/**
* 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
*
* 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 org.apache.hadoop.hbase.catalog;
import java.io.EOFException;
import java.io.IOException;
import java.net.ConnectException;
import java.net.NoRouteToHostException;
import java.net.SocketException;
import java.net.SocketTimeoutException;
import java.util.concurrent.atomic.AtomicBoolean;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.Abortable;
import org.apache.hadoop.hbase.HRegionInfo;
import org.apache.hadoop.hbase.NotAllMetaRegionsOnlineException;
import org.apache.hadoop.hbase.ServerName;
import org.apache.hadoop.hbase.client.HConnection;
import org.apache.hadoop.hbase.client.HConnectionManager;
import org.apache.hadoop.hbase.client.RetriesExhaustedException;
import org.apache.hadoop.hbase.ipc.HRegionInterface;
import org.apache.hadoop.hbase.ipc.ServerNotRunningYetException;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.hbase.zookeeper.MetaNodeTracker;
import org.apache.hadoop.hbase.zookeeper.RootRegionTracker;
import org.apache.hadoop.hbase.zookeeper.ZooKeeperWatcher;
import org.apache.hadoop.ipc.RemoteException;
/**
* Tracks the availability of the catalog tables <code>-ROOT-</code> and
* <code>.META.</code>.
*
* This class is "read-only" in that the locations of the catalog tables cannot
* be explicitly set. Instead, ZooKeeper is used to learn of the availability
* and location of <code>-ROOT-</code>. <code>-ROOT-</code> is used to learn of
* the location of <code>.META.</code> If not available in <code>-ROOT-</code>,
* ZooKeeper is used to monitor for a new location of <code>.META.</code>.
*
* <p>Call {@link #start()} to start up operation. Call {@link #stop()}} to
* interrupt waits and close up shop.
*/
public class CatalogTracker {
// TODO: This class needs a rethink. The original intent was that it would be
// the one-stop-shop for root and meta locations and that it would get this
// info from reading and watching zk state. The class was to be used by
// servers when they needed to know of root and meta movement but also by
// client-side (inside in HTable) so rather than figure root and meta
// locations on fault, the client would instead get notifications out of zk.
//
// But this original intent is frustrated by the fact that this class has to
// read an hbase table, the -ROOT- table, to figure out the .META. region
// location which means we depend on an HConnection. HConnection will do
// retrying but also, it has its own mechanism for finding root and meta
// locations (and for 'verifying'; it tries the location and if it fails, does
// new lookup, etc.). So, at least for now, HConnection (or HTable) can't
// have a CT since CT needs a HConnection (Even then, do want HT to have a CT?
// For HT keep up a session with ZK? Rather, shouldn't we do like asynchbase
// where we'd open a connection to zk, read what we need then let the
// connection go?). The 'fix' is make it so both root and meta addresses
// are wholey up in zk -- not in zk (root) -- and in an hbase table (meta).
//
// But even then, this class does 'verification' of the location and it does
// this by making a call over an HConnection (which will do its own root
// and meta lookups). Isn't this verification 'useless' since when we
// return, whatever is dependent on the result of this call then needs to
// use HConnection; what we have verified may change in meantime (HConnection
// uses the CT primitives, the root and meta trackers finding root locations).
//
// When meta is moved to zk, this class may make more sense. In the
// meantime, it does not cohere. It should just watch meta and root and not
// NOT do verification -- let that be out in HConnection since its going to
// be done there ultimately anyways.
//
// This class has spread throughout the codebase. It needs to be reigned in.
// This class should be used server-side only, even if we move meta location
// up into zk. Currently its used over in the client package. Its used in
// MetaReader and MetaEditor classes usually just to get the Configuration
// its using (It does this indirectly by asking its HConnection for its
// Configuration and even then this is just used to get an HConnection out on
// the other end). I made https://issues.apache.org/jira/browse/HBASE-4495 for
// doing CT fixup. St.Ack 09/30/2011.
//
private static final Log LOG = LogFactory.getLog(CatalogTracker.class);
private final HConnection connection;
private final ZooKeeperWatcher zookeeper;
private final RootRegionTracker rootRegionTracker;
private final MetaNodeTracker metaNodeTracker;
private final AtomicBoolean metaAvailable = new AtomicBoolean(false);
private boolean instantiatedzkw = false;
private Abortable abortable;
/*
* Do not clear this address once set. Its needed when we do
* server shutdown processing -- we need to know who had .META. last. If you
* want to know if the address is good, rely on {@link #metaAvailable} value.
*/
private ServerName metaLocation;
/*
* Timeout waiting on root or meta to be set.
*/
private final int defaultTimeout;
private boolean stopped = false;
static final byte [] ROOT_REGION_NAME =
HRegionInfo.ROOT_REGIONINFO.getRegionName();
static final byte [] META_REGION_NAME =
HRegionInfo.FIRST_META_REGIONINFO.getRegionName();
/**
* Constructs a catalog tracker. Find current state of catalog tables.
* Begin active tracking by executing {@link #start()} post construction. Does
* not timeout.
*
* @param conf
* the {@link Configuration} from which a {@link HConnection} will be
* obtained; if problem, this connections
* {@link HConnection#abort(String, Throwable)} will be called.
* @throws IOException
*/
public CatalogTracker(final Configuration conf) throws IOException {
this(null, conf, null);
}
/**
* Constructs the catalog tracker. Find current state of catalog tables.
* Begin active tracking by executing {@link #start()} post construction.
* Does not timeout.
* @param zk If zk is null, we'll create an instance (and shut it down
* when {@link #stop()} is called) else we'll use what is passed.
* @param conf
* @param abortable If fatal exception we'll call abort on this. May be null.
* If it is we'll use the Connection associated with the passed
* {@link Configuration} as our Abortable.
* @throws IOException
*/
public CatalogTracker(final ZooKeeperWatcher zk, final Configuration conf,
final Abortable abortable)
throws IOException {
this(zk, conf, abortable,
conf.getInt("hbase.catalogtracker.default.timeout", 1000));
}
/**
* Constructs the catalog tracker. Find current state of catalog tables.
* Begin active tracking by executing {@link #start()} post construction.
* @param zk If zk is null, we'll create an instance (and shut it down
* when {@link #stop()} is called) else we'll use what is passed.
* @param conf
* @param abortable If fatal exception we'll call abort on this. May be null.
* If it is we'll use the Connection associated with the passed
* {@link Configuration} as our Abortable.
* @param defaultTimeout Timeout to use. Pass zero for no timeout
* ({@link Object#wait(long)} when passed a <code>0</code> waits for ever).
* @throws IOException
*/
public CatalogTracker(final ZooKeeperWatcher zk, final Configuration conf,
Abortable abortable, final int defaultTimeout)
throws IOException {
this(zk, conf, HConnectionManager.getConnection(conf), abortable, defaultTimeout);
}
CatalogTracker(final ZooKeeperWatcher zk, final Configuration conf,
HConnection connection, Abortable abortable, final int defaultTimeout)
throws IOException {
this.connection = connection;
if (abortable == null) {
// A connection is abortable.
this.abortable = this.connection;
}
Abortable throwableAborter = new Abortable() {
@Override
public void abort(String why, Throwable e) {
throw new RuntimeException(why, e);
}
@Override
public boolean isAborted() {
return true;
}
};
if (zk == null) {
// Create our own. Set flag so we tear it down on stop.
this.zookeeper =
new ZooKeeperWatcher(conf, "catalogtracker-on-" + connection.toString(),
abortable);
instantiatedzkw = true;
} else {
this.zookeeper = zk;
}
this.rootRegionTracker = new RootRegionTracker(zookeeper, throwableAborter);
final CatalogTracker ct = this;
// Override nodeDeleted so we get notified when meta node deleted
this.metaNodeTracker = new MetaNodeTracker(zookeeper, throwableAborter) {
public void nodeDeleted(String path) {
if (!path.equals(node)) return;
ct.resetMetaLocation();
}
};
this.defaultTimeout = defaultTimeout;
}
/**
* Starts the catalog tracker.
* Determines current availability of catalog tables and ensures all further
* transitions of either region are tracked.
* @throws IOException
* @throws InterruptedException
*/
public void start() throws IOException, InterruptedException {
LOG.debug("Starting catalog tracker " + this);
try {
this.rootRegionTracker.start();
this.metaNodeTracker.start();
} catch (RuntimeException e) {
Throwable t = e.getCause();
this.abortable.abort(e.getMessage(), t);
throw new IOException("Attempt to start root/meta tracker failed.", t);
}
}
/**
* Stop working.
* Interrupts any ongoing waits.
*/
public void stop() {
if (!this.stopped) {
LOG.debug("Stopping catalog tracker " + this);
this.stopped = true;
this.rootRegionTracker.stop();
this.metaNodeTracker.stop();
try {
if (this.connection != null) {
this.connection.close();
}
} catch (IOException e) {
// Although the {@link Closeable} interface throws an {@link
// IOException}, in reality, the implementation would never do that.
LOG.error("Attempt to close catalog tracker's connection failed.", e);
}
if (this.instantiatedzkw) {
this.zookeeper.close();
}
// Call this and it will interrupt any ongoing waits on meta.
synchronized (this.metaAvailable) {
this.metaAvailable.notifyAll();
}
}
}
/**
* Gets the current location for <code>-ROOT-</code> or null if location is
* not currently available.
* @return {@link ServerName} for server hosting <code>-ROOT-</code> or null
* if none available
* @throws InterruptedException
*/
public ServerName getRootLocation() throws InterruptedException {
return this.rootRegionTracker.getRootRegionLocation();
}
/**
* @return {@link ServerName} for server hosting <code>.META.</code> or null
* if none available
*/
public ServerName getMetaLocation() {
return this.metaLocation;
}
/**
* Method used by master on startup trying to figure state of cluster.
* Returns the current meta location unless its null. In this latter case,
* it has not yet been set so go check whats up in <code>-ROOT-</code> and
* return that.
* @return {@link ServerName} for server hosting <code>.META.</code> or if null,
* we'll read the location that is up in <code>-ROOT-</code> table (which
* could be null or just plain stale).
* @throws IOException
*/
public ServerName getMetaLocationOrReadLocationFromRoot() throws IOException {
ServerName sn = getMetaLocation();
return sn != null? sn: MetaReader.getMetaRegionLocation(this);
}
/**
* Waits indefinitely for availability of <code>-ROOT-</code>. Used during
* cluster startup.
* @throws InterruptedException if interrupted while waiting
*/
public void waitForRoot()
throws InterruptedException {
this.rootRegionTracker.blockUntilAvailable();
}
/**
* Gets the current location for <code>-ROOT-</code> if available and waits
* for up to the specified timeout if not immediately available. Returns null
* if the timeout elapses before root is available.
* @param timeout maximum time to wait for root availability, in milliseconds
* @return {@link ServerName} for server hosting <code>-ROOT-</code> or null
* if none available
* @throws InterruptedException if interrupted while waiting
* @throws NotAllMetaRegionsOnlineException if root not available before
* timeout
*/
ServerName waitForRoot(final long timeout)
throws InterruptedException, NotAllMetaRegionsOnlineException {
ServerName sn = rootRegionTracker.waitRootRegionLocation(timeout);
if (sn == null) {
throw new NotAllMetaRegionsOnlineException("Timed out; " + timeout + "ms");
}
return sn;
}
/**
* Gets a connection to the server hosting root, as reported by ZooKeeper,
* waiting up to the specified timeout for availability.
* @param timeout How long to wait on root location
* @see #waitForRoot(long) for additional information
* @return connection to server hosting root
* @throws InterruptedException
* @throws NotAllMetaRegionsOnlineException if timed out waiting
* @throws IOException
* @deprecated Use #getRootServerConnection(long)
*/
public HRegionInterface waitForRootServerConnection(long timeout)
throws InterruptedException, NotAllMetaRegionsOnlineException, IOException {
return getRootServerConnection(timeout);
}
/**
* Gets a connection to the server hosting root, as reported by ZooKeeper,
* waiting up to the specified timeout for availability.
* <p>WARNING: Does not retry. Use an {@link HTable} instead.
* @param timeout How long to wait on root location
* @see #waitForRoot(long) for additional information
* @return connection to server hosting root
* @throws InterruptedException
* @throws NotAllMetaRegionsOnlineException if timed out waiting
* @throws IOException
*/
HRegionInterface getRootServerConnection(long timeout)
throws InterruptedException, NotAllMetaRegionsOnlineException, IOException {
return getCachedConnection(waitForRoot(timeout));
}
/**
* Gets a connection to the server hosting root, as reported by ZooKeeper,
* waiting for the default timeout specified on instantiation.
* @see #waitForRoot(long) for additional information
* @return connection to server hosting root
* @throws NotAllMetaRegionsOnlineException if timed out waiting
* @throws IOException
* @deprecated Use #getRootServerConnection(long)
*/
public HRegionInterface waitForRootServerConnectionDefault()
throws NotAllMetaRegionsOnlineException, IOException {
try {
return getRootServerConnection(this.defaultTimeout);
} catch (InterruptedException e) {
throw new NotAllMetaRegionsOnlineException("Interrupted");
}
}
/**
* Gets a connection to the server currently hosting <code>.META.</code> or
* null if location is not currently available.
* <p>
* If a location is known, a connection to the cached location is returned.
* If refresh is true, the cached connection is verified first before
* returning. If the connection is not valid, it is reset and rechecked.
* <p>
* If no location for meta is currently known, method checks ROOT for a new
* location, verifies META is currently there, and returns a cached connection
* to the server hosting META.
*
* @return connection to server hosting meta, null if location not available
* @throws IOException
* @throws InterruptedException
*/
private HRegionInterface getMetaServerConnection()
throws IOException, InterruptedException {
synchronized (metaAvailable) {
if (metaAvailable.get()) {
HRegionInterface current = getCachedConnection(this.metaLocation);
// If we are to refresh, verify we have a good connection by making
// an invocation on it.
if (verifyRegionLocation(current, this.metaLocation, META_REGION_NAME)) {
return current;
}
resetMetaLocation();
}
// We got here because there is no meta available or because whats
// available is bad.
// Now read the current .META. content from -ROOT-. Note: This goes via
// an HConnection. It has its own way of figuring root and meta locations
// which we have to wait on.
ServerName newLocation = MetaReader.getMetaRegionLocation(this);
if (newLocation == null) return null;
HRegionInterface newConnection = getCachedConnection(newLocation);
if (verifyRegionLocation(newConnection, newLocation, META_REGION_NAME)) {
setMetaLocation(newLocation);
return newConnection;
} else {
if (LOG.isTraceEnabled()) {
LOG.trace("New .META. server: " + newLocation + " isn't valid." +
" Cached .META. server: " + this.metaLocation);
}
}
return null;
}
}
/**
* Waits indefinitely for availability of <code>.META.</code>. Used during
* cluster startup. Does not verify meta, just that something has been
* set up in zk.
* @see #waitForMeta(long)
* @throws InterruptedException if interrupted while waiting
*/
public void waitForMeta() throws InterruptedException {
while (!this.stopped) {
try {
if (waitForMeta(100) != null) break;
} catch (NotAllMetaRegionsOnlineException e) {
if (LOG.isTraceEnabled()) {
LOG.info(".META. still not available, sleeping and retrying." +
" Reason: " + e.getMessage());
}
} catch (IOException e) {
LOG.info("Retrying", e);
}
}
}
/**
* Gets the current location for <code>.META.</code> if available and waits
* for up to the specified timeout if not immediately available. Throws an
* exception if timed out waiting. This method differs from {@link #waitForMeta()}
* in that it will go ahead and verify the location gotten from ZooKeeper and
* -ROOT- region by trying to use returned connection.
* @param timeout maximum time to wait for meta availability, in milliseconds
* @return {@link ServerName} for server hosting <code>.META.</code> or null
* if none available
* @throws InterruptedException if interrupted while waiting
* @throws IOException unexpected exception connecting to meta server
* @throws NotAllMetaRegionsOnlineException if meta not available before
* timeout
*/
public ServerName waitForMeta(long timeout)
throws InterruptedException, IOException, NotAllMetaRegionsOnlineException {
long stop = System.currentTimeMillis() + timeout;
long waitTime = Math.min(50, timeout);
synchronized (metaAvailable) {
while(!stopped && (timeout == 0 || System.currentTimeMillis() < stop)) {
if (getMetaServerConnection() != null) {
return metaLocation;
}
// perhaps -ROOT- region isn't available, let us wait a bit and retry.
metaAvailable.wait(waitTime);
}
if (getMetaServerConnection() == null) {
throw new NotAllMetaRegionsOnlineException("Timed out (" + timeout + "ms)");
}
return metaLocation;
}
}
/**
* Gets a connection to the server hosting meta, as reported by ZooKeeper,
* waiting up to the specified timeout for availability.
* @see #waitForMeta(long) for additional information
* @return connection to server hosting meta
* @throws InterruptedException
* @throws NotAllMetaRegionsOnlineException if timed out waiting
* @throws IOException
* @deprecated Does not retry; use an HTable instance instead.
*/
public HRegionInterface waitForMetaServerConnection(long timeout)
throws InterruptedException, NotAllMetaRegionsOnlineException, IOException {
return getCachedConnection(waitForMeta(timeout));
}
/**
* Gets a connection to the server hosting meta, as reported by ZooKeeper,
* waiting up to the specified timeout for availability.
* Used in tests.
* @see #waitForMeta(long) for additional information
* @return connection to server hosting meta
* @throws NotAllMetaRegionsOnlineException if timed out or interrupted
* @throws IOException
* @deprecated Does not retry; use an HTable instance instead.
*/
public HRegionInterface waitForMetaServerConnectionDefault()
throws NotAllMetaRegionsOnlineException, IOException {
try {
return getCachedConnection(waitForMeta(defaultTimeout));
} catch (InterruptedException e) {
throw new NotAllMetaRegionsOnlineException("Interrupted");
}
}
/**
* Called when we figure current meta is off (called from zk callback).
*/
public void resetMetaLocation() {
LOG.debug("Current cached META location, " + metaLocation +
", is not valid, resetting");
synchronized(this.metaAvailable) {
this.metaAvailable.set(false);
this.metaAvailable.notifyAll();
}
}
/**
* @param metaLocation
*/
void setMetaLocation(final ServerName metaLocation) {
LOG.debug("Set new cached META location: " + metaLocation);
synchronized (this.metaAvailable) {
this.metaLocation = metaLocation;
this.metaAvailable.set(true);
// no synchronization because these are private and already under lock
this.metaAvailable.notifyAll();
}
}
/**
* @param sn ServerName to get a connection against.
* @return The HRegionInterface we got when we connected to <code>sn</code>
* May have come from cache, may not be good, may have been setup by this
* invocation, or may be null.
* @throws IOException
*/
private HRegionInterface getCachedConnection(ServerName sn)
throws IOException {
if (sn == null) {
return null;
}
HRegionInterface protocol = null;
try {
protocol = connection.getHRegionConnection(sn.getHostname(), sn.getPort());
} catch (RetriesExhaustedException e) {
if (e.getCause() != null && e.getCause() instanceof ConnectException) {
// Catch this; presume it means the cached connection has gone bad.
} else {
throw e;
}
} catch (SocketTimeoutException e) {
LOG.debug("Timed out connecting to " + sn);
} catch (NoRouteToHostException e) {
LOG.debug("Connecting to " + sn, e);
} catch (SocketException e) {
LOG.debug("Exception connecting to " + sn);
} catch (IOException ioe) {
Throwable cause = ioe.getCause();
if (cause != null && cause instanceof EOFException) {
// Catch. Other end disconnected us.
} else if (cause != null && cause.getMessage() != null &&
cause.getMessage().toLowerCase().contains("connection reset")) {
// Catch. Connection reset.
} else {
throw ioe;
}
}
return protocol;
}
/**
* Verify we can connect to <code>hostingServer</code> and that its carrying
* <code>regionName</code>.
* @param hostingServer Interface to the server hosting <code>regionName</code>
* @param serverName The servername that goes with the <code>metaServer</code>
* Interface. Used logging.
* @param regionName The regionname we are interested in.
* @return True if we were able to verify the region located at other side of
* the Interface.
* @throws IOException
*/
// TODO: We should be able to get the ServerName from the HRegionInterface
// rather than have to pass it in. Its made awkward by the fact that the
// HRI is likely a proxy against remote server so the getServerName needs
// to be fixed to go to a local method or to a cache before we can do this.
private boolean verifyRegionLocation(HRegionInterface hostingServer,
final ServerName address, final byte [] regionName)
throws IOException {
if (hostingServer == null) {
LOG.info("Passed hostingServer is null");
return false;
}
Throwable t = null;
try {
// Try and get regioninfo from the hosting server.
return hostingServer.getRegionInfo(regionName) != null;
} catch (ConnectException e) {
t = e;
} catch (RemoteException e) {
IOException ioe = e.unwrapRemoteException();
t = ioe;
} catch (IOException e) {
Throwable cause = e.getCause();
if (cause != null && cause instanceof EOFException) {
t = cause;
} else if (cause != null && cause.getMessage() != null
&& cause.getMessage().contains("Connection reset")) {
t = cause;
} else {
t = e;
}
}
LOG.info("Failed verification of " + Bytes.toStringBinary(regionName) +
" at address=" + address + "; " + t);
return false;
}
/**
* Verify <code>-ROOT-</code> is deployed and accessible.
* @param timeout How long to wait on zk for root address (passed through to
* the internal call to {@link #waitForRootServerConnection(long)}.
* @return True if the <code>-ROOT-</code> location is healthy.
* @throws IOException
* @throws InterruptedException
*/
public boolean verifyRootRegionLocation(final long timeout)
throws InterruptedException, IOException {
HRegionInterface connection = null;
try {
connection = waitForRootServerConnection(timeout);
} catch (NotAllMetaRegionsOnlineException e) {
// Pass
} catch (ServerNotRunningYetException e) {
// Pass -- remote server is not up so can't be carrying root
}
return (connection == null)? false:
verifyRegionLocation(connection,
this.rootRegionTracker.getRootRegionLocation(), ROOT_REGION_NAME);
}
/**
* Verify <code>.META.</code> is deployed and accessible.
* @param timeout How long to wait on zk for <code>.META.</code> address
* (passed through to the internal call to {@link #waitForMetaServerConnection(long)}.
* @return True if the <code>.META.</code> location is healthy.
* @throws IOException Some unexpected IOE.
* @throws InterruptedException
*/
public boolean verifyMetaRegionLocation(final long timeout)
throws InterruptedException, IOException {
HRegionInterface connection = null;
try {
connection = waitForMetaServerConnection(timeout);
} catch (NotAllMetaRegionsOnlineException e) {
// Pass
} catch (ServerNotRunningYetException e) {
// Pass -- remote server is not up so can't be carrying .META.
}
return connection != null;
}
// Used by tests.
MetaNodeTracker getMetaNodeTracker() {
return this.metaNodeTracker;
}
public HConnection getConnection() {
return this.connection;
}
}