1 files changed, 131 insertions, 440 deletions

diff --git a/builtin-rev-list.c b/builtin-rev-list.c
index 436afa45f5..193993cf44 100644
--- a/builtin-rev-list.c
+++ b/builtin-rev-list.c
@@ -1,20 +1,12 @@
 #include "cache.h"
-#include "refs.h"
-#include "tag.h"
 #include "commit.h"
-#include "tree.h"
-#include "blob.h"
-#include "tree-walk.h"
 #include "diff.h"
 #include "revision.h"
 #include "list-objects.h"
 #include "builtin.h"
 #include "log-tree.h"
 #include "graph.h"
-
-/* bits #0-15 in revision.h */
-
-#define COUNTED		(1u<<16)
+#include "bisect.h"
 
 static const char rev_list_usage[] =
 "git rev-list [OPTION] <commit-id>... [ -- paths... ]\n"
@@ -50,73 +42,69 @@ static const char rev_list_usage[] =
 "    --bisect-all"
 ;
 
-static struct rev_info revs;
-
-static int bisect_list;
-static int show_timestamp;
-static int hdr_termination;
-static const char *header_prefix;
-
-static void finish_commit(struct commit *commit);
-static void show_commit(struct commit *commit)
+static void finish_commit(struct commit *commit, void *data);
+static void show_commit(struct commit *commit, void *data)
 {
-	graph_show_commit(revs.graph);
+	struct rev_list_info *info = data;
+	struct rev_info *revs = info->revs;
+
+	graph_show_commit(revs->graph);
 
-	if (show_timestamp)
+	if (info->show_timestamp)
 		printf("%lu ", commit->date);
-	if (header_prefix)
-		fputs(header_prefix, stdout);
+	if (info->header_prefix)
+		fputs(info->header_prefix, stdout);
 
-	if (!revs.graph) {
+	if (!revs->graph) {
 		if (commit->object.flags & BOUNDARY)
 			putchar('-');
 		else if (commit->object.flags & UNINTERESTING)
 			putchar('^');
-		else if (revs.left_right) {
+		else if (revs->left_right) {
 			if (commit->object.flags & SYMMETRIC_LEFT)
 				putchar('<');
 			else
 				putchar('>');
 		}
 	}
-	if (revs.abbrev_commit && revs.abbrev)
-		fputs(find_unique_abbrev(commit->object.sha1, revs.abbrev),
+	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) {
+	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) {
+	if (revs->children.name) {
 		struct commit_list *children;
 
-		children = lookup_decoration(&revs.children, &commit->object);
+		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)
+	show_decorations(revs, commit);
+	if (revs->commit_format == CMIT_FMT_ONELINE)
 		putchar(' ');
 	else
 		putchar('\n');
 
-	if (revs.verbose_header && commit->buffer) {
+	if (revs->verbose_header && commit->buffer) {
 		struct strbuf buf = STRBUF_INIT;
-		pretty_print_commit(revs.commit_format, commit,
-				    &buf, revs.abbrev, NULL, NULL,
-				    revs.date_mode, 0);
-		if (revs.graph) {
+		pretty_print_commit(revs->commit_format, commit,
+				    &buf, revs->abbrev, NULL, NULL,
+				    revs->date_mode, 0);
+		if (revs->graph) {
 			if (buf.len) {
-				if (revs.commit_format != CMIT_FMT_ONELINE)
-					graph_show_oneline(revs.graph);
+				if (revs->commit_format != CMIT_FMT_ONELINE)
+					graph_show_oneline(revs->graph);
 
-				graph_show_commit_msg(revs.graph, &buf);
+				graph_show_commit_msg(revs->graph, &buf);
 
 				/*
 				 * Add a newline after the commit message.
@@ -134,7 +122,7 @@ static void show_commit(struct commit *commit)
 				 * format doesn't explicitly end in a newline.)
 				 */
 				if (buf.len && buf.buf[buf.len - 1] == '\n')
-					graph_show_padding(revs.graph);
+					graph_show_padding(revs->graph);
 				putchar('\n');
 			} else {
 				/*
@@ -142,23 +130,23 @@ static void show_commit(struct commit *commit)
 				 * the rest of the graph output for this
 				 * commit.
 				 */
-				if (graph_show_remainder(revs.graph))
+				if (graph_show_remainder(revs->graph))
 					putchar('\n');
 			}
 		} else {
 			if (buf.len)
-				printf("%s%c", buf.buf, hdr_termination);
+				printf("%s%c", buf.buf, info->hdr_termination);
 		}
 		strbuf_release(&buf);
 	} else {
-		if (graph_show_remainder(revs.graph))
+		if (graph_show_remainder(revs->graph))
 			putchar('\n');
 	}
 	maybe_flush_or_die(stdout, "stdout");
-	finish_commit(commit);
+	finish_commit(commit, data);
 }
 
-static void finish_commit(struct commit *commit)
+static void finish_commit(struct commit *commit, void *data)
 {
 	if (commit->parents) {
 		free_commit_list(commit->parents);
@@ -168,20 +156,20 @@ static void finish_commit(struct commit *commit)
 	commit->buffer = NULL;
 }
 
-static void finish_object(struct object_array_entry *p)
+static void finish_object(struct object_array_entry *p, void *data)
 {
 	if (p->item->type == OBJ_BLOB && !has_sha1_file(p->item->sha1))
 		die("missing blob object '%s'", sha1_to_hex(p->item->sha1));
 }
 
-static void show_object(struct object_array_entry *p)
+static void show_object(struct object_array_entry *p, void *data)
 {
 	/* An object with name "foo\n0000000..." can be used to
 	 * confuse downstream "git pack-objects" very badly.
 	 */
 	const char *ep = strchr(p->name, '\n');
 
-	finish_object(p);
+	finish_object(p, data);
 	if (ep) {
 		printf("%s %.*s\n", sha1_to_hex(p->item->sha1),
 		       (int) (ep - p->name),
@@ -196,389 +184,122 @@ static void show_edge(struct commit *commit)
 	printf("-%s\n", sha1_to_hex(commit->object.sha1));
 }
 
-/*
- * 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)
+static inline int log2i(int n)
 {
-	while (list) {
-		struct commit *commit = list->item;
-		commit->object.flags &= ~COUNTED;
-		list = list->next;
-	}
-}
+	int log2 = 0;
 
-#define DEBUG_BISECT 0
+	for (; n > 1; n >>= 1)
+		log2++;
 
-static inline int weight(struct commit_list *elem)
-{
-	return *((int*)(elem->item->util));
+	return log2;
 }
 
-static inline void weight_set(struct commit_list *elem, int weight)
+static inline int exp2i(int n)
 {
-	*((int*)(elem->item->util)) = weight;
+	return 1 << n;
 }
 
-static int count_interesting_parents(struct commit *commit)
+/*
+ * Estimate the number of bisect steps left (after the current step)
+ *
+ * For any x between 0 included and 2^n excluded, the probability for
+ * n - 1 steps left looks like:
+ *
+ * P(2^n + x) == (2^n - x) / (2^n + x)
+ *
+ * and P(2^n + x) < 0.5 means 2^n < 3x
+ */
+static int estimate_bisect_steps(int all)
 {
-	struct commit_list *p;
-	int count;
+	int n, x, e;
 
-	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)
+	if (all < 3)
 		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;
+	n = log2i(all);
+	e = exp2i(n);
+	x = all - e;
 
-	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);
+	return (e < 3 * x) ? n : n - 1;
 }
 
-static struct commit_list *best_bisection_sorted(struct commit_list *list, int nr)
+static void show_tried_revs(struct commit_list *tried, int stringed)
 {
-	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;
+	printf("bisect_tried='");
+	for (;tried; tried = tried->next) {
+		char *format = tried->next ? "%s|" : "%s";
+		printf(format, sha1_to_hex(tried->item->object.sha1));
 	}
-	if (p)
-		p->next = NULL;
-	free(array);
-	return list;
+	printf(stringed ? "' &&\n" : "'\n");
 }
 
-/*
- * 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 show_bisect_vars(struct rev_list_info *info, int reaches, int 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;
-		}
-	}
+	int cnt, flags = info->bisect_show_flags;
+	char hex[41] = "", *format;
+	struct commit_list *tried;
+	struct rev_info *revs = info->revs;
 
-	show_list("bisection 2 initialize", counted, nr, list);
+	if (!revs->commits && !(flags & BISECT_SHOW_TRIED))
+		return 1;
+
+	revs->commits = filter_skipped(revs->commits, &tried, flags & BISECT_SHOW_ALL);
 
 	/*
-	 * 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.
+	 * 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.
 	 */
-	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++;
-	}
+	cnt = all - reaches;
+	if (cnt < reaches)
+		cnt = reaches;
 
-	show_list("bisection 2 count_distance", counted, nr, list);
+	if (revs->commits)
+		strcpy(hex, sha1_to_hex(revs->commits->item->object.sha1));
 
-	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;
-		}
+	if (flags & BISECT_SHOW_ALL) {
+		traverse_commit_list(revs, show_commit, show_object, info);
+		printf("------\n");
 	}
 
-	show_list("bisection 2 counted all", counted, nr, list);
-
-	if (!find_all)
-		return best_bisection(list, nr);
-	else
-		return best_bisection_sorted(list, nr);
-}
-
-static 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);
+	if (flags & BISECT_SHOW_TRIED)
+		show_tried_revs(tried, flags & BISECT_SHOW_STRINGED);
+	format = (flags & BISECT_SHOW_STRINGED) ?
+		"bisect_rev=%s &&\n"
+		"bisect_nr=%d &&\n"
+		"bisect_good=%d &&\n"
+		"bisect_bad=%d &&\n"
+		"bisect_all=%d &&\n"
+		"bisect_steps=%d\n"
+		:
+		"bisect_rev=%s\n"
+		"bisect_nr=%d\n"
+		"bisect_good=%d\n"
+		"bisect_bad=%d\n"
+		"bisect_all=%d\n"
+		"bisect_steps=%d\n";
+	printf(format,
+	       hex,
+	       cnt - 1,
+	       all - reaches - 1,
+	       reaches - 1,
+	       all,
+	       estimate_bisect_steps(all));
 
-	/*
-	 * 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;
+	return 0;
 }
 
 int cmd_rev_list(int argc, const char **argv, const char *prefix)
 {
-	struct commit_list *list;
+	struct rev_info revs;
+	struct rev_list_info info;
 	int i;
 	int read_from_stdin = 0;
+	int bisect_list = 0;
 	int bisect_show_vars = 0;
 	int bisect_find_all = 0;
 	int quiet = 0;
@@ -589,6 +310,9 @@ int cmd_rev_list(int argc, const char **argv, const char *prefix)
 	revs.commit_format = CMIT_FMT_UNSPECIFIED;
 	argc = setup_revisions(argc, argv, &revs, NULL);
 
+	memset(&info, 0, sizeof(info));
+	info.revs = &revs;
+
 	quiet = DIFF_OPT_TST(&revs.diffopt, QUIET);
 	for (i = 1 ; i < argc; i++) {
 		const char *arg = argv[i];
@@ -598,7 +322,7 @@ int cmd_rev_list(int argc, const char **argv, const char *prefix)
 			continue;
 		}
 		if (!strcmp(arg, "--timestamp")) {
-			show_timestamp = 1;
+			info.show_timestamp = 1;
 			continue;
 		}
 		if (!strcmp(arg, "--bisect")) {
@@ -608,6 +332,7 @@ int cmd_rev_list(int argc, const char **argv, const char *prefix)
 		if (!strcmp(arg, "--bisect-all")) {
 			bisect_list = 1;
 			bisect_find_all = 1;
+			info.bisect_show_flags = BISECT_SHOW_ALL;
 			revs.show_decorations = 1;
 			continue;
 		}
@@ -627,19 +352,17 @@ int cmd_rev_list(int argc, const char **argv, const char *prefix)
 	}
 	if (revs.commit_format != CMIT_FMT_UNSPECIFIED) {
 		/* The command line has a --pretty  */
-		hdr_termination = '\n';
+		info.hdr_termination = '\n';
 		if (revs.commit_format == CMIT_FMT_ONELINE)
-			header_prefix = "";
+			info.header_prefix = "";
 		else
-			header_prefix = "commit ";
+			info.header_prefix = "commit ";
 	}
 	else if (revs.verbose_header)
 		/* Only --header was specified */
 		revs.commit_format = CMIT_FMT_RAW;
 
-	list = revs.commits;
-
-	if ((!list &&
+	if ((!revs.commits &&
 	     (!(revs.tag_objects||revs.tree_objects||revs.blob_objects) &&
 	      !revs.pending.nr)) ||
 	    revs.diff)
@@ -660,47 +383,15 @@ int cmd_rev_list(int argc, const char **argv, const char *prefix)
 
 		revs.commits = find_bisection(revs.commits, &reaches, &all,
 					      bisect_find_all);
-		if (bisect_show_vars) {
-			int cnt;
-			char hex[41];
-			if (!revs.commits)
-				return 1;
-			/*
-			 * 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;
-			strcpy(hex, sha1_to_hex(revs.commits->item->object.sha1));
-
-			if (bisect_find_all) {
-				traverse_commit_list(&revs, show_commit, show_object);
-				printf("------\n");
-			}
 
-			printf("bisect_rev=%s\n"
-			       "bisect_nr=%d\n"
-			       "bisect_good=%d\n"
-			       "bisect_bad=%d\n"
-			       "bisect_all=%d\n",
-			       hex,
-			       cnt - 1,
-			       all - reaches - 1,
-			       reaches - 1,
-			       all);
-			return 0;
-		}
+		if (bisect_show_vars)
+			return show_bisect_vars(&info, reaches, all);
 	}
 
 	traverse_commit_list(&revs,
-		quiet ? finish_commit : show_commit,
-		quiet ? finish_object : show_object);
+			     quiet ? finish_commit : show_commit,
+			     quiet ? finish_object : show_object,
+			     &info);
 
 	return 0;
 }