git-commit-vandalism/builtin/rev-list.c
Vicent Marti aa32939fea rev-list: add bitmap mode to speed up object lists
The bitmap reachability index used to speed up the counting objects
phase during `pack-objects` can also be used to optimize a normal
rev-list if the only thing required are the SHA1s of the objects during
the list (i.e., not the path names at which trees and blobs were found).

Calling `git rev-list --objects --use-bitmap-index [committish]` will
perform an object iteration based on a bitmap result instead of actually
walking the object graph.

These are some example timings for `torvalds/linux` (warm cache,
best-of-five):

    $ time git rev-list --objects master > /dev/null

    real    0m34.191s
    user    0m33.904s
    sys     0m0.268s

    $ time git rev-list --objects --use-bitmap-index master > /dev/null

    real    0m1.041s
    user    0m0.976s
    sys     0m0.064s

Likewise, using `git rev-list --count --use-bitmap-index` will speed up
the counting operation by building the resulting bitmap and performing a
fast popcount (number of bits set on the bitmap) on the result.

Here are some sample timings of different ways to count commits in
`torvalds/linux`:

    $ time git rev-list master | wc -l
        399882

        real    0m6.524s
        user    0m6.060s
        sys     0m3.284s

    $ time git rev-list --count master
        399882

        real    0m4.318s
        user    0m4.236s
        sys     0m0.076s

    $ time git rev-list --use-bitmap-index --count master
        399882

        real    0m0.217s
        user    0m0.176s
        sys     0m0.040s

This also respects negative refs, so you can use it to count
a slice of history:

        $ time git rev-list --count v3.0..master
        144843

        real    0m1.971s
        user    0m1.932s
        sys     0m0.036s

        $ time git rev-list --use-bitmap-index --count v3.0..master
        real    0m0.280s
        user    0m0.220s
        sys     0m0.056s

Though note that the closer the endpoints, the less it helps. In the
traversal case, we have fewer commits to cross, so we take less time.
But the bitmap time is dominated by generating the pack revindex, which
is constant with respect to the refs given.

Note that you cannot yet get a fast --left-right count of a symmetric
difference (e.g., "--count --left-right master...topic"). The slow part
of that walk actually happens during the merge-base determination when
we parse "master...topic". Even though a count does not actually need to
know the real merge base (it only needs to take the symmetric difference
of the bitmaps), the revision code would require some refactoring to
handle this case.

Additionally, a `--test-bitmap` flag has been added that will perform
the same rev-list manually (i.e. using a normal revwalk) and using
bitmaps, and verify that the results are the same. This can be used to
exercise the bitmap code, and also to verify that the contents of the
.bitmap file are sane.

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>
2013-12-30 12:19:22 -08:00

405 lines
10 KiB
C

#include "cache.h"
#include "commit.h"
#include "diff.h"
#include "revision.h"
#include "list-objects.h"
#include "pack.h"
#include "pack-bitmap.h"
#include "builtin.h"
#include "log-tree.h"
#include "graph.h"
#include "bisect.h"
static const char rev_list_usage[] =
"git rev-list [OPTION] <commit-id>... [ -- paths... ]\n"
" limiting output:\n"
" --max-count=<n>\n"
" --max-age=<epoch>\n"
" --min-age=<epoch>\n"
" --sparse\n"
" --no-merges\n"
" --min-parents=<n>\n"
" --no-min-parents\n"
" --max-parents=<n>\n"
" --no-max-parents\n"
" --remove-empty\n"
" --all\n"
" --branches\n"
" --tags\n"
" --remotes\n"
" --stdin\n"
" --quiet\n"
" ordering output:\n"
" --topo-order\n"
" --date-order\n"
" --reverse\n"
" formatting output:\n"
" --parents\n"
" --children\n"
" --objects | --objects-edge\n"
" --unpacked\n"
" --header | --pretty\n"
" --abbrev=<n> | --no-abbrev\n"
" --abbrev-commit\n"
" --left-right\n"
" special purpose:\n"
" --bisect\n"
" --bisect-vars\n"
" --bisect-all"
;
static void finish_commit(struct commit *commit, void *data);
static void show_commit(struct commit *commit, void *data)
{
struct rev_list_info *info = data;
struct rev_info *revs = info->revs;
if (info->flags & REV_LIST_QUIET) {
finish_commit(commit, data);
return;
}
graph_show_commit(revs->graph);
if (revs->count) {
if (commit->object.flags & PATCHSAME)
revs->count_same++;
else if (commit->object.flags & SYMMETRIC_LEFT)
revs->count_left++;
else
revs->count_right++;
finish_commit(commit, data);
return;
}
if (info->show_timestamp)
printf("%lu ", commit->date);
if (info->header_prefix)
fputs(info->header_prefix, stdout);
if (!revs->graph)
fputs(get_revision_mark(revs, commit), stdout);
if (revs->abbrev_commit && revs->abbrev)
fputs(find_unique_abbrev(commit->object.sha1, revs->abbrev),
stdout);
else
fputs(sha1_to_hex(commit->object.sha1), stdout);
if (revs->print_parents) {
struct commit_list *parents = commit->parents;
while (parents) {
printf(" %s", sha1_to_hex(parents->item->object.sha1));
parents = parents->next;
}
}
if (revs->children.name) {
struct commit_list *children;
children = lookup_decoration(&revs->children, &commit->object);
while (children) {
printf(" %s", sha1_to_hex(children->item->object.sha1));
children = children->next;
}
}
show_decorations(revs, commit);
if (revs->commit_format == CMIT_FMT_ONELINE)
putchar(' ');
else
putchar('\n');
if (revs->verbose_header && commit->buffer) {
struct strbuf buf = STRBUF_INIT;
struct pretty_print_context ctx = {0};
ctx.abbrev = revs->abbrev;
ctx.date_mode = revs->date_mode;
ctx.date_mode_explicit = revs->date_mode_explicit;
ctx.fmt = revs->commit_format;
ctx.output_encoding = get_log_output_encoding();
pretty_print_commit(&ctx, commit, &buf);
if (revs->graph) {
if (buf.len) {
if (revs->commit_format != CMIT_FMT_ONELINE)
graph_show_oneline(revs->graph);
graph_show_commit_msg(revs->graph, &buf);
/*
* Add a newline after the commit message.
*
* Usually, this newline produces a blank
* padding line between entries, in which case
* we need to add graph padding on this line.
*
* However, the commit message may not end in a
* newline. In this case the newline simply
* ends the last line of the commit message,
* and we don't need any graph output. (This
* always happens with CMIT_FMT_ONELINE, and it
* happens with CMIT_FMT_USERFORMAT when the
* format doesn't explicitly end in a newline.)
*/
if (buf.len && buf.buf[buf.len - 1] == '\n')
graph_show_padding(revs->graph);
putchar('\n');
} else {
/*
* If the message buffer is empty, just show
* the rest of the graph output for this
* commit.
*/
if (graph_show_remainder(revs->graph))
putchar('\n');
if (revs->commit_format == CMIT_FMT_ONELINE)
putchar('\n');
}
} else {
if (revs->commit_format != CMIT_FMT_USERFORMAT ||
buf.len) {
fwrite(buf.buf, 1, buf.len, stdout);
putchar(info->hdr_termination);
}
}
strbuf_release(&buf);
} else {
if (graph_show_remainder(revs->graph))
putchar('\n');
}
maybe_flush_or_die(stdout, "stdout");
finish_commit(commit, data);
}
static void finish_commit(struct commit *commit, void *data)
{
if (commit->parents) {
free_commit_list(commit->parents);
commit->parents = NULL;
}
free(commit->buffer);
commit->buffer = NULL;
}
static void finish_object(struct object *obj,
const struct name_path *path, const char *name,
void *cb_data)
{
struct rev_list_info *info = cb_data;
if (obj->type == OBJ_BLOB && !has_sha1_file(obj->sha1))
die("missing blob object '%s'", sha1_to_hex(obj->sha1));
if (info->revs->verify_objects && !obj->parsed && obj->type != OBJ_COMMIT)
parse_object(obj->sha1);
}
static void show_object(struct object *obj,
const struct name_path *path, const char *component,
void *cb_data)
{
struct rev_list_info *info = cb_data;
finish_object(obj, path, component, cb_data);
if (info->flags & REV_LIST_QUIET)
return;
show_object_with_name(stdout, obj, path, component);
}
static void show_edge(struct commit *commit)
{
printf("-%s\n", sha1_to_hex(commit->object.sha1));
}
static void print_var_str(const char *var, const char *val)
{
printf("%s='%s'\n", var, val);
}
static void print_var_int(const char *var, int val)
{
printf("%s=%d\n", var, val);
}
static int show_bisect_vars(struct rev_list_info *info, int reaches, int all)
{
int cnt, flags = info->flags;
char hex[41] = "";
struct commit_list *tried;
struct rev_info *revs = info->revs;
if (!revs->commits)
return 1;
revs->commits = filter_skipped(revs->commits, &tried,
flags & BISECT_SHOW_ALL,
NULL, NULL);
/*
* revs->commits can reach "reaches" commits among
* "all" commits. If it is good, then there are
* (all-reaches) commits left to be bisected.
* On the other hand, if it is bad, then the set
* to bisect is "reaches".
* A bisect set of size N has (N-1) commits further
* to test, as we already know one bad one.
*/
cnt = all - reaches;
if (cnt < reaches)
cnt = reaches;
if (revs->commits)
strcpy(hex, sha1_to_hex(revs->commits->item->object.sha1));
if (flags & BISECT_SHOW_ALL) {
traverse_commit_list(revs, show_commit, show_object, info);
printf("------\n");
}
print_var_str("bisect_rev", hex);
print_var_int("bisect_nr", cnt - 1);
print_var_int("bisect_good", all - reaches - 1);
print_var_int("bisect_bad", reaches - 1);
print_var_int("bisect_all", all);
print_var_int("bisect_steps", estimate_bisect_steps(all));
return 0;
}
static int show_object_fast(
const unsigned char *sha1,
enum object_type type,
int exclude,
uint32_t name_hash,
struct packed_git *found_pack,
off_t found_offset)
{
fprintf(stdout, "%s\n", sha1_to_hex(sha1));
return 1;
}
int cmd_rev_list(int argc, const char **argv, const char *prefix)
{
struct rev_info revs;
struct rev_list_info info;
int i;
int bisect_list = 0;
int bisect_show_vars = 0;
int bisect_find_all = 0;
int use_bitmap_index = 0;
git_config(git_default_config, NULL);
init_revisions(&revs, prefix);
revs.abbrev = DEFAULT_ABBREV;
revs.commit_format = CMIT_FMT_UNSPECIFIED;
argc = setup_revisions(argc, argv, &revs, NULL);
memset(&info, 0, sizeof(info));
info.revs = &revs;
if (revs.bisect)
bisect_list = 1;
if (DIFF_OPT_TST(&revs.diffopt, QUICK))
info.flags |= REV_LIST_QUIET;
for (i = 1 ; i < argc; i++) {
const char *arg = argv[i];
if (!strcmp(arg, "--header")) {
revs.verbose_header = 1;
continue;
}
if (!strcmp(arg, "--timestamp")) {
info.show_timestamp = 1;
continue;
}
if (!strcmp(arg, "--bisect")) {
bisect_list = 1;
continue;
}
if (!strcmp(arg, "--bisect-all")) {
bisect_list = 1;
bisect_find_all = 1;
info.flags |= BISECT_SHOW_ALL;
revs.show_decorations = 1;
continue;
}
if (!strcmp(arg, "--bisect-vars")) {
bisect_list = 1;
bisect_show_vars = 1;
continue;
}
if (!strcmp(arg, "--use-bitmap-index")) {
use_bitmap_index = 1;
continue;
}
if (!strcmp(arg, "--test-bitmap")) {
test_bitmap_walk(&revs);
return 0;
}
usage(rev_list_usage);
}
if (revs.commit_format != CMIT_FMT_UNSPECIFIED) {
/* The command line has a --pretty */
info.hdr_termination = '\n';
if (revs.commit_format == CMIT_FMT_ONELINE)
info.header_prefix = "";
else
info.header_prefix = "commit ";
}
else if (revs.verbose_header)
/* Only --header was specified */
revs.commit_format = CMIT_FMT_RAW;
if ((!revs.commits &&
(!(revs.tag_objects||revs.tree_objects||revs.blob_objects) &&
!revs.pending.nr)) ||
revs.diff)
usage(rev_list_usage);
save_commit_buffer = (revs.verbose_header ||
revs.grep_filter.pattern_list ||
revs.grep_filter.header_list);
if (bisect_list)
revs.limited = 1;
if (use_bitmap_index) {
if (revs.count && !revs.left_right && !revs.cherry_mark) {
uint32_t commit_count;
if (!prepare_bitmap_walk(&revs)) {
count_bitmap_commit_list(&commit_count, NULL, NULL, NULL);
printf("%d\n", commit_count);
return 0;
}
} else if (revs.tag_objects && revs.tree_objects && revs.blob_objects) {
if (!prepare_bitmap_walk(&revs)) {
traverse_bitmap_commit_list(&show_object_fast);
return 0;
}
}
}
if (prepare_revision_walk(&revs))
die("revision walk setup failed");
if (revs.tree_objects)
mark_edges_uninteresting(&revs, show_edge);
if (bisect_list) {
int reaches = reaches, all = all;
revs.commits = find_bisection(revs.commits, &reaches, &all,
bisect_find_all);
if (bisect_show_vars)
return show_bisect_vars(&info, reaches, all);
}
traverse_commit_list(&revs, show_commit, show_object, &info);
if (revs.count) {
if (revs.left_right && revs.cherry_mark)
printf("%d\t%d\t%d\n", revs.count_left, revs.count_right, revs.count_same);
else if (revs.left_right)
printf("%d\t%d\n", revs.count_left, revs.count_right);
else if (revs.cherry_mark)
printf("%d\t%d\n", revs.count_left + revs.count_right, revs.count_same);
else
printf("%d\n", revs.count_left + revs.count_right);
}
return 0;
}