PgProcess

Namespace: Ankus

Assembly: Ankus.Runtime.dll

Runs code when the current PostgreSQL process exits, as a C extension’s before_shmem_exit callback does.

public static class PgProcess

Inheritance: object

Methods

OnExit(Action<int>)

Registers a callback that runs when this process exits, before it detaches from shared memory.

public static IDisposable OnExit(Action<int> callback)

Parameters:

callback — Action<int>

The callback, given the exit code: zero for a normal exit, nonzero after a FATAL error or a termination request.

Returns: IDisposable

A registration whose disposal removes the callback before it runs.

Callbacks run newest first, after a normal exit, after a FATAL error and when PostgreSQL stops a worker, but not when the process crashes or the server restarts after a crash. A background worker uses one to release the shared-memory slot it claimed, as pglogical's workers do.

A callback can use shared memory and lightweight locks, but not SQL or logging, because the transaction may be aborted and PostgreSQL is shutting the process down. It must not wait for a lock this process may already hold. An exception is reported as a warning and the remaining callbacks still run. Registration belongs to the calling process; register in the backend or worker that needs the callback, not while the library loads in the postmaster.