Function SharedFileSetAttach

src/backend/storage/file/sharedfileset.c:126–148

* Attach to a set of directories that was created with SharedFileSetInit. */

 * Attach to a set of directories that was created with SharedFileSetInit.
 */
void
SharedFileSetAttach(SharedFileSet *fileset, dsm_segment *seg)
{
	bool		success;

	SpinLockAcquire(&fileset->mutex);
	if (fileset->refcnt == 0)
		success = false;
	else
	{
		++fileset->refcnt;
		success = true;
	}
	SpinLockRelease(&fileset->mutex);

	if (!success)
		ereport(ERROR,
				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
				 errmsg("could not attach to a SharedFileSet that is already destroyed")));

	/* Register our cleanup callback. */
	on_dsm_detach(seg, SharedFileSetOnDetach, PointerGetDatum(fileset));
}

/*
 * Create a new file in the given set.