1 files changed, 59 insertions, 125 deletions

diff --git a/storage/innobase/buf/buf0lru.cc b/storage/innobase/buf/buf0lru.cc
index 2a8d6ff2..33d01b6b 100644
--- a/storage/innobase/buf/buf0lru.cc
+++ b/storage/innobase/buf/buf0lru.cc
@@ -385,142 +385,76 @@ we put it to free list to be used.
 @return the free control block, in state BUF_BLOCK_MEMORY */
 buf_block_t *buf_LRU_get_free_block(bool have_mutex)
 {
-	ulint		n_iterations	= 0;
-	ulint		flush_failures	= 0;
-	MONITOR_INC(MONITOR_LRU_GET_FREE_SEARCH);
-	if (have_mutex) {
-		mysql_mutex_assert_owner(&buf_pool.mutex);
-		goto got_mutex;
-	}
-	DBUG_EXECUTE_IF("recv_ran_out_of_buffer",
-			if (recv_recovery_is_on()
-			    && recv_sys.apply_log_recs) {
-				mysql_mutex_lock(&buf_pool.mutex);
-				goto flush_lru;
-			});
-get_mutex:
-	mysql_mutex_lock(&buf_pool.mutex);
-got_mutex:
-	buf_LRU_check_size_of_non_data_objects();
-	buf_block_t* block;
+  bool waited= false;
+  MONITOR_INC(MONITOR_LRU_GET_FREE_SEARCH);
+  if (!have_mutex)
+    mysql_mutex_lock(&buf_pool.mutex);
+
+  buf_LRU_check_size_of_non_data_objects();
 
-	IF_DBUG(static bool buf_lru_free_blocks_error_printed,);
-	DBUG_EXECUTE_IF("ib_lru_force_no_free_page",
-		if (!buf_lru_free_blocks_error_printed) {
-			n_iterations = 21;
-			goto not_found;});
+  buf_block_t *block;
 
 retry:
-	/* If there is a block in the free list, take it */
-	if ((block = buf_LRU_get_free_only()) != nullptr) {
+  /* If there is a block in the free list, take it */
+  block= buf_LRU_get_free_only();
+  if (block)
+  {
 got_block:
-		const ulint LRU_size = UT_LIST_GET_LEN(buf_pool.LRU);
-		const ulint available = UT_LIST_GET_LEN(buf_pool.free);
-		const ulint scan_depth = srv_LRU_scan_depth / 2;
-		ut_ad(LRU_size <= BUF_LRU_MIN_LEN || available >= scan_depth
-		      || buf_pool.need_LRU_eviction());
-
-		if (!have_mutex) {
-			mysql_mutex_unlock(&buf_pool.mutex);
-		}
-
-		if (UNIV_UNLIKELY(available < scan_depth)
-		    && LRU_size > BUF_LRU_MIN_LEN) {
-			mysql_mutex_lock(&buf_pool.flush_list_mutex);
-			if (!buf_pool.page_cleaner_active()) {
-				buf_pool.page_cleaner_wakeup(true);
-			}
-			mysql_mutex_unlock(&buf_pool.flush_list_mutex);
-		}
-
-		block->page.zip.clear();
-		return block;
-	}
+    const ulint LRU_size= UT_LIST_GET_LEN(buf_pool.LRU);
+    const ulint available= UT_LIST_GET_LEN(buf_pool.free);
+    const ulint scan_depth= srv_LRU_scan_depth / 2;
+    ut_ad(LRU_size <= BUF_LRU_MIN_LEN ||
+          available >= scan_depth || buf_pool.need_LRU_eviction());
 
-	MONITOR_INC( MONITOR_LRU_GET_FREE_LOOPS );
-	if (n_iterations || buf_pool.try_LRU_scan) {
-		/* If no block was in the free list, search from the
-		end of the LRU list and try to free a block there.
-		If we are doing for the first time we'll scan only
-		tail of the LRU list otherwise we scan the whole LRU
-		list. */
-		if (buf_LRU_scan_and_free_block(n_iterations
-						? ULINT_UNDEFINED : 100)) {
-			goto retry;
-		}
+    if (UNIV_UNLIKELY(available < scan_depth) && LRU_size > BUF_LRU_MIN_LEN)
+    {
+      mysql_mutex_lock(&buf_pool.flush_list_mutex);
+      if (!buf_pool.page_cleaner_active())
+        buf_pool.page_cleaner_wakeup(true);
+      mysql_mutex_unlock(&buf_pool.flush_list_mutex);
+    }
 
-		/* Tell other threads that there is no point
-		in scanning the LRU list. */
-		buf_pool.try_LRU_scan = false;
-	}
+    if (!have_mutex)
+      mysql_mutex_unlock(&buf_pool.mutex);
 
-	for (;;) {
-		if ((block = buf_LRU_get_free_only()) != nullptr) {
-			goto got_block;
-		}
-		const bool wake = buf_pool.need_LRU_eviction();
-		mysql_mutex_unlock(&buf_pool.mutex);
-		mysql_mutex_lock(&buf_pool.flush_list_mutex);
-		const auto n_flush = buf_pool.n_flush();
-		if (wake && !buf_pool.page_cleaner_active()) {
-			buf_pool.page_cleaner_wakeup(true);
-		}
-		mysql_mutex_unlock(&buf_pool.flush_list_mutex);
-		mysql_mutex_lock(&buf_pool.mutex);
-		if (!n_flush) {
-			goto not_found;
-		}
-		if (!buf_pool.try_LRU_scan) {
-			my_cond_wait(&buf_pool.done_free,
-				     &buf_pool.mutex.m_mutex);
-		}
-	}
-
-not_found:
-	if (n_iterations > 1) {
-		MONITOR_INC( MONITOR_LRU_GET_FREE_WAITS );
-	}
+    block->page.zip.clear();
+    return block;
+  }
 
-	if (n_iterations == 21
-	    && srv_buf_pool_old_size == srv_buf_pool_size
-	    && buf_pool.LRU_warned.test_and_set(std::memory_order_acquire)) {
-		IF_DBUG(buf_lru_free_blocks_error_printed = true,);
-		mysql_mutex_unlock(&buf_pool.mutex);
-		ib::warn() << "Difficult to find free blocks in the buffer pool"
-			" (" << n_iterations << " search iterations)! "
-			<< flush_failures << " failed attempts to"
-			" flush a page!"
-			" Consider increasing innodb_buffer_pool_size."
-			" Pending flushes (fsync): "
-			<< fil_n_pending_tablespace_flushes
-			<< ". " << os_n_file_reads << " OS file reads, "
-			<< os_n_file_writes << " OS file writes, "
-			<< os_n_fsyncs
-			<< " OS fsyncs.";
-		mysql_mutex_lock(&buf_pool.mutex);
-	}
+  MONITOR_INC(MONITOR_LRU_GET_FREE_LOOPS);
+  if (waited || buf_pool.try_LRU_scan)
+  {
+    /* If no block was in the free list, search from the end of the
+    LRU list and try to free a block there.  If we are doing for the
+    first time we'll scan only tail of the LRU list otherwise we scan
+    the whole LRU list. */
+    if (buf_LRU_scan_and_free_block(waited ? ULINT_UNDEFINED : 100))
+      goto retry;
+
+    /* Tell other threads that there is no point in scanning the LRU
+    list. */
+    buf_pool.try_LRU_scan= false;
+  }
 
-	/* No free block was found: try to flush the LRU list.
-	The freed blocks will be up for grabs for all threads.
+  waited= true;
 
-	TODO: A more elegant way would have been to return one freed
-	up block to the caller here but the code that deals with
-	removing the block from buf_pool.page_hash and buf_pool.LRU is fairly
-	involved (particularly in case of ROW_FORMAT=COMPRESSED pages). We
-	can do that in a separate patch sometime in future. */
-#ifndef DBUG_OFF
-flush_lru:
-#endif
-	if (!buf_flush_LRU(innodb_lru_flush_size, true)) {
-		MONITOR_INC(MONITOR_LRU_SINGLE_FLUSH_FAILURE_COUNT);
-		++flush_failures;
-	}
+  while (!(block= buf_LRU_get_free_only()))
+  {
+    buf_pool.stat.LRU_waits++;
+
+    timespec abstime;
+    set_timespec(abstime, 1);
+
+    mysql_mutex_lock(&buf_pool.flush_list_mutex);
+    if (!buf_pool.page_cleaner_active())
+      buf_pool.page_cleaner_wakeup(true);
+    mysql_mutex_unlock(&buf_pool.flush_list_mutex);
+    if (my_cond_timedwait(&buf_pool.done_free, &buf_pool.mutex.m_mutex,
+                          &abstime))
+      buf_pool.LRU_warn();
+  }
 
-	n_iterations++;
-	buf_pool.stat.LRU_waits++;
-	mysql_mutex_unlock(&buf_pool.mutex);
-	buf_dblwr.flush_buffered_writes();
-	goto get_mutex;
+  goto got_block;
 }
 
 /** Move the LRU_old pointer so that the length of the old blocks list