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git/revision.h
Vicent Marti 2db1a43f41 add ignore_missing_links mode to revwalk
When pack-objects is computing the reachability bitmap to
serve a fetch request, it can erroneously die() if some of
the UNINTERESTING objects are not present. Upload-pack
throws away HAVE lines from the client for objects we do not
have, but we may have a tip object without all of its
ancestors (e.g., if the tip is no longer reachable and was
new enough to survive a `git prune`, but some of its
reachable objects did get pruned).

In the non-bitmap case, we do a revision walk with the HAVE
objects marked as UNINTERESTING. The revision walker
explicitly ignores errors in accessing UNINTERESTING commits
to handle this case (and we do not bother looking at
UNINTERESTING trees or blobs at all).

When we have bitmaps, however, the process is quite
different.  The bitmap index for a pack-objects run is
calculated in two separate steps:

First, we perform an extensive walk from all the HAVEs to
find the full set of objects reachable from them. This walk
is usually optimized away because we are expected to hit an
object with a bitmap during the traversal, which allows us
to terminate early.

Secondly, we perform an extensive walk from all the WANTs,
which usually also terminates early because we hit a commit
with an existing bitmap.

Once we have the resulting bitmaps from the two walks, we
AND-NOT them together to obtain the resulting set of objects
we need to pack.

When we are walking the HAVE objects, the revision walker
does not know that we are walking it only to mark the
results as uninteresting. We strip out the UNINTERESTING flag,
because those objects _are_ interesting to us during the
first walk. We want to keep going to get a complete set of
reachable objects if we can.

We need some way to tell the revision walker that it's OK to
silently truncate the HAVE walk, just like it does for the
UNINTERESTING case. This patch introduces a new
`ignore_missing_links` flag to the `rev_info` struct, which
we set only for the HAVE walk.

It also adds tests to cover UNINTERESTING objects missing
from several positions: a missing blob, a missing tree, and
a missing parent commit. The missing blob already worked (as
we do not care about its contents at all), but the other two
cases caused us to die().

Note that there are a few cases we do not need to test:

  1. We do not need to test a missing tree, with the blob
     still present. Without the tree that refers to it, we
     would not know that the blob is relevant to our walk.

  2. We do not need to test a tip commit that is missing.
     Upload-pack omits these for us (and in fact, we
     complain even in the non-bitmap case if it fails to do
     so).

Reported-by: Siddharth Agarwal <sid0@fb.com>
Signed-off-by: Vicent Marti <tanoku@gmail.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-04-04 13:31:38 -07:00

300 lines
7.4 KiB
C

#ifndef REVISION_H
#define REVISION_H
#include "parse-options.h"
#include "grep.h"
#include "notes.h"
#include "commit.h"
#define SEEN (1u<<0)
#define UNINTERESTING (1u<<1)
#define TREESAME (1u<<2)
#define SHOWN (1u<<3)
#define TMP_MARK (1u<<4) /* for isolated cases; clean after use */
#define BOUNDARY (1u<<5)
#define CHILD_SHOWN (1u<<6)
#define ADDED (1u<<7) /* Parents already parsed and added? */
#define SYMMETRIC_LEFT (1u<<8)
#define PATCHSAME (1u<<9)
#define BOTTOM (1u<<10)
#define ALL_REV_FLAGS ((1u<<11)-1)
#define DECORATE_SHORT_REFS 1
#define DECORATE_FULL_REFS 2
struct rev_info;
struct log_info;
struct string_list;
struct saved_parents;
struct rev_cmdline_info {
unsigned int nr;
unsigned int alloc;
struct rev_cmdline_entry {
struct object *item;
const char *name;
enum {
REV_CMD_REF,
REV_CMD_PARENTS_ONLY,
REV_CMD_LEFT,
REV_CMD_RIGHT,
REV_CMD_MERGE_BASE,
REV_CMD_REV
} whence;
unsigned flags;
} *rev;
};
#define REVISION_WALK_WALK 0
#define REVISION_WALK_NO_WALK_SORTED 1
#define REVISION_WALK_NO_WALK_UNSORTED 2
struct rev_info {
/* Starting list */
struct commit_list *commits;
struct object_array pending;
/* Parents of shown commits */
struct object_array boundary_commits;
/* The end-points specified by the end user */
struct rev_cmdline_info cmdline;
/* Basic information */
const char *prefix;
const char *def;
struct pathspec prune_data;
/* topo-sort */
enum rev_sort_order sort_order;
unsigned int early_output:1,
ignore_missing:1,
ignore_missing_links:1;
/* Traversal flags */
unsigned int dense:1,
prune:1,
no_walk:2,
show_all:1,
remove_empty_trees:1,
simplify_history:1,
topo_order:1,
simplify_merges:1,
simplify_by_decoration:1,
tag_objects:1,
tree_objects:1,
blob_objects:1,
verify_objects:1,
edge_hint:1,
limited:1,
unpacked:1,
boundary:2,
count:1,
left_right:1,
left_only:1,
right_only:1,
rewrite_parents:1,
print_parents:1,
show_source:1,
show_decorations:1,
reverse:1,
reverse_output_stage:1,
cherry_pick:1,
cherry_mark:1,
bisect:1,
ancestry_path:1,
first_parent_only:1,
line_level_traverse:1;
/* Diff flags */
unsigned int diff:1,
full_diff:1,
show_root_diff:1,
no_commit_id:1,
verbose_header:1,
ignore_merges:1,
combine_merges:1,
dense_combined_merges:1,
always_show_header:1;
/* Format info */
unsigned int shown_one:1,
shown_dashes:1,
show_merge:1,
show_notes:1,
show_notes_given:1,
show_signature:1,
pretty_given:1,
abbrev_commit:1,
abbrev_commit_given:1,
use_terminator:1,
missing_newline:1,
date_mode_explicit:1,
preserve_subject:1;
unsigned int disable_stdin:1;
unsigned int leak_pending:1;
enum date_mode date_mode;
unsigned int abbrev;
enum cmit_fmt commit_format;
struct log_info *loginfo;
int nr, total;
const char *mime_boundary;
const char *patch_suffix;
int numbered_files;
int reroll_count;
char *message_id;
struct ident_split from_ident;
struct string_list *ref_message_ids;
int add_signoff;
const char *extra_headers;
const char *log_reencode;
const char *subject_prefix;
int no_inline;
int show_log_size;
struct string_list *mailmap;
/* Filter by commit log message */
struct grep_opt grep_filter;
/* Display history graph */
struct git_graph *graph;
/* special limits */
int skip_count;
int max_count;
unsigned long max_age;
unsigned long min_age;
int min_parents;
int max_parents;
int (*include_check)(struct commit *, void *);
void *include_check_data;
/* diff info for patches and for paths limiting */
struct diff_options diffopt;
struct diff_options pruning;
struct reflog_walk_info *reflog_info;
struct decoration children;
struct decoration merge_simplification;
struct decoration treesame;
/* notes-specific options: which refs to show */
struct display_notes_opt notes_opt;
/* commit counts */
int count_left;
int count_right;
int count_same;
/* line level range that we are chasing */
struct decoration line_log_data;
/* copies of the parent lists, for --full-diff display */
struct saved_parents *saved_parents_slab;
};
#define REV_TREE_SAME 0
#define REV_TREE_NEW 1 /* Only new files */
#define REV_TREE_OLD 2 /* Only files removed */
#define REV_TREE_DIFFERENT 3 /* Mixed changes */
/* revision.c */
typedef void (*show_early_output_fn_t)(struct rev_info *, struct commit_list *);
extern volatile show_early_output_fn_t show_early_output;
struct setup_revision_opt {
const char *def;
void (*tweak)(struct rev_info *, struct setup_revision_opt *);
const char *submodule;
int assume_dashdash;
unsigned revarg_opt;
};
extern void init_revisions(struct rev_info *revs, const char *prefix);
extern int setup_revisions(int argc, const char **argv, struct rev_info *revs,
struct setup_revision_opt *);
extern void parse_revision_opt(struct rev_info *revs, struct parse_opt_ctx_t *ctx,
const struct option *options,
const char * const usagestr[]);
#define REVARG_CANNOT_BE_FILENAME 01
#define REVARG_COMMITTISH 02
extern int handle_revision_arg(const char *arg, struct rev_info *revs,
int flags, unsigned revarg_opt);
extern void reset_revision_walk(void);
extern int prepare_revision_walk(struct rev_info *revs);
extern struct commit *get_revision(struct rev_info *revs);
extern char *get_revision_mark(const struct rev_info *revs,
const struct commit *commit);
extern void put_revision_mark(const struct rev_info *revs,
const struct commit *commit);
extern void mark_parents_uninteresting(struct commit *commit);
extern void mark_tree_uninteresting(struct tree *tree);
struct name_path {
struct name_path *up;
int elem_len;
const char *elem;
};
char *path_name(const struct name_path *path, const char *name);
extern void show_object_with_name(FILE *, struct object *,
const struct name_path *, const char *);
extern void add_object(struct object *obj,
struct object_array *p,
struct name_path *path,
const char *name);
extern void add_pending_object(struct rev_info *revs,
struct object *obj, const char *name);
extern void add_pending_sha1(struct rev_info *revs,
const char *name, const unsigned char *sha1,
unsigned int flags);
extern void add_head_to_pending(struct rev_info *);
enum commit_action {
commit_ignore,
commit_show,
commit_error
};
extern enum commit_action get_commit_action(struct rev_info *revs,
struct commit *commit);
extern enum commit_action simplify_commit(struct rev_info *revs,
struct commit *commit);
enum rewrite_result {
rewrite_one_ok,
rewrite_one_noparents,
rewrite_one_error
};
typedef enum rewrite_result (*rewrite_parent_fn_t)(struct rev_info *revs, struct commit **pp);
extern int rewrite_parents(struct rev_info *revs, struct commit *commit,
rewrite_parent_fn_t rewrite_parent);
/*
* Save a copy of the parent list, and return the saved copy. This is
* used by the log machinery to retrieve the original parents when
* commit->parents has been modified by history simpification.
*
* You may only call save_parents() once per commit (this is checked
* for non-root commits).
*
* get_saved_parents() will transparently return commit->parents if
* history simplification is off.
*/
extern void save_parents(struct rev_info *revs, struct commit *commit);
extern struct commit_list *get_saved_parents(struct rev_info *revs, const struct commit *commit);
extern void free_saved_parents(struct rev_info *revs);
#endif