res/res_odbc: Remove unneeded queries when determining if a table exists

This patch modifies the ast_odbc_find_table function such that it only performs
a lookup of the requested table if the table is not already known. Prior to
this patch, a queries would be executed against the database even if the table
was already known and cached.

Review: https://reviewboard.asterisk.org/r/4405/

ASTERISK-24742 #close
Reported by: ibercom
patches:
  patch.diff uploaded by ibercom (License 6599)
........

Merged revisions 431617 from http://svn.asterisk.org/svn/asterisk/branches/11

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/13@431618 65c4cc65-6c06-0410-ace0-fbb531ad65f3

diff --git a/res/res_odbc.c b/res/res_odbc.c
index d029c88c0a13c89b935a933595b6b3a4ad0bb604..259467ace4ab2849280b597ca04aedfe0b9aa393 100644 (file)
--- a/res/res_odbc.c
+++ b/res/res_odbc.c
@@ -461,7 +461,7 @@ struct odbc_cache_tables *ast_odbc_find_table(const char *database, const char *
        SQLLEN sqlptr;
        SQLHSTMT stmt = NULL;
        int res = 0, error = 0, try = 0;
-       struct odbc_obj *obj = ast_odbc_request_obj(database, 0);
+       struct odbc_obj *obj;
 
        AST_RWLIST_RDLOCK(&odbc_tables);
        AST_RWLIST_TRAVERSE(&odbc_tables, tableptr, list) {
@@ -472,13 +472,10 @@ struct odbc_cache_tables *ast_odbc_find_table(const char *database, const char *
        if (tableptr) {
                AST_RWLIST_RDLOCK(&tableptr->columns);
                AST_RWLIST_UNLOCK(&odbc_tables);
-               if (obj) {
-                       ast_odbc_release_obj(obj);
-               }
                return tableptr;
        }
 
-       if (!obj) {
+       if (!(obj = ast_odbc_request_obj(database, 0))) {
                ast_log(LOG_WARNING, "Unable to retrieve database handle for table description '%s@%s'\n", tablename, database);
                AST_RWLIST_UNLOCK(&odbc_tables);
                return NULL;
@@ -564,9 +561,7 @@ struct odbc_cache_tables *ast_odbc_find_table(const char *database, const char *
                destroy_table_cache(tableptr);
                tableptr = NULL;
        }
-       if (obj) {
-               ast_odbc_release_obj(obj);
-       }
+       ast_odbc_release_obj(obj);
        return tableptr;
 }