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Presently, the dynamic shared memory (DSM) registry only provides GetNamedDSMSegment(), which allocates a fixed-size segment. To use the DSM registry for more sophisticated things like dynamic shared memory areas (DSAs) or a hash table backed by a DSA (dshash), users need to create a DSM segment that stores various handles and LWLock tranche IDs and to write fairly complicated initialization code. Furthermore, there is likely little variation in this initialization code between libraries. This commit introduces functions that simplify allocating a DSA or dshash within the DSM registry. These functions are very similar to GetNamedDSMSegment(). Notable differences include the lack of an initialization callback parameter and the prohibition of calling the functions more than once for a given entry in each backend (which should be trivially avoidable in most circumstances). While at it, this commit bumps the maximum DSM registry entry name length from 63 bytes to 127 bytes. Also note that even though one could presumably detach/destroy the DSAs and dshashes created in the registry, such use-cases are not yet well-supported, if for no other reason than the associated DSM registry entries cannot be removed. Adding such support is left as a future exercise. The test_dsm_registry test module contains tests for the new functions and also serves as a complete usage example. Reviewed-by: Dagfinn Ilmari Mannsåker <ilmari@ilmari.org> Reviewed-by: Sami Imseih <samimseih@gmail.com> Reviewed-by: Florents Tselai <florents.tselai@gmail.com> Reviewed-by: Rahila Syed <rahilasyed90@gmail.com> Discussion: https://postgr.es/m/aEC8HGy2tRQjZg_8%40nathan
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.
Copyright and license information can be found in the file COPYRIGHT.
General documentation about this version of PostgreSQL can be found at https://www.postgresql.org/docs/devel/. In particular, information about building PostgreSQL from the source code can be found at https://www.postgresql.org/docs/devel/installation.html.
The latest version of this software, and related software, may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.