MDEV-6712 THD specifics for plugins

thd_specifics service

include/mysql/plugin_audit.h.pp

@@ -185,6 +185,18 @@
 char *thd_get_error_context_description(void* thd,
                                         char *buffer, unsigned int length,
                                         unsigned int max_query_length);
+#include <mysql/service_thd_specifics.h>
+typedef int MYSQL_THD_KEY_T;
+extern struct thd_specifics_service_st {
+  int (*thd_key_create_func)(MYSQL_THD_KEY_T *key);
+  void (*thd_key_delete_func)(MYSQL_THD_KEY_T *key);
+  void *(*thd_getspecific_func)(void* thd, MYSQL_THD_KEY_T key);
+  int (*thd_setspecific_func)(void* thd, MYSQL_THD_KEY_T key, void *value);
+} *thd_specifics_service;
+int thd_key_create(MYSQL_THD_KEY_T *key);
+void thd_key_delete(MYSQL_THD_KEY_T *key);
+void* thd_getspecific(void* thd, MYSQL_THD_KEY_T key);
+int thd_setspecific(void* thd, MYSQL_THD_KEY_T key, void *value);
 struct st_mysql_xid {
   long formatID;
   long gtrid_length;

include/mysql/plugin_auth.h.pp

@@ -185,6 +185,18 @@
 char *thd_get_error_context_description(void* thd,
                                         char *buffer, unsigned int length,
                                         unsigned int max_query_length);
+#include <mysql/service_thd_specifics.h>
+typedef int MYSQL_THD_KEY_T;
+extern struct thd_specifics_service_st {
+  int (*thd_key_create_func)(MYSQL_THD_KEY_T *key);
+  void (*thd_key_delete_func)(MYSQL_THD_KEY_T *key);
+  void *(*thd_getspecific_func)(void* thd, MYSQL_THD_KEY_T key);
+  int (*thd_setspecific_func)(void* thd, MYSQL_THD_KEY_T key, void *value);
+} *thd_specifics_service;
+int thd_key_create(MYSQL_THD_KEY_T *key);
+void thd_key_delete(MYSQL_THD_KEY_T *key);
+void* thd_getspecific(void* thd, MYSQL_THD_KEY_T key);
+int thd_setspecific(void* thd, MYSQL_THD_KEY_T key, void *value);
 struct st_mysql_xid {
   long formatID;
   long gtrid_length;

include/mysql/plugin_ftparser.h.pp

@@ -185,6 +185,18 @@
 char *thd_get_error_context_description(void* thd,
                                         char *buffer, unsigned int length,
                                         unsigned int max_query_length);
+#include <mysql/service_thd_specifics.h>
+typedef int MYSQL_THD_KEY_T;
+extern struct thd_specifics_service_st {
+  int (*thd_key_create_func)(MYSQL_THD_KEY_T *key);
+  void (*thd_key_delete_func)(MYSQL_THD_KEY_T *key);
+  void *(*thd_getspecific_func)(void* thd, MYSQL_THD_KEY_T key);
+  int (*thd_setspecific_func)(void* thd, MYSQL_THD_KEY_T key, void *value);
+} *thd_specifics_service;
+int thd_key_create(MYSQL_THD_KEY_T *key);
+void thd_key_delete(MYSQL_THD_KEY_T *key);
+void* thd_getspecific(void* thd, MYSQL_THD_KEY_T key);
+int thd_setspecific(void* thd, MYSQL_THD_KEY_T key, void *value);
 struct st_mysql_xid {
   long formatID;
   long gtrid_length;

include/mysql/plugin_password_validation.h.pp

@@ -185,6 +185,18 @@
 char *thd_get_error_context_description(void* thd,
                                         char *buffer, unsigned int length,
                                         unsigned int max_query_length);
+#include <mysql/service_thd_specifics.h>
+typedef int MYSQL_THD_KEY_T;
+extern struct thd_specifics_service_st {
+  int (*thd_key_create_func)(MYSQL_THD_KEY_T *key);
+  void (*thd_key_delete_func)(MYSQL_THD_KEY_T *key);
+  void *(*thd_getspecific_func)(void* thd, MYSQL_THD_KEY_T key);
+  int (*thd_setspecific_func)(void* thd, MYSQL_THD_KEY_T key, void *value);
+} *thd_specifics_service;
+int thd_key_create(MYSQL_THD_KEY_T *key);
+void thd_key_delete(MYSQL_THD_KEY_T *key);
+void* thd_getspecific(void* thd, MYSQL_THD_KEY_T key);
+int thd_setspecific(void* thd, MYSQL_THD_KEY_T key, void *value);
 struct st_mysql_xid {
   long formatID;
   long gtrid_length;

include/mysql/service_thd_specifics.h

@@ -0,0 +1,110 @@
+#ifndef MYSQL_SERVICE_THD_SPECIFICS_INCLUDED
+/* Copyright (c) 2009, 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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */
+
+/**
+  @file
+
+  THD specific for plugin(s)
+
+  This API provides pthread_getspecific like functionality to plugin authors.
+  This is a functional alternative to the declarative MYSQL_THDVAR
+
+  A plugin should at init call thd_key_create that create a key that
+  will have storage in each THD. The key should be used by all threads
+  and can be used concurrently from all threads.
+
+  A plugin should at deinit call thd_key_delete.
+
+  Alternatively, a plugin can use thd_key_create_from_var(K,V) to create
+  a key that corresponds to a named MYSQL_THDVAR variable.
+
+  This API is also safe when using pool-of-threads in which case
+  pthread_getspecific is not, because the actual OS thread may change.
+
+  @note
+
+  Normally one should prefer MYSQL_THDVAR declarative API.
+
+  The benefits are:
+
+  - It supports typed variables (int, char*, enum, etc), not only void*.
+  - The memory allocated for MYSQL_THDVAR is free'd automatically
+    (if PLUGIN_VAR_MEMALLOC is specified).
+  - Continuous loading and unloading of the same plugin does not allocate
+    memory for same variables over and over again.
+
+  An example of using MYSQL_THDVAR for a thd local storage:
+
+    MYSQL_THDVAR_STR(my_tls,
+            PLUGIN_VAR_MEMALLOC | PLUGIN_VAR_NOSYSVAR | PLUGIN_VAR_NOCMDOPT,
+            "thd local storage example", 0, 0, 0);
+*/
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef int MYSQL_THD_KEY_T;
+
+extern struct thd_specifics_service_st {
+  int (*thd_key_create_func)(MYSQL_THD_KEY_T *key);
+  void (*thd_key_delete_func)(MYSQL_THD_KEY_T *key);
+  void *(*thd_getspecific_func)(MYSQL_THD thd, MYSQL_THD_KEY_T key);
+  int  (*thd_setspecific_func)(MYSQL_THD thd, MYSQL_THD_KEY_T key, void *value);
+} *thd_specifics_service;
+
+#define thd_key_create_from_var(K, V) do { *(K)= MYSQL_SYSVAR_NAME(V).offset; } while(0)
+
+#ifdef MYSQL_DYNAMIC_PLUGIN
+
+#define thd_key_create(K) (thd_specifics_service->thd_key_create_func(K))
+#define thd_key_delete(K) (thd_specifics_service->thd_key_delete_func(K))
+#define thd_getspecific(T, K) (thd_specifics_service->thd_getspecific_func(T, K))
+#define thd_setspecific(T, K, V) (thd_specifics_service->thd_setspecific_func(T, K, V))
+
+#else
+
+/**
+ * create THD specific storage
+ * @return 0 on success
+ *    else errno is returned
+ */
+int thd_key_create(MYSQL_THD_KEY_T *key);
+
+/**
+ * delete THD specific storage
+ */
+void thd_key_delete(MYSQL_THD_KEY_T *key);
+
+/**
+ * get/set thd specific storage
+ *  - first time this is called from a thread it will return 0
+ *  - this call is thread-safe in that different threads may call this
+ *    simultaneously if operating on different THDs.
+ *  - this call acquires no mutexes and is implemented as an array lookup
+ */
+void* thd_getspecific(MYSQL_THD thd, MYSQL_THD_KEY_T key);
+int thd_setspecific(MYSQL_THD thd, MYSQL_THD_KEY_T key, void *value);
+
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#define MYSQL_SERVICE_THD_SPECIFICS_INCLUDED
+#endif
+

include/mysql/services.h

@@ -31,6 +31,7 @@ extern "C" {
 #include <mysql/service_logger.h>
 #include <mysql/service_thd_autoinc.h>
 #include <mysql/service_thd_error_context.h>
+#include <mysql/service_thd_specifics.h>
 /*#include <mysql/service_wsrep.h>*/
 
 #ifdef __cplusplus

include/service_versions.h

@@ -34,3 +34,5 @@
 #define VERSION_logger                  0x0100
 #define VERSION_thd_autoinc             0x0100
 #define VERSION_thd_error_context       0x0100
+#define VERSION_thd_specifics           0x0100
+

libservices/CMakeLists.txt

@@ -22,6 +22,7 @@ SET(MYSQLSERVICES_SOURCES
   thd_timezone_service.c
   thd_autoinc_service.c
   thd_error_context_service.c
+  thd_specifics_service.c
   progress_report_service.c
   debug_sync_service.c
   my_sha1_service.c

libservices/thd_specifics_service.c

@@ -0,0 +1,17 @@
+/* Copyright (C) 2014 MariaDB
+
+   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 */
+
+#include <service_versions.h>
+SERVICE_VERSION thd_specifics_service= (void *) VERSION_thd_specifics;

sql/sql_plugin.cc

@@ -4094,3 +4094,51 @@ static void restore_ptr_backup(uint n, st_ptr_backup *backup)
     (backup++)->restore();
 }
 
+/****************************************************************************
+  thd specifics service, see include/mysql/service_thd_specifics.h
+****************************************************************************/
+static const int INVALID_THD_KEY= -1;
+static uint thd_key_no = 42;
+
+int thd_key_create(MYSQL_THD_KEY_T *key)
+{
+  int flags= PLUGIN_VAR_THDLOCAL | PLUGIN_VAR_STR |
+             PLUGIN_VAR_NOSYSVAR | PLUGIN_VAR_NOCMDOPT;
+  char namebuf[256];
+  snprintf(namebuf, sizeof(namebuf), "%u", thd_key_no++);
+  mysql_rwlock_wrlock(&LOCK_system_variables_hash);
+  // non-letters in the name as an extra safety
+  st_bookmark *bookmark= register_var("\a\v\a\t\a\r", namebuf, flags);
+  mysql_rwlock_unlock(&LOCK_system_variables_hash);
+  if (bookmark)
+  {
+    *key= bookmark->offset;
+    return 0;
+  }
+  return ENOMEM;
+}
+
+void thd_key_delete(MYSQL_THD_KEY_T *key)
+{
+  *key= INVALID_THD_KEY;
+}
+
+void* thd_getspecific(MYSQL_THD thd, MYSQL_THD_KEY_T key)
+{
+  DBUG_ASSERT(key != INVALID_THD_KEY);
+  if (key == INVALID_THD_KEY || (!thd && !(thd= current_thd)))
+    return 0;
+
+  return *(void**)(intern_sys_var_ptr(thd, key, true));
+}
+
+int thd_setspecific(MYSQL_THD thd, MYSQL_THD_KEY_T key, void *value)
+{
+  DBUG_ASSERT(key != INVALID_THD_KEY);
+  if (key == INVALID_THD_KEY || (!thd && !(thd= current_thd)))
+    return EINVAL;
+
+  memcpy(intern_sys_var_ptr(thd, key, true), &value, sizeof(void*));
+  return 0;
+}
+

sql/sql_plugin_services.h

@@ -139,6 +139,14 @@ static struct wsrep_service_st wsrep_handler = {
   wsrep_unlock_rollback
 };
 
+static struct thd_specifics_service_st thd_specifics_handler=
+{
+  thd_key_create,
+  thd_key_delete,
+  thd_getspecific,
+  thd_setspecific
+};
+
 static struct st_service_ref list_of_services[]=
 {
   { "my_snprintf_service",         VERSION_my_snprintf,         &my_snprintf_handler },
@@ -153,6 +161,7 @@ static struct st_service_ref list_of_services[]=
   { "logger_service",              VERSION_logger,              &logger_service_handler },
   { "thd_autoinc_service",         VERSION_thd_autoinc,         &thd_autoinc_handler },
   { "wsrep_service",               VERSION_wsrep,               &wsrep_handler },
+  { "thd_specifics_service",       VERSION_thd_specifics,       &thd_specifics_handler },
   { "thd_error_context_service",   VERSION_thd_error_context,   &thd_error_conext_handler },
 };