WL#5363: Thread Pool Service Interface

In order to allow thread schedulers to be dynamically loaded,
it is necessary to make the following changes to the server:

- Two new service interfaces

- Modifications to InnoDB to inform the thread scheduler of state changes.

- Changes to the VIO subsystem for checking if data is available on a socket.

- Elimination of remains of the old thread pool implementation.

The two new service interfaces introduces are:

my_thread_scheduler
  A service interface to register a thread
  scheduler.

thd_wait
  A service interface to inform thread scheduler
  that the thread is about to start waiting.

In addition, the patch adds code that:

- Add a call to thd_wait for table locks in mysys
  thd_lock.c by introducing a set function that
  can be used to set a callback to be used when
  waiting on a lock and resuming from waiting.

- Calling the mysys set function from the server
  to set the callbacks correctly.

include/mysql/plugin.h

@@ -71,7 +71,7 @@ typedef struct st_mysql_xid MYSQL_XID;
   Plugin API. Common for all plugin types.
 */
 
-#define MYSQL_PLUGIN_INTERFACE_VERSION 0x0101
+#define MYSQL_PLUGIN_INTERFACE_VERSION 0x0102
 
 /*
   The allowable types of plugins

include/mysql/plugin.h.pp

@@ -33,6 +33,27 @@ void *thd_memdup(void* thd, const void* str, unsigned int size);
 MYSQL_LEX_STRING *thd_make_lex_string(void* thd, MYSQL_LEX_STRING *lex_str,
                                       const char *str, unsigned int size,
                                       int allocate_lex_string);
+#include <mysql/service_thd_wait.h>
+typedef enum _thd_wait_type_e {
+  THD_WAIT_MUTEX= 1,
+  THD_WAIT_DISKIO= 2,
+  THD_WAIT_ROW_TABLE_LOCK= 3,
+  THD_WAIT_GLOBAL_LOCK= 4
+} thd_wait_type;
+extern struct thd_wait_service_st {
+  void (*thd_wait_begin_func)(void*, thd_wait_type);
+  void (*thd_wait_end_func)(void*);
+} *thd_wait_service;
+void thd_wait_begin(void* thd, thd_wait_type wait_type);
+void thd_wait_end(void* thd);
+#include <mysql/service_thread_scheduler.h>
+struct scheduler_functions;
+extern struct my_thread_scheduler_service {
+  int (*set)(struct scheduler_functions *scheduler);
+  int (*reset)();
+} *my_thread_scheduler_service;
+int my_thread_scheduler_set(struct scheduler_functions *scheduler);
+int my_thread_scheduler_reset();
 struct st_mysql_xid {
   long formatID;
   long gtrid_length;

include/mysql/service_thd_wait.h

@@ -0,0 +1,83 @@
+/* Copyright (C) 2010, 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  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
+extern "C" {
+#endif
+
+typedef enum _thd_wait_type_e {
+  THD_WAIT_MUTEX= 1,
+  THD_WAIT_DISKIO= 2,
+  THD_WAIT_ROW_TABLE_LOCK= 3,
+  THD_WAIT_GLOBAL_LOCK= 4
+} thd_wait_type;
+
+extern struct thd_wait_service_st {
+  void (*thd_wait_begin_func)(MYSQL_THD, thd_wait_type);
+  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, thd_wait_type wait_type);
+void thd_wait_end(MYSQL_THD thd);
+
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+

include/mysql/service_thread_scheduler.h

@@ -0,0 +1,65 @@
+/*
+  Copyright (C) 2010, 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+*/
+
+#ifndef SERVICE_THREAD_SCHEDULER_INCLUDED
+#define SERVICE_THREAD_SCHEDULER_INCLUDED
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct scheduler_functions;
+
+extern struct my_thread_scheduler_service {
+  int (*set)(struct scheduler_functions *scheduler);
+  int (*reset)();
+} *my_thread_scheduler_service;
+
+#ifdef MYSQL_DYNAMIC_PLUGIN
+
+#define my_thread_scheduler_set(F) my_thread_scheduler_service->set((F))
+#define my_thread_scheduler_reset() my_thread_scheduler_service->reset()
+
+#else
+
+/**
+  Set the thread scheduler to use for the server.
+
+  @param scheduler Pointer to scheduler callbacks to use.
+  @retval 0 Scheduler installed correctly.
+  @retval 1 Invalid value (NULL) used for scheduler.
+*/
+int my_thread_scheduler_set(struct scheduler_functions *scheduler);
+
+/**
+  Restore the previous thread scheduler.
+
+  @note If no thread scheduler was installed previously with
+  thd_set_thread_scheduler, this function will report an error.
+
+  @retval 0 Scheduler installed correctly.
+  @retval 1 No scheduler installed.
+*/
+int my_thread_scheduler_reset();
+
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* SERVICE_THREAD_SCHEDULER_INCLUDED */

include/mysql/services.h

@@ -20,6 +20,8 @@ extern "C" {
 
 #include <mysql/service_my_snprintf.h>
 #include <mysql/service_thd_alloc.h>
+#include <mysql/service_thd_wait.h>
+#include <mysql/service_thread_scheduler.h>
 
 #ifdef __cplusplus
 }