[Tarantool-patches] [PATCH 13/14] WIP: module api: expose box_tuple_extract_key_ex()

[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. Also there is no <MULTIKEY_NONE> constant in the
backport.

XXX: Add a module API test.

Part of #5273
---
 src/CMakeLists.txt    |  1 +
 src/box/field_map.h   |  4 ++++
 src/box/key_def_api.c |  7 +++++++
 src/box/key_def_api.h | 20 ++++++++++++++++++++
 src/exports.h         |  1 +
 5 files changed, 33 insertions(+)

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 89e5bbc34..9efc636df 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -155,6 +155,7 @@ set(api_headers
     ${CMAKE_SOURCE_DIR}/src/box/index.h
     ${CMAKE_SOURCE_DIR}/src/box/iterator_type.h
     ${CMAKE_SOURCE_DIR}/src/box/error.h
+    ${CMAKE_SOURCE_DIR}/src/box/field_map.h
     ${CMAKE_SOURCE_DIR}/src/box/lua/call.h
     ${CMAKE_SOURCE_DIR}/src/box/lua/tuple.h
     ${CMAKE_SOURCE_DIR}/src/lib/core/latch.h
diff --git a/src/box/field_map.h b/src/box/field_map.h
index d8ef726a1..6e3c5be25 100644
--- a/src/box/field_map.h
+++ b/src/box/field_map.h
@@ -38,12 +38,16 @@
 struct region;
 struct field_map_builder_slot;
 
+/** \cond public */
+
 /**
  * A special value of multikey index that means that the key
  * definition is not multikey and no indirection is expected.
  */
 enum { MULTIKEY_NONE = -1 };
 
+/** \endcond public */
+
 /**
  * A field map is a special area is reserved before tuple's
  * MessagePack data. It is a sequence of the 32-bit unsigned
diff --git a/src/box/key_def_api.c b/src/box/key_def_api.c
index 740fb4339..1257e9060 100644
--- a/src/box/key_def_api.c
+++ b/src/box/key_def_api.c
@@ -298,4 +298,11 @@ box_key_def_merge(const box_key_def_t *first, const box_key_def_t *second)
 	return key_def_merge(first, second);
 }
 
+char *
+box_tuple_extract_key_ex(box_tuple_t *tuple, box_key_def_t *key_def,
+			 int multikey_idx, uint32_t *key_size_ptr)
+{
+	return tuple_extract_key(tuple, key_def, multikey_idx, key_size_ptr);
+}
+
 /* }}} API functions implementations */
diff --git a/src/box/key_def_api.h b/src/box/key_def_api.h
index 0cef7d1ea..28fcc32da 100644
--- a/src/box/key_def_api.h
+++ b/src/box/key_def_api.h
@@ -243,6 +243,26 @@ 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 tuple - tuple from which need to extract key
+ * @param key_def - definition of key that need to extract
+ * @param multikey_idx - multikey index hint
+ * @param key_size_ptr - here will be size of extracted key
+ *
+ * @retval not NULL Success
+ * @retval NULL     Memory allocation error
+ */
+API_EXPORT char *
+box_tuple_extract_key_ex(box_tuple_t *tuple, box_key_def_t *key_def,
+			 int multikey_idx, uint32_t *key_size_ptr);
+
 /** \endcond public */
 
 /*
diff --git a/src/exports.h b/src/exports.h
index be8144036..6ddc2e9b0 100644
--- a/src/exports.h
+++ b/src/exports.h
@@ -56,6 +56,7 @@ EXPORT(box_tuple_bsize)
 EXPORT(box_tuple_compare)
 EXPORT(box_tuple_compare_with_key)
 EXPORT(box_tuple_extract_key)
+EXPORT(box_tuple_extract_key_ex)
 EXPORT(box_tuple_field)
 EXPORT(box_tuple_field_count)
 EXPORT(box_tuple_format)
-- 
2.25.0