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v0.7.0
v0.7.0
Revision cb99a34e23e32ca8e94bafaa9699cfd133a17fd3 authored by Derrick Stolee on 24 October 2019, 13:40:42 UTC, committed by Junio C Hamano on 25 October 2019, 02:19:16 UTC
The previous commit includes a failing test for an issue around fetch.writeCommitGraph and fetching in a repo with a submodule. Here, we fix that bug and set the test to "test_expect_success". The problem arises with this set of commands when the remote repo at <url> has a submodule. Note that --recurse-submodules is not needed to demonstrate the bug. $ git clone <url> test $ cd test $ git -c fetch.writeCommitGraph=true fetch origin Computing commit graph generation numbers: 100% (12/12), done. BUG: commit-graph.c:886: missing parent <hash1> for commit <hash2> Aborted (core dumped) As an initial fix, I converted the code in builtin/fetch.c that calls write_commit_graph_reachable() to instead launch a "git commit-graph write --reachable --split" process. That code worked, but is not how we want the feature to work long-term. That test did demonstrate that the issue must be something to do with internal state of the 'git fetch' process. The write_commit_graph() method in commit-graph.c ensures the commits we plan to write are "closed under reachability" using close_reachable(). This method walks from the input commits, and uses the UNINTERESTING flag to mark which commits have already been visited. This allows the walk to take O(N) time, where N is the number of commits, instead of O(P) time, where P is the number of paths. (The number of paths can be exponential in the number of commits.) However, the UNINTERESTING flag is used in lots of places in the codebase. This flag usually means some barrier to stop a commit walk, such as in revision-walking to compare histories. It is not often cleared after the walk completes because the starting points of those walks do not have the UNINTERESTING flag, and clear_commit_marks() would stop immediately. This is happening during a 'git fetch' call with a remote. The fetch negotiation is comparing the remote refs with the local refs and marking some commits as UNINTERESTING. I tested running clear_commit_marks_many() to clear the UNINTERESTING flag inside close_reachable(), but the tips did not have the flag, so that did nothing. It turns out that the calculate_changed_submodule_paths() method is at fault. Thanks, Peff, for pointing out this detail! More specifically, for each submodule, the collect_changed_submodules() runs a revision walk to essentially do file-history on the list of submodules. That revision walk marks commits UNININTERESTING if they are simplified away by not changing the submodule. Instead, I finally arrived on the conclusion that I should use a flag that is not used in any other part of the code. In commit-reach.c, a number of flags were defined for commit walk algorithms. The REACHABLE flag seemed like it made the most sense, and it seems it was not actually used in the file. The REACHABLE flag was used in early versions of commit-reach.c, but was removed by 4fbcca4 (commit-reach: make can_all_from_reach... linear, 2018-07-20). Add the REACHABLE flag to commit-graph.c and use it instead of UNINTERESTING in close_reachable(). This fixes the bug in manual testing. Reported-by: Johannes Schindelin <johannes.schindelin@gmx.de> Helped-by: Jeff King <peff@peff.net> Helped-by: Szeder Gábor <szeder.dev@gmail.com> Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
1 parent e88aab9
commit-graph.h
#ifndef COMMIT_GRAPH_H
#define COMMIT_GRAPH_H
#include "git-compat-util.h"
#include "repository.h"
#include "string-list.h"
#include "cache.h"
#define GIT_TEST_COMMIT_GRAPH "GIT_TEST_COMMIT_GRAPH"
#define GIT_TEST_COMMIT_GRAPH_DIE_ON_LOAD "GIT_TEST_COMMIT_GRAPH_DIE_ON_LOAD"
struct commit;
char *get_commit_graph_filename(const char *obj_dir);
int open_commit_graph(const char *graph_file, int *fd, struct stat *st);
/*
* 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 repository *r, 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 repository *r, struct commit *item);
struct tree *get_commit_tree_in_graph(struct repository *r,
const struct commit *c);
struct commit_graph {
int graph_fd;
const unsigned char *data;
size_t data_len;
unsigned char hash_len;
unsigned char num_chunks;
uint32_t num_commits;
struct object_id oid;
char *filename;
const char *obj_dir;
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;
const unsigned char *chunk_extra_edges;
const unsigned char *chunk_base_graphs;
};
struct commit_graph *load_commit_graph_one_fd_st(int fd, struct stat *st);
struct commit_graph *read_commit_graph_one(struct repository *r, const char *obj_dir);
struct commit_graph *parse_commit_graph(void *graph_map, int fd,
size_t graph_size);
/*
* Return 1 if and only if the repository has a commit-graph
* file and generation numbers are computed in that file.
*/
int generation_numbers_enabled(struct repository *r);
#define COMMIT_GRAPH_APPEND (1 << 0)
#define COMMIT_GRAPH_PROGRESS (1 << 1)
#define COMMIT_GRAPH_SPLIT (1 << 2)
struct split_commit_graph_opts {
int size_multiple;
int max_commits;
timestamp_t expire_time;
};
/*
* The write_commit_graph* methods return zero on success
* and a negative value on failure. Note that if the repository
* is not compatible with the commit-graph feature, then the
* methods will return 0 without writing a commit-graph.
*/
int write_commit_graph_reachable(const char *obj_dir, unsigned int flags,
const struct split_commit_graph_opts *split_opts);
int write_commit_graph(const char *obj_dir,
struct string_list *pack_indexes,
struct string_list *commit_hex,
unsigned int flags,
const struct split_commit_graph_opts *split_opts);
#define COMMIT_GRAPH_VERIFY_SHALLOW (1 << 0)
int verify_commit_graph(struct repository *r, struct commit_graph *g, int flags);
void close_commit_graph(struct raw_object_store *);
void free_commit_graph(struct commit_graph *);
#endif
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