diff options
Diffstat (limited to 'bisect.c')
| -rw-r--r-- | bisect.c | 556 |
1 files changed, 556 insertions, 0 deletions
diff --git a/bisect.c b/bisect.c new file mode 100644 index 0000000..58f7e6f --- /dev/null +++ b/bisect.c @@ -0,0 +1,556 @@ +#include "cache.h" +#include "commit.h" +#include "diff.h" +#include "revision.h" +#include "refs.h" +#include "list-objects.h" +#include "quote.h" +#include "sha1-lookup.h" +#include "bisect.h" + +static unsigned char (*skipped_sha1)[20]; +static int skipped_sha1_nr; +static int skipped_sha1_alloc; + +static const char **rev_argv; +static int rev_argv_nr; +static int rev_argv_alloc; + +/* bits #0-15 in revision.h */ + +#define COUNTED (1u<<16) + +/* + * This is a truly stupid algorithm, but it's only + * used for bisection, and we just don't care enough. + * + * We care just barely enough to avoid recursing for + * non-merge entries. + */ +static int count_distance(struct commit_list *entry) +{ + int nr = 0; + + while (entry) { + struct commit *commit = entry->item; + struct commit_list *p; + + if (commit->object.flags & (UNINTERESTING | COUNTED)) + break; + if (!(commit->object.flags & TREESAME)) + nr++; + commit->object.flags |= COUNTED; + p = commit->parents; + entry = p; + if (p) { + p = p->next; + while (p) { + nr += count_distance(p); + p = p->next; + } + } + } + + return nr; +} + +static void clear_distance(struct commit_list *list) +{ + while (list) { + struct commit *commit = list->item; + commit->object.flags &= ~COUNTED; + list = list->next; + } +} + +#define DEBUG_BISECT 0 + +static inline int weight(struct commit_list *elem) +{ + return *((int*)(elem->item->util)); +} + +static inline void weight_set(struct commit_list *elem, int weight) +{ + *((int*)(elem->item->util)) = weight; +} + +static int count_interesting_parents(struct commit *commit) +{ + struct commit_list *p; + int count; + + for (count = 0, p = commit->parents; p; p = p->next) { + if (p->item->object.flags & UNINTERESTING) + continue; + count++; + } + return count; +} + +static inline int halfway(struct commit_list *p, int nr) +{ + /* + * Don't short-cut something we are not going to return! + */ + if (p->item->object.flags & TREESAME) + return 0; + if (DEBUG_BISECT) + return 0; + /* + * 2 and 3 are halfway of 5. + * 3 is halfway of 6 but 2 and 4 are not. + */ + switch (2 * weight(p) - nr) { + case -1: case 0: case 1: + return 1; + default: + return 0; + } +} + +#if !DEBUG_BISECT +#define show_list(a,b,c,d) do { ; } while (0) +#else +static void show_list(const char *debug, int counted, int nr, + struct commit_list *list) +{ + struct commit_list *p; + + fprintf(stderr, "%s (%d/%d)\n", debug, counted, nr); + + for (p = list; p; p = p->next) { + struct commit_list *pp; + struct commit *commit = p->item; + unsigned flags = commit->object.flags; + enum object_type type; + unsigned long size; + char *buf = read_sha1_file(commit->object.sha1, &type, &size); + char *ep, *sp; + + fprintf(stderr, "%c%c%c ", + (flags & TREESAME) ? ' ' : 'T', + (flags & UNINTERESTING) ? 'U' : ' ', + (flags & COUNTED) ? 'C' : ' '); + if (commit->util) + fprintf(stderr, "%3d", weight(p)); + else + fprintf(stderr, "---"); + fprintf(stderr, " %.*s", 8, sha1_to_hex(commit->object.sha1)); + for (pp = commit->parents; pp; pp = pp->next) + fprintf(stderr, " %.*s", 8, + sha1_to_hex(pp->item->object.sha1)); + + sp = strstr(buf, "\n\n"); + if (sp) { + sp += 2; + for (ep = sp; *ep && *ep != '\n'; ep++) + ; + fprintf(stderr, " %.*s", (int)(ep - sp), sp); + } + fprintf(stderr, "\n"); + } +} +#endif /* DEBUG_BISECT */ + +static struct commit_list *best_bisection(struct commit_list *list, int nr) +{ + struct commit_list *p, *best; + int best_distance = -1; + + best = list; + for (p = list; p; p = p->next) { + int distance; + unsigned flags = p->item->object.flags; + + if (flags & TREESAME) + continue; + distance = weight(p); + if (nr - distance < distance) + distance = nr - distance; + if (distance > best_distance) { + best = p; + best_distance = distance; + } + } + + return best; +} + +struct commit_dist { + struct commit *commit; + int distance; +}; + +static int compare_commit_dist(const void *a_, const void *b_) +{ + struct commit_dist *a, *b; + + a = (struct commit_dist *)a_; + b = (struct commit_dist *)b_; + if (a->distance != b->distance) + return b->distance - a->distance; /* desc sort */ + return hashcmp(a->commit->object.sha1, b->commit->object.sha1); +} + +static struct commit_list *best_bisection_sorted(struct commit_list *list, int nr) +{ + struct commit_list *p; + struct commit_dist *array = xcalloc(nr, sizeof(*array)); + int cnt, i; + + for (p = list, cnt = 0; p; p = p->next) { + int distance; + unsigned flags = p->item->object.flags; + + if (flags & TREESAME) + continue; + distance = weight(p); + if (nr - distance < distance) + distance = nr - distance; + array[cnt].commit = p->item; + array[cnt].distance = distance; + cnt++; + } + qsort(array, cnt, sizeof(*array), compare_commit_dist); + for (p = list, i = 0; i < cnt; i++) { + struct name_decoration *r = xmalloc(sizeof(*r) + 100); + struct object *obj = &(array[i].commit->object); + + sprintf(r->name, "dist=%d", array[i].distance); + r->next = add_decoration(&name_decoration, obj, r); + p->item = array[i].commit; + p = p->next; + } + if (p) + p->next = NULL; + free(array); + return list; +} + +/* + * zero or positive weight is the number of interesting commits it can + * reach, including itself. Especially, weight = 0 means it does not + * reach any tree-changing commits (e.g. just above uninteresting one + * but traversal is with pathspec). + * + * weight = -1 means it has one parent and its distance is yet to + * be computed. + * + * weight = -2 means it has more than one parent and its distance is + * unknown. After running count_distance() first, they will get zero + * or positive distance. + */ +static struct commit_list *do_find_bisection(struct commit_list *list, + int nr, int *weights, + int find_all) +{ + int n, counted; + struct commit_list *p; + + counted = 0; + + for (n = 0, p = list; p; p = p->next) { + struct commit *commit = p->item; + unsigned flags = commit->object.flags; + + p->item->util = &weights[n++]; + switch (count_interesting_parents(commit)) { + case 0: + if (!(flags & TREESAME)) { + weight_set(p, 1); + counted++; + show_list("bisection 2 count one", + counted, nr, list); + } + /* + * otherwise, it is known not to reach any + * tree-changing commit and gets weight 0. + */ + break; + case 1: + weight_set(p, -1); + break; + default: + weight_set(p, -2); + break; + } + } + + show_list("bisection 2 initialize", counted, nr, list); + + /* + * If you have only one parent in the resulting set + * then you can reach one commit more than that parent + * can reach. So we do not have to run the expensive + * count_distance() for single strand of pearls. + * + * However, if you have more than one parents, you cannot + * just add their distance and one for yourself, since + * they usually reach the same ancestor and you would + * end up counting them twice that way. + * + * So we will first count distance of merges the usual + * way, and then fill the blanks using cheaper algorithm. + */ + for (p = list; p; p = p->next) { + if (p->item->object.flags & UNINTERESTING) + continue; + if (weight(p) != -2) + continue; + weight_set(p, count_distance(p)); + clear_distance(list); + + /* Does it happen to be at exactly half-way? */ + if (!find_all && halfway(p, nr)) + return p; + counted++; + } + + show_list("bisection 2 count_distance", counted, nr, list); + + while (counted < nr) { + for (p = list; p; p = p->next) { + struct commit_list *q; + unsigned flags = p->item->object.flags; + + if (0 <= weight(p)) + continue; + for (q = p->item->parents; q; q = q->next) { + if (q->item->object.flags & UNINTERESTING) + continue; + if (0 <= weight(q)) + break; + } + if (!q) + continue; + + /* + * weight for p is unknown but q is known. + * add one for p itself if p is to be counted, + * otherwise inherit it from q directly. + */ + if (!(flags & TREESAME)) { + weight_set(p, weight(q)+1); + counted++; + show_list("bisection 2 count one", + counted, nr, list); + } + else + weight_set(p, weight(q)); + + /* Does it happen to be at exactly half-way? */ + if (!find_all && halfway(p, nr)) + return p; + } + } + + show_list("bisection 2 counted all", counted, nr, list); + + if (!find_all) + return best_bisection(list, nr); + else + return best_bisection_sorted(list, nr); +} + +struct commit_list *find_bisection(struct commit_list *list, + int *reaches, int *all, + int find_all) +{ + int nr, on_list; + struct commit_list *p, *best, *next, *last; + int *weights; + + show_list("bisection 2 entry", 0, 0, list); + + /* + * Count the number of total and tree-changing items on the + * list, while reversing the list. + */ + for (nr = on_list = 0, last = NULL, p = list; + p; + p = next) { + unsigned flags = p->item->object.flags; + + next = p->next; + if (flags & UNINTERESTING) + continue; + p->next = last; + last = p; + if (!(flags & TREESAME)) + nr++; + on_list++; + } + list = last; + show_list("bisection 2 sorted", 0, nr, list); + + *all = nr; + weights = xcalloc(on_list, sizeof(*weights)); + + /* Do the real work of finding bisection commit. */ + best = do_find_bisection(list, nr, weights, find_all); + if (best) { + if (!find_all) + best->next = NULL; + *reaches = weight(best); + } + free(weights); + return best; +} + +static int register_ref(const char *refname, const unsigned char *sha1, + int flags, void *cb_data) +{ + if (!strcmp(refname, "bad")) { + ALLOC_GROW(rev_argv, rev_argv_nr + 1, rev_argv_alloc); + rev_argv[rev_argv_nr++] = xstrdup(sha1_to_hex(sha1)); + } else if (!prefixcmp(refname, "good-")) { + const char *hex = sha1_to_hex(sha1); + char *good = xmalloc(strlen(hex) + 2); + *good = '^'; + memcpy(good + 1, hex, strlen(hex) + 1); + ALLOC_GROW(rev_argv, rev_argv_nr + 1, rev_argv_alloc); + rev_argv[rev_argv_nr++] = good; + } else if (!prefixcmp(refname, "skip-")) { + ALLOC_GROW(skipped_sha1, skipped_sha1_nr + 1, + skipped_sha1_alloc); + hashcpy(skipped_sha1[skipped_sha1_nr++], sha1); + } + + return 0; +} + +static int read_bisect_refs(void) +{ + return for_each_ref_in("refs/bisect/", register_ref, NULL); +} + +void read_bisect_paths(void) +{ + struct strbuf str = STRBUF_INIT; + const char *filename = git_path("BISECT_NAMES"); + FILE *fp = fopen(filename, "r"); + + if (!fp) + die("Could not open file '%s': %s", filename, strerror(errno)); + + while (strbuf_getline(&str, fp, '\n') != EOF) { + char *quoted; + int res; + + strbuf_trim(&str); + quoted = strbuf_detach(&str, NULL); + res = sq_dequote_to_argv(quoted, &rev_argv, + &rev_argv_nr, &rev_argv_alloc); + if (res) + die("Badly quoted content in file '%s': %s", + filename, quoted); + } + + strbuf_release(&str); + fclose(fp); +} + +static int skipcmp(const void *a, const void *b) +{ + return hashcmp(a, b); +} + +static void prepare_skipped(void) +{ + qsort(skipped_sha1, skipped_sha1_nr, sizeof(*skipped_sha1), skipcmp); +} + +static const unsigned char *skipped_sha1_access(size_t index, void *table) +{ + unsigned char (*skipped)[20] = table; + return skipped[index]; +} + +static int lookup_skipped(unsigned char *sha1) +{ + return sha1_pos(sha1, skipped_sha1, skipped_sha1_nr, + skipped_sha1_access); +} + +struct commit_list *filter_skipped(struct commit_list *list, + struct commit_list **tried, + int show_all) +{ + struct commit_list *filtered = NULL, **f = &filtered; + + *tried = NULL; + + if (!skipped_sha1_nr) + return list; + + prepare_skipped(); + + while (list) { + struct commit_list *next = list->next; + list->next = NULL; + if (0 <= lookup_skipped(list->item->object.sha1)) { + /* Move current to tried list */ + *tried = list; + tried = &list->next; + } else { + if (!show_all) + return list; + /* Move current to filtered list */ + *f = list; + f = &list->next; + } + list = next; + } + + return filtered; +} + +static void bisect_rev_setup(struct rev_info *revs, const char *prefix) +{ + init_revisions(revs, prefix); + revs->abbrev = 0; + revs->commit_format = CMIT_FMT_UNSPECIFIED; + + /* argv[0] will be ignored by setup_revisions */ + ALLOC_GROW(rev_argv, rev_argv_nr + 1, rev_argv_alloc); + rev_argv[rev_argv_nr++] = xstrdup("bisect_rev_setup"); + + if (read_bisect_refs()) + die("reading bisect refs failed"); + + ALLOC_GROW(rev_argv, rev_argv_nr + 1, rev_argv_alloc); + rev_argv[rev_argv_nr++] = xstrdup("--"); + + read_bisect_paths(); + + ALLOC_GROW(rev_argv, rev_argv_nr + 1, rev_argv_alloc); + rev_argv[rev_argv_nr++] = NULL; + + setup_revisions(rev_argv_nr, rev_argv, revs, NULL); + + revs->limited = 1; +} + +int bisect_next_vars(const char *prefix) +{ + struct rev_info revs; + struct rev_list_info info; + int reaches = 0, all = 0; + + memset(&info, 0, sizeof(info)); + info.revs = &revs; + info.bisect_show_flags = BISECT_SHOW_TRIED | BISECT_SHOW_STRINGED; + + bisect_rev_setup(&revs, prefix); + + if (prepare_revision_walk(&revs)) + die("revision walk setup failed"); + if (revs.tree_objects) + mark_edges_uninteresting(revs.commits, &revs, NULL); + + revs.commits = find_bisection(revs.commits, &reaches, &all, + !!skipped_sha1_nr); + + return show_bisect_vars(&info, reaches, all); +} |