Queue V4: how to set up vanilla/indexed like in V3?

[arbitrage...@gmail.com]

Hi,

i think every body is excited of waiting the new technical doc of the v4.
hope that this v4 will be as excellent as the v3.

also before we were used to do:

while(true){
   if(tailer.hasNext()){
   ...
   }
}

1- what the approach now.
2- how to set up the rolling period
3- how to handle the indexed style queue like in v3

[Rob Austin]

I hope these code snippets help, please look at the project git test cases for other examples

1. hasNext 

check for dc.isPresent() == true to see if there is a next entry.

see code in net.openhft.chronicle.queue.impl.single.SingleChronicleQueueTest#testReadingDocument

try (final DocumentContext dc = tailer.readingDocument()) {
    assert dc.isPresent();
    assert dc.isData();
    dc.wire().read(() -> "key").text(sb);
    Assert.assertEquals("value=0", sb.toString());
}

2 Rolling 

 

see net.openhft.chronicle.queue.RollCycles

for example see net.openhft.chronicle.queue.impl.single.SingleChronicleQueueTest#testReadingDocumentWithFirstAMove

    try (final RollingChronicleQueue queue = SingleChronicleQueueBuilder.binary(getTmpDir())
        .wireType(this.wireType)
        .rollCycle(RollCycles.HOURLY)
        .build()) {
….
        }

3. indexes 

see net.openhft.chronicle.queue.LastIndexAppendedTest#testLastIndexAppendedAcrossRestarts

@Test
public void testLastIndexAppendedAcrossRestarts() throws Exception {
    String path = OS.TARGET + "/deleteme.q-" + System.nanoTime();

    long expectedIndex = 0;
    for (int i = 0; i < 5; i++) {
        try (SingleChronicleQueue queue = ChronicleQueueBuilder.single(path).build()) {
            ExcerptAppender appender = queue.createAppender();

            try (DocumentContext documentContext = appender.writingDocument()) {
                long expectedIndex2 = documentContext.index();
                assertTrue("expectedIndex: " + expectedIndex2, expectedIndex2 > 0);
                if (expectedIndex == 0)
                    expectedIndex = expectedIndex2;
                else
                    assertEquals(++expectedIndex, expectedIndex2);

                documentContext.wire().write().text("hello world");
            }
            final long lastIndex = queue.nextIndexToWrite();
            assertEquals(expectedIndex + 1, lastIndex);

            assertEquals(expectedIndex, appender.lastIndexAppended());
        }
    }
    try {
        IOTools.deleteDirWithFiles(path, 2);
    } catch (Exception index) {
    }
}

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