To implement AIO writes, the backend initiating writes needs to transfer the lock ownership to the AIO subsystem, so the lock held during the write can be released in another backend. Other backends need to be able to "complete" an asynchronously started IO to avoid deadlocks (consider e.g. one backend starting IO for a buffer and then waiting for a heavyweight lock held by another relation followed by the current holder of the heavyweight lock waiting for the IO to complete). To that end, this commit adds LWLockDisown() and LWLockReleaseDisowned(). If code uses LWLockDisown() it's the code's responsibility to ensure that the lock is released in case of errors. Reviewed-by: Heikki Linnakangas <hlinnaka@iki.fi> Discussion: https://postgr.es/m/1f6b50a7-38ef-4d87-8246-786d39f46ab9@iki.fi
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/.