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Normally when we use object-oriented programming techniques, we provide a pointer to an object and then some way of looking up the associated table of callbacks, but walmethods.c/h took the alternative approach of providing only a pointer to the table of callbacks and thus imposed the artificial restriction that there could only ever be one object of each type, so that the callbacks could find it via a global variable. That doesn't seem like the right idea, so revise the approach. Each callback which does not already have an argument of type Walfile * now takes a pointer to the relevant WalWriteMethod * so that these callbacks need not rely on there being only one object of each type. Freeing a WalWriteMethod is now performed via a callback provided for that purpose rather than requiring the caller to know which WAL method they want to free. Discussion: http://postgr.es/m/CA+TgmoZS0Kw98fOoAcGz8B9iDhdqB4Be4e=vDZaJZ5A-xMYBqA@mail.gmail.com
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/.