Examples with DbusEventAppender com.linkedin.databus.core.test.DbusEventAppender used on opensource projects

Example 16 with DbusEventAppender

use of com.linkedin.databus.core.test.DbusEventAppender in project databus by linkedin.

the class ReadEventsTestParams method testStatsMinMaxScn.

@Test
public void testStatsMinMaxScn() throws Exception {
    // Src Event producer
    Vector<DbusEvent> srcTestEvents = new Vector<DbusEvent>();
    EventBufferTestInput input = new EventBufferTestInput();
    int numEvents = 10000;
    long startScn = 1000;
    int numWinScn = 10;
    // set sharedBufferSize to a value much smaller than total size required
    input.setNumEvents(numEvents).setWindowSize(numEvents / numWinScn).setSharedBufferSize(numEvents / 5).setStagingBufferSize(numEvents / 5).setIndexSize(numEvents / 10).setIndividualBufferSize(numEvents / 2).setBatchSize(numEvents / 5).setProducerBufferSize(numEvents / 2).setPayloadSize(100).setDeleteInterval(1).setProdQueuePolicy(QueuePolicy.OVERWRITE_ON_WRITE);
    input.setTestName("testStatsMinMaxScn");
    DbusEventsStatisticsCollector emitterStats = new DbusEventsStatisticsCollector(1, "appenderStats", true, true, null);
    DbusEventGenerator evGen = new DbusEventGenerator(startScn);
    if (evGen.generateEvents(numEvents, input.getWindowSize(), 512, input.getPayloadSize(), true, srcTestEvents) <= 0) {
        fail();
        return;
    }
    // sleep 10 ms;
    int eventSize = srcTestEvents.get(0).size();
    DbusEventBuffer prodEventBuffer = new DbusEventBuffer(getConfig(input.getProducerBufferSize() * eventSize, input.getIndividualBufferSize() * eventSize, input.getIndexSize() * eventSize, input.getStagingBufferSize() * eventSize, AllocationPolicy.HEAP_MEMORY, input.getProdQueuePolicy(), input.getProdBufferAssertLevel()));
    DbusEventAppender eventProducer = new DbusEventAppender(srcTestEvents, prodEventBuffer, emitterStats);
    Thread tEmitter = new Thread(eventProducer);
    tEmitter.start();
    tEmitter.join();
    // sleep 10 ms;
    int msDelay = 10;
    Thread.sleep(msDelay);
    long min = (numWinScn - 3) * input.getWindowSize() + startScn;
    long max = numWinScn * input.getWindowSize() + startScn;
    // note : event generator generates events such that a one second lag exists between the latest event and prev event
    long expectedRange = (max - min) + input.getWindowSize() - 1;
    System.out.printf("Total timespan = %d\n", (srcTestEvents.get(numEvents - 1).timestampInNanos() - srcTestEvents.get(0).timestampInNanos()) / NANOSECONDS);
    System.out.printf("prevScn=%d\n", emitterStats.getTotalStats().getPrevScn());
    System.out.printf("min = %d , max=%d  buf=%d ,%d\n", emitterStats.getTotalStats().getMinScn(), emitterStats.getTotalStats().getMaxScn(), prodEventBuffer.getMinScn(), prodEventBuffer.lastWrittenScn());
    System.out.printf("timespan=%d , timeSinceLastEvent = %d , timeSinceLastAccess %d\n", emitterStats.getTotalStats().getTimeSpan() / MILLISECONDS, emitterStats.getTotalStats().getTimeSinceLastEvent(), emitterStats.getTotalStats().getTimeSinceLastAccess());
    assertEquals(numEvents, srcTestEvents.size());
    assertEquals(numEvents, emitterStats.getTotalStats().getNumDataEvents());
    assertEquals(min, emitterStats.getTotalStats().getMinScn());
    assertEquals(max, emitterStats.getTotalStats().getMaxScn());
    assertEquals(min - input.getWindowSize(), emitterStats.getTotalStats().getPrevScn());
    assertEquals(emitterStats.getTotalStats().getSizeDataEvents() * numEvents, numEvents * eventSize);
    long tsSpanInSec = emitterStats.getTotalStats().getTimeSpan() / MILLISECONDS;
    assertEquals(expectedRange, tsSpanInSec);
    long tsSinceLastEvent = emitterStats.getTotalStats().getTimeSinceLastEvent();
    assertTrue(tsSinceLastEvent >= msDelay);
    assertTrue(emitterStats.getTotalStats().getTimeLag() >= 0);
    assertTrue(emitterStats.getTotalStats().getMinTimeLag() >= 0);
    assertTrue(emitterStats.getTotalStats().getMaxTimeLag() >= 0);
    DbusEventBuffer readEventBuffer = new DbusEventBuffer(getConfig(numEvents * 2L * eventSize, numEvents * eventSize, (numEvents / 10) * eventSize, numEvents * 2 * eventSize, AllocationPolicy.HEAP_MEMORY, input.getProdQueuePolicy(), input.getProdBufferAssertLevel()));
    // check streaming
    Vector<Long> seenScns = new Vector<Long>();
    Checkpoint cp = new Checkpoint();
    cp.setConsumptionMode(DbusClientMode.ONLINE_CONSUMPTION);
    // case: where sinceScn < min , > prevScn ; return the entire buffer
    cp.setWindowScn(min - 1);
    cp.setWindowOffset(-1);
    seenScns.clear();
    readEventBuffer.clear();
    streamWriterReader(prodEventBuffer, numEvents * 2 * eventSize, cp, "scn", readEventBuffer, seenScns);
    int expectedNumWin = (int) (max - min) / input.getWindowSize() + 1;
    assertEquals(expectedNumWin, seenScns.size());
    assertEquals(Long.valueOf(min), seenScns.get(0));
    assertEquals(Long.valueOf(max), seenScns.get(expectedNumWin - 1));
    // case : where sinceScn < prevScn ; exception thrown;
    cp.setWindowScn(startScn);
    cp.setWindowOffset(-1);
    seenScns.clear();
    readEventBuffer.clear();
    streamWriterReader(prodEventBuffer, numEvents * 2 * eventSize, cp, "scn", readEventBuffer, seenScns);
    assertEquals(0, seenScns.size());
    // case: where sinceScn < min , = prevScn ; offset=-1 ,return the entire buffer
    cp.setWindowScn(prodEventBuffer.getPrevScn());
    cp.setWindowOffset(-1);
    seenScns.clear();
    readEventBuffer.clear();
    streamWriterReader(prodEventBuffer, numEvents * 2 * eventSize, cp, "scn", readEventBuffer, seenScns);
    assertEquals(expectedNumWin, seenScns.size());
    assertEquals(Long.valueOf(min), seenScns.get(0));
    assertEquals(Long.valueOf(max), seenScns.get(expectedNumWin - 1));
    // case: where sinceScn < min , = prevScn ; offset=0 ,return nothing
    cp.setWindowScn(prodEventBuffer.getPrevScn());
    cp.setWindowOffset(0);
    seenScns.clear();
    readEventBuffer.clear();
    assertFalse(streamWriterReader(prodEventBuffer, numEvents * 2 * eventSize, cp, "scn", readEventBuffer, seenScns));
    assertEquals(0, seenScns.size());
}

Example 17 with DbusEventAppender

use of com.linkedin.databus.core.test.DbusEventAppender in project databus by linkedin.

the class ReadEventsTestParams method testReadEventsAssertSpanError.

/**
 * Test to reproduce DDSDBUS-388.
 */
@Test
public void testReadEventsAssertSpanError() throws Exception {
    final Logger log = Logger.getLogger("TestDbusEventBuffer.testReadEventsAssertSpanError");
    // log.setLevel(Level.INFO);
    log.info("start");
    DbusEventBuffer dbusBuf = new DbusEventBuffer(getConfig(10000, 10000, 320, 5000, AllocationPolicy.HEAP_MEMORY, QueuePolicy.OVERWRITE_ON_WRITE, AssertLevel.ALL));
    // dbusBuf.getLog().setLevel(Level.DEBUG);
    DbusEventGenerator generator = new DbusEventGenerator();
    Vector<DbusEvent> events = new Vector<DbusEvent>();
    // event size:  10 + 61 = 71
    // window size:  5 * 71 + 61 = 416
    // layout: [61 + 23 * 416 + 5 * 71 = 9984 ] <WrapAround> [ 61 + 22 * 416 + 2 * 71 + 61 = 9416 ]
    // [ H=Gen:0,Ofs:0,    T=Gen:0,Ofs:9984, L=10000 ]
    // [ H=Gen:0,Ofs:9629, T=Gen:1,Ofs:9416, L=9984 ]
    generator.generateEvents(232, 5, 100, 10, events);
    // Add events to the EventBuffer
    DbusEventAppender appender = new DbusEventAppender(events, dbusBuf, null);
    appender.run();
    log.info("Dbus Event Buffer is :" + dbusBuf);
    log.info("SCNIndex is :" + dbusBuf.getScnIndex());
    final BufferPosition headPos = new BufferPosition(dbusBuf.getHead(), dbusBuf.getBufferPositionParser(), dbusBuf.getBuffer());
    final BufferPosition tailPos = new BufferPosition(dbusBuf.getTail(), dbusBuf.getBufferPositionParser(), dbusBuf.getBuffer());
    Assert.assertEquals(0, headPos.bufferGenId());
    Assert.assertEquals(0, headPos.bufferIndex());
    Assert.assertEquals(9629, headPos.bufferOffset());
    Assert.assertEquals(1, tailPos.bufferGenId());
    Assert.assertEquals(0, tailPos.bufferIndex());
    Assert.assertEquals(9416, tailPos.bufferOffset());
    Assert.assertEquals(9984, dbusBuf.getBuffer()[0].limit());
    dbusBuf.getScnIndex().assertHeadPosition(dbusBuf.getHead());
    final BufferPosition lastWinStart = new BufferPosition(61 + 22 * 416, dbusBuf.getBufferPositionParser(), dbusBuf.getBuffer());
    dbusBuf.getScnIndex().assertLastWrittenPos(lastWinStart);
    long lastScn = events.get(events.size() - 1).sequence();
    generator = new DbusEventGenerator(lastScn - 1);
    events.clear();
    // event size: 10 + 61 = 71
    generator.generateEvents(2, 2, 75, 10, events);
    // intended layout: append 2 * 71  = 142 bytes
    // [ H=Gen:0,Ofs:9629, T=Gen:1,Ofs:9558, L=9984 ]
    lastScn = events.get(events.size() - 1).sequence();
    generator = new DbusEventGenerator(lastScn - 1);
    // event size: 500 + 61 = 561
    // partial window size: 561  = 622
    generator.generateEvents(1, 1, 800, 500, events);
    // intended layout: append 561 bytes;
    // [ H=Gen:1,Ofs:893, T=Gen:2,Ofs:561, L=9558 ]
    // head moves to first window after 561: 61 + 2 * 416 = 893 > 561
    // Set up the ReadChannel with new events
    ByteArrayOutputStream oStream = new ByteArrayOutputStream();
    WritableByteChannel oChannel = Channels.newChannel(oStream);
    for (DbusEvent e : events) {
        assertTrue("invalid event", e.isValid());
        ((DbusEventInternalReadable) e).writeTo(oChannel, Encoding.BINARY);
        log.debug("event size is: " + e.size());
    }
    byte[] writeBytes = oStream.toByteArray();
    ByteArrayInputStream iStream = new ByteArrayInputStream(writeBytes);
    final ReadableByteChannel rChannel = Channels.newChannel(iStream);
    dbusBuf.readEvents(rChannel);
    log.info("Dbus Event Buffer is :" + dbusBuf);
    log.info("SCNIndex is :" + dbusBuf.getScnIndex());
    // expected layout:
    // [ H=Gen:1,Ofs:893, T=Gen:2,Ofs:561, L=9558 ]
    headPos.setPosition(dbusBuf.getHead());
    Assert.assertEquals(1, headPos.bufferGenId());
    Assert.assertEquals(0, headPos.bufferIndex());
    Assert.assertEquals(893, headPos.bufferOffset());
    tailPos.setPosition(dbusBuf.getTail());
    Assert.assertEquals(2, tailPos.bufferGenId());
    Assert.assertEquals(0, tailPos.bufferIndex());
    Assert.assertEquals(561, tailPos.bufferOffset());
    Assert.assertEquals(9558, dbusBuf.getBuffer()[0].limit());
    dbusBuf.getBufferPositionParser().assertSpan(dbusBuf.getHead(), dbusBuf.getTail(), true);
    dbusBuf.getScnIndex().assertHeadPosition(dbusBuf.getHead());
    // the second write did not add EOP so the SCN index tail should not have changed
    dbusBuf.getScnIndex().assertLastWrittenPos(lastWinStart);
}

Example 18 with DbusEventAppender

use of com.linkedin.databus.core.test.DbusEventAppender in project databus by linkedin.

the class ReadEventsTestParams method testBasicRollback.

// Add a full window plus one event to the buffer, leaving room at the end, and then roll back.
// The write pointer should come back to the end of the event.
@Test
public void testBasicRollback() throws Exception {
    // We have 7 byte buffers now, the last one having 200 bytes, others with 500 bytes.
    DbusEventBuffer dbusBuf = new DbusEventBuffer(getConfig(3200, 500, 100, 500, AllocationPolicy.HEAP_MEMORY, QueuePolicy.OVERWRITE_ON_WRITE, AssertLevel.ALL));
    DbusEventGenerator generator = new DbusEventGenerator();
    Vector<DbusEvent> events = new Vector<DbusEvent>();
    DbusEventAppender appender = new DbusEventAppender(events, dbusBuf, null, false);
    events.clear();
    // Same test case as before, with the first 3 byte buffers having data now.
    // total event size = 499
    generator.generateEvents(1, 20, 500, 438, events);
    // total event size = 71
    generator.generateEvents(1, 20, 500, 10, events);
    // total event size = 428
    generator.generateEvents(1, 20, 500, 367, events);
    // event + EOP = 132.
    generator.generateEvents(1, 1, 500, 10, events);
    appender.run();
    DbusEventBufferReflector reflector = appender.getDbusEventReflector();
    // Now we should be able to add an event and roll it back as well.
    events.clear();
    // event size = 71, can append.
    generator.generateEvents(1, 20, 500, 10, events);
    long cwp1 = reflector.getCurrentWritePosition().getPosition();
    dbusBuf.startEvents();
    int evCount = 0;
    evCount = appender.addEventToBuffer(events.firstElement(), evCount);
    Assert.assertEquals(1, evCount);
    long cwp2 = reflector.getCurrentWritePosition().getPosition();
    Assert.assertTrue("Cwp should differ event write", cwp1 != cwp2);
    // Roll back.
    dbusBuf.rollbackEvents();
    Assert.assertEquals(cwp1, reflector.getCurrentWritePosition().getPosition());
}

Example 19 with DbusEventAppender

use of com.linkedin.databus.core.test.DbusEventAppender in project databus by linkedin.

the class ReadEventsTestParams method testAppendEventOverlapNeq0.

/*
   * This test-case is to recreate the bug where appendEvents incorrectly writes event without
   *  moving head.
   *
   *  The following is the issue.
   *
   *  head is at location x and tail is at location y
   *  The next event window is such that after adding "some" number of events in the window, both head
   *  and currentWritePosition is same (differing only in genId). Now adding the next event corrupts the
   *  buffer (and scnIndex) as head is not moved ahead.
   *
   */
/**
 * Recreate the head and tail position such that the eventBuffer is in the below state:
 *
 * <pre>
 *                       NETBW
 *                      |-----|
 * ------------------------------------------------------------
 * ^      ^             ^                                     ^
 * |      |             |                                     |
 * 0      tail       CWP,head                                 capacity
 *
 * CWP : Current Write Position
 * NETBW : Next Event to be written
 * </pre>
 *
 * In this case, all pointers except head will be at (n+1)th generation while head
 * is at nth generation.
 *
 * Two test cases are covered here:
 *   1. n = 0
 *   2. n > 0
 */
@Test
public void testAppendEventOverlapNeq0() throws Exception // Case n = 0;
{
    final DbusEventBuffer dbusBuf = new DbusEventBuffer(getConfig(1145, 5000, 100, 500, AllocationPolicy.HEAP_MEMORY, QueuePolicy.OVERWRITE_ON_WRITE, AssertLevel.ALL));
    BufferPositionParser parser = dbusBuf.getBufferPositionParser();
    DbusEventGenerator generator = new DbusEventGenerator();
    Vector<DbusEvent> events = new Vector<DbusEvent>();
    generator.generateEvents(9, 3, 120, 39, events);
    // Add events to the EventBuffer. Now the buffer is full
    DbusEventAppender appender = new DbusEventAppender(events, dbusBuf, null);
    // Logger.getRootLogger().setLevel(Level.ALL);
    // running in the same thread
    appender.run();
    LOG.info("Head:" + parser.toString(dbusBuf.getHead()) + ",Tail:" + parser.toString(dbusBuf.getTail()));
    long headPos = dbusBuf.getHead();
    long tailPos = dbusBuf.getTail();
    long scnIndexHead = dbusBuf.getScnIndex().getHead();
    long scnIndexTail = dbusBuf.getScnIndex().getTail();
    long headGenId = parser.bufferGenId(headPos);
    long headIndexId = parser.bufferIndex(headPos);
    long headOffset = parser.bufferOffset(headPos);
    long tailGenId = parser.bufferGenId(tailPos);
    long tailIndexId = parser.bufferIndex(tailPos);
    long tailOffset = parser.bufferOffset(tailPos);
    assertEquals("Head GenId", 0, headGenId);
    assertEquals("Head Index", 0, headIndexId);
    assertEquals("Head Offset", 0, headOffset);
    assertEquals("Tail GenId", 0, tailGenId);
    assertEquals("Tail Index", 0, tailIndexId);
    assertEquals("Tail Offset", 1144, tailOffset);
    assertEquals("SCNIndex Head", 0, scnIndexHead);
    assertEquals("SCNIndex Tail", 80, scnIndexTail);
    LOG.info("ScnIndex Head is :" + scnIndexHead + ", ScnIndex Tail is :" + scnIndexTail);
    events = new Vector<DbusEvent>();
    generator = new DbusEventGenerator(100);
    /*
     * The event size is carefully created such that after adding 2nd
     * event CWP and tail points to the same location. Now the 3rd event corrupts the EVB and index (in the presence of bug).
     */
    generator.generateEvents(3, 2, 150, 89, events);
    appender = new DbusEventAppender(events, dbusBuf, null);
    // running in the same thread
    appender.run();
    LOG.info("Head:" + parser.toString(dbusBuf.getHead()) + ",Tail:" + parser.toString(dbusBuf.getTail()));
    headPos = dbusBuf.getHead();
    tailPos = dbusBuf.getTail();
    headGenId = parser.bufferGenId(headPos);
    headIndexId = parser.bufferIndex(headPos);
    headOffset = parser.bufferOffset(headPos);
    tailGenId = parser.bufferGenId(tailPos);
    tailIndexId = parser.bufferIndex(tailPos);
    tailOffset = parser.bufferOffset(tailPos);
    scnIndexHead = dbusBuf.getScnIndex().getHead();
    scnIndexTail = dbusBuf.getScnIndex().getTail();
    assertEquals("Head GenId", 0, headGenId);
    assertEquals("Head Index", 0, headIndexId);
    assertEquals("Head Offset", 783, headOffset);
    assertEquals("Tail GenId", 1, tailGenId);
    assertEquals("Tail Index", 0, tailIndexId);
    assertEquals("Tail Offset", 633, tailOffset);
    assertEquals("SCNIndex Head", 64, scnIndexHead);
    assertEquals("SCNIndex Tail", 48, scnIndexTail);
}

Example 20 with DbusEventAppender

use of com.linkedin.databus.core.test.DbusEventAppender in project databus by linkedin.

the class ReadEventsTestParams method testAppendEventOverlapMany.

// Case where we dump lot of events while reaching the error case many times during this process.
@Test
public void testAppendEventOverlapMany() throws Exception {
    final DbusEventBuffer dbusBuf = new DbusEventBuffer(getConfig(1145, 5000, 100, 500, AllocationPolicy.HEAP_MEMORY, QueuePolicy.OVERWRITE_ON_WRITE, AssertLevel.ALL));
    BufferPositionParser parser = dbusBuf.getBufferPositionParser();
    DbusEventGenerator generator = new DbusEventGenerator();
    Vector<DbusEvent> events = new Vector<DbusEvent>();
    generator.generateEvents(9, 3, 120, 39, events);
    // Add events to the EventBuffer. Now the buffer is full
    DbusEventAppender appender = new DbusEventAppender(events, dbusBuf, null);
    // running in the same thread
    appender.run();
    LOG.info("Head:" + parser.toString(dbusBuf.getHead()) + ",Tail:" + parser.toString(dbusBuf.getTail()));
    long headPos = dbusBuf.getHead();
    long tailPos = dbusBuf.getTail();
    long scnIndexHead = dbusBuf.getScnIndex().getHead();
    long scnIndexTail = dbusBuf.getScnIndex().getTail();
    long headGenId = parser.bufferGenId(headPos);
    long headIndexId = parser.bufferIndex(headPos);
    long headOffset = parser.bufferOffset(headPos);
    long tailGenId = parser.bufferGenId(tailPos);
    long tailIndexId = parser.bufferIndex(tailPos);
    long tailOffset = parser.bufferOffset(tailPos);
    assertEquals("Head GenId", 0, headGenId);
    assertEquals("Head Index", 0, headIndexId);
    assertEquals("Head Offset", 0, headOffset);
    assertEquals("Tail GenId", 0, tailGenId);
    assertEquals("Tail Index", 0, tailIndexId);
    assertEquals("Tail Offset", 1144, tailOffset);
    assertEquals("SCNIndex Head", 0, scnIndexHead);
    assertEquals("SCNIndex Tail", 80, scnIndexTail);
    LOG.info("ScnIndex Head is :" + scnIndexHead + ", ScnIndex Tail is :" + scnIndexTail);
    /*
     * Dump lots of events
     */
    events = new Vector<DbusEvent>();
    generator = new DbusEventGenerator(100);
    generator.generateEvents(655, 3, 150, 89, events);
    appender = new DbusEventAppender(events, dbusBuf, null);
    // running in the same thread
    appender.run();
    LOG.info("Head:" + parser.toString(dbusBuf.getHead()) + ",Tail:" + parser.toString(dbusBuf.getTail()));
    headPos = dbusBuf.getHead();
    tailPos = dbusBuf.getTail();
    headGenId = parser.bufferGenId(headPos);
    headIndexId = parser.bufferIndex(headPos);
    headOffset = parser.bufferOffset(headPos);
    tailGenId = parser.bufferGenId(tailPos);
    tailIndexId = parser.bufferIndex(tailPos);
    tailOffset = parser.bufferOffset(tailPos);
    scnIndexHead = dbusBuf.getScnIndex().getHead();
    scnIndexTail = dbusBuf.getScnIndex().getTail();
    assertEquals("Head GenId", 109, headGenId);
    assertEquals("Head Index", 0, headIndexId);
    assertEquals("Head Offset", 511, headOffset);
    assertEquals("Tail GenId", 110, tailGenId);
    assertEquals("Tail Index", 0, tailIndexId);
    assertEquals("Tail Offset", 211, tailOffset);
    assertEquals("SCNIndex Head", 32, scnIndexHead);
    assertEquals("SCNIndex Tail", 16, scnIndexTail);
    /*
     * The event size is carefully created such that after adding 2nd
     * event CWP and tail points to the same location.
     */
    events = new Vector<DbusEvent>();
    generator = new DbusEventGenerator(10000);
    generator.generateEvents(3, 5, 100, 28, events);
    appender = new DbusEventAppender(events, dbusBuf, null);
    // running in the same thread
    appender.run();
    LOG.info("Head:" + parser.toString(dbusBuf.getHead()) + ",Tail:" + parser.toString(dbusBuf.getTail()));
    events = new Vector<DbusEvent>();
    generator = new DbusEventGenerator(10000);
    generator.generateEvents(3, 3, 120, 19, events);
    headPos = dbusBuf.getHead();
    tailPos = dbusBuf.getTail();
    headGenId = parser.bufferGenId(headPos);
    headIndexId = parser.bufferIndex(headPos);
    headOffset = parser.bufferOffset(headPos);
    tailGenId = parser.bufferGenId(tailPos);
    tailIndexId = parser.bufferIndex(tailPos);
    tailOffset = parser.bufferOffset(tailPos);
    scnIndexHead = dbusBuf.getScnIndex().getHead();
    scnIndexTail = dbusBuf.getScnIndex().getTail();
    assertEquals("Head GenId", 110, headGenId);
    assertEquals("Head Index", 0, headIndexId);
    assertEquals("Head Offset", 0, headOffset);
    assertEquals("Tail GenId", 110, tailGenId);
    assertEquals("Tail Index", 0, tailIndexId);
    assertEquals("Tail Offset", 600, tailOffset);
    assertEquals("SCNIndex Head", 0, scnIndexHead);
    assertEquals("SCNIndex Tail", 32, scnIndexTail);
}