branches/zip: Minor improvements to the buddy allocator.

buf_buddy_alloc(), buf_buddy_alloc_low(): Add parameter "lru" for
enabling allocation from the list of least-recently-used blocks.

buf_buddy_alloc_low(): Release buf_pool->mutex while calling
buf_LRU_get_free_block().

buf/buf0buddy.c

@@ -209,7 +209,8 @@ buf_buddy_alloc_low(
 /*================*/
 			/* out: allocated block, or NULL
 			if buf_pool->zip_free[] was empty */
-	ulint	i)	/* in: index of buf_pool->zip_free[] */
+	ulint	i,	/* in: index of buf_pool->zip_free[] */
+	ibool	lru)	/* in: TRUE=allocate from the LRU list if needed */
 {
 	buf_block_t*	block;
 
@@ -233,6 +234,11 @@ buf_buddy_alloc_low(
 		goto alloc_big;
 	}
 
+	if (!lru) {
+
+		return(NULL);
+	}
+
 	/* Try replacing a compressed-only page in the buffer pool. */
 
 	block = buf_buddy_alloc_clean_zip(i);
@@ -243,7 +249,9 @@ buf_buddy_alloc_low(
 	}
 
 	/* Try replacing an uncompressed page in the buffer pool. */
+	mutex_exit(&buf_pool->mutex);
 	block = buf_LRU_get_free_block(0);
+	mutex_enter(&buf_pool->mutex);
 
 alloc_big:
 	buf_buddy_block_register(block);

include/buf0buddy.h

@@ -48,7 +48,8 @@ void*
 buf_buddy_alloc(
 /*============*/
 			/* out: pointer to the start of the block */
-	ulint	size)	/* in: block size, up to UNIV_PAGE_SIZE / 2 */
+	ulint	size,	/* in: block size, up to UNIV_PAGE_SIZE / 2 */
+	ibool	lru)	/* in: TRUE=allocate from the LRU list if needed */
 	__attribute__((malloc));
 
 /**************************************************************************

include/buf0buddy.ic

@@ -25,7 +25,8 @@ void*
 buf_buddy_alloc_low(
 /*================*/
 			/* out: pointer to the start of the block */
-	ulint	i)	/* in: index of buf_pool->zip_free[] */
+	ulint	i,	/* in: index of buf_pool->zip_free[] */
+	ibool	lru)	/* in: TRUE=allocate from the LRU list if needed */
 	__attribute__((malloc));
 
 /**************************************************************************
@@ -84,13 +85,14 @@ void*
 buf_buddy_alloc(
 /*============*/
 			/* out: pointer to the start of the block */
-	ulint	size)	/* in: block size, up to UNIV_PAGE_SIZE / 2 */
+	ulint	size,	/* in: block size, up to UNIV_PAGE_SIZE / 2 */
+	ibool	lru)	/* in: TRUE=allocate from the LRU list if needed */
 {
 #ifdef UNIV_SYNC_DEBUG
 	ut_a(mutex_own(&buf_pool->mutex));
 #endif /* UNIV_SYNC_DEBUG */
 
-	return(buf_buddy_alloc_low(buf_buddy_get_slot(size)));
+	return(buf_buddy_alloc_low(buf_buddy_get_slot(size), lru));
 }
 
 /**************************************************************************