Retire info/rev-cache

It was one of those things that were well intentioned but did not turn
out to be useful in practice.

Signed-off-by: Junio C Hamano <junkio@cox.net>

12 files changed, 4 insertions, 558 deletions

diff --git a/.gitignore b/.gitignore
index 31c03f4..9fde27f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -6,7 +6,6 @@ git-applypatch
 git-archimport
 git-bisect
 git-branch
-git-build-rev-cache
 git-cat-file
 git-checkout
 git-checkout-index
@@ -78,7 +77,6 @@ git-sh-setup
 git-shortlog
 git-show-branch
 git-show-index
-git-show-rev-cache
 git-ssh-fetch
 git-ssh-upload
 git-status
diff --git a/Documentation/git-build-rev-cache.txt b/Documentation/git-build-rev-cache.txt
deleted file mode 100644
index 1dbad77..0000000
--- a/Documentation/git-build-rev-cache.txt
+++ /dev/null
@@ -1,38 +0,0 @@
-git-build-rev-cache(1)
-======================
-
-NAME
-----
-git-build-rev-cache - Create or update a rev-cache file.
-
-SYNOPSIS
---------
-'git-build-rev-cache' [-v] <rev-cache-file> < list-of-heads
-
-DESCRIPTION
------------
-Creates or updates a file that describes the commit ancestry reachable
-from the list-of-head read from stdin. This file is in an append-only
-binary format to make the server side friendly to rsync mirroring
-scheme, and can be read by the git-show-rev-cache command.
-
-OPTIONS
--------
--v::
-	Verbose.
-
-<rev-cache-file>::
-	The rev-cache to operate on.
-
-Author
-------
-Written by Junio C Hamano <junkio@cox.net>
-
-Documentation
---------------
-Documentation by Junio C Hamano and the git-list <git@vger.kernel.org>.
-
-GIT
----
-Part of the link:git.html[git] suite
-
diff --git a/Documentation/git-show-rev-cache.txt b/Documentation/git-show-rev-cache.txt
deleted file mode 100644
index 104ecb7..0000000
--- a/Documentation/git-show-rev-cache.txt
+++ /dev/null
@@ -1,37 +0,0 @@
-git-show-rev-cache(1)
-=====================
-
-NAME
-----
-git-show-rev-cache - Show the contents of a rev-cache file.
-
-SYNOPSIS
---------
-'git-show-rev-cache' <rev-cache-file>
-
-DESCRIPTION
------------
-Show the contents of <rev-cache-file>.
-
-A rev-cache file describes the commit ancestry reachable from references
-supplied as input to get-build-rev-cache. This file is in an
-append-only binary format to make the server side friendly to rsync
-mirroring scheme.
-
-OPTIONS
--------
-<rev-cache-file>::
-	Rev-cache file to display.
-
-Author
-------
-Written by Junio C Hamano <junkio@cox.net>
-
-Documentation
---------------
-Documentation by Junio C Hamano and the git-list <git@vger.kernel.org>.
-
-GIT
----
-Part of the link:git.html[git] suite
-
diff --git a/Documentation/git-update-server-info.txt b/Documentation/git-update-server-info.txt
index 74c4364..39222c3 100644
--- a/Documentation/git-update-server-info.txt
+++ b/Documentation/git-update-server-info.txt
@@ -38,8 +38,6 @@ of what they are for:
 
 * info/refs
 
-* info/rev-cache
-
 
 BUGS
 ----
diff --git a/Documentation/git.txt b/Documentation/git.txt
index 31dd474..bec562e 100644
--- a/Documentation/git.txt
+++ b/Documentation/git.txt
@@ -359,9 +359,6 @@ link:git-tag.html[git-tag]::
 
 Interrogators:
 
-link:git-build-rev-cache.html[git-build-rev-cache]::
-	Create or update a rev-cache file.
-
 link:git-cherry.html[git-cherry]::
 	Find commits not merged upstream.
 
@@ -402,9 +399,6 @@ link:git-send-email.html[git-send-email]::
 	Send patch e-mails out of "format-patch --mbox" output.
 	Previously this command was known as git-send-email-script.
 
-link:git-show-rev-cache.html[git-show-rev-cache]::
-	Show the contents of a rev-cache file.
-
 link:git-stripspace.html[git-stripspace]::
 	Filter out empty lines.
 
diff --git a/Documentation/repository-layout.txt b/Documentation/repository-layout.txt
index 499b070..d20fa80 100644
--- a/Documentation/repository-layout.txt
+++ b/Documentation/repository-layout.txt
@@ -117,13 +117,6 @@ info/grafts::
 	listing their 40-byte hexadecimal object names separated
 	by a space and terminated by a newline.
 
-info/rev-cache::
-	No higher-level tool currently takes advantage of this
-	file, but it is generated when `git update-server-info`
-	is run.  It records the commit ancestry information of
-	the commits in this repository in a concise binary
-	format, and can be read with `git-show-rev-cache`.
-
 info/exclude::
 	This file, by convention among Porcelains, stores the
 	exclude pattern list.  `git status` looks at it, but
diff --git a/Makefile b/Makefile
index 88189fb..e8421cc 100644
--- a/Makefile
+++ b/Makefile
@@ -92,7 +92,7 @@ SIMPLE_PROGRAMS = \
 
 # ... and all the rest
 PROGRAMS = \
-	git-apply git-build-rev-cache git-cat-file \
+	git-apply git-cat-file \
 	git-checkout-index git-clone-pack git-commit-tree \
 	git-convert-objects git-diff-files \
 	git-diff-helper git-diff-index git-diff-stages \
@@ -103,7 +103,7 @@ PROGRAMS = \
 	git-peek-remote git-prune-packed git-read-tree \
 	git-receive-pack git-rev-list git-rev-parse \
 	git-rev-tree git-send-pack git-show-branch \
-	git-show-index git-show-rev-cache git-ssh-fetch \
+	git-show-index git-ssh-fetch \
 	git-ssh-upload git-tar-tree git-unpack-file \
 	git-unpack-objects git-update-index git-update-server-info \
 	git-upload-pack git-verify-pack git-write-tree \
@@ -125,7 +125,7 @@ LIB_FILE=libgit.a
 LIB_H = \
 	blob.h cache.h commit.h count-delta.h csum-file.h delta.h \
 	diff.h epoch.h object.h pack.h pkt-line.h quote.h refs.h \
-	rev-cache.h run-command.h strbuf.h tag.h tree.h
+	run-command.h strbuf.h tag.h tree.h
 
 DIFF_OBJS = \
 	diff.o diffcore-break.o diffcore-order.o diffcore-pathspec.o \
@@ -135,7 +135,7 @@ LIB_OBJS = \
 	blob.o commit.o connect.o count-delta.o csum-file.o \
 	date.o diff-delta.o entry.o ident.o index.o \
 	object.o pack-check.o patch-delta.o path.o pkt-line.o \
-	quote.o read-cache.o refs.o rev-cache.o run-command.o \
+	quote.o read-cache.o refs.o run-command.o \
 	server-info.o setup.o sha1_file.o sha1_name.o strbuf.o \
 	tag.o tree.o usage.o $(DIFF_OBJS)
 
diff --git a/build-rev-cache.c b/build-rev-cache.c
deleted file mode 100644
index 948898b..0000000
--- a/build-rev-cache.c
+++ /dev/null
@@ -1,56 +0,0 @@
-#include "refs.h"
-#include "cache.h"
-#include "commit.h"
-#include "rev-cache.h"
-
-static void process_head_list(int verbose)
-{
-	char buf[512];
-
-	while (fgets(buf, sizeof(buf), stdin)) {
-		unsigned char sha1[20];
-		struct commit *commit;
-
-		if (get_sha1_hex(buf, sha1)) {
-			error("ignoring: %s", buf);
-			continue;
-		}
-		if (!(commit = lookup_commit_reference(sha1))) {
-			error("not a commit: %s", sha1_to_hex(sha1));
-			continue;
-		}
-		record_rev_cache(commit->object.sha1, verbose ? stderr : NULL);
-	}
-}
-
-
-static const char *build_rev_cache_usage =
-"git-build-rev-cache <rev-cache-file> < list-of-heads";
-
-int main(int ac, char **av)
-{
-	int verbose = 0;
-	const char *path;
-
-	while (1 < ac && av[1][0] == '-') {
-		if (!strcmp(av[1], "-v"))
-			verbose = 1;
-		else
-			usage(build_rev_cache_usage);
-		ac--; av++;
-	}
-
-	if (ac != 2)
-		usage(build_rev_cache_usage);
-
-	path = av[1];
-
-	/* read existing rev-cache */
-	read_rev_cache(path, NULL, 0);
-
-	process_head_list(verbose);
-
-	/* update the rev-cache database by appending newly found one to it */
-	write_rev_cache(path, path);
-	return 0;
-}
diff --git a/rev-cache.c b/rev-cache.c
deleted file mode 100644
index 6344d62..0000000
--- a/rev-cache.c
+++ /dev/null
@@ -1,318 +0,0 @@
-#include "refs.h"
-#include "cache.h"
-#include "rev-cache.h"
-
-struct rev_cache **rev_cache;
-int nr_revs, alloc_revs;
-
-static struct rev_list_elem *rle_free;
-
-#define BATCH_SIZE 512
-
-int find_rev_cache(const unsigned char *sha1)
-{
-	int lo = 0, hi = nr_revs;
-	while (lo < hi) {
-		int mi = (lo + hi) / 2;
-		struct rev_cache *ri = rev_cache[mi];
-		int cmp = memcmp(sha1, ri->sha1, 20);
-		if (!cmp)
-			return mi;
-		if (cmp < 0)
-			hi = mi;
-		else
-			lo = mi + 1;
-	}
-	return -lo - 1;
-}
-
-static struct rev_list_elem *alloc_list_elem(void)
-{
-	struct rev_list_elem *rle;
-	if (!rle_free) {
-		int i;
-
-		rle = xmalloc(sizeof(*rle) * BATCH_SIZE);
-		for (i = 0; i < BATCH_SIZE - 1; i++) {
-			rle[i].ri = NULL;
-			rle[i].next = &rle[i + 1];
-		}
-		rle[BATCH_SIZE - 1].ri = NULL;
-		rle[BATCH_SIZE - 1].next = NULL;
-		rle_free = rle;
-	}
-	rle = rle_free;
-	rle_free = rle->next;
-	return rle;
-}
-
-static struct rev_cache *create_rev_cache(const unsigned char *sha1)
-{
-	struct rev_cache *ri;
-	int pos = find_rev_cache(sha1);
-
-	if (0 <= pos)
-		return rev_cache[pos];
-	pos = -pos - 1;
-	if (alloc_revs <= ++nr_revs) {
-		alloc_revs = alloc_nr(alloc_revs);
-		rev_cache = xrealloc(rev_cache, sizeof(ri) * alloc_revs);
-	}
-	if (pos < nr_revs)
-		memmove(rev_cache + pos + 1, rev_cache + pos,
-			(nr_revs - pos - 1) * sizeof(ri));
-	ri = xcalloc(1, sizeof(*ri));
-	memcpy(ri->sha1, sha1, 20);
-	rev_cache[pos] = ri;
-	return ri;
-}
-
-static unsigned char last_sha1[20];
-
-static void write_one_rev_cache(FILE *rev_cache_file, struct rev_cache *ri)
-{
-	unsigned char flag;
-	struct rev_list_elem *rle;
-
-	if (ri->written)
-		return;
-
-	if (ri->parsed) {
-		/* We use last_sha1 compression only for the first parent;
-		 * otherwise the resulting rev-cache would lose the parent
-		 * order information.
-		 */
-		if (ri->parents &&
-		    !memcmp(ri->parents->ri->sha1, last_sha1, 20))
-			flag = (ri->num_parents - 1) | 0x80;
-		else
-			flag = ri->num_parents;
-
-		fwrite(ri->sha1, 20, 1, rev_cache_file);
-		fwrite(&flag, 1, 1, rev_cache_file);
-		for (rle = ri->parents; rle; rle = rle->next) {
-			if (flag & 0x80 && rle == ri->parents)
-				continue;
-			fwrite(rle->ri->sha1, 20, 1, rev_cache_file);
-		}
-		memcpy(last_sha1, ri->sha1, 20);
-		ri->written = 1;
-	}
-	/* recursively write children depth first */
-	for (rle = ri->children; rle; rle = rle->next)
-		write_one_rev_cache(rev_cache_file, rle->ri);
-}
-
-void write_rev_cache(const char *newpath, const char *oldpath)
-{
-	/* write the following commit ancestry information in
-	 * $GIT_DIR/info/rev-cache.
-	 *
-	 * The format is:
-	 * 20-byte SHA1 (commit ID)
-	 * 1-byte flag:
-	 * - bit 0-6 records "number of parent commit SHA1s to
-	 *   follow" (i.e. up to 127 children can be listed).
-	 * - when the bit 7 is on, then "the entry immediately
-	 *   before this entry is one of the parents of this
-         *   commit".
-	 * N x 20-byte SHA1 (parent commit IDs)
-	 */
-	FILE *rev_cache_file;
-	int i;
-	struct rev_cache *ri;
-
-	if (!strcmp(newpath, oldpath)) {
-		/* If we are doing it in place */
-		rev_cache_file = fopen(newpath, "a");
-	}
-	else {
-		char buf[8096];
-		size_t sz;
-		FILE *oldfp = fopen(oldpath, "r");
-		rev_cache_file = fopen(newpath, "w");
-		if (oldfp) {
-			while (1) {
-				sz = fread(buf, 1, sizeof(buf), oldfp);
-				if (sz == 0)
-					break;
-				fwrite(buf, 1, sz, rev_cache_file);
-			}
-			fclose(oldfp);
-		}
-	}
-
-	memset(last_sha1, 0, 20);
-
-	/* Go through available rev_cache structures, starting from
-	 * parentless ones first, so that we would get most out of
-	 * last_sha1 optimization by the depth first behaviour of
-	 * write_one_rev_cache().
-	 */
-	for (i = 0; i < nr_revs; i++) {
-		ri = rev_cache[i];
-		if (ri->num_parents)
-			continue;
-		write_one_rev_cache(rev_cache_file, ri);
-	}
-	/* Then the rest */
-	for (i = 0; i < nr_revs; i++) {
-		ri = rev_cache[i];
-		write_one_rev_cache(rev_cache_file, ri);
-	}
-	fclose(rev_cache_file);
-}
-
-static void add_parent(struct rev_cache *child,
-		       const unsigned char *parent_sha1)
-{
-	struct rev_cache *parent = create_rev_cache(parent_sha1);
-	struct rev_list_elem *e = alloc_list_elem();
-
-	/* Keep the parent list ordered in the same way the commit
-	 * object records them.
-	 */
-	e->ri = parent;
-	e->next = NULL;
-	if (!child->parents_tail)
-		child->parents = e;
-	else
-		child->parents_tail->next = e;
-	child->parents_tail = e;
-	child->num_parents++;
-
-	/* There is no inherent order of the children so we just
-	 * LIFO them together.
-	 */
-	e = alloc_list_elem();
-	e->next = parent->children;
-	parent->children = e;
-	e->ri = child;
-	parent->num_children++;
-}
-
-int read_rev_cache(const char *path, FILE *dumpfile, int dry_run)
-{
-	unsigned char *map;
-	int fd;
-	struct stat st;
-	unsigned long ofs, len;
-	struct rev_cache *ri = NULL;
-
-	fd = open(path, O_RDONLY);
-	if (fd < 0) {
-		if (dry_run)
-			return error("cannot open %s", path);
-		if (errno == ENOENT)
-			return 0;
-		return -1;
-	}
-	if (fstat(fd, &st)) {
-		close(fd);
-		return -1;
-	}
-	map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
-	close(fd);
-	if (map == MAP_FAILED)
-		return -1;
-
-	memset(last_sha1, 0, 20);
-	ofs = 0;
-	len = st.st_size;
-	while (ofs < len) {
-		unsigned char sha1[20];
-		int flag, cnt, i;
-		if (len < ofs + 21)
-			die("rev-cache too short");
-		memcpy(sha1, map + ofs, 20);
-		flag = map[ofs + 20];
-		ofs += 21;
-		cnt = (flag & 0x7f) + ((flag & 0x80) != 0);
-		if (len < ofs + (flag & 0x7f) * 20)
-			die("rev-cache too short to have %d more parents",
-			    (flag & 0x7f));
-		if (dumpfile)
-			fprintf(dumpfile, "%s", sha1_to_hex(sha1));
-		if (!dry_run) {
-			ri = create_rev_cache(sha1);
-			if (!ri)
-				die("cannot create rev-cache for %s",
-				    sha1_to_hex(sha1));
-			ri->written = ri->parsed = 1;
-		}
-		i = 0;
-		if (flag & 0x80) {
-			if (!dry_run)
-				add_parent(ri, last_sha1);
-			if (dumpfile)
-				fprintf(dumpfile, " %s",
-					sha1_to_hex(last_sha1));
-			i++;
-		}
-		while (i++ < cnt) {
-			if (!dry_run)
-				add_parent(ri, map + ofs);
-			if (dumpfile)
-				fprintf(dumpfile, " %s",
-					sha1_to_hex(last_sha1));
-			ofs += 20;
-		}
-		if (dumpfile)
-			fprintf(dumpfile, "\n");
-		memcpy(last_sha1, sha1, 20);
-	}
-	if (ofs != len)
-		die("rev-cache truncated?");
-	munmap(map, len);
-	return 0;
-}
-
-int record_rev_cache(const unsigned char *sha1, FILE *dumpfile)
-{
-	unsigned char parent[20];
-	char type[20];
-	unsigned long size, ofs;
-	unsigned int cnt, i;
-	void *buf;
-	struct rev_cache *ri;
-
-	buf = read_sha1_file(sha1, type, &size);
-	if (!buf)
-		return error("%s: not found", sha1_to_hex(sha1));
-	if (strcmp(type, "commit")) {
-		free(buf);
-		return error("%s: not a commit but a %s",
-			     sha1_to_hex(sha1), type);
-	}
-	ri = create_rev_cache(sha1);
-	if (ri->parsed)
-		return 0;
-	if (dumpfile)
-		fprintf(dumpfile, "commit %s\n", sha1_to_hex(sha1));
-
-	cnt = 0;
-	ofs = 46; /* "tree " + hex-sha1 + "\n" */
-	while (!memcmp(buf + ofs, "parent ", 7) &&
-	       !get_sha1_hex(buf + ofs + 7, parent)) {
-		ofs += 48;
-		cnt++;
-	}
-	if (cnt * 48 + 46 != ofs) {
-		free(buf);
-		die("internal error in record_rev_cache");
-	}
-
-	ri = create_rev_cache(sha1);
-	ri->parsed = 1;
-
-	for (i = 0; i < cnt; i++) {
-		unsigned char parent_sha1[20];
-
-		ofs = 46 + i * 48 + 7;
-		get_sha1_hex(buf + ofs, parent_sha1);
-		add_parent(ri, parent_sha1);
-		record_rev_cache(parent_sha1, dumpfile);
-	}
-	free(buf);
-	return 0;
-}
diff --git a/rev-cache.h b/rev-cache.h
deleted file mode 100644
index b238ac6..0000000
--- a/rev-cache.h
+++ /dev/null
@@ -1,29 +0,0 @@
-#ifndef REV_CACHE_H
-#define REV_CACHE_H
-
-extern struct rev_cache {
-	struct rev_cache *head_list;
-	struct rev_list_elem *children;
-	struct rev_list_elem *parents;
-	struct rev_list_elem *parents_tail;
-	unsigned short num_parents;
-	unsigned short num_children;
-	unsigned int written : 1;
-	unsigned int parsed : 1;
-	unsigned int work : 30;
-	void *work_ptr;
-	unsigned char sha1[20];
-} **rev_cache;
-extern int nr_revs, alloc_revs;
-
-struct rev_list_elem {
-	struct rev_list_elem *next;
-	struct rev_cache *ri;
-};
-
-extern int find_rev_cache(const unsigned char *);
-extern int read_rev_cache(const char *, FILE *, int);
-extern int record_rev_cache(const unsigned char *, FILE *);
-extern void write_rev_cache(const char *new, const char *old);
-
-#endif
diff --git a/server-info.c b/server-info.c
index 2b3aeca..3263035 100644
--- a/server-info.c
+++ b/server-info.c
@@ -3,7 +3,6 @@
 #include "object.h"
 #include "commit.h"
 #include "tag.h"
-#include "rev-cache.h"
 
 /* refs */
 static FILE *info_ref_fp;
@@ -516,45 +515,6 @@ static int update_info_packs(int force)
 	return 0;
 }
 
-/* rev-cache */
-static int record_rev_cache_ref(const char *path, const unsigned char *sha1)
-{
-	struct object *obj = parse_object(sha1);
-
-	if (!obj)
-		return error("ref %s has bad sha %s", path, sha1_to_hex(sha1));
-	while (obj && obj->type == tag_type)
-		obj = parse_object(((struct tag *)obj)->tagged->sha1);
-	if (!obj || obj->type != commit_type)
-		/* tag pointing at a non-commit */
-		return 0;
-	return record_rev_cache(obj->sha1, NULL);
-}
-
-static int update_info_revs(int force)
-{
-	char *path0 = strdup(git_path("info/rev-cache"));
-	int len = strlen(path0);
-	char *path1 = xmalloc(len + 2);
-
-	strcpy(path1, path0);
-	strcpy(path1 + len, "+");
-
-	/* read existing rev-cache */
-	if (!force)
-		read_rev_cache(path0, NULL, 0);
-	safe_create_leading_directories(path0);
-
-	for_each_ref(record_rev_cache_ref);
-
-	/* update the rev-cache database */
-	write_rev_cache(path1, force ? "/dev/null" : path0);
-	rename(path1, path0);
-	free(path1);
-	free(path0);
-	return 0;
-}
-
 /* public */
 int update_server_info(int force)
 {
@@ -566,7 +526,6 @@ int update_server_info(int force)
 
 	errs = errs | update_info_refs(force);
 	errs = errs | update_info_packs(force);
-	errs = errs | update_info_revs(force);
 
 	return errs;
 }
diff --git a/show-rev-cache.c b/show-rev-cache.c
deleted file mode 100644
index fa92b87..0000000
--- a/show-rev-cache.c
+++ /dev/null
@@ -1,18 +0,0 @@
-#include "cache.h"
-#include "rev-cache.h"
-
-static char *show_rev_cache_usage =
-"git-show-rev-cache <rev-cache-file>";
-
-int main(int ac, char **av)
-{
-	while (1 < ac && av[0][1] == '-') {
-		/* do flags here */
-		break;
-		ac--; av++;
-	}
-	if (ac != 2)
-		usage(show_rev_cache_usage);
-
-	return read_rev_cache(av[1], stdout, 1);
-}