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Fix reference issue in background dns
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@tootedom
tootedom committed May 17, 2018
1 parent 52066bd commit 964095e
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Showing 2 changed files with 55 additions and 35 deletions.
64 changes: 34 additions & 30 deletions src/main/java/org/greencheek/caching/herdcache/memcached/factory/BackgroundDnsResolver.java
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Original file line number Diff line number Diff line change
Expand Up @@ -14,10 +14,7 @@
import java.util.Arrays;
import java.util.Comparator;
import java.util.List;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.*;
import java.util.concurrent.atomic.AtomicReference;
import java.util.stream.Collectors;

Expand Down Expand Up @@ -56,45 +53,52 @@ public BackgroundDnsResolver(Host host,long backgroundPollingTimeInMillis,
ReferencedClientFactory connnectionFactory, AddressResolver resolver) {
this.scheduledExecutorService = Executors.newSingleThreadScheduledExecutor(DEFAULT_THREAD_FACTORY);
this.host = host;
this.connnectionFactory = connnectionFactory;
this.resolver = resolver;


scheduledExecutorService.scheduleWithFixedDelay(
backgroundResolver(),
0,backgroundPollingTimeInMillis,
ScheduledFuture f= scheduledExecutorService.scheduleWithFixedDelay(
backgroundResolver(resolver,connnectionFactory,host),
0, backgroundPollingTimeInMillis,
TimeUnit.MILLISECONDS);


this.connnectionFactory = connnectionFactory;
this.resolver = resolver;
}

private Runnable backgroundResolver() {
private Runnable backgroundResolver(final AddressResolver resolver, final ReferencedClientFactory connnectionFactory,
final Host host ) {
return () -> {
String hostName = host.getHost();
Holder currentResolvedAddresses = client.get();
InetAddress[] addresses = resolver.resolve(hostName);
try {
String hostName = host.getHost();
Holder currentResolvedAddresses = client.get();
InetAddress[] addresses = resolver.resolve(hostName);

addresses = checkForCollisionResponses(addresses, hostName);

InetAddress[] existingAddresses = currentResolvedAddresses.addresses;
addresses = checkForCollisionResponses(addresses, hostName);

if(addresses.length == 0) {
if(existingAddresses.length==0) {
LOG.error("Failed to resolve address for '{}', no pre-cached addresses to re-use", host);
} else {
LOG.error("Failed to resolve address for '{}', old pre-cached addresses will be kept",host);
}
} else {
if (haveAddressesChanged(addresses,existingAddresses)) {
ReferencedClient referencedClient = connnectionFactory.createClient(toSocketAddresses(addresses));
if (referencedClient != SpyReferencedClient.UNAVAILABLE_REFERENCE_CLIENT) {
client.set(new Holder(referencedClient,addresses));
InetAddress[] existingAddresses = currentResolvedAddresses.addresses;

if (addresses.length == 0) {
if (existingAddresses.length == 0) {
LOG.error("Failed to resolve address for '{}', no pre-cached addresses to re-use", host.getHost());
} else {
LOG.error("Failed to resolve address for '{}', old pre-cached addresses will be kept", host.getHost());
}
LOG.debug("[{}] Addresses available: {}", host, toCommaSeparated(addresses));
} else {
LOG.debug("[{}] Has Same Addresses: {}", host, toCommaSeparated(addresses));
if (haveAddressesChanged(addresses, existingAddresses)) {
ReferencedClient referencedClient = connnectionFactory.createClient(toSocketAddresses(addresses));
if (referencedClient != SpyReferencedClient.UNAVAILABLE_REFERENCE_CLIENT) {
client.set(new Holder(referencedClient, addresses));
}
LOG.debug("[{}] Addresses available: {}", host, toCommaSeparated(addresses));
} else {
LOG.debug("[{}] Has Same Addresses: {}", host, toCommaSeparated(addresses));
}
}
} catch(Exception e) {
LOG.error("Exception Encountered During Background DNS Resolver. Caught Error so as to not stop further executions. Investigation in cause suggested.",e);
}



};
}

Expand Down
26 changes: 21 additions & 5 deletions ...st/java/org/greencheek/caching/herdcache/memcached/factory/BackgroundDnsResolverTest.java
View file
Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,8 @@
import java.net.InetSocketAddress;
import java.net.UnknownHostException;
import java.util.List;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;

import static org.junit.Assert.assertEquals;
Expand All @@ -24,6 +26,7 @@ public class BackgroundDnsResolverTest {


class SimpleCircularAddressResolver implements AddressResolver{
private final CountDownLatch startSignal = new CountDownLatch(1);
private AtomicInteger called = new AtomicInteger(0);
private final InetAddress[][] addresses;

Expand All @@ -33,12 +36,17 @@ public SimpleCircularAddressResolver(InetAddress[][] addressesToReturn) {

@Override
public InetAddress[] resolve(String host) {
startSignal.countDown();
if(called.get()==addresses.length) {
called.set(0);
}

return addresses[called.getAndIncrement()];
}

public CountDownLatch getStartSignal() {
return startSignal;
}
}

ReferencedClientFactory reffactory;
Expand Down Expand Up @@ -74,8 +82,11 @@ public void updateOfDnsIsCaptured() throws UnknownHostException, InterruptedExce
addresses3[1] = InetAddress.getByName("127.0.0.2");
addresses3[2] = InetAddress.getByName("127.0.0.3");

BackgroundDnsResolver resolver = new BackgroundDnsResolver(new Host("bob.com",11211),10000,reffactory,new SimpleCircularAddressResolver(new InetAddress[][]{addresses1,addresses2,addresses3}));
SimpleCircularAddressResolver addressResolver = new SimpleCircularAddressResolver(new InetAddress[][]{addresses1,addresses2,addresses3});
CountDownLatch latch = addressResolver.getStartSignal();
BackgroundDnsResolver resolver = new BackgroundDnsResolver(new Host("bob.com",11211),10000,reffactory,addressResolver);
try {
latch.await(10000, TimeUnit.SECONDS);
Thread.sleep(2000);
ReferencedClient client = resolver.getClient();
assertNotSame(client, SpyReferencedClient.UNAVAILABLE_REFERENCE_CLIENT);
Expand Down Expand Up @@ -112,8 +123,11 @@ public void updateOfDnsIsNotChangedWhenInvalidAddressesReturned() throws Unknown
addresses3[1] = InetAddress.getByName("127.0.53.53");
addresses3[2] = InetAddress.getByName("127.0.53.53");

BackgroundDnsResolver resolver = new BackgroundDnsResolver(new Host("bob.com",11211),10000,reffactory,new SimpleCircularAddressResolver(new InetAddress[][]{addresses1,addresses2,addresses3}));
SimpleCircularAddressResolver addressResolver = new SimpleCircularAddressResolver(new InetAddress[][]{addresses1,addresses2,addresses3});
CountDownLatch latch = addressResolver.getStartSignal();
BackgroundDnsResolver resolver = new BackgroundDnsResolver(new Host("bob.com",11211),10000,reffactory,addressResolver);
try {
latch.await(10000, TimeUnit.SECONDS);
Thread.sleep(2000);
ReferencedClient client = resolver.getClient();
assertNotSame(client, SpyReferencedClient.UNAVAILABLE_REFERENCE_CLIENT);
Expand Down Expand Up @@ -147,10 +161,12 @@ public void updateOfDnsIsChangedAndFaultyAddressRemoved() throws UnknownHostExce
addresses2[2] = InetAddress.getByName("127.0.0.5");



BackgroundDnsResolver resolver = new BackgroundDnsResolver(new Host("bob.com",11211),10000,reffactory,new SimpleCircularAddressResolver(new InetAddress[][]{addresses1,addresses2}));
SimpleCircularAddressResolver addressResolver = new SimpleCircularAddressResolver(new InetAddress[][]{addresses1,addresses2});
CountDownLatch latch = addressResolver.getStartSignal();
BackgroundDnsResolver resolver = new BackgroundDnsResolver(new Host("bob.com",11211),10000,reffactory,addressResolver);
try {
Thread.sleep(5000);
latch.await(10000, TimeUnit.SECONDS);
Thread.sleep(2000);
ReferencedClient client = resolver.getClient();
assertNotSame(client, SpyReferencedClient.UNAVAILABLE_REFERENCE_CLIENT);
Thread.sleep(13000);
Expand Down

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