/*
* Copyright (C) 2012-2015 DataStax Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.datastax.driver.core;
import com.google.common.collect.Lists;
import com.google.common.util.concurrent.*;
import org.apache.log4j.Level;
import org.apache.log4j.Logger;
import org.testng.annotations.Test;
import java.util.List;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import static org.assertj.core.api.Assertions.assertThat;
import static org.testng.Assert.assertEquals;
import static org.testng.Assert.fail;
public class ThreadLocalMonotonicTimestampGeneratorTest {
@Test(groups = "unit")
public void should_generate_incrementing_timestamps_for_each_thread() throws InterruptedException {
// Create a generator with a fixed millisecond value
final long fixedTime = 1;
final ThreadLocalMonotonicTimestampGenerator generator = new ThreadLocalMonotonicTimestampGenerator();
generator.clock = new MockClocks.FixedTimeClock(fixedTime);
// Generate 1000 timestamps on each thread
int testThreadsCount = 2;
ListeningExecutorService executor = MoreExecutors.listeningDecorator(Executors.newFixedThreadPool(testThreadsCount));
List<ListenableFuture<?>> futures = Lists.newArrayListWithExpectedSize(testThreadsCount);
for (int i = 0; i < testThreadsCount; i++) {
futures.add(executor.submit(
new Runnable() {
@Override
public void run() {
// Ensure that each thread gets the 1000 microseconds for the mocked millisecond value,
// in order
for (int i = 0; i < 1000; i++)
assertEquals(generator.next(), fixedTime + i);
}
}));
}
executor.shutdown();
executor.awaitTermination(1, TimeUnit.SECONDS);
try {
Futures.allAsList(futures).get();
} catch (ExecutionException e) {
Throwable cause = e.getCause();
if (cause instanceof AssertionError)
throw (AssertionError) cause;
else
fail("Error in a test thread", cause);
}
}
@Test(groups = "unit")
public void should_generate_incrementing_timestamps_on_clock_resync() {
ThreadLocalMonotonicTimestampGenerator generator = new ThreadLocalMonotonicTimestampGenerator(0, TimeUnit.SECONDS, 1, TimeUnit.SECONDS);
generator.clock = new MockClocks.BackInTimeClock();
MemoryAppender appender = new MemoryAppender();
Logger logger = Logger.getLogger(TimestampGenerator.class);
Level originalLevel = logger.getLevel();
logger.setLevel(Level.WARN);
logger.addAppender(appender);
String logFormat = "Clock skew detected: current tick (%d) was %d microseconds " +
"behind the last generated timestamp (%d), returned timestamps will be artificially incremented " +
"to guarantee monotonicity.";
try {
long start = generator.next();
long previous = start;
long next = 0;
for (int i = 0; i < 1001; i++) {
next = generator.next();
assertEquals(next, previous + 1);
previous = next;
}
// Ensure log statement generated indicating clock skew, but only once.
assertEquals(next, start + 1001);
assertThat(appender.getNext())
.containsOnlyOnce("Clock skew detected:")
.containsOnlyOnce(String.format(logFormat, start - 1, 1, start));
// Wait for 1.1 seconds to see if we get an additional clock skew message. We wait slightly longer
// than 1 second to deal with system clock precision on platforms like windows.
Uninterruptibles.sleepUninterruptibly(1100, TimeUnit.MILLISECONDS);
next = generator.next();
assertThat(next).isEqualTo(previous + 1);
// Clock has gone backwards 1002 us since we've had that many iterations.
// The difference should be 2003 (clock backwards 1002 + 1001 prior compute next calls).
// Current timestamp should match the previous one.
assertThat(appender.getNext())
.containsOnlyOnce("Clock skew detected:")
.containsOnlyOnce(String.format(logFormat, start - 1002, 2003, previous));
} finally {
logger.removeAppender(appender);
logger.setLevel(originalLevel);
}
}
}