From 354bb40e75d94466e91fe6960523612c9d17ccfb Mon Sep 17 00:00:00 2001
From: Karen Arutyunov <karen@codesynthesis.com>
Date: Thu, 2 Nov 2017 23:11:29 +0300
Subject: Add implementation

---
 mysql/mysql/service_thd_wait.h | 114 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 114 insertions(+)
 create mode 100644 mysql/mysql/service_thd_wait.h

(limited to 'mysql/mysql/service_thd_wait.h')

diff --git a/mysql/mysql/service_thd_wait.h b/mysql/mysql/service_thd_wait.h
new file mode 100644
index 0000000..62f2ea4
--- /dev/null
+++ b/mysql/mysql/service_thd_wait.h
@@ -0,0 +1,114 @@
+/* Copyright (c) 2010, 2015, Oracle and/or its affiliates. All rights reserved.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; version 2 of the License.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */
+
+#ifndef MYSQL_SERVICE_THD_WAIT_INCLUDED
+#define MYSQL_SERVICE_THD_WAIT_INCLUDED
+
+/**
+  @file include/mysql/service_thd_wait.h
+  This service provides functions for plugins and storage engines to report
+  when they are going to sleep/stall.
+  
+  SYNOPSIS
+  thd_wait_begin() - call just before a wait begins
+  thd                     Thread object
+                          Use NULL if the thd is NOT known.
+  wait_type               Type of wait
+                          1 -- short wait (e.g. for mutex)
+                          2 -- medium wait (e.g. for disk io)
+                          3 -- large wait (e.g. for locked row/table)
+  NOTES
+    This is used by the threadpool to have better knowledge of which
+    threads that currently are actively running on CPUs. When a thread
+    reports that it's going to sleep/stall, the threadpool scheduler is
+    free to start another thread in the pool most likely. The expected wait
+    time is simply an indication of how long the wait is expected to
+    become, the real wait time could be very different.
+
+  thd_wait_end() called immediately after the wait is complete
+
+  thd_wait_end() MUST be called if thd_wait_begin() was called.
+
+  Using thd_wait_...() service is optional but recommended.  Using it will
+  improve performance as the thread pool will be more active at managing the
+  thread workload.
+*/
+
+#ifdef __cplusplus
+class THD;
+#define MYSQL_THD THD*
+#else
+#define MYSQL_THD void*
+#endif
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+  One should only report wait events that could potentially block for a
+  long time. A mutex wait is too short of an event to report. The reason
+  is that an event which is reported leads to a new thread starts
+  executing a query and this has a negative impact of usage of CPU caches
+  and thus the expected gain of starting a new thread must be higher than
+  the expected cost of lost performance due to starting a new thread.
+
+  Good examples of events that should be reported are waiting for row locks
+  that could easily be for many milliseconds or even seconds and the same
+  holds true for global read locks, table locks and other meta data locks.
+  Another event of interest is going to sleep for an extended time.
+
+  Note that user-level locks no longer use THD_WAIT_USER_LOCK wait type.
+  Since their implementation relies on metadata locks manager it uses
+  THD_WAIT_META_DATA_LOCK instead.
+*/
+typedef enum _thd_wait_type_e {
+  THD_WAIT_SLEEP= 1,
+  THD_WAIT_DISKIO= 2,
+  THD_WAIT_ROW_LOCK= 3,
+  THD_WAIT_GLOBAL_LOCK= 4,
+  THD_WAIT_META_DATA_LOCK= 5,
+  THD_WAIT_TABLE_LOCK= 6,
+  THD_WAIT_USER_LOCK= 7,
+  THD_WAIT_BINLOG= 8,
+  THD_WAIT_GROUP_COMMIT= 9,
+  THD_WAIT_SYNC= 10,
+  THD_WAIT_LAST= 11
+} thd_wait_type;
+
+extern struct thd_wait_service_st {
+  void (*thd_wait_begin_func)(MYSQL_THD, int);
+  void (*thd_wait_end_func)(MYSQL_THD);
+} *thd_wait_service;
+
+#ifdef MYSQL_DYNAMIC_PLUGIN
+
+#define thd_wait_begin(_THD, _WAIT_TYPE) \
+  thd_wait_service->thd_wait_begin_func(_THD, _WAIT_TYPE)
+#define thd_wait_end(_THD) thd_wait_service->thd_wait_end_func(_THD)
+
+#else
+
+void thd_wait_begin(MYSQL_THD thd, int wait_type);
+void thd_wait_end(MYSQL_THD thd);
+
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+
-- 
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