branches/zip rb://176

Do not invalidate buffer pool while an LRU batch is active. Added
code to buf_pool_invalidate() to wait for the running batches to finish.

This patch also resets the state of buf_pool struct at invalidation. This
addresses the concern where buf_pool->freed_page_clock becomes non-zero
because we read in a system tablespace page for file format info at
startup.

Approved by: Marko

buf/buf0buf.c

@@ -3287,7 +3287,32 @@ void
 buf_pool_invalidate(void)
 /*=====================*/
 {
-	ibool	freed;
+	ibool		freed;
+	enum buf_flush	i;
+
+	buf_pool_mutex_enter();
+
+	for (i = BUF_FLUSH_LRU; i < BUF_FLUSH_N_TYPES; i++) {
+
+		/* As this function is called during startup and
+		during redo application phase during recovery, InnoDB
+		is single threaded (apart from IO helper threads) at
+		this stage. No new write batch can be in intialization
+		stage at this point. */
+		ut_ad(buf_pool->init_flush[i] == FALSE);
+
+		/* However, it is possible that a write batch that has
+		been posted earlier is still not complete. For buffer
+		pool invalidation to proceed we must ensure there is NO
+		write activity happening. */
+		if (buf_pool->n_flush[i] > 0) {
+			buf_pool_mutex_exit();
+			buf_flush_wait_batch_end(i);
+			buf_pool_mutex_enter();
+		}
+	}
+
+	buf_pool_mutex_exit();
 
 	ut_ad(buf_all_freed());
 
@@ -3302,6 +3327,14 @@ buf_pool_invalidate(void)
 	ut_ad(UT_LIST_GET_LEN(buf_pool->LRU) == 0);
 	ut_ad(UT_LIST_GET_LEN(buf_pool->unzip_LRU) == 0);
 
+	buf_pool->freed_page_clock = 0;
+	buf_pool->LRU_old = NULL;
+	buf_pool->LRU_old_len = 0;
+	buf_pool->LRU_flush_ended = 0;
+
+	memset(&buf_pool->stat, 0x00, sizeof(buf_pool->stat));
+	buf_refresh_io_stats();
+
 	buf_pool_mutex_exit();
 }