reftable/table: move printing logic into test helper

The logic to print individual blocks in a table is hosted in the
reftable library. This is only the case due to historical reasons though
because users of the library had no interfaces to read blocks one by
one. Otherwise, printing individual blocks has no place in the reftable
library given that the format will not be generic in the first place.

We have now grown a public interface to iterate through blocks contained
in a table, and thus we can finally move the logic to print them into
the test helper.

Move over the logic and refactor it accordingly. Note that the iterator
also trivially allows us to access index sections, which we previously
didn't print at all. This omission wasn't intentional though, so start
dumping those sections as well so that we can assert that indices are
written as expected.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

reftable/reftable-table.h

@@ -97,9 +97,6 @@ uint64_t reftable_table_max_update_index(struct reftable_table *t);
 /* return the min_update_index for a table */
 uint64_t reftable_table_min_update_index(struct reftable_table *t);
 
-/* print blocks onto stdout for debugging. */
-int reftable_table_print_blocks(const char *tablename);
-
 /*
  * An iterator that iterates through the blocks contained in a given table.
  */

reftable/table.c

@@ -740,71 +740,6 @@ uint64_t reftable_table_min_update_index(struct reftable_table *t)
 	return t->min_update_index;
 }
 
-int reftable_table_print_blocks(const char *tablename)
-{
-	struct {
-		const char *name;
-		int type;
-	} sections[] = {
-		{
-			.name = "ref",
-			.type = REFTABLE_BLOCK_TYPE_REF,
-		},
-		{
-			.name = "obj",
-			.type = REFTABLE_BLOCK_TYPE_OBJ,
-		},
-		{
-			.name = "log",
-			.type = REFTABLE_BLOCK_TYPE_LOG,
-		},
-	};
-	struct reftable_block_source src = { 0 };
-	struct reftable_table *table = NULL;
-	struct table_iter ti = { 0 };
-	size_t i;
-	int err;
-
-	err = reftable_block_source_from_file(&src, tablename);
-	if (err < 0)
-		goto done;
-
-	err = reftable_table_new(&table, &src, tablename);
-	if (err < 0)
-		goto done;
-
-	table_iter_init(&ti, table);
-
-	printf("header:\n");
-	printf("  block_size: %d\n", table->block_size);
-
-	for (i = 0; i < sizeof(sections) / sizeof(*sections); i++) {
-		err = table_iter_seek_start(&ti, sections[i].type, 0);
-		if (err < 0)
-			goto done;
-		if (err > 0)
-			continue;
-
-		printf("%s:\n", sections[i].name);
-
-		while (1) {
-			printf("  - length: %u\n", ti.block.restart_off);
-			printf("    restarts: %u\n", ti.block.restart_count);
-
-			err = table_iter_next_block(&ti);
-			if (err < 0)
-				goto done;
-			if (err > 0)
-				break;
-		}
-	}
-
-done:
-	reftable_table_decref(table);
-	table_iter_close(&ti);
-	return err;
-}
-
 int reftable_table_iterator_init(struct reftable_table_iterator *it,
 				 struct reftable_table *t)
 {

t/helper/test-reftable.c

@@ -2,6 +2,7 @@
 #include "hash.h"
 #include "hex.h"
 #include "reftable/system.h"
+#include "reftable/reftable-constants.h"
 #include "reftable/reftable-error.h"
 #include "reftable/reftable-merged.h"
 #include "reftable/reftable-stack.h"
@@ -20,6 +21,72 @@ static void print_help(void)
 	       "\n");
 }
 
+static int dump_blocks(const char *tablename)
+{
+	struct reftable_table_iterator ti = { 0 };
+	struct reftable_block_source src = { 0 };
+	struct reftable_table *table = NULL;
+	uint8_t section_type = 0;
+	int err;
+
+	err = reftable_block_source_from_file(&src, tablename);
+	if (err < 0)
+		goto done;
+
+	err = reftable_table_new(&table, &src, tablename);
+	if (err < 0)
+		goto done;
+
+	err = reftable_table_iterator_init(&ti, table);
+	if (err < 0)
+		goto done;
+
+	printf("header:\n");
+	printf("  block_size: %d\n", table->block_size);
+
+	while (1) {
+		const struct reftable_block *block;
+
+		err = reftable_table_iterator_next(&ti, &block);
+		if (err < 0)
+			goto done;
+		if (err > 0)
+			break;
+
+		if (block->block_type != section_type) {
+			const char *section;
+			switch (block->block_type) {
+			case REFTABLE_BLOCK_TYPE_LOG:
+				section = "log";
+				break;
+			case REFTABLE_BLOCK_TYPE_REF:
+				section = "ref";
+				break;
+			case REFTABLE_BLOCK_TYPE_OBJ:
+				section = "obj";
+				break;
+			case REFTABLE_BLOCK_TYPE_INDEX:
+				section = "idx";
+				break;
+			default:
+				err = -1;
+				goto done;
+			}
+
+			section_type = block->block_type;
+			printf("%s:\n", section);
+		}
+
+		printf("  - length: %u\n", block->restart_off);
+		printf("    restarts: %u\n", block->restart_count);
+	}
+
+done:
+	reftable_table_iterator_release(&ti);
+	reftable_table_decref(table);
+	return err;
+}
+
 static int dump_table(struct reftable_merged_table *mt)
 {
 	struct reftable_iterator it = { NULL };
@@ -184,7 +251,7 @@ int cmd__dump_reftable(int argc, const char **argv)
 	arg = argv[1];
 
 	if (opt_dump_blocks) {
-		err = reftable_table_print_blocks(arg);
+		err = dump_blocks(arg);
 	} else if (opt_dump_table) {
 		err = dump_reftable(arg);
 	} else if (opt_dump_stack) {

t/t0613-reftable-write-options.sh

@@ -93,6 +93,9 @@ test_expect_success 'many refs results in multiple blocks' '
 		    restarts: 3
 		  - length: 3289
 		    restarts: 3
+		idx:
+		  - length: 103
+		    restarts: 1
 		EOF
 		test-tool dump-reftable -b .git/reftable/*.ref >actual &&
 		test_cmp expect actual
@@ -241,6 +244,9 @@ test_expect_success 'object index gets written by default with ref index' '
 		    restarts: 1
 		  - length: 80
 		    restarts: 1
+		idx:
+		  - length: 55
+		    restarts: 2
 		obj:
 		  - length: 11
 		    restarts: 1
@@ -277,6 +283,9 @@ test_expect_success 'object index can be disabled' '
 		    restarts: 1
 		  - length: 80
 		    restarts: 1
+		idx:
+		  - length: 55
+		    restarts: 2
 		EOF
 		test-tool dump-reftable -b .git/reftable/*.ref >actual &&
 		test_cmp expect actual