box: remove cord_slab_cache symbol from public API export

`cord_slab_cache` was not designed to offer a backward compatible API, and
leaving it exposed inevitably leads to errors like those highlighted in
tarantool#7124 and tarantool/memcached#96: hence, remove it from the public API
export.

Closes tarantool#7124

@TarantoolBot document
Title: `cord_slab_cache` was removed from public API export

The `cord_slab_cache` needs to be removed from the C API reference of the
fiber module.

changelogs/unreleased/gh-7124-remove-cord-slab-cache-symbol-from-public-api-export.md

@@ -0,0 +1,4 @@
+## bugfix/box
+
+* **[Breaking change]** The `cord_slab_cache` symbol was removed from the public
+  API export (gh-7124).

extra/exports

@@ -169,7 +169,6 @@ console_set_output_format
 cord_ibuf_drop
 cord_ibuf_put
 cord_ibuf_take
-cord_slab_cache
 crc32_calc
 crypto_ERR_error_string
 crypto_ERR_get_error

src/lib/core/fiber.h

@@ -172,6 +172,12 @@ enum {
 	FIBER_DEFAULT_FLAGS	= 0
 };
 
+/**
+ * Return slab_cache suitable to use with tarantool/small library
+ */
+struct slab_cache *
+cord_slab_cache(void);
+
 /** \cond public */
 
 /**
@@ -425,14 +431,6 @@ fiber_clock64(void);
 API_EXPORT void
 fiber_reschedule(void);
 
-struct slab_cache;
-
-/**
- * Return slab_cache suitable to use with tarantool/small library
- */
-API_EXPORT struct slab_cache *
-cord_slab_cache(void);
-
 /**
  * box region allocator
  *

test/app-tap/CMakeLists.txt

@@ -1,5 +1,5 @@
 build_module(module_api module_api.c)
-target_link_libraries(module_api msgpuck)
+target_link_libraries(module_api small msgpuck)
 
 # gh-5313: verify that module.h actually conforms to the C99
 # standard.

test/app-tap/module_api.c

@@ -5,6 +5,9 @@
 #include <module.h>
 
 #include <small/ibuf.h>
+#include <small/quota.h>
+#include <small/slab_arena.h>
+#include <small/slab_cache.h>
 #include <msgpuck/msgpuck.h>
 
 #include <errno.h>
@@ -184,11 +187,16 @@ test_checkint64(lua_State *L)
 static int
 test_box_ibuf(lua_State *L)
 {
-	struct slab_cache *slabc = cord_slab_cache();
-	fail_unless(slabc != NULL);
+	struct quota quota;
+	quota_init(&quota, QUOTA_MAX);
+	struct slab_arena arena;
+	fail_unless(slab_arena_create(&arena, &quota, 0, SLAB_MIN_SIZE,
+				      SLAB_ARENA_PRIVATE) == 0);
+	struct slab_cache slabc;
+	slab_cache_create(&slabc, &arena);
 	box_ibuf_t ibuf;
 
-	ibuf_create(&ibuf, slabc, 16320);
+	ibuf_create(&ibuf, &slabc, 16320);
 	fail_unless(ibuf_used(&ibuf) == 0);
 	void *ptr = box_ibuf_reserve(&ibuf, 65536);
 	fail_unless(ptr != NULL);
@@ -220,6 +228,8 @@ test_box_ibuf(lua_State *L)
 	fail_unless(ibuf_used(&ibuf) == 0);
 	fail_unless(*rpos == *wpos);
 
+	slab_arena_destroy(&arena);
+
 	lua_pushboolean(L, 1);
 	return 1;
 }
@@ -334,19 +344,6 @@ test_fiber_set_ctx(lua_State *L)
 	return 1;
 }
 
-static int
-test_cord(lua_State *L)
-{
-	struct slab_cache *slabc = cord_slab_cache();
-	fail_unless(slabc != NULL);
-	struct ibuf ibuf;
-	ibuf_create(&ibuf, slabc, 16320);
-	ibuf_destroy(&ibuf);
-
-	lua_pushboolean(L, 1);
-	return 1;
-}
-
 static int
 test_pushcdata(lua_State *L)
 {
@@ -3172,7 +3169,6 @@ luaopen_module_api(lua_State *L)
 		{"test_toint64", test_toint64 },
 		{"test_fiber", test_fiber },
 		{"test_fiber_set_ctx", test_fiber_set_ctx },
-		{"test_cord", test_cord },
 		{"pushcdata", test_pushcdata },
 		{"checkcdata", test_checkcdata },
 		{"test_clock", test_clock },

test/app-tap/module_api.test.lua

@@ -664,7 +664,7 @@ local function test_box_iproto_override(test, module)
 end
 
 require('tap').test("module_api", function(test)
-    test:plan(49)
+    test:plan(48)
     local status, module = pcall(require, 'module_api')
     test:is(status, true, "module")
     test:ok(status, "module is loaded")