Function get_shareinput_fileset

src/backend/executor/nodeShareInputScan.c:748–789

* Get reference to the SharedFileSet used to hold all the tuplestore files. * * This is exported so that it can also be used by the INITPLAN function * tuplestores. */

 * tuplestores.
 */
SharedFileSet *
get_shareinput_fileset(void)
{
	dsm_handle		handle;

	if (shareinput_Xslice_fileset == NULL)
	{
		dsm_segment *seg;

		LWLockAcquire(ShareInputScanLock, LW_EXCLUSIVE);

		handle = *shareinput_Xslice_dsm_handle_ptr;

		if (handle)
		{
			seg = dsm_attach(handle);
			if (seg == NULL)
				elog(ERROR, "could not attach to ShareInputScan DSM segment");
			dsm_pin_mapping(seg);

			shareinput_Xslice_fileset = dsm_segment_address(seg);
		}
		else
		{
			seg = dsm_create(sizeof(SharedFileSet), 0);
			dsm_pin_segment(seg);
			*shareinput_Xslice_dsm_handle_ptr = dsm_segment_handle(seg);
			dsm_pin_mapping(seg);

			shareinput_Xslice_fileset = dsm_segment_address(seg);
		}

		if (shareinput_Xslice_fileset->refcnt == 0)
			SharedFileSetInit(shareinput_Xslice_fileset, seg);
		else
			SharedFileSetAttach(shareinput_Xslice_fileset, seg);

		LWLockRelease(ShareInputScanLock);
	}

	return shareinput_Xslice_fileset;
}

/*
 * Get a reference to slot in shared memory for this shared scan.