e530be9685
The pg_atomic_compare_exchange_xxx functions are defined to update *expected to whatever they read from the target variable. Therefore, there's no need to do additional explicit reads after we've initialized the "old" variable. The actual benefit of this is somewhat debatable, but it seems fairly unlikely to hurt anything, especially since we will override the generic implementations in most performance-sensitive cases. Yura Sokolov, reviewed by Jesper Pedersen and myself Discussion: https://postgr.es/m/7f65886daca545067f82bf2b463b218d@postgrespro.ru
PostgreSQL Database Management System ===================================== This directory contains the source code distribution of the PostgreSQL database management system. PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings. PostgreSQL has many language interfaces, many of which are listed here: https://www.postgresql.org/download See the file INSTALL for instructions on how to build and install PostgreSQL. That file also lists supported operating systems and hardware platforms and contains information regarding any other software packages that are required to build or run the PostgreSQL system. Copyright and license information can be found in the file COPYRIGHT. A comprehensive documentation set is included in this distribution; it can be read as described in the installation instructions. The latest version of this software may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.