Added automatic index generation to fast-import.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

fast-import.c

@@ -8,11 +8,75 @@
 
 static int max_depth = 10;
 static unsigned long object_count;
+static unsigned long duplicate_count;
+static unsigned long packoff;
+static unsigned long overflow_count;
 static int packfd;
 static int current_depth;
 static void *lastdat;
 static unsigned long lastdatlen;
 static unsigned char lastsha1[20];
+static unsigned char packsha1[20];
+
+struct object_entry
+{
+	struct object_entry *next;
+	unsigned long offset;
+	unsigned char sha1[20];
+};
+
+struct overflow_object_entry
+{
+	struct overflow_object_entry *next;
+	struct object_entry oe;
+};
+
+struct object_entry *pool_start;
+struct object_entry *pool_next;
+struct object_entry *pool_end;
+struct overflow_object_entry *overflow;
+struct object_entry *table[1 << 16];
+
+static struct object_entry* new_object(unsigned char *sha1)
+{
+	if (pool_next != pool_end) {
+		struct object_entry *e = pool_next++;
+		memcpy(e->sha1, sha1, sizeof(e->sha1));
+		return e;
+	} else {
+		struct overflow_object_entry *e;
+
+		e = xmalloc(sizeof(struct overflow_object_entry));
+		e->next = overflow;
+		memcpy(e->oe.sha1, sha1, sizeof(e->oe.sha1));
+		overflow = e;
+		overflow_count++;
+		return &e->oe;
+	}
+}
+
+static struct object_entry* insert_object(unsigned char *sha1)
+{
+	unsigned int h = sha1[0] << 8 | sha1[1];
+	struct object_entry *e = table[h];
+	struct object_entry *p = 0;
+
+	while (e) {
+		if (!memcmp(sha1, e->sha1, sizeof(e->sha1)))
+			return e;
+		p = e;
+		e = e->next;
+	}
+
+	e = new_object(sha1);
+	e->next = 0;
+	e->offset = 0;
+	if (p)
+		p->next = e;
+	else
+		table[h] = e;
+	return e;
+}
 
 static ssize_t yread(int fd, void *buffer, size_t length)
 {
@@ -66,7 +130,7 @@ static unsigned long encode_header(enum object_type type, unsigned long size, un
 	return n;
 }
 
-static void write_blob (void *dat, unsigned long datlen)
+static void write_blob(void *dat, unsigned long datlen)
 {
 	z_stream s;
 	void *out, *delta;
@@ -92,6 +156,7 @@ static void write_blob (void *dat, unsigned long datlen)
 			die("Can't write object header: %s", strerror(errno));
 		if (ywrite(packfd, lastsha1, sizeof(lastsha1)) != sizeof(lastsha1))
 			die("Can't write object base: %s", strerror(errno));
+		packoff += hdrlen + sizeof(lastsha1);
 	} else {
 		current_depth = 0;
 		s.next_in = dat;
@@ -99,6 +164,7 @@ static void write_blob (void *dat, unsigned long datlen)
 		hdrlen = encode_header(OBJ_BLOB, datlen, hdr);
 		if (ywrite(packfd, hdr, hdrlen) != hdrlen)
 			die("Can't write object header: %s", strerror(errno));
+		packoff += hdrlen;
 	}
 
 	s.avail_out = deflateBound(&s, s.avail_in);
@@ -109,13 +175,14 @@ static void write_blob (void *dat, unsigned long datlen)
 
 	if (ywrite(packfd, out, s.total_out) != s.total_out)
 		die("Failed writing compressed data %s", strerror(errno));
+	packoff += s.total_out;
 
 	free(out);
 	if (delta)
 		free(delta);
 }
 
-static void init_pack_header ()
+static void init_pack_header()
 {
 	const char* magic = "PACK";
 	unsigned long version = 2;
@@ -129,13 +196,13 @@ static void init_pack_header ()
 		die("Can't write pack version: %s", strerror(errno));
 	if (ywrite(packfd, &zero, 4) != 4)
 		die("Can't write 0 object count: %s", strerror(errno));
+	packoff = 4 * 3;
 }
 
-static void fixup_header_footer ()
+static void fixup_header_footer()
 {
 	SHA_CTX c;
 	char hdr[8];
-	unsigned char sha1[20];
 	unsigned long cnt;
 	char *buf;
 	size_t n;
@@ -148,7 +215,6 @@ static void fixup_header_footer ()
 		die("Failed reading header: %s", strerror(errno));
 	SHA1_Update(&c, hdr, 8);
 
-fprintf(stderr, "%lu objects\n", object_count);
 	cnt = htonl(object_count);
 	SHA1_Update(&c, &cnt, 4);
 	if (ywrite(packfd, &cnt, 4) != 4)
@@ -163,16 +229,81 @@ fprintf(stderr, "%lu objects\n", object_count);
 	}
 	free(buf);
 
-	SHA1_Final(sha1, &c);
-	if (ywrite(packfd, sha1, sizeof(sha1)) != sizeof(sha1))
+	SHA1_Final(packsha1, &c);
+	if (ywrite(packfd, packsha1, sizeof(packsha1)) != sizeof(packsha1))
 		die("Failed writing pack checksum: %s", strerror(errno));
 }
 
-int main (int argc, const char **argv)
+static int oecmp (const void *_a, const void *_b)
 {
-	packfd = open(argv[1], O_RDWR|O_CREAT|O_TRUNC, 0666);
+	struct object_entry *a = *((struct object_entry**)_a);
+	struct object_entry *b = *((struct object_entry**)_b);
+	return memcmp(a->sha1, b->sha1, sizeof(a->sha1));
+}
+
+static void write_index(const char *idx_name)
+{
+	struct sha1file *f;
+	struct object_entry **idx, **c, **last;
+	struct object_entry *e;
+	struct overflow_object_entry *o;
+	unsigned int array[256];
+	int i;
+
+	/* Build the sorted table of object IDs. */
+	idx = xmalloc(object_count * sizeof(struct object_entry*));
+	c = idx;
+	for (e = pool_start; e != pool_next; e++)
+		*c++ = e;
+	for (o = overflow; o; o = o->next)
+		*c++ = &o->oe;
+	last = idx + object_count;
+	qsort(idx, object_count, sizeof(struct object_entry*), oecmp);
+
+	/* Generate the fan-out array. */
+	c = idx;
+	for (i = 0; i < 256; i++) {
+		struct object_entry **next = c;;
+		while (next < last) {
+			if ((*next)->sha1[0] != i)
+				break;
+			next++;
+		}
+		array[i] = htonl(next - idx);
+		c = next;
+	}
+
+	f = sha1create("%s", idx_name);
+	sha1write(f, array, 256 * sizeof(int));
+	for (c = idx; c != last; c++) {
+		unsigned int offset = htonl((*c)->offset);
+		sha1write(f, &offset, 4);
+		sha1write(f, (*c)->sha1, sizeof((*c)->sha1));
+	}
+	sha1write(f, packsha1, sizeof(packsha1));
+	sha1close(f, NULL, 1);
+	free(idx);
+}
+
+int main(int argc, const char **argv)
+{
+	const char *base_name = argv[1];
+	int est_obj_cnt = atoi(argv[2]);
+	char *pack_name;
+	char *idx_name;
+
+	pack_name = xmalloc(strlen(base_name) + 6);
+	sprintf(pack_name, "%s.pack", base_name);
+	idx_name = xmalloc(strlen(base_name) + 5);
+	sprintf(idx_name, "%s.idx", base_name);
+
+	packfd = open(pack_name, O_RDWR|O_CREAT|O_TRUNC, 0666);
 	if (packfd < 0)
-		die("Can't create pack file %s: %s", argv[1], strerror(errno));
+		die("Can't create pack file %s: %s", pack_name, strerror(errno));
+
+	pool_start = xmalloc(est_obj_cnt * sizeof(struct object_entry));
+	pool_next = pool_start;
+	pool_end = pool_start + est_obj_cnt;
 
 	init_pack_header();
 	for (;;) {
@@ -182,8 +313,10 @@ int main (int argc, const char **argv)
 		char hdr[128];
 		unsigned char sha1[20];
 		SHA_CTX c;
+		struct object_entry *e;
 
 		if (yread(0, &datlen, 4) != 4)
+
 			break;
 
 		dat = xmalloc(datlen);
@@ -196,19 +329,30 @@ int main (int argc, const char **argv)
 		SHA1_Update(&c, dat, datlen);
 		SHA1_Final(sha1, &c);
 
-		write_blob(dat, datlen);
-		object_count++;
-		printf("%s\n", sha1_to_hex(sha1));
-		fflush(stdout);
+		e = insert_object(sha1);
+		if (!e->offset) {
+			e->offset = packoff;
+			write_blob(dat, datlen);
+			object_count++;
+			printf("%s\n", sha1_to_hex(sha1));
+			fflush(stdout);
 
-		if (lastdat)
-			free(lastdat);
-		lastdat = dat;
-		lastdatlen = datlen;
-		memcpy(lastsha1, sha1, sizeof(sha1));
+			if (lastdat)
+				free(lastdat);
+			lastdat = dat;
+			lastdatlen = datlen;
+			memcpy(lastsha1, sha1, sizeof(sha1));
+		} else {
+			duplicate_count++;
+			free(dat);
+		}
 	}
 	fixup_header_footer();
 	close(packfd);
+	write_index(idx_name);
+
+	fprintf(stderr, "%lu objects, %lu duplicates, %lu pool overflow\n",
+		object_count, duplicate_count, overflow_count);
 
 	return 0;
 }