introduce HASH_REPLACE() for hash_table_t

HASH_REPLACE(): allows to not travel through linked list twice
when HASH_INSERT() happens right after HASH_DELETE()

Author: kevgs

storage/innobase/buf/buf0buf.cc

@@ -2212,8 +2212,8 @@ buf_page_realloc(
 		ut_d(block->page.in_page_hash = FALSE);
 		ulint	fold = block->page.id.fold();
 		ut_ad(fold == new_block->page.id.fold());
-		HASH_DELETE(buf_page_t, hash, buf_pool->page_hash, fold, (&block->page));
-		HASH_INSERT(buf_page_t, hash, buf_pool->page_hash, fold, (&new_block->page));
+		HASH_REPLACE(buf_page_t, hash, buf_pool->page_hash, fold,
+			     &block->page, &new_block->page);
 
 		ut_ad(new_block->page.in_page_hash);
 
@@ -3329,8 +3329,8 @@ buf_relocate(
 	/* relocate buf_pool->page_hash */
 	ulint	fold = bpage->id.fold();
 	ut_ad(fold == dpage->id.fold());
-	HASH_DELETE(buf_page_t, hash, buf_pool->page_hash, fold, bpage);
-	HASH_INSERT(buf_page_t, hash, buf_pool->page_hash, fold, dpage);
+	HASH_REPLACE(buf_page_t, hash, buf_pool->page_hash, fold, bpage,
+		     dpage);
 }
 
 /** Hazard Pointer implementation. */

storage/innobase/include/hash0hash.h

@@ -184,6 +184,18 @@ do {\
 	HASH_INVALIDATE(DATA, NAME);\
 } while (0)
 
+#define HASH_REPLACE(TYPE, NAME, TABLE, FOLD, DATA_OLD, DATA_NEW)             \
+	do {                                                                  \
+		(DATA_NEW)->NAME = (DATA_OLD)->NAME;                          \
+                                                                              \
+		hash_cell_t& cell3333                                         \
+			= TABLE->array[hash_calc_hash(FOLD, TABLE)];          \
+		TYPE** struct3333 = (TYPE**)&cell3333.node;                   \
+		while (*struct3333 != DATA_OLD) {                             \
+			struct3333 = &((*struct3333)->NAME);                  \
+		}                                                             \
+		*struct3333 = DATA_NEW;                                       \
+	} while (0)
 /*******************************************************************//**
 Gets the first struct in a hash chain, NULL if none. */