On 4/18/2018 8:02 PM, Jakub Narebski wrote:
Derrick Stolee <dsto...@microsoft.com> writes:Most code paths load commits using lookup_commit() and then parse_commit(). In some cases, including some branch lookups, the commit is parsed using parse_object_buffer() which side-steps parse_commit() in favor of parse_commit_buffer(). With generation numbers in the commit-graph, we need to ensure that any commit that exists in the commit-graph file has its generation number loaded.All right, that is nice explanation of the why behind this change.Create new load_commit_graph_info() method to fill in the information for a commit that exists only in the commit-graph file. Call it from parse_commit_buffer() after loading the other commit information from the given buffer. Only fill this information when specified by the 'check_graph' parameter. This avoids duplicate work when we already checked the graph in parse_commit_gently() or when simply checking the buffer contents in check_commit().Couldn't this 'check_graph' parameter be a global variable similar to the 'commit_graph' variable? Maybe I am not understanding it.
See the two callers at the bottom of the patch. They have different purposes: one needs to fill in a valid commit struct, the other needs to check the commit buffer is valid (then throws away the struct). They have different values for 'check_graph'. Also, in parse_commit_gently() we check parse_commit_in_graph() before we call parse_commit_buffer, so we do not want to repeat work; in the case of a valid commit-graph file, but the commit is not in the commit-graph, we would repeat our binary search for the same commit.
Signed-off-by: Derrick Stolee <dsto...@microsoft.com> --- commit-graph.c | 51 ++++++++++++++++++++++++++++++++------------------ commit-graph.h | 8 ++++++++ commit.c | 7 +++++-- commit.h | 2 +- object.c | 2 +- sha1_file.c | 2 +- 6 files changed, 49 insertions(+), 23 deletions(-) diff --git a/commit-graph.c b/commit-graph.c index 688d5b1801..21e853c21a 100644 --- a/commit-graph.c +++ b/commit-graph.c @@ -245,13 +245,19 @@ static struct commit_list **insert_parent_or_die(struct commit_graph *g, return &commit_list_insert(c, pptr)->next; }+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; + item->generation = get_be32(commit_data + g->hash_len + 8) >> 2; +} + static int fill_commit_in_graph(struct commit *item, struct commit_graph *g, uint32_t pos) { 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; + const unsigned char *commit_data = g->chunk_commit_data + GRAPH_DATA_WIDTH * pos;I'm probably wrong, but isn't it unrelated change?
You're right. I saw this while I was in here, and there was a similar comment on this change in a different patch. Probably best to keep these cleanup things in a separate commit.
item->object.parsed = 1; item->graph_pos = pos; @@ -292,31 +298,40 @@ static int fill_commit_in_graph(struct commit *item, struct commit_graph *g, uin return 1; }+static int find_commit_in_graph(struct commit *item, struct commit_graph *g, uint32_t *pos)+{ + if (item->graph_pos != COMMIT_NOT_FROM_GRAPH) { + *pos = item->graph_pos; + return 1; + } else { + return bsearch_graph(commit_graph, &(item->object.oid), pos); + } +}All right (after the fix).+ int parse_commit_in_graph(struct commit *item) { + uint32_t pos; + + if (item->object.parsed) + return 0; if (!core_commit_graph) return 0; - if (item->object.parsed) - return 1;Hmmm... previously the function returned 1 if item->object.parsed, now it returns 0 for this situation. I don't understand this change.
The good news is that this change is unimportant (the only caller is parse_commit_gently() which checks item->object.parsed before calling parse_commit_in_graph()). I wonder why I reordered those things, anyway. I'll revert to simplify the patch.
- 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); - } - + if (commit_graph && find_commit_in_graph(item, commit_graph, &pos)) + return fill_commit_in_graph(item, commit_graph, pos);Nice refactoring.return 0; }+void load_commit_graph_info(struct commit *item)+{ + uint32_t pos; + if (!core_commit_graph) + return; + prepare_commit_graph(); + if (commit_graph && find_commit_in_graph(item, commit_graph, &pos)) + fill_commit_graph_info(item, commit_graph, pos); +}And the reason for the refactoring.+ static struct tree *load_tree_for_commit(struct commit_graph *g, struct commit *c) { struct object_id oid; diff --git a/commit-graph.h b/commit-graph.h index 260a468e73..96cccb10f3 100644 --- a/commit-graph.h +++ b/commit-graph.h @@ -17,6 +17,14 @@ char *get_commit_graph_filename(const char *obj_dir); */ int parse_commit_in_graph(struct commit *item);+/*+ * It is possible that we loaded commit contents from the commit buffer, + * but we also want to ensure the commit-graph content is correctly + * checked and filled. Fill the graph_pos and generation members of + * the given commit. + */ +void load_commit_graph_info(struct commit *item); + struct tree *get_commit_tree_in_graph(const struct commit *c);struct commit_graph {diff --git a/commit.c b/commit.c index a70f120878..9ef6f699bd 100644 --- a/commit.c +++ b/commit.c @@ -331,7 +331,7 @@ const void *detach_commit_buffer(struct commit *commit, unsigned long *sizep) return ret; }-int parse_commit_buffer(struct commit *item, const void *buffer, unsigned long size)+int parse_commit_buffer(struct commit *item, const void *buffer, unsigned long size, int check_graph) { const char *tail = buffer; const char *bufptr = buffer; @@ -386,6 +386,9 @@ int parse_commit_buffer(struct commit *item, const void *buffer, unsigned long s } item->date = parse_commit_date(bufptr, tail);+ if (check_graph)+ load_commit_graph_info(item); + return 0; }@@ -412,7 +415,7 @@ int parse_commit_gently(struct commit *item, int quiet_on_missing)return error("Object %s not a commit", oid_to_hex(&item->object.oid)); } - ret = parse_commit_buffer(item, buffer, size); + ret = parse_commit_buffer(item, buffer, size, 0); if (save_commit_buffer && !ret) { set_commit_buffer(item, buffer, size); return 0; diff --git a/commit.h b/commit.h index 64436ff44e..b5afde1ae9 100644 --- a/commit.h +++ b/commit.h @@ -72,7 +72,7 @@ struct commit *lookup_commit_reference_by_name(const char *name); */ struct commit *lookup_commit_or_die(const struct object_id *oid, const char *ref_name);-int parse_commit_buffer(struct commit *item, const void *buffer, unsigned long size);+int parse_commit_buffer(struct commit *item, const void *buffer, unsigned long size, int check_graph); int parse_commit_gently(struct commit *item, int quiet_on_missing); static inline int parse_commit(struct commit *item) { diff --git a/object.c b/object.c index e6ad3f61f0..efe4871325 100644 --- a/object.c +++ b/object.c @@ -207,7 +207,7 @@ struct object *parse_object_buffer(const struct object_id *oid, enum object_type } else if (type == OBJ_COMMIT) { struct commit *commit = lookup_commit(oid); if (commit) { - if (parse_commit_buffer(commit, buffer, size)) + if (parse_commit_buffer(commit, buffer, size, 1)) return NULL; if (!get_cached_commit_buffer(commit, NULL)) { set_commit_buffer(commit, buffer, size); diff --git a/sha1_file.c b/sha1_file.c index 1b94f39c4c..0fd4f0b8b6 100644 --- a/sha1_file.c +++ b/sha1_file.c @@ -1755,7 +1755,7 @@ static void check_commit(const void *buf, size_t size) { struct commit c; memset(&c, 0, sizeof(c)); - if (parse_commit_buffer(&c, buf, size)) + if (parse_commit_buffer(&c, buf, size, 0)) die("corrupt commit"); }
