cat-file: batch-command uses content_limit

As with the normal `--batch' mode, we can use the content_limit
round trip optimization to avoid a redundant lookup.  The only
tricky thing here is we need to enable/disable setting the
object_info.contentp field depending on whether we hit an `info'
or `contents' command.

t1006 is updated to ensure we can switch back and forth between
`info' and `contents' commands without problems.

Signed-off-by: Eric Wong <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: Eric Wong

builtin/cat-file.c

@@ -417,7 +417,8 @@ static void print_object_or_die(struct batch_options *opt, struct expand_data *d
 		case OI_DBCACHED:
 			unlock_delta_base_cache();
 		}
-	} else if (data->type == OBJ_BLOB) {
+	} else {
+		assert(data->type == OBJ_BLOB);
 		if (opt->buffer_output)
 			fflush(stdout);
 		if (opt->transform_mode) {
@@ -452,30 +453,6 @@ static void print_object_or_die(struct batch_options *opt, struct expand_data *d
 			stream_blob(oid);
 		}
 	}
-	else {
-		enum object_type type;
-		unsigned long size;
-		void *contents;
-
-		contents = repo_read_object_file(the_repository, oid, &type,
-						 &size);
-		if (!contents)
-			die("object %s disappeared", oid_to_hex(oid));
-
-		if (use_mailmap) {
-			size_t s = size;
-			contents = replace_idents_using_mailmap(contents, &s);
-			size = cast_size_t_to_ulong(s);
-		}
-
-		if (type != data->type)
-			die("object %s changed type!?", oid_to_hex(oid));
-		if (data->info.sizep && size != data->size && !use_mailmap)
-			die("object %s changed size!?", oid_to_hex(oid));
-
-		batch_write(opt, contents, size);
-		free(contents);
-	}
 }
 
 static void print_default_format(struct strbuf *scratch, struct expand_data *data,
@@ -689,6 +666,7 @@ static void parse_cmd_contents(struct batch_options *opt,
 			     struct expand_data *data)
 {
 	opt->batch_mode = BATCH_MODE_CONTENTS;
+	data->info.contentp = &data->content;
 	batch_one_object(line, output, opt, data);
 }
 
@@ -698,6 +676,7 @@ static void parse_cmd_info(struct batch_options *opt,
 			   struct expand_data *data)
 {
 	opt->batch_mode = BATCH_MODE_INFO;
+	data->info.contentp = NULL;
 	batch_one_object(line, output, opt, data);
 }
 
@@ -839,7 +818,8 @@ static int batch_objects(struct batch_options *opt)
 	 * Likewise, grab the content in the initial request if it's small
 	 * and we're not planning to filter it.
 	 */
-	if (opt->batch_mode == BATCH_MODE_CONTENTS) {
+	if ((opt->batch_mode == BATCH_MODE_CONTENTS) ||
+			(opt->batch_mode == BATCH_MODE_QUEUE_AND_DISPATCH)) {
 		data.info.typep = &data.type;
 		if (!opt->transform_mode) {
 			data.info.sizep = &data.size;