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/**
* 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.hive.ql.lockmgr;
import org.apache.hadoop.hive.conf.HiveConf;
import org.apache.hadoop.hive.ql.exec.DDLTask;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.hadoop.hive.common.JavaUtils;
import org.apache.hadoop.hive.common.metrics.common.Metrics;
import org.apache.hadoop.hive.common.metrics.common.MetricsConstant;
import org.apache.hadoop.hive.common.metrics.common.MetricsFactory;
import org.apache.hadoop.hive.metastore.api.*;
import org.apache.hadoop.hive.ql.Driver.LockedDriverState;
import org.apache.hadoop.hive.ql.ErrorMsg;
import org.apache.thrift.TException;
import java.io.ByteArrayOutputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Objects;
import java.util.Set;
import java.util.concurrent.TimeUnit;
/**
* An implementation of HiveLockManager for use with {@link org.apache.hadoop.hive.ql.lockmgr.DbTxnManager}.
* Note, this lock manager is not meant to be stand alone. It cannot be used without the DbTxnManager.
* See {@link DbTxnManager#getMS()} for important concurrency/metastore access notes.
*/
public final class DbLockManager implements HiveLockManager{
static final private String CLASS_NAME = DbLockManager.class.getName();
static final private Logger LOG = LoggerFactory.getLogger(CLASS_NAME);
private long MAX_SLEEP;
//longer term we should always have a txn id and then we won't need to track locks here at all
private Set locks;
private long nextSleep = 50;
private final HiveConf conf;
private final DbTxnManager txnManager;
DbLockManager(HiveConf conf, DbTxnManager txnManager) {
locks = new HashSet<>();
this.conf = conf;
this.txnManager = txnManager;
}
@Override
public void setContext(HiveLockManagerCtx ctx) throws LockException {
}
@Override
public HiveLock lock(HiveLockObject key, HiveLockMode mode,
boolean keepAlive) throws LockException {
throw new UnsupportedOperationException();
}
@Override
public List lock(List objs, boolean keepAlive, LockedDriverState lDrvState) throws
LockException {
throw new UnsupportedOperationException();
}
/**
* Send a lock request to the metastore. This is intended for use by
* {@link DbTxnManager}.
* @param lock lock request
* @param isBlocking if true, will block until locks have been acquired
* @throws LockException
* @return the result of the lock attempt
*/
LockState lock(LockRequest lock, String queryId, boolean isBlocking, List acquiredLocks) throws LockException {
Objects.requireNonNull(queryId, "queryId cannot be null");
nextSleep = 50;
/*
* get from conf to pick up changes; make sure not to set too low and kill the metastore
* MAX_SLEEP is the max time each backoff() will wait for, thus the total time to wait for
* successful lock acquisition is approximately (see backoff()) maxNumWaits * MAX_SLEEP.
*/
MAX_SLEEP = Math.max(15000, conf.getTimeVar(HiveConf.ConfVars.HIVE_LOCK_SLEEP_BETWEEN_RETRIES, TimeUnit.MILLISECONDS));
int maxNumWaits = Math.max(0, conf.getIntVar(HiveConf.ConfVars.HIVE_LOCK_NUMRETRIES));
try {
LOG.info("Requesting: queryId=" + queryId + " " + lock);
LockResponse res = txnManager.getMS().lock(lock);
//link lockId to queryId
LOG.info("Response to queryId=" + queryId + " " + res);
if(!isBlocking) {
if(res.getState() == LockState.WAITING) {
return LockState.WAITING;
}
}
int numRetries = 0;
long startRetry = System.currentTimeMillis();
while (res.getState() == LockState.WAITING && numRetries++ < maxNumWaits) {
backoff();
res = txnManager.getMS().checkLock(res.getLockid());
}
long retryDuration = System.currentTimeMillis() - startRetry;
DbHiveLock hl = new DbHiveLock(res.getLockid(), queryId, lock.getTxnid());
if(locks.size() > 0) {
boolean logMsg = false;
for(DbHiveLock l : locks) {
if(l.txnId != hl.txnId) {
//locks from different transactions detected (or from transaction and read-only query in autocommit)
logMsg = true;
break;
}
else if(l.txnId == 0) {
if(!l.queryId.equals(hl.queryId)) {
//here means no open transaction, but different queries
logMsg = true;
break;
}
}
}
if(logMsg) {
LOG.warn("adding new DbHiveLock(" + hl + ") while we are already tracking locks: " + locks);
}
}
locks.add(hl);
if (res.getState() != LockState.ACQUIRED) {
if(res.getState() == LockState.WAITING) {
/**
* the {@link #unlock(HiveLock)} here is more about future proofing when support for
* multi-statement txns is added. In that case it's reasonable for the client
* to retry this part of txn or try something else w/o aborting the whole txn.
* Also for READ_COMMITTED (when and if that is supported).
*/
unlock(hl);//remove the locks in Waiting state
LockException le = new LockException(null, ErrorMsg.LOCK_ACQUIRE_TIMEDOUT,
lock.toString(), Long.toString(retryDuration), res.toString());
if(conf.getBoolVar(HiveConf.ConfVars.TXN_MGR_DUMP_LOCK_STATE_ON_ACQUIRE_TIMEOUT)) {
showLocksNewFormat(le.getMessage());
}
throw le;
}
throw new LockException(ErrorMsg.LOCK_CANNOT_BE_ACQUIRED.getMsg() + " " + res);
}
acquiredLocks.add(hl);
Metrics metrics = MetricsFactory.getInstance();
if (metrics != null) {
try {
metrics.incrementCounter(MetricsConstant.METASTORE_HIVE_LOCKS);
} catch (Exception e) {
LOG.warn("Error Reporting hive client metastore lock operation to Metrics system", e);
}
}
return res.getState();
} catch (NoSuchTxnException e) {
LOG.error("Metastore could not find " + JavaUtils.txnIdToString(lock.getTxnid()));
throw new LockException(e, ErrorMsg.TXN_NO_SUCH_TRANSACTION, JavaUtils.txnIdToString(lock.getTxnid()));
} catch (TxnAbortedException e) {
LockException le = new LockException(e, ErrorMsg.TXN_ABORTED, JavaUtils.txnIdToString(lock.getTxnid()), e.getMessage());
LOG.error(le.getMessage());
throw le;
} catch (TException e) {
throw new LockException(ErrorMsg.METASTORE_COMMUNICATION_FAILED.getMsg(),
e);
}
}
private void showLocksNewFormat(String preamble) throws LockException {
ShowLocksResponse rsp = getLocks();
// write the results in the file
ByteArrayOutputStream baos = new ByteArrayOutputStream(1024*2);
DataOutputStream os = new DataOutputStream(baos);
try {
DDLTask.dumpLockInfo(os, rsp);
os.flush();
LOG.info(baos.toString());
}
catch(IOException ex) {
LOG.error("Dumping lock info for " + preamble + " failed: " + ex.getMessage(), ex);
}
}
/**
* Used to make another attempt to acquire a lock (in Waiting state)
* @param extLockId
* @return result of the attempt
* @throws LockException
*/
LockState checkLock(long extLockId) throws LockException {
try {
return txnManager.getMS().checkLock(extLockId).getState();
} catch (TException e) {
throw new LockException(ErrorMsg.METASTORE_COMMUNICATION_FAILED.getMsg(),
e);
}
}
@Override
public void unlock(HiveLock hiveLock) throws LockException {
long lockId = ((DbHiveLock)hiveLock).lockId;
boolean removed = false;
try {
LOG.debug("Unlocking " + hiveLock);
txnManager.getMS().unlock(lockId);
//important to remove after unlock() in case it fails
removed = locks.remove(hiveLock);
Metrics metrics = MetricsFactory.getInstance();
if (metrics != null) {
try {
metrics.decrementCounter(MetricsConstant.METASTORE_HIVE_LOCKS);
} catch (Exception e) {
LOG.warn("Error Reporting hive client metastore unlock operation to Metrics system", e);
}
}
LOG.debug("Removed a lock " + removed);
} catch (NoSuchLockException e) {
//if metastore has no record of this lock, it most likely timed out; either way
//there is no point tracking it here any longer
removed = locks.remove(hiveLock);
LOG.error("Metastore could find no record of lock " + JavaUtils.lockIdToString(lockId));
throw new LockException(e, ErrorMsg.LOCK_NO_SUCH_LOCK, JavaUtils.lockIdToString(lockId));
} catch (TxnOpenException e) {
throw new RuntimeException("Attempt to unlock lock " + JavaUtils.lockIdToString(lockId) +
"associated with an open transaction, " + e.getMessage(), e);
} catch (TException e) {
throw new LockException(ErrorMsg.METASTORE_COMMUNICATION_FAILED.getMsg(),
e);
}
finally {
if(removed) {
LOG.debug("Removed a lock " + hiveLock);
}
}
}
@Override
public void releaseLocks(List hiveLocks) {
LOG.info("releaseLocks: " + hiveLocks);
for (HiveLock lock : hiveLocks) {
try {
unlock(lock);
} catch (LockException e) {
// Not sure why this method doesn't throw any exceptions,
// but since the interface doesn't allow it we'll just swallow them and
// move on.
//This OK-ish since releaseLocks() is only called for RO/AC queries; it
//would be really bad to eat exceptions here for write operations
}
}
}
@Override
public List getLocks(boolean verifyTablePartitions,
boolean fetchData) throws LockException {
return new ArrayList(locks);
}
@Override
public List getLocks(HiveLockObject key,
boolean verifyTablePartitions,
boolean fetchData) throws LockException {
throw new UnsupportedOperationException();
}
public ShowLocksResponse getLocks() throws LockException {
return getLocks(new ShowLocksRequest());
}
public ShowLocksResponse getLocks(ShowLocksRequest showLocksRequest) throws LockException {
try {
return txnManager.getMS().showLocks(showLocksRequest);
} catch (TException e) {
throw new LockException(ErrorMsg.METASTORE_COMMUNICATION_FAILED.getMsg(), e);
}
}
@Override
public void close() throws LockException {
for (HiveLock lock : locks) {
unlock(lock);
}
locks.clear();
}
@Override
public void prepareRetry() throws LockException {
// NOP
}
@Override
public void refresh() {
// NOP
}
static class DbHiveLock extends HiveLock {
long lockId;
String queryId;
long txnId;
DbHiveLock(long id) {
lockId = id;
}
DbHiveLock(long id, String queryId, long txnId) {
lockId = id;
this.queryId = queryId;
this.txnId = txnId;
}
@Override
public HiveLockObject getHiveLockObject() {
throw new UnsupportedOperationException();
}
@Override
public HiveLockMode getHiveLockMode() {
throw new UnsupportedOperationException();
}
@Override
public boolean equals(Object other) {
if (other instanceof DbHiveLock) {
return lockId == ((DbHiveLock)other).lockId;
} else {
return false;
}
}
@Override
public int hashCode() {
return (int)(lockId % Integer.MAX_VALUE);
}
@Override
public String toString() {
return JavaUtils.lockIdToString(lockId) + " queryId=" + queryId + " " + JavaUtils.txnIdToString(txnId);
}
}
/**
* Clear the memory of the locks in this object. This won't clear the locks from the database.
* It is for use with
* {@link #DbLockManager(HiveConf, DbTxnManager)} .commitTxn} and
* {@link #DbLockManager(HiveConf, DbTxnManager)} .rollbackTxn}.
*/
void clearLocalLockRecords() {
locks.clear();
}
// Sleep before we send checkLock again, but do it with a back off
// off so we don't sit and hammer the metastore in a tight loop
private void backoff() {
nextSleep *= 2;
if (nextSleep > MAX_SLEEP) nextSleep = MAX_SLEEP;
try {
Thread.sleep(nextSleep);
} catch (InterruptedException e) {
}
}
}
