+ cd verify-chain &&
+ corrupt_file "$graphdir/commit-graph-chain" 60 "G" &&
+ git commit-graph verify 2>test_err &&
+ grep -v "^+" test_err >err &&
+ test_i18ngrep "invalid commit-graph chain" err &&
+ corrupt_file "$graphdir/commit-graph-chain" 60 "A" &&
+ git commit-graph verify 2>test_err &&
+ grep -v "^+" test_err >err &&
+ test_i18ngrep "unable to find all commit-graph files" err
+ )
+'
+
+test_expect_success 'verify across alternates' '
+ git clone --no-hardlinks . verify-alt &&
+ (
+ cd verify-alt &&
+ rm -rf $graphdir &&
+ altdir="$(pwd)/../.git/objects" &&
+ echo "$altdir" >.git/objects/info/alternates &&
+ git commit-graph verify --object-dir="$altdir/" &&
+ test_commit extra &&
+ git commit-graph write --reachable --split &&
+ tip_file=$graphdir/graph-$(tail -n 1 $graphdir/commit-graph-chain).graph &&
+ corrupt_file "$tip_file" 100 "\01" &&
+ test_must_fail git commit-graph verify --shallow 2>test_err &&
+ grep -v "^+" test_err >err &&
+ test_i18ngrep "commit-graph has incorrect fanout value" err
+ )
+'
+
+test_expect_success 'add octopus merge' '
+ git reset --hard commits/10 &&
+ git merge commits/3 commits/4 &&
+ git branch merge/octopus &&
+ git commit-graph write --reachable --split &&
+ git commit-graph verify &&
+ test_line_count = 3 $graphdir/commit-graph-chain
+'
+
+graph_git_behavior 'graph exists' merge/octopus commits/12
+
+test_expect_success 'split across alternate where alternate is not split' '
+ git commit-graph write --reachable &&
+ test_path_is_file .git/objects/info/commit-graph &&
+ cp .git/objects/info/commit-graph . &&
+ git clone --no-hardlinks . alt-split &&
+ (
+ cd alt-split &&
+ echo "$(pwd)"/../.git/objects >.git/objects/info/alternates &&
+ test_commit 18 &&
+ git commit-graph write --reachable --split &&
+ test_line_count = 1 $graphdir/commit-graph-chain
+ ) &&
+ test_cmp commit-graph .git/objects/info/commit-graph
+'
+
+test_done