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HDFS-13779. [SBN read] Implement proper failover and observer failure handling logic for for ObserverReadProxyProvider. Contributed by Erik Krogen.

This commit is contained in:
Erik Krogen 2018-08-24 05:04:27 -07:00 committed by Konstantin V Shvachko
parent f9fc01cd7f
commit aa42fb0db7
4 changed files with 534 additions and 103 deletions
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16
hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/server/namenode/ha/AbstractNNFailoverProxyProvider.java
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@ -30,6 +30,7 @@ import java.util.concurrent.atomic.AtomicBoolean;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.CommonConfigurationKeysPublic;
import org.apache.hadoop.ha.HAServiceProtocol.HAServiceState;
import org.apache.hadoop.hdfs.DFSUtilClient;
import org.apache.hadoop.hdfs.HAUtilClient;
import org.apache.hadoop.hdfs.client.HdfsClientConfigKeys;
@ -111,6 +112,12 @@ public abstract class AbstractNNFailoverProxyProvider<T> implements
*/
public static class NNProxyInfo<T> extends ProxyInfo<T> {
private InetSocketAddress address;
/**
* The currently known state of the NameNode represented by this ProxyInfo.
* This may be out of date if the NameNode has changed state since the last
* time the state was checked.
*/
private HAServiceState cachedState;
public NNProxyInfo(InetSocketAddress address) {
super(null, address.toString());
@ -120,6 +127,15 @@ public abstract class AbstractNNFailoverProxyProvider<T> implements
public InetSocketAddress getAddress() {
return address;
}
public void setCachedState(HAServiceState state) {
cachedState = state;
}
public HAServiceState getCachedState() {
return cachedState;
}
}
@Override

259
hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/server/namenode/ha/ObserverReadProxyProvider.java
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@ -20,18 +20,24 @@ package org.apache.hadoop.hdfs.server.namenode.ha;
import java.io.Closeable;
import java.io.IOException;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.net.URI;
import java.util.ArrayList;
import java.util.List;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.permission.FsAction;
import org.apache.hadoop.ha.HAServiceProtocol.HAServiceState;
import org.apache.hadoop.hdfs.ClientGSIContext;
import org.apache.hadoop.hdfs.client.HdfsClientConfigKeys;
import org.apache.hadoop.hdfs.protocol.ClientProtocol;
import org.apache.hadoop.hdfs.protocol.LocatedBlock;
import org.apache.hadoop.io.retry.AtMostOnce;
import org.apache.hadoop.io.retry.Idempotent;
import org.apache.hadoop.io.retry.RetryPolicies;
import org.apache.hadoop.io.retry.RetryPolicy;
import org.apache.hadoop.io.retry.RetryPolicy.RetryAction;
import org.apache.hadoop.ipc.AlignmentContext;
import org.apache.hadoop.ipc.RPC;
import org.apache.hadoop.ipc.RemoteException;
@ -59,16 +65,18 @@ public class ObserverReadProxyProvider<T extends ClientProtocol>
private static final Logger LOG = LoggerFactory.getLogger(
ObserverReadProxyProvider.class);
/** Client-side context for syncing with the NameNode server side */
private AlignmentContext alignmentContext;
/** Client-side context for syncing with the NameNode server side. */
private final AlignmentContext alignmentContext;
private AbstractNNFailoverProxyProvider<T> failoverProxy;
/** All NameNdoe proxies */
private List<NNProxyInfo<T>> nameNodeProxies =
new ArrayList<NNProxyInfo<T>>();
/** Proxies for the observer namenodes */
private final List<NNProxyInfo<T>> observerProxies =
new ArrayList<NNProxyInfo<T>>();
/** The inner proxy provider used for active/standby failover. */
private final AbstractNNFailoverProxyProvider<T> failoverProxy;
/** List of all NameNode proxies. */
private final List<NNProxyInfo<T>> nameNodeProxies;
/** The policy used to determine if an exception is fatal or retriable. */
private final RetryPolicy observerRetryPolicy;
/** The combined proxy which redirects to other proxies as necessary. */
private final ProxyInfo<T> combinedProxy;
/**
* Whether reading from observer is enabled. If this is false, all read
@ -77,12 +85,19 @@ public class ObserverReadProxyProvider<T extends ClientProtocol>
private boolean observerReadEnabled;
/**
* Thread-local index to record the current index in the observer list.
* The index into the nameNodeProxies list currently being used. Should only
* be accessed in synchronized methods.
*/
private static final ThreadLocal<Integer> currentIndex =
ThreadLocal.withInitial(() -> 0);
private int currentIndex = -1;
/**
* The proxy being used currently; this will match with currentIndex above.
* This field is volatile to allow reads without synchronization; updates
* should still be performed synchronously to maintain consistency between
* currentIndex and this field.
*/
private volatile NNProxyInfo<T> currentProxy;
/** The last proxy that has been used. Only used for testing */
/** The last proxy that has been used. Only used for testing. */
private volatile ProxyInfo<T> lastProxy = null;
/**
@ -90,63 +105,53 @@ public class ObserverReadProxyProvider<T extends ClientProtocol>
* {@link ConfiguredFailoverProxyProvider} for failover.
*/
public ObserverReadProxyProvider(
Configuration conf, URI uri, Class<T> xface, HAProxyFactory<T> factory)
throws IOException {
Configuration conf, URI uri, Class<T> xface, HAProxyFactory<T> factory) {
this(conf, uri, xface, factory,
new ConfiguredFailoverProxyProvider<T>(conf, uri, xface,factory));
new ConfiguredFailoverProxyProvider<>(conf, uri, xface,factory));
}
@SuppressWarnings("unchecked")
public ObserverReadProxyProvider(
Configuration conf, URI uri, Class<T> xface, HAProxyFactory<T> factory,
AbstractNNFailoverProxyProvider<T> failoverProxy)
throws IOException {
AbstractNNFailoverProxyProvider<T> failoverProxy) {
super(conf, uri, xface, factory);
this.failoverProxy = failoverProxy;
this.alignmentContext = new ClientGSIContext();
((ClientHAProxyFactory<T>) factory).setAlignmentContext(alignmentContext);
// Don't bother configuring the number of retries and such on the retry
// policy since it is mainly only used for determining whether or not an
// exception is retriable or fatal
observerRetryPolicy = RetryPolicies.failoverOnNetworkException(
RetryPolicies.TRY_ONCE_THEN_FAIL, 1);
// Get all NameNode proxies
nameNodeProxies = getProxyAddresses(uri,
HdfsClientConfigKeys.DFS_NAMENODE_RPC_ADDRESS_KEY);
// Find out all the observer proxies
for (NNProxyInfo<T> pi : nameNodeProxies) {
createProxyIfNeeded(pi);
if (isObserverState(pi)) {
observerProxies.add(pi);
}
}
// TODO: No observers is not an error
// Just direct all reads go to the active NameNode
if (observerProxies.isEmpty()) {
throw new RuntimeException("Couldn't find any namenode proxy in " +
"OBSERVER state");
}
}
public synchronized AlignmentContext getAlignmentContext() {
return alignmentContext;
}
@SuppressWarnings("unchecked")
@Override
public synchronized ProxyInfo<T> getProxy() {
// We just create a wrapped proxy containing all the proxies
// Create a wrapped proxy containing all the proxies. Since this combined
// proxy is just redirecting to other proxies, all invocations can share it.
StringBuilder combinedInfo = new StringBuilder("[");
for (int i = 0; i < this.observerProxies.size(); i++) {
for (int i = 0; i < nameNodeProxies.size(); i++) {
if (i > 0) {
combinedInfo.append(",");
}
combinedInfo.append(observerProxies.get(i).proxyInfo);
combinedInfo.append(nameNodeProxies.get(i).proxyInfo);
}
combinedInfo.append(']');
T wrappedProxy = (T) Proxy.newProxyInstance(
ObserverReadInvocationHandler.class.getClassLoader(),
new Class<?>[]{xface},
new ObserverReadInvocationHandler(observerProxies));
return new ProxyInfo<>(wrappedProxy, combinedInfo.toString());
new Class<?>[] { xface }, new ObserverReadInvocationHandler());
combinedProxy = new ProxyInfo<>(wrappedProxy, combinedInfo.toString());
}
public AlignmentContext getAlignmentContext() {
return alignmentContext;
}
@Override
public ProxyInfo<T> getProxy() {
return combinedProxy;
}
@Override
@ -159,8 +164,11 @@ public class ObserverReadProxyProvider<T extends ClientProtocol>
*
* @return whether the 'method' is a read-only operation.
*/
private boolean isRead(Method method) {
return method.isAnnotationPresent(ReadOnly.class);
private static boolean isRead(Method method) {
if (!method.isAnnotationPresent(ReadOnly.class)) {
return false;
}
return !method.getAnnotationsByType(ReadOnly.class)[0].activeOnly();
}
@VisibleForTesting
@ -168,21 +176,13 @@ public class ObserverReadProxyProvider<T extends ClientProtocol>
this.observerReadEnabled = flag;
}
/**
* After getting exception 'ex', whether we should retry the current request
* on a different observer.
*/
private boolean shouldRetry(Exception ex) throws Exception {
// TODO: implement retry policy
return true;
}
@VisibleForTesting
ProxyInfo<T> getLastProxy() {
return lastProxy;
}
boolean isObserverState(NNProxyInfo<T> pi) {
private static <T extends ClientProtocol> HAServiceState getServiceState(
NNProxyInfo<T> pi) {
// TODO: should introduce new ClientProtocol method to verify the
// underlying service state, which does not require superuser access
// The is a workaround
@ -190,7 +190,7 @@ public class ObserverReadProxyProvider<T extends ClientProtocol>
try {
// Verify write access first
pi.proxy.reportBadBlocks(new LocatedBlock[0]);
return false; // Only active NameNode allows write
return HAServiceState.ACTIVE; // Only active NameNode allows write
} catch (RemoteException re) {
IOException sbe = re.unwrapRemoteException(StandbyException.class);
if (!(sbe instanceof StandbyException)) {
@ -200,15 +200,16 @@ public class ObserverReadProxyProvider<T extends ClientProtocol>
ioe = e;
}
if (ioe != null) {
LOG.error("Failed to connect to {}", pi.getAddress(), ioe);
return false;
LOG.warn("Failed to connect to {}", pi.getAddress(), ioe);
return HAServiceState.STANDBY; // Just assume standby in this case
// Anything besides observer is fine
}
// Verify read access
// For now we assume only Observer nodes allow reads
// Stale reads on StandbyNode should be turned off
try {
pi.proxy.checkAccess("/", FsAction.READ);
return true;
return HAServiceState.OBSERVER;
} catch (RemoteException re) {
IOException sbe = re.unwrapRemoteException(StandbyException.class);
if (!(sbe instanceof StandbyException)) {
@ -218,29 +219,60 @@ public class ObserverReadProxyProvider<T extends ClientProtocol>
ioe = e;
}
if (ioe != null) {
LOG.error("Failed to connect to {}", pi.getAddress(), ioe);
LOG.warn("Failed to connect to {}", pi.getAddress(), ioe);
}
return false;
return HAServiceState.STANDBY;
}
class ObserverReadInvocationHandler implements InvocationHandler {
final List<NNProxyInfo<T>> observerProxies;
final ProxyInfo<T> activeProxy;
ObserverReadInvocationHandler(List<NNProxyInfo<T>> observerProxies) {
this.observerProxies = observerProxies;
this.activeProxy = failoverProxy.getProxy();
/**
* Return the currently used proxy. If there is none, first calls
* {@link #changeProxy(NNProxyInfo)} to initialize one.
*/
private NNProxyInfo<T> getCurrentProxy() {
if (currentProxy == null) {
changeProxy(null);
}
return currentProxy;
}
/**
* Move to the next proxy in the proxy list. If the NNProxyInfo supplied by
* the caller does not match the current proxy, the call is ignored; this is
* to handle concurrent calls (to avoid changing the proxy multiple times).
* The service state of the newly selected proxy will be updated before
* returning.
*
* @param initial The expected current proxy
*/
private synchronized void changeProxy(NNProxyInfo<T> initial) {
if (currentProxy != initial) {
// Must have been a concurrent modification; ignore the move request
return;
}
// Attempt to force concurrent callers of getCurrentProxy to wait for the
// new proxy; best-effort by setting currentProxy to null
currentProxy = null;
currentIndex = (currentIndex + 1) % nameNodeProxies.size();
currentProxy = createProxyIfNeeded(nameNodeProxies.get(currentIndex));
currentProxy.setCachedState(getServiceState(currentProxy));
LOG.debug("Changed current proxy from {} to {}",
initial == null ? "none" : initial.proxyInfo,
currentProxy.proxyInfo);
}
/**
* An InvocationHandler to handle incoming requests. This class's invoke
* method contains the primary logic for redirecting to observers.
*
* If observer reads are enabled, attempt to send read operations to the
* current proxy. If it is not an observer, or the observer fails, adjust
* the current proxy and retry on the next one. If all proxies are tried
* without success, the request is forwarded to the active.
*
* Write requests are always forwarded to the active.
*/
private class ObserverReadInvocationHandler implements InvocationHandler {
/**
* Sends read operations to the observer (if enabled) specified by the
* current index, and send write operations to the active. If a observer
* fails, we increment the index and retry the next one. If all observers
* fail, the request is forwarded to the active.
*
* Write requests are always forwarded to the active.
*/
@Override
public Object invoke(Object proxy, final Method method, final Object[] args)
throws Throwable {
@ -248,33 +280,65 @@ public class ObserverReadProxyProvider<T extends ClientProtocol>
Object retVal;
if (observerReadEnabled && isRead(method)) {
// Loop through all the proxies, starting from the current index.
for (int i = 0; i < observerProxies.size(); i++) {
NNProxyInfo<T> current = observerProxies.get(currentIndex.get());
int failedObserverCount = 0;
int activeCount = 0;
int standbyCount = 0;
for (int i = 0; i < nameNodeProxies.size(); i++) {
NNProxyInfo<T> current = getCurrentProxy();
HAServiceState currState = current.getCachedState();
if (currState != HAServiceState.OBSERVER) {
if (currState == HAServiceState.ACTIVE) {
activeCount++;
} else if (currState == HAServiceState.STANDBY) {
standbyCount++;
}
LOG.debug("Skipping proxy {} for {} because it is in state {}",
current.proxyInfo, method.getName(), currState);
changeProxy(current);
continue;
}
LOG.debug("Attempting to service {} using proxy {}",
method.getName(), current.proxyInfo);
try {
retVal = method.invoke(current.proxy, args);
lastProxy = current;
LOG.debug("Invocation of {} using {} was successful",
method.getName(), current.proxyInfo);
return retVal;
} catch (Exception e) {
if (!shouldRetry(e)) {
throw e;
} catch (InvocationTargetException ite) {
if (!(ite.getCause() instanceof Exception)) {
throw ite.getCause();
}
Exception e = (Exception) ite.getCause();
RetryAction retryInfo = observerRetryPolicy.shouldRetry(e, 0, 0,
method.isAnnotationPresent(Idempotent.class)
|| method.isAnnotationPresent(AtMostOnce.class));
if (retryInfo.action == RetryAction.RetryDecision.FAIL) {
throw e;
} else {
failedObserverCount++;
LOG.warn(
"Invocation returned exception on [{}]; {} failure(s) so far",
current.proxyInfo, failedObserverCount, e);
changeProxy(current);
}
currentIndex.set((currentIndex.get() + 1) % observerProxies.size());
LOG.warn("Invocation returned exception on [{}]",
current.proxyInfo, e.getCause());
}
}
// If we get here, it means all observers have failed.
LOG.warn("All observers have failed for read request {}. " +
"Fall back on active: {}", method.getName(), activeProxy);
LOG.warn("{} observers have failed for read request {}; also found " +
"{} standby and {} active. Falling back to active.",
failedObserverCount, standbyCount, activeCount, method.getName());
}
// Either all observers have failed, or that it is a write request.
// In either case, we'll forward the request to active NameNode.
LOG.debug("Using failoverProxy to service {}", method.getName());
ProxyInfo<T> activeProxy = failoverProxy.getProxy();
try {
retVal = method.invoke(activeProxy.proxy, args);
} catch (Exception e) {
} catch (InvocationTargetException e) {
// This exception will be handled by higher layers
throw e.getCause();
}
lastProxy = activeProxy;
@ -284,7 +348,6 @@ public class ObserverReadProxyProvider<T extends ClientProtocol>
@Override
public synchronized void close() throws IOException {
failoverProxy.close();
for (ProxyInfo<T> pi : nameNodeProxies) {
if (pi.proxy != null) {
if (pi.proxy instanceof Closeable) {
@ -292,8 +355,12 @@ public class ObserverReadProxyProvider<T extends ClientProtocol>
} else {
RPC.stopProxy(pi.proxy);
}
// Set to null to avoid the failoverProxy having to re-do the close
// if it is sharing a proxy instance
pi.proxy = null;
}
}
failoverProxy.close();
}
@Override

27
hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestObserverNode.java
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@ -27,22 +27,23 @@ import org.apache.hadoop.hdfs.qjournal.MiniQJMHACluster;
import org.apache.hadoop.hdfs.server.namenode.NameNode;
import org.apache.hadoop.io.retry.FailoverProxyProvider;
import org.apache.hadoop.io.retry.RetryInvocationHandler;
import org.apache.hadoop.test.GenericTestUtils;
import org.junit.After;
import org.junit.Before;
import org.junit.Ignore;
import org.junit.Test;
import java.io.File;
import java.io.IOException;
import java.lang.reflect.Proxy;
import java.net.URI;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_HA_LOGROLL_PERIOD_KEY;
import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_HA_TAILEDITS_PERIOD_KEY;
import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_HA_TAILEDITS_INPROGRESS_KEY;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertTrue;
import static org.junit.Assert.fail;
@ -200,6 +201,9 @@ public class TestObserverNode {
// Start the observer again - requests should go to observer
dfsCluster.restartNameNode(2);
dfsCluster.transitionToObserver(2);
// The first request goes to the active because it has not refreshed yet;
// the second will properly go to the observer
dfs.getFileStatus(testPath);
dfs.getFileStatus(testPath);
assertSentTo(2);
}
@ -231,6 +235,9 @@ public class TestObserverNode {
dfsCluster.transitionToObserver(2);
dfs.getFileStatus(testPath);
// The first request goes to the active because it has not refreshed yet;
// the second will properly go to the observer
dfs.getFileStatus(testPath);
assertSentTo(2);
}
@ -291,6 +298,10 @@ public class TestObserverNode {
assertEquals(0, rc);
}
// TODO this does not currently work because fetching the service state from
// e.g. the StandbyNameNode also waits for the transaction ID to catch up.
// This is disabled pending HDFS-13872 and HDFS-13749.
@Ignore("Disabled until HDFS-13872 and HDFS-13749 are committed")
@Test
public void testMsyncSimple() throws Exception {
// disable fast path here because this test's assertions are based on the
@ -304,7 +315,8 @@ public class TestObserverNode {
setUpCluster(1);
setObserverRead(true);
AtomicBoolean readSucceed = new AtomicBoolean(false);
// 0 == not completed, 1 == succeeded, -1 == failed
AtomicInteger readStatus = new AtomicInteger(0);
dfs.mkdir(testPath, FsPermission.getDefault());
assertSentTo(0);
@ -313,20 +325,21 @@ public class TestObserverNode {
try {
// this read will block until roll and tail edits happen.
dfs.getFileStatus(testPath);
readSucceed.set(true);
readStatus.set(1);
} catch (IOException e) {
e.printStackTrace();
readStatus.set(-1);
}
});
reader.start();
// the reader is still blocking, not succeeded yet.
assertFalse(readSucceed.get());
assertEquals(0, readStatus.get());
rollEditLogAndTail(0);
// wait a while for all the change to be done
Thread.sleep(100);
GenericTestUtils.waitFor(() -> readStatus.get() != 0, 100, 10000);
// the reader should have succeed.
assertTrue(readSucceed.get());
assertEquals(1, readStatus.get());
}
private void setUpCluster(int numObservers) throws Exception {

335
hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestObserverReadProxyProvider.java Normal file
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@ -0,0 +1,335 @@
/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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
* <p>
* http://www.apache.org/licenses/LICENSE-2.0
* <p>
* 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 org.apache.hadoop.hdfs.server.namenode.ha;
import com.google.common.base.Joiner;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.URI;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.atomic.AtomicBoolean;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.permission.FsAction;
import org.apache.hadoop.hdfs.client.HdfsClientConfigKeys;
import org.apache.hadoop.hdfs.protocol.ClientProtocol;
import org.apache.hadoop.hdfs.protocol.LocatedBlock;
import org.apache.hadoop.ipc.RemoteException;
import org.apache.hadoop.ipc.StandbyException;
import org.apache.hadoop.security.UserGroupInformation;
import org.junit.Before;
import org.junit.Test;
import org.mockito.Mockito;
import org.mockito.invocation.InvocationOnMock;
import org.mockito.stubbing.Answer;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.fail;
import static org.mockito.Mockito.mock;
/**
* Tests for {@link ObserverReadProxyProvider} under various configurations of
* NameNode states. Mainly testing that the proxy provider picks the correct
* NameNode to communicate with.
*/
public class TestObserverReadProxyProvider {
private static final LocatedBlock[] EMPTY_BLOCKS = new LocatedBlock[0];
private String ns;
private URI nnURI;
private Configuration conf;
private ObserverReadProxyProvider<ClientProtocol> proxyProvider;
private ClientProtocolAnswer[] namenodeAnswers;
private String[] namenodeAddrs;
@Before
public void setup() throws Exception {
ns = "testcluster";
nnURI = URI.create("hdfs://" + ns);
conf = new Configuration();
conf.set(HdfsClientConfigKeys.DFS_NAMESERVICES, ns);
}
private void setupProxyProvider(int namenodeCount) throws Exception {
String[] namenodeIDs = new String[namenodeCount];
namenodeAddrs = new String[namenodeCount];
namenodeAnswers = new ClientProtocolAnswer[namenodeCount];
ClientProtocol[] proxies = new ClientProtocol[namenodeCount];
Map<String, ClientProtocol> proxyMap = new HashMap<>();
for (int i = 0; i < namenodeCount; i++) {
namenodeIDs[i] = "nn" + i;
namenodeAddrs[i] = "namenode" + i + ".test:8020";
conf.set(HdfsClientConfigKeys.DFS_NAMENODE_RPC_ADDRESS_KEY + "." + ns +
"." + namenodeIDs[i], namenodeAddrs[i]);
namenodeAnswers[i] = new ClientProtocolAnswer();
proxies[i] = mock(ClientProtocol.class);
doWrite(Mockito.doAnswer(namenodeAnswers[i]).when(proxies[i]));
doRead(Mockito.doAnswer(namenodeAnswers[i]).when(proxies[i]));
proxyMap.put(namenodeAddrs[i], proxies[i]);
}
conf.set(HdfsClientConfigKeys.DFS_HA_NAMENODES_KEY_PREFIX + "." + ns,
Joiner.on(",").join(namenodeIDs));
proxyProvider = new ObserverReadProxyProvider<>(conf, nnURI,
ClientProtocol.class, new ClientHAProxyFactory<ClientProtocol>() {
@Override
public ClientProtocol createProxy(Configuration conf,
InetSocketAddress nnAddr, Class<ClientProtocol> xface,
UserGroupInformation ugi, boolean withRetries,
AtomicBoolean fallbackToSimpleAuth) {
return proxyMap.get(nnAddr.toString());
}
});
proxyProvider.setObserverReadEnabled(true);
}
@Test
public void testReadOperationOnObserver() throws Exception {
setupProxyProvider(3);
namenodeAnswers[0].setActiveState();
namenodeAnswers[2].setObserverState();
doRead();
assertHandledBy(2);
}
@Test
public void testWriteOperationOnActive() throws Exception {
setupProxyProvider(3);
namenodeAnswers[0].setActiveState();
namenodeAnswers[2].setObserverState();
doWrite();
assertHandledBy(0);
}
@Test
public void testUnreachableObserverWithNoBackup() throws Exception {
setupProxyProvider(2);
namenodeAnswers[0].setActiveState();
namenodeAnswers[1].setObserverState();
namenodeAnswers[1].setUnreachable(true);
// Confirm that read still succeeds even though observer is not available
doRead();
assertHandledBy(0);
}
@Test
public void testUnreachableObserverWithMultiple() throws Exception {
setupProxyProvider(4);
namenodeAnswers[0].setActiveState();
namenodeAnswers[2].setObserverState();
namenodeAnswers[3].setObserverState();
doRead();
assertHandledBy(2);
namenodeAnswers[2].setUnreachable(true);
doRead();
// Fall back to the second observer node
assertHandledBy(3);
namenodeAnswers[2].setUnreachable(false);
doRead();
// Current index has changed, so although the first observer is back,
// it should continue requesting from the second observer
assertHandledBy(3);
namenodeAnswers[3].setUnreachable(true);
doRead();
// Now that second is unavailable, go back to using the first observer
assertHandledBy(2);
namenodeAnswers[2].setUnreachable(true);
doRead();
// Both observers are now unavailable, so it should fall back to active
assertHandledBy(0);
}
@Test
public void testObserverToActive() throws Exception {
setupProxyProvider(3);
namenodeAnswers[0].setActiveState();
namenodeAnswers[1].setObserverState();
namenodeAnswers[2].setObserverState();
doWrite();
assertHandledBy(0);
// Transition an observer to active
namenodeAnswers[0].setStandbyState();
namenodeAnswers[1].setActiveState();
try {
doWrite();
fail("Write should fail; failover required");
} catch (RemoteException re) {
assertEquals(re.getClassName(),
StandbyException.class.getCanonicalName());
}
proxyProvider.performFailover(proxyProvider.getProxy().proxy);
doWrite();
// After failover, previous observer is now active
assertHandledBy(1);
doRead();
assertHandledBy(2);
// Transition back to original state but second observer not available
namenodeAnswers[0].setActiveState();
namenodeAnswers[1].setObserverState();
namenodeAnswers[2].setUnreachable(true);
for (int i = 0; i < 2; i++) {
try {
doWrite();
fail("Should have failed");
} catch (IOException ioe) {
proxyProvider.performFailover(proxyProvider.getProxy().proxy);
}
}
doWrite();
assertHandledBy(0);
doRead();
assertHandledBy(1);
}
@Test
public void testObserverToStandby() throws Exception {
setupProxyProvider(3);
namenodeAnswers[0].setActiveState();
namenodeAnswers[1].setObserverState();
namenodeAnswers[2].setObserverState();
doRead();
assertHandledBy(1);
namenodeAnswers[1].setStandbyState();
doRead();
assertHandledBy(2);
namenodeAnswers[2].setStandbyState();
doRead();
assertHandledBy(0);
namenodeAnswers[1].setObserverState();
doRead();
assertHandledBy(1);
}
@Test
public void testSingleObserverToStandby() throws Exception {
setupProxyProvider(2);
namenodeAnswers[0].setActiveState();
namenodeAnswers[1].setObserverState();
doRead();
assertHandledBy(1);
namenodeAnswers[1].setStandbyState();
doRead();
assertHandledBy(0);
namenodeAnswers[1].setObserverState();
// The proxy provider still thinks the second NN is in observer state,
// so it will take a second call for it to notice the new observer
doRead();
doRead();
assertHandledBy(1);
}
private void doRead() throws Exception {
doRead(proxyProvider.getProxy().proxy);
}
private void doWrite() throws Exception {
doWrite(proxyProvider.getProxy().proxy);
}
private void assertHandledBy(int namenodeIdx) {
assertEquals(namenodeAddrs[namenodeIdx],
proxyProvider.getLastProxy().proxyInfo);
}
private static void doWrite(ClientProtocol client) throws Exception {
client.reportBadBlocks(EMPTY_BLOCKS);
}
private static void doRead(ClientProtocol client) throws Exception {
client.checkAccess("/", FsAction.READ);
}
/**
* An {@link Answer} used for mocking of a {@link ClientProtocol}. Setting
* the state or unreachability of this Answer will make the linked
* ClientProtocol respond as if it was communicating with a NameNode of
* the corresponding state. It is in Standby state by default.
*/
private static class ClientProtocolAnswer implements Answer<Void> {
private volatile boolean unreachable = false;
// Standby state by default
private volatile boolean allowWrites = false;
private volatile boolean allowReads = false;
@Override
public Void answer(InvocationOnMock invocationOnMock) throws Throwable {
if (unreachable) {
throw new IOException("Unavailable");
}
switch (invocationOnMock.getMethod().getName()) {
case "reportBadBlocks":
if (!allowWrites) {
throw new RemoteException(StandbyException.class.getCanonicalName(),
"No writes!");
}
return null;
case "checkAccess":
if (!allowReads) {
throw new RemoteException(StandbyException.class.getCanonicalName(),
"No reads!");
}
return null;
default:
throw new IllegalArgumentException(
"Only reportBadBlocks and checkAccess supported!");
}
}
void setUnreachable(boolean unreachable) {
this.unreachable = unreachable;
}
void setActiveState() {
allowReads = true;
allowWrites = true;
}
void setStandbyState() {
allowReads = false;
allowWrites = false;
}
void setObserverState() {
allowReads = true;
allowWrites = false;
}
}
}