Function tuplestore_alloc_read_pointer

src/backend/utils/sort/tuplestore.c:447–474

* tuplestore_alloc_read_pointer - allocate another read pointer. * * Returns the pointer's index. * * The new pointer initially copies the position of read pointer 0. * It can have its own eflags, but if any data has been inserted into * the tuplestore, these eflags must not represent an increase in * requirements. */

 * requirements.
 */
int
tuplestore_alloc_read_pointer(Tuplestorestate *state, int eflags)
{
	/* Check for possible increase of requirements */
	if (state->status != TSS_INMEM || state->memtupcount != 0)
	{
		if ((state->eflags | eflags) != state->eflags)
			elog(ERROR, "too late to require new tuplestore eflags");
	}

	/* Make room for another read pointer if needed */
	if (state->readptrcount >= state->readptrsize)
	{
		int			newcnt = state->readptrsize * 2;

		state->readptrs = (TSReadPointer *)
			repalloc(state->readptrs, newcnt * sizeof(TSReadPointer));
		state->readptrsize = newcnt;
	}

	/* And set it up */
	state->readptrs[state->readptrcount] = state->readptrs[0];
	state->readptrs[state->readptrcount].eflags = eflags;

	state->eflags |= eflags;

	return state->readptrcount++;
}

/*
 * tuplestore_clear