1 files changed, 110 insertions, 0 deletions
diff --git a/include/mysql/service_thd_specifics.h b/include/mysql/service_thd_specifics.h
new file mode 100644
index 00000000..a4078bd5
--- /dev/null
+++ b/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 02110-1335  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
+