[Tarantool-patches] [PATCH v2 14/15] WIP: module api: expose box_key_def_extract_key()

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

Unlike box_tuple_extract_key() it accepts a key_def structure, not
space_id, index_id pair.

Another difference from box_tuple_extract_key() is that this function
allows to pass so called multikey index. See commit 2.2.0-259-gf1d9f2575
('box: introduce multikey indexes in memtx') for details.

Note: The <multikey_idx> parameter is ignored on the backported version
of the patch on 1.10.

XXX: Add a module API test.

Part of #5273
---
 src/box/key_def.c |  7 +++++++
 src/box/key_def.h | 20 ++++++++++++++++++++
 src/exports.h     |  1 +
 3 files changed, 28 insertions(+)

diff --git a/src/box/key_def.c b/src/box/key_def.c
index 25a8decf0..c13951375 100644
--- a/src/box/key_def.c
+++ b/src/box/key_def.c
@@ -620,6 +620,13 @@ box_key_def_merge(const box_key_def_t *first, const box_key_def_t *second)
 	return key_def_merge(first, second);
 }
 
+char *
+box_key_def_extract_key(box_key_def_t *key_def, box_tuple_t *tuple,
+			int multikey_idx, uint32_t *key_size_ptr)
+{
+	return tuple_extract_key(tuple, key_def, multikey_idx, key_size_ptr);
+}
+
 /* }}} Module API functions */
 
 int
diff --git a/src/box/key_def.h b/src/box/key_def.h
index 224b56eb9..d0ce92be3 100644
--- a/src/box/key_def.h
+++ b/src/box/key_def.h
@@ -512,6 +512,26 @@ box_tuple_compare_with_key(box_tuple_t *tuple_a, const char *key_b,
 API_EXPORT box_key_def_t *
 box_key_def_merge(const box_key_def_t *first, const box_key_def_t *second);
 
+/**
+ * Extract key from tuple by given key definition and return
+ * buffer allocated on the box region with this key.
+ * @sa <box_region_truncate>().
+ *
+ * This function has O(n) complexity, where n is the number of key
+ * parts.
+ *
+ * @param key_def       Definition of key that need to extract.
+ * @param tuple         Tuple from which need to extract key.
+ * @param multikey_idx  Multikey index hint or -1.
+ * @param key_size_ptr  Here will be size of extracted key.
+ *
+ * @retval not NULL  Success.
+ * @retval NULL      Memory allocation error.
+ */
+API_EXPORT char *
+box_key_def_extract_key(box_key_def_t *key_def, box_tuple_t *tuple,
+			int multikey_idx, uint32_t *key_size_ptr);
+
 /** \endcond public */
 
 /*
diff --git a/src/exports.h b/src/exports.h
index 223390d52..a0c7ac84d 100644
--- a/src/exports.h
+++ b/src/exports.h
@@ -31,6 +31,7 @@ EXPORT(box_iterator_free)
 EXPORT(box_iterator_next)
 EXPORT(box_key_def_delete)
 EXPORT(box_key_def_dump_parts)
+EXPORT(box_key_def_extract_key)
 EXPORT(box_key_def_merge)
 EXPORT(box_key_def_new)
 EXPORT(box_key_def_new_v2)
-- 
2.25.0