@Test
public void testSwap() throws Exception {

	final int numSegments = MEMORY_SIZE / MEMORY_PAGE_SIZE;
	final List<MemorySegment> memory = this.memoryManager.allocatePages(new DummyInvokable(), numSegments);
	
	NormalizedKeySorter<Tuple2<Integer, String>> sorter = newSortBuffer(memory);
	TestData.TupleGenerator generator = new TestData.TupleGenerator(SEED, KEY_MAX, VALUE_LENGTH, KeyMode.RANDOM,
		ValueMode.RANDOM_LENGTH);
	
	// write the records
	Tuple2<Integer, String> record = new Tuple2<>();
	int num = -1;
	do {
		generator.next(record);
		num++;
	}
	while (sorter.write(record));
	
	// swap the records
	int start = 0, end = num - 1;
	while (start < end) {
		sorter.swap(start++, end--);
	}
	
	// re-read the records
	generator.reset();
	Tuple2<Integer, String> readTarget = new Tuple2<>();
	
	int i = num - 1;
	while (i >= 0) {
		generator.next(record);
		readTarget = sorter.getRecord(readTarget, i--);
		
		int rk = readTarget.f0;
		int gk = record.f0;
		
		String rv = readTarget.f1;
		String gv = record.f1;
		
		Assert.assertEquals("The re-read key is wrong", gk, rk);
		Assert.assertEquals("The re-read value is wrong", gv, rv);
	}
	
	// release the memory occupied by the buffers
	sorter.dispose();
	this.memoryManager.release(memory);
}