[Tarantool-patches] [PATCH 1.10 12/16] WIP: module api: add box_key_def_dump_parts()

[Alexander Turenko <alexander.turenko@tarantool.org>]

The function dumps an opacue <box_key_def_t> structure into a non-opacue
array of <box_key_part_def_t> structures in order to allow an external
module to obtain information about the key definition.

XXX: Add a module API test.

Part of #5273

(backported from commit 94bccf8d2647debb1c1184af95713d48acf4c504)
---
 extra/exports         |  1 +
 src/box/key_def_api.c | 50 +++++++++++++++++++++++++++++++++++++++++++
 src/box/key_def_api.h |  9 ++++++++
 3 files changed, 60 insertions(+)

diff --git a/extra/exports b/extra/exports
index b70560db7..97d2a21b8 100644
--- a/extra/exports
+++ b/extra/exports
@@ -147,6 +147,7 @@ box_txn_alloc
 box_txn_id
 box_key_def_new
 box_key_def_delete
+box_key_def_dump_parts
 box_key_def_new_ex
 box_key_part_def_create
 box_tuple_format_default
diff --git a/src/box/key_def_api.c b/src/box/key_def_api.c
index f19f30950..30ddde9c8 100644
--- a/src/box/key_def_api.c
+++ b/src/box/key_def_api.c
@@ -179,6 +179,56 @@ box_key_def_delete(box_key_def_t *key_def)
 	key_def_delete(key_def);
 }
 
+box_key_part_def_t *
+box_key_def_dump_parts(const box_key_def_t *key_def, uint32_t *part_count_ptr)
+{
+	struct region *region = &fiber()->gc;
+	size_t region_svp = region_used(region);
+	size_t size;
+	box_key_part_def_t *parts = region_alloc_array(
+		region, typeof(parts[0]), key_def->part_count, &size);
+	if (parts == NULL) {
+		diag_set(OutOfMemory, size, "region_alloc_array", "parts");
+		return NULL;
+	}
+
+	for (uint32_t i = 0; i < key_def->part_count; i++) {
+		const struct key_part *part = &key_def->parts[i];
+		box_key_part_def_t *part_def = &parts[i];
+		box_key_part_def_create(part_def);
+
+		/* Set part->{fieldno,flags,field_type}. */
+		part_def->fieldno = part->fieldno;
+		part_def->flags = 0;
+		if (part->is_nullable)
+			part_def->flags |= BOX_KEY_PART_DEF_IS_NULLABLE_MASK;
+		assert(part->type >= 0 && part->type < field_type_MAX);
+		part_def->field_type = field_type_strs[part->type];
+
+		/* Set part->collation. */
+		if (part->coll_id != COLL_NONE) {
+			struct coll_id *coll_id = coll_by_id(part->coll_id);
+			/*
+			 * A collation may be removed after
+			 * key_def creation.
+			 */
+			if (coll_id == NULL) {
+				diag_set(CollationError,
+					 "key_def holds dead collation id %d",
+					 part->coll_id);
+				region_truncate(region, region_svp);
+				return NULL;
+			}
+			part_def->collation = coll_id->name;
+		}
+	}
+
+	if (part_count_ptr != NULL)
+		*part_count_ptr = key_def->part_count;
+
+	return parts;
+}
+
 int
 box_tuple_compare(const box_tuple_t *tuple_a, const box_tuple_t *tuple_b,
 		  box_key_def_t *key_def)
diff --git a/src/box/key_def_api.h b/src/box/key_def_api.h
index 6025afe67..ee967c510 100644
--- a/src/box/key_def_api.h
+++ b/src/box/key_def_api.h
@@ -160,6 +160,15 @@ box_key_def_new_ex(box_key_part_def_t *parts, uint32_t part_count);
 API_EXPORT void
 box_key_def_delete(box_key_def_t *key_def);
 
+/**
+ * Dump key part definitions of given key_def.
+ *
+ * The function allocates key parts on the box region.
+ * @sa <box_region_truncate>().
+ */
+API_EXPORT box_key_part_def_t *
+box_key_def_dump_parts(const box_key_def_t *key_def, uint32_t *part_count_ptr);
+
 /**
  * Compare tuples using the key definition.
  * @param tuple_a first tuple
-- 
2.25.0