!1101 支持插件自定义会话级变量

Merge pull request !1101 from chenxiaobin/extension_session

src/common/backend/utils/fmgr/dfmgr.cpp

@@ -179,6 +179,7 @@ void* internal_load_library(const char* libname)
     DynamicFileList* file_scanner = NULL;
     FileListInit* file_init_scanner = NULL;
     PGModuleMagicFunction magic_func;
+    void (*set_extension_index)(uint32);
     struct stat stat_buf;
     PG_init_t PG_init = NULL;
     char* file = last_dir_separator(libname);
@@ -311,6 +312,13 @@ void* internal_load_library(const char* libname)
                     errhint("Extension libraries are required to use the PG_MODULE_MAGIC macro.")));
         }
 
+        /* Look up the set_extension_index function within extension's so */
+        set_extension_index = (void(*)(uint32))pg_dlsym(file_scanner->handle, "set_extension_index");
+        if (set_extension_index) {
+            uint32 idx = pg_atomic_fetch_add_u32(&g_instance.extensionNum, 1);
+            (*set_extension_index)(idx);
+        }
+
         /* OK to link it into list */
         if (file_list == NULL)
             file_list = file_scanner;

src/common/backend/utils/init/postinit.cpp

@@ -86,6 +86,11 @@
 #include "instruments/percentile.h"
 #include "instruments/instr_workload.h"
 #include "gs_policy/policy_common.h"
+#ifndef WIN32_ONLY_COMPILER
+#include "dynloader.h"
+#else
+#include "port/dynloader/win32.h"
+#endif
 
 #ifdef PGXC
 #include "catalog/pgxc_node.h"
@@ -1737,6 +1742,8 @@ void PostgresInitializer::InitSession()
 
     InitSettings();
 
+    InitExtensionVariable();
+
     FinishInit();
 
     AuditUserLogin();
@@ -2260,6 +2267,28 @@ void PostgresInitializer::InitSettings()
     InitializeClientEncoding();
 }
 
+void PostgresInitializer::InitExtensionVariable()
+{
+    int initExtArraySize = 10;
+    void (*init_session_vars)(void);
+
+    /* initialize u_sess->attr.attr_common.extension_session_vars_array */
+    u_sess->attr.attr_common.extension_session_vars_array_size = initExtArraySize;
+    u_sess->attr.attr_common.extension_session_vars_array =
+        (void**)MemoryContextAllocZero(u_sess->self_mem_cxt, (Size)(initExtArraySize * sizeof(void*)));
+
+    DynamicFileList* file_scanner = NULL;
+    for (file_scanner = file_list; file_scanner != NULL; file_scanner = file_scanner->next) {
+        /* 
+        * If the library has a init_session_vars() function, call it for
+        * initializing extension session variables.
+        */
+        init_session_vars = (void(*)(void))pg_dlsym(file_scanner->handle, "init_session_vars");
+        if (init_session_vars != NULL)
+            (*init_session_vars)();
+    }
+}
+
 void PostgresInitializer::FinishInit()
 {
     /* report this backend in the PgBackendStatus array */

src/gausskernel/optimizer/commands/extension.cpp

@@ -2889,3 +2889,25 @@ void AlterExtensionOwner_oid(Oid extensionOid, Oid newOwnerId)
 
     heap_close(rel, NoLock);
 }
+
+/* 
+ * Expand the size of extension_session_vars_array_size by twice the number
+ * of extensions each time if latter is bigger.
+ */
+void RepallocSessionVarsArrayIfNecessary()
+{
+    uint32 currExtensionNum = pg_atomic_read_u32(&g_instance.extensionNum);
+    uint32 currArraySize = u_sess->attr.attr_common.extension_session_vars_array_size;
+    int rc;
+
+    if (currExtensionNum >= currArraySize) {
+        u_sess->attr.attr_common.extension_session_vars_array = (void**)repalloc(
+            u_sess->attr.attr_common.extension_session_vars_array, currExtensionNum * 2 * sizeof(void*));
+
+        rc = memset_s(&u_sess->attr.attr_common.extension_session_vars_array[currArraySize],
+            (currExtensionNum * 2 - currArraySize) * sizeof(void*), 0,
+            (currExtensionNum * 2 - currArraySize) * sizeof(void*));
+        securec_check(rc, "", "");
+        u_sess->attr.attr_common.extension_session_vars_array_size = currExtensionNum * 2;
+    }
+}

src/gausskernel/process/threadpool/knl_instance.cpp

@@ -550,6 +550,7 @@ void knl_instance_init()
     g_instance.stat_cxt.track_memory_inited = false;
     g_instance.proc_base = NULL;
     g_instance.proc_array_idx = NULL;
+    pg_atomic_init_u32(&g_instance.extensionNum, 0);
 
     /*
      * Set up the process wise memory context. The memory allocated from this

src/gausskernel/process/threadpool/knl_session.cpp

@@ -91,6 +91,8 @@ static void knl_u_attr_init(knl_session_attr* attr)
     attr->attr_sql.under_explain = false;
     attr->attr_resource.enable_auto_explain = false;
     attr->attr_sql.enable_upsert_to_merge = false;
+    attr->attr_common.extension_session_vars_array_size = 0;
+    attr->attr_common.extension_session_vars_array = NULL;
 }
 
 void knl_u_executor_init(knl_u_executor_context* exec_cxt)

src/include/commands/extension.h

@@ -42,4 +42,6 @@ extern void AlterExtensionNamespace(List* names, const char* newschema);
 
 extern void AlterExtensionOwner_oid(Oid extensionOid, Oid newOwnerId);
 
+extern void RepallocSessionVarsArrayIfNecessary();
+
 #endif /* EXTENSION_H */

src/include/knl/knl_guc/knl_session_attr_common.h

@@ -208,6 +208,8 @@ typedef struct knl_session_attr_common {
     char* router_att;
     bool enable_router;
     int gpc_clean_timeout;
+    uint32 extension_session_vars_array_size;
+    void** extension_session_vars_array;
 } knl_session_attr_common;
 
 #endif /* SRC_INCLUDE_KNL_KNL_SESSION_ATTR_COMMON_H_ */

src/include/knl/knl_instance.h

@@ -870,6 +870,7 @@ typedef struct knl_instance_context {
     void *raw_parser_hook[DB_CMPT_MAX];
     void *plsql_parser_hook[DB_CMPT_MAX];
 #endif
+    pg_atomic_uint32 extensionNum;
 } knl_instance_context;
 
 extern long random();

src/include/utils/postinit.h

@@ -160,6 +160,8 @@ private:
 
     void InitSettings();
 
+    void InitExtensionVariable();
+
     void FinishInit();
 
     void AuditUserLogin();