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/*
* Copyright 2012-2016 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Amazon Software License (the "License").
* You may not use this file except in compliance with the License.
* A copy of the License is located at
*
* http://aws.amazon.com/asl/
*
* or in the "license" file accompanying this file. This file 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.amazonaws.services.kinesis.leases.impl;
import java.util.Collection;
import java.util.Map;
import java.util.UUID;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.LinkedTransferQueue;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import com.amazonaws.services.kinesis.clientlibrary.lib.worker.KinesisClientLibConfiguration;
import com.amazonaws.services.kinesis.leases.exceptions.DependencyException;
import com.amazonaws.services.kinesis.leases.exceptions.InvalidStateException;
import com.amazonaws.services.kinesis.leases.exceptions.LeasingException;
import com.amazonaws.services.kinesis.leases.exceptions.ProvisionedThroughputException;
import com.amazonaws.services.kinesis.leases.interfaces.ILeaseManager;
import com.amazonaws.services.kinesis.leases.interfaces.ILeaseRenewer;
import com.amazonaws.services.kinesis.leases.interfaces.ILeaseTaker;
import com.amazonaws.services.kinesis.metrics.impl.LogMetricsFactory;
import com.amazonaws.services.kinesis.metrics.impl.MetricsHelper;
import com.amazonaws.services.kinesis.metrics.interfaces.IMetricsFactory;
import com.amazonaws.services.kinesis.metrics.interfaces.IMetricsScope;
import com.amazonaws.services.kinesis.metrics.interfaces.MetricsLevel;
import com.google.common.util.concurrent.ThreadFactoryBuilder;
/**
* LeaseCoordinator abstracts away LeaseTaker and LeaseRenewer from the application code that's using leasing. It owns
* the scheduling of the two previously mentioned components as well as informing LeaseRenewer when LeaseTaker takes new
* leases.
*
*/
public class LeaseCoordinator {
/*
* Name of the dimension used when setting worker identifier on IMetricsScopes. Exposed so that users of this class
* can easily create InterceptingMetricsFactories that rename this dimension to suit the destination metrics system.
*/
public static final String WORKER_IDENTIFIER_METRIC = "WorkerIdentifier";
private static final Log LOG = LogFactory.getLog(LeaseCoordinator.class);
// Time to wait for in-flight Runnables to finish when calling .stop();
private static final long STOP_WAIT_TIME_MILLIS = 2000L;
private static final int DEFAULT_MAX_LEASES_FOR_WORKER = Integer.MAX_VALUE;
private static final int DEFAULT_MAX_LEASES_TO_STEAL_AT_ONE_TIME = 1;
private static final ThreadFactory LEASE_COORDINATOR_THREAD_FACTORY = new ThreadFactoryBuilder()
.setNameFormat("LeaseCoordinator-%04d").setDaemon(true).build();
private static final ThreadFactory LEASE_RENEWAL_THREAD_FACTORY = new ThreadFactoryBuilder()
.setNameFormat("LeaseRenewer-%04d").setDaemon(true).build();
private final ILeaseRenewer leaseRenewer;
private final ILeaseTaker leaseTaker;
private final long renewerIntervalMillis;
private final long takerIntervalMillis;
private final Object shutdownLock = new Object();
protected final IMetricsFactory metricsFactory;
private ScheduledExecutorService leaseCoordinatorThreadPool;
private final ExecutorService leaseRenewalThreadpool;
private volatile boolean running = false;
private ScheduledFuture takerFuture;
/**
* Constructor.
*
* @param leaseManager LeaseManager instance to use
* @param workerIdentifier Identifies the worker (e.g. useful to track lease ownership)
* @param leaseDurationMillis Duration of a lease
* @param epsilonMillis Allow for some variance when calculating lease expirations
*/
public LeaseCoordinator(ILeaseManager leaseManager,
String workerIdentifier,
long leaseDurationMillis,
long epsilonMillis) {
this(leaseManager, workerIdentifier, leaseDurationMillis, epsilonMillis, new LogMetricsFactory());
}
/**
* Constructor.
*
* @param leaseManager LeaseManager instance to use
* @param workerIdentifier Identifies the worker (e.g. useful to track lease ownership)
* @param leaseDurationMillis Duration of a lease
* @param epsilonMillis Allow for some variance when calculating lease expirations
* @param metricsFactory Used to publish metrics about lease operations
*/
public LeaseCoordinator(ILeaseManager leaseManager,
String workerIdentifier,
long leaseDurationMillis,
long epsilonMillis,
IMetricsFactory metricsFactory) {
this(leaseManager, workerIdentifier, leaseDurationMillis, epsilonMillis,
DEFAULT_MAX_LEASES_FOR_WORKER, DEFAULT_MAX_LEASES_TO_STEAL_AT_ONE_TIME,
KinesisClientLibConfiguration.DEFAULT_MAX_LEASE_RENEWAL_THREADS, metricsFactory);
}
/**
* Constructor.
*
* @param leaseManager LeaseManager instance to use
* @param workerIdentifier Identifies the worker (e.g. useful to track lease ownership)
* @param leaseDurationMillis Duration of a lease
* @param epsilonMillis Allow for some variance when calculating lease expirations
* @param maxLeasesForWorker Max leases this Worker can handle at a time
* @param maxLeasesToStealAtOneTime Steal up to these many leases at a time (for load balancing)
* @param metricsFactory Used to publish metrics about lease operations
*/
public LeaseCoordinator(ILeaseManager leaseManager,
String workerIdentifier,
long leaseDurationMillis,
long epsilonMillis,
int maxLeasesForWorker,
int maxLeasesToStealAtOneTime,
int maxLeaseRenewerThreadCount,
IMetricsFactory metricsFactory) {
this.leaseRenewalThreadpool = getLeaseRenewalExecutorService(maxLeaseRenewerThreadCount);
this.leaseTaker = new LeaseTaker(leaseManager, workerIdentifier, leaseDurationMillis)
.withMaxLeasesForWorker(maxLeasesForWorker)
.withMaxLeasesToStealAtOneTime(maxLeasesToStealAtOneTime);
this.leaseRenewer = new LeaseRenewer(
leaseManager, workerIdentifier, leaseDurationMillis, leaseRenewalThreadpool);
this.renewerIntervalMillis = leaseDurationMillis / 3 - epsilonMillis;
this.takerIntervalMillis = (leaseDurationMillis + epsilonMillis) * 2;
this.metricsFactory = metricsFactory;
LOG.info(String.format(
"With failover time %d ms and epsilon %d ms, LeaseCoordinator will renew leases every %d ms, take" +
"leases every %d ms, process maximum of %d leases and steal %d lease(s) at a time.",
leaseDurationMillis,
epsilonMillis,
renewerIntervalMillis,
takerIntervalMillis,
maxLeasesForWorker,
maxLeasesToStealAtOneTime));
}
private class TakerRunnable implements Runnable {
@Override
public void run() {
try {
runTaker();
} catch (LeasingException e) {
LOG.error("LeasingException encountered in lease taking thread", e);
} catch (Throwable t) {
LOG.error("Throwable encountered in lease taking thread", t);
}
}
}
private class RenewerRunnable implements Runnable {
@Override
public void run() {
try {
runRenewer();
} catch (LeasingException e) {
LOG.error("LeasingException encountered in lease renewing thread", e);
} catch (Throwable t) {
LOG.error("Throwable encountered in lease renewing thread", t);
}
}
}
/**
* Start background LeaseHolder and LeaseTaker threads.
* @throws ProvisionedThroughputException If we can't talk to DynamoDB due to insufficient capacity.
* @throws InvalidStateException If the lease table doesn't exist
* @throws DependencyException If we encountered exception taking to DynamoDB
*/
public void start() throws DependencyException, InvalidStateException, ProvisionedThroughputException {
leaseRenewer.initialize();
// 2 because we know we'll have at most 2 concurrent tasks at a time.
leaseCoordinatorThreadPool = Executors.newScheduledThreadPool(2, LEASE_COORDINATOR_THREAD_FACTORY);
// Taker runs with fixed DELAY because we want it to run slower in the event of performance degredation.
takerFuture = leaseCoordinatorThreadPool.scheduleWithFixedDelay(new TakerRunnable(),
0L,
takerIntervalMillis,
TimeUnit.MILLISECONDS);
// Renewer runs at fixed INTERVAL because we want it to run at the same rate in the event of degredation.
leaseCoordinatorThreadPool.scheduleAtFixedRate(new RenewerRunnable(),
0L,
renewerIntervalMillis,
TimeUnit.MILLISECONDS);
running = true;
}
/**
* Runs a single iteration of the lease taker - used by integration tests.
*
* @throws InvalidStateException
* @throws DependencyException
*/
protected void runTaker() throws DependencyException, InvalidStateException {
IMetricsScope scope = MetricsHelper.startScope(metricsFactory, "TakeLeases");
long startTime = System.currentTimeMillis();
boolean success = false;
try {
Map takenLeases = leaseTaker.takeLeases();
// Only add taken leases to renewer if coordinator is still running.
synchronized (shutdownLock) {
if (running) {
leaseRenewer.addLeasesToRenew(takenLeases.values());
}
}
success = true;
} finally {
scope.addDimension(WORKER_IDENTIFIER_METRIC, getWorkerIdentifier());
MetricsHelper.addSuccessAndLatency(startTime, success, MetricsLevel.SUMMARY);
MetricsHelper.endScope();
}
}
/**
* Runs a single iteration of the lease renewer - used by integration tests.
*
* @throws InvalidStateException
* @throws DependencyException
*/
protected void runRenewer() throws DependencyException, InvalidStateException {
IMetricsScope scope = MetricsHelper.startScope(metricsFactory, "RenewAllLeases");
long startTime = System.currentTimeMillis();
boolean success = false;
try {
leaseRenewer.renewLeases();
success = true;
} finally {
scope.addDimension(WORKER_IDENTIFIER_METRIC, getWorkerIdentifier());
MetricsHelper.addSuccessAndLatency(startTime, success, MetricsLevel.SUMMARY);
MetricsHelper.endScope();
}
}
/**
* @return currently held leases
*/
public Collection getAssignments() {
return leaseRenewer.getCurrentlyHeldLeases().values();
}
/**
* @param leaseKey lease key to fetch currently held lease for
*
* @return deep copy of currently held Lease for given key, or null if we don't hold the lease for that key
*/
public T getCurrentlyHeldLease(String leaseKey) {
return leaseRenewer.getCurrentlyHeldLease(leaseKey);
}
/**
* @return workerIdentifier
*/
public String getWorkerIdentifier() {
return leaseTaker.getWorkerIdentifier();
}
/**
* Stops background threads and waits for {@link #STOP_WAIT_TIME_MILLIS} for all background tasks to complete.
* If tasks are not completed after this time, method will shutdown thread pool forcefully and return.
*/
public void stop() {
if (leaseCoordinatorThreadPool != null) {
leaseCoordinatorThreadPool.shutdown();
try {
if (leaseCoordinatorThreadPool.awaitTermination(STOP_WAIT_TIME_MILLIS, TimeUnit.MILLISECONDS)) {
LOG.info(String.format("Worker %s has successfully stopped lease-tracking threads",
leaseTaker.getWorkerIdentifier()));
} else {
leaseCoordinatorThreadPool.shutdownNow();
LOG.info(String.format("Worker %s stopped lease-tracking threads %dms after stop",
leaseTaker.getWorkerIdentifier(),
STOP_WAIT_TIME_MILLIS));
}
} catch (InterruptedException e) {
LOG.debug("Encountered InterruptedException when awaiting threadpool termination");
}
} else {
LOG.debug("Threadpool was null, no need to shutdown/terminate threadpool.");
}
leaseRenewalThreadpool.shutdownNow();
synchronized (shutdownLock) {
leaseRenewer.clearCurrentlyHeldLeases();
running = false;
}
}
/**
* Requests the cancellation of the lease taker.
*/
public void stopLeaseTaker() {
takerFuture.cancel(false);
}
/**
* Requests that renewals for the given lease are stopped.
*
* @param lease the lease to stop renewing.
*/
public void dropLease(T lease) {
synchronized (shutdownLock) {
if (lease != null) {
leaseRenewer.dropLease(lease);
}
}
}
/**
* @return true if this LeaseCoordinator is running
*/
public boolean isRunning() {
return running;
}
/**
* Updates application-specific lease values in DynamoDB.
*
* @param lease lease object containing updated values
* @param concurrencyToken obtained by calling Lease.getConcurrencyToken for a currently held lease
*
* @return true if update succeeded, false otherwise
*
* @throws InvalidStateException if lease table does not exist
* @throws ProvisionedThroughputException if DynamoDB update fails due to lack of capacity
* @throws DependencyException if DynamoDB update fails in an unexpected way
*/
public boolean updateLease(T lease, UUID concurrencyToken)
throws DependencyException, InvalidStateException, ProvisionedThroughputException {
return leaseRenewer.updateLease(lease, concurrencyToken);
}
/**
* Returns executor service that should be used for lease renewal.
* @param maximumPoolSize Maximum allowed thread pool size
* @return Executor service that should be used for lease renewal.
*/
private static ExecutorService getLeaseRenewalExecutorService(int maximumPoolSize) {
int coreLeaseCount = Math.max(maximumPoolSize / 4, 2);
return new ThreadPoolExecutor(coreLeaseCount, maximumPoolSize, 60, TimeUnit.SECONDS,
new LinkedTransferQueue(), LEASE_RENEWAL_THREAD_FACTORY);
}
}
