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/*
* Licensed 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 io.trino.execution.scheduler.faulttolerant;
import com.google.common.base.Stopwatch;
import com.google.common.base.Ticker;
import com.google.common.collect.HashMultimap;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.SetMultimap;
import com.google.common.util.concurrent.Futures;
import com.google.common.util.concurrent.ListenableFuture;
import com.google.common.util.concurrent.SettableFuture;
import com.google.errorprone.annotations.ThreadSafe;
import com.google.inject.Inject;
import io.airlift.log.Logger;
import io.airlift.units.DataSize;
import io.trino.Session;
import io.trino.execution.TaskId;
import io.trino.execution.scheduler.NodeSchedulerConfig;
import io.trino.memory.ClusterMemoryManager;
import io.trino.memory.MemoryInfo;
import io.trino.memory.MemoryManagerConfig;
import io.trino.metadata.InternalNode;
import io.trino.metadata.InternalNodeManager;
import io.trino.metadata.InternalNodeManager.NodesSnapshot;
import io.trino.spi.TrinoException;
import io.trino.spi.memory.MemoryPoolInfo;
import jakarta.annotation.PostConstruct;
import jakarta.annotation.PreDestroy;
import org.assertj.core.util.VisibleForTesting;
import java.time.Duration;
import java.util.Comparator;
import java.util.Deque;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import java.util.Set;
import java.util.concurrent.ConcurrentLinkedDeque;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ScheduledThreadPoolExecutor;
import java.util.concurrent.Semaphore;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.atomic.AtomicReference;
import java.util.function.Supplier;
import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkState;
import static com.google.common.collect.ImmutableList.toImmutableList;
import static com.google.common.collect.Sets.newConcurrentHashSet;
import static io.airlift.concurrent.Threads.daemonThreadsNamed;
import static io.trino.execution.scheduler.faulttolerant.TaskExecutionClass.EAGER_SPECULATIVE;
import static io.trino.execution.scheduler.faulttolerant.TaskExecutionClass.SPECULATIVE;
import static io.trino.execution.scheduler.faulttolerant.TaskExecutionClass.STANDARD;
import static io.trino.spi.StandardErrorCode.NO_NODES_AVAILABLE;
import static java.lang.Math.max;
import static java.lang.Thread.currentThread;
import static java.util.Comparator.comparing;
import static java.util.Objects.requireNonNull;
@ThreadSafe
public class BinPackingNodeAllocatorService
implements NodeAllocatorService, NodeAllocator
{
private static final Logger log = Logger.get(BinPackingNodeAllocatorService.class);
@VisibleForTesting
static final int PROCESS_PENDING_ACQUIRES_DELAY_SECONDS = 5;
private final InternalNodeManager nodeManager;
private final Supplier>> workerMemoryInfoSupplier;
private final ScheduledThreadPoolExecutor executor = new ScheduledThreadPoolExecutor(2, daemonThreadsNamed("bin-packing-node-allocator"));
private final AtomicBoolean started = new AtomicBoolean();
private final AtomicBoolean stopped = new AtomicBoolean();
private final Semaphore processSemaphore = new Semaphore(0);
private final AtomicReference> nodePoolMemoryInfos = new AtomicReference<>(ImmutableMap.of());
private final boolean scheduleOnCoordinator;
private final DataSize taskRuntimeMemoryEstimationOverhead;
private final DataSize eagerSpeculativeTasksNodeMemoryOvercommit;
private final Ticker ticker;
private final Deque pendingAcquires = new ConcurrentLinkedDeque<>();
private final Set fulfilledAcquires = newConcurrentHashSet();
private final Duration allowedNoMatchingNodePeriod;
@Inject
public BinPackingNodeAllocatorService(
InternalNodeManager nodeManager,
ClusterMemoryManager clusterMemoryManager,
NodeSchedulerConfig nodeSchedulerConfig,
MemoryManagerConfig memoryManagerConfig)
{
this(nodeManager,
clusterMemoryManager::getWorkerMemoryInfo,
nodeSchedulerConfig.isIncludeCoordinator(),
Duration.ofMillis(nodeSchedulerConfig.getAllowedNoMatchingNodePeriod().toMillis()),
memoryManagerConfig.getFaultTolerantExecutionTaskRuntimeMemoryEstimationOverhead(),
memoryManagerConfig.getFaultTolerantExecutionEagerSpeculativeTasksNodeMemoryOvercommit(),
Ticker.systemTicker());
}
@VisibleForTesting
BinPackingNodeAllocatorService(
InternalNodeManager nodeManager,
Supplier>> workerMemoryInfoSupplier,
boolean scheduleOnCoordinator,
Duration allowedNoMatchingNodePeriod,
DataSize taskRuntimeMemoryEstimationOverhead,
DataSize eagerSpeculativeTasksNodeMemoryOvercommit,
Ticker ticker)
{
this.nodeManager = requireNonNull(nodeManager, "nodeManager is null");
this.workerMemoryInfoSupplier = requireNonNull(workerMemoryInfoSupplier, "workerMemoryInfoSupplier is null");
this.scheduleOnCoordinator = scheduleOnCoordinator;
this.allowedNoMatchingNodePeriod = requireNonNull(allowedNoMatchingNodePeriod, "allowedNoMatchingNodePeriod is null");
this.taskRuntimeMemoryEstimationOverhead = requireNonNull(taskRuntimeMemoryEstimationOverhead, "taskRuntimeMemoryEstimationOverhead is null");
this.eagerSpeculativeTasksNodeMemoryOvercommit = eagerSpeculativeTasksNodeMemoryOvercommit;
this.ticker = requireNonNull(ticker, "ticker is null");
}
@PostConstruct
public void start()
{
if (started.compareAndSet(false, true)) {
executor.schedule(() -> {
while (!stopped.get()) {
try {
// pending acquires are processed when node is released (semaphore is bumped) and periodically (every couple seconds)
// in case node list in cluster have changed.
processSemaphore.tryAcquire(PROCESS_PENDING_ACQUIRES_DELAY_SECONDS, TimeUnit.SECONDS);
processSemaphore.drainPermits();
processPendingAcquires();
}
catch (InterruptedException e) {
currentThread().interrupt();
}
catch (Exception e) {
// ignore to avoid getting unscheduled
log.warn(e, "Error updating nodes");
}
}
}, 0, TimeUnit.SECONDS);
}
refreshNodePoolMemoryInfos();
executor.scheduleWithFixedDelay(() -> {
try {
refreshNodePoolMemoryInfos();
}
catch (Throwable e) {
// ignore to avoid getting unscheduled
log.error(e, "Unexpected error while refreshing node pool memory infos");
}
}, 1, 1, TimeUnit.SECONDS);
}
@PreDestroy
public void stop()
{
stopped.set(true);
executor.shutdownNow();
}
@VisibleForTesting
void refreshNodePoolMemoryInfos()
{
ImmutableMap.Builder newNodePoolMemoryInfos = ImmutableMap.builder();
Map> workerMemoryInfos = workerMemoryInfoSupplier.get();
long maxNodePoolSizeBytes = -1;
for (Map.Entry> entry : workerMemoryInfos.entrySet()) {
if (entry.getValue().isEmpty()) {
continue;
}
MemoryPoolInfo poolInfo = entry.getValue().get().getPool();
newNodePoolMemoryInfos.put(entry.getKey(), poolInfo);
maxNodePoolSizeBytes = Math.max(poolInfo.getMaxBytes(), maxNodePoolSizeBytes);
}
nodePoolMemoryInfos.set(newNodePoolMemoryInfos.buildOrThrow());
}
@VisibleForTesting
synchronized void processPendingAcquires()
{
// Process EAGER_SPECULATIVE first; it increases the chance that tasks which have potential to end query early get scheduled to worker nodes.
// Even though EAGER_SPECULATIVE tasks depend on upstream STANDARD tasks this logic will not lead to deadlock.
// When processing STANDARD acquires below, we will ignore EAGER_SPECULATIVE (and SPECULATIVE) tasks when assessing if node has enough resources for processing task.
processPendingAcquires(EAGER_SPECULATIVE);
processPendingAcquires(STANDARD);
boolean hasNonSpeculativePendingAcquires = pendingAcquires.stream().anyMatch(pendingAcquire -> !pendingAcquire.isSpeculative());
if (!hasNonSpeculativePendingAcquires) {
processPendingAcquires(SPECULATIVE);
}
}
private void processPendingAcquires(TaskExecutionClass executionClass)
{
// synchronized only for sake manual triggering in test code. In production code it should only be called by single thread
Iterator iterator = pendingAcquires.iterator();
BinPackingSimulation simulation = new BinPackingSimulation(
nodeManager.getActiveNodesSnapshot(),
nodePoolMemoryInfos.get(),
fulfilledAcquires,
scheduleOnCoordinator,
taskRuntimeMemoryEstimationOverhead,
executionClass == EAGER_SPECULATIVE ? eagerSpeculativeTasksNodeMemoryOvercommit : DataSize.ofBytes(0),
executionClass == STANDARD); // if we are processing non-speculative pending acquires we are ignoring speculative acquired ones
while (iterator.hasNext()) {
PendingAcquire pendingAcquire = iterator.next();
if (pendingAcquire.getFuture().isCancelled()) {
// request aborted
iterator.remove();
continue;
}
if (pendingAcquire.getExecutionClass() != executionClass) {
continue;
}
BinPackingSimulation.ReserveResult result = simulation.tryReserve(pendingAcquire);
switch (result.getStatus()) {
case RESERVED:
InternalNode reservedNode = result.getNode();
fulfilledAcquires.add(pendingAcquire.getLease());
pendingAcquire.getFuture().set(reservedNode);
if (pendingAcquire.getFuture().isCancelled()) {
// completing future was unsuccessful - request was cancelled in the meantime
fulfilledAcquires.remove(pendingAcquire.getLease());
// run once again when we are done
wakeupProcessPendingAcquires();
}
iterator.remove();
break;
case NONE_MATCHING:
Duration noMatchingNodePeriod = pendingAcquire.markNoMatchingNodeFound();
if (noMatchingNodePeriod.compareTo(allowedNoMatchingNodePeriod) <= 0) {
// wait some more time
break;
}
pendingAcquire.getFuture().setException(new TrinoException(NO_NODES_AVAILABLE, "No nodes available to run query"));
iterator.remove();
break;
case NOT_ENOUGH_RESOURCES_NOW:
pendingAcquire.resetNoMatchingNodeFound();
break; // nothing to be done
default:
throw new IllegalArgumentException("unknown status: " + result.getStatus());
}
}
}
private void wakeupProcessPendingAcquires()
{
processSemaphore.release();
}
@Override
public NodeAllocator getNodeAllocator(Session session)
{
return this;
}
@Override
public NodeLease acquire(NodeRequirements nodeRequirements, DataSize memoryRequirement, TaskExecutionClass executionClass)
{
BinPackingNodeLease nodeLease = new BinPackingNodeLease(memoryRequirement.toBytes(), executionClass);
PendingAcquire pendingAcquire = new PendingAcquire(nodeRequirements, nodeLease, ticker);
pendingAcquires.add(pendingAcquire);
wakeupProcessPendingAcquires();
return nodeLease;
}
@Override
public void close()
{
// nothing to do here. leases should be released by the calling party.
// TODO would be great to be able to validate if it actually happened but close() is called from SqlQueryScheduler code
// and that can be done before all leases are yet returned from running (soon to be failed) tasks.
}
private static class PendingAcquire
{
private final NodeRequirements nodeRequirements;
private final BinPackingNodeLease lease;
private final Stopwatch noMatchingNodeStopwatch;
private PendingAcquire(NodeRequirements nodeRequirements, BinPackingNodeLease lease, Ticker ticker)
{
this.nodeRequirements = requireNonNull(nodeRequirements, "nodeRequirements is null");
this.lease = requireNonNull(lease, "lease is null");
this.noMatchingNodeStopwatch = Stopwatch.createUnstarted(ticker);
}
public NodeRequirements getNodeRequirements()
{
return nodeRequirements;
}
public BinPackingNodeLease getLease()
{
return lease;
}
public SettableFuture getFuture()
{
return lease.getNodeSettableFuture();
}
public long getMemoryLease()
{
return lease.getMemoryLease();
}
public Duration markNoMatchingNodeFound()
{
if (!noMatchingNodeStopwatch.isRunning()) {
noMatchingNodeStopwatch.start();
}
return noMatchingNodeStopwatch.elapsed();
}
public void resetNoMatchingNodeFound()
{
noMatchingNodeStopwatch.reset();
}
public boolean isSpeculative()
{
return lease.isSpeculative();
}
public TaskExecutionClass getExecutionClass()
{
return lease.getExecutionClass();
}
}
private class BinPackingNodeLease
implements NodeAllocator.NodeLease
{
private final SettableFuture node = SettableFuture.create();
private final AtomicBoolean released = new AtomicBoolean();
private final AtomicLong memoryLease;
private final AtomicReference taskId = new AtomicReference<>();
private final AtomicReference executionClass;
private BinPackingNodeLease(long memoryLease, TaskExecutionClass executionClass)
{
this.memoryLease = new AtomicLong(memoryLease);
requireNonNull(executionClass, "executionClass is null");
this.executionClass = new AtomicReference<>(executionClass);
}
@Override
public ListenableFuture getNode()
{
return node;
}
InternalNode getAssignedNode()
{
try {
return Futures.getDone(node);
}
catch (ExecutionException e) {
throw new RuntimeException(e);
}
}
SettableFuture getNodeSettableFuture()
{
return node;
}
@Override
public void attachTaskId(TaskId taskId)
{
if (!this.taskId.compareAndSet(null, taskId)) {
throw new IllegalStateException("cannot attach taskId " + taskId + "; already attached to " + this.taskId.get());
}
}
@Override
public void setExecutionClass(TaskExecutionClass newExecutionClass)
{
TaskExecutionClass changedFrom = this.executionClass.getAndUpdate(oldExecutionClass -> {
checkArgument(oldExecutionClass.canTransitionTo(newExecutionClass), "cannot change execution class from %s to %s", oldExecutionClass, newExecutionClass);
return newExecutionClass;
});
if (changedFrom != newExecutionClass) {
wakeupProcessPendingAcquires();
}
}
public boolean isSpeculative()
{
return executionClass.get().isSpeculative();
}
public TaskExecutionClass getExecutionClass()
{
return executionClass.get();
}
public Optional getAttachedTaskId()
{
return Optional.ofNullable(this.taskId.get());
}
@Override
public void setMemoryRequirement(DataSize memoryRequirement)
{
long newBytes = memoryRequirement.toBytes();
long previousBytes = memoryLease.getAndSet(newBytes);
if (newBytes < previousBytes) {
wakeupProcessPendingAcquires();
}
}
public long getMemoryLease()
{
return memoryLease.get();
}
@Override
public void release()
{
if (released.compareAndSet(false, true)) {
node.cancel(true);
if (node.isDone() && !node.isCancelled()) {
checkState(fulfilledAcquires.remove(this), "node lease %s not found in fulfilledAcquires %s", this, fulfilledAcquires);
wakeupProcessPendingAcquires();
}
}
else {
throw new IllegalStateException("Node " + node + " already released");
}
}
}
private static class BinPackingSimulation
{
private final NodesSnapshot nodesSnapshot;
private final List allNodesSorted;
private final boolean ignoreAcquiredSpeculative;
private final Map nodesRemainingMemory;
private final Map nodesRemainingMemoryRuntimeAdjusted;
private final Map speculativeMemoryReserved;
private final Map nodeMemoryPoolInfos;
private final boolean scheduleOnCoordinator;
public BinPackingSimulation(
NodesSnapshot nodesSnapshot,
Map nodeMemoryPoolInfos,
Set fulfilledAcquires,
boolean scheduleOnCoordinator,
DataSize taskRuntimeMemoryEstimationOverhead,
DataSize nodeMemoryOvercommit,
boolean ignoreAcquiredSpeculative)
{
this.nodesSnapshot = requireNonNull(nodesSnapshot, "nodesSnapshot is null");
// use same node ordering for each simulation
this.allNodesSorted = nodesSnapshot.getAllNodes().stream()
.sorted(comparing(InternalNode::getNodeIdentifier))
.collect(toImmutableList());
this.ignoreAcquiredSpeculative = ignoreAcquiredSpeculative;
requireNonNull(nodeMemoryPoolInfos, "nodeMemoryPoolInfos is null");
this.nodeMemoryPoolInfos = ImmutableMap.copyOf(nodeMemoryPoolInfos);
this.scheduleOnCoordinator = scheduleOnCoordinator;
Map> realtimeTasksMemoryPerNode = new HashMap<>();
for (InternalNode node : nodesSnapshot.getAllNodes()) {
MemoryPoolInfo memoryPoolInfo = nodeMemoryPoolInfos.get(node.getNodeIdentifier());
if (memoryPoolInfo == null) {
realtimeTasksMemoryPerNode.put(node.getNodeIdentifier(), ImmutableMap.of());
continue;
}
realtimeTasksMemoryPerNode.put(node.getNodeIdentifier(), memoryPoolInfo.getTaskMemoryReservations());
}
Map preReservedMemory = new HashMap<>();
speculativeMemoryReserved = new HashMap<>();
SetMultimap fulfilledAcquiresByNode = HashMultimap.create();
for (BinPackingNodeLease fulfilledAcquire : fulfilledAcquires) {
InternalNode node = fulfilledAcquire.getAssignedNode();
long memoryLease = fulfilledAcquire.getMemoryLease();
if (ignoreAcquiredSpeculative && fulfilledAcquire.isSpeculative()) {
speculativeMemoryReserved.merge(node.getNodeIdentifier(), memoryLease, Long::sum);
}
else {
fulfilledAcquiresByNode.put(node.getNodeIdentifier(), fulfilledAcquire);
preReservedMemory.merge(node.getNodeIdentifier(), memoryLease, Long::sum);
}
}
nodesRemainingMemory = new HashMap<>();
for (InternalNode node : nodesSnapshot.getAllNodes()) {
MemoryPoolInfo memoryPoolInfo = nodeMemoryPoolInfos.get(node.getNodeIdentifier());
if (memoryPoolInfo == null) {
nodesRemainingMemory.put(node.getNodeIdentifier(), 0L);
continue;
}
long nodeReservedMemory = preReservedMemory.getOrDefault(node.getNodeIdentifier(), 0L);
nodesRemainingMemory.put(node.getNodeIdentifier(), max(memoryPoolInfo.getMaxBytes() + nodeMemoryOvercommit.toBytes() - nodeReservedMemory, 0L));
}
nodesRemainingMemoryRuntimeAdjusted = new HashMap<>();
for (InternalNode node : nodesSnapshot.getAllNodes()) {
MemoryPoolInfo memoryPoolInfo = nodeMemoryPoolInfos.get(node.getNodeIdentifier());
if (memoryPoolInfo == null) {
nodesRemainingMemoryRuntimeAdjusted.put(node.getNodeIdentifier(), 0L);
continue;
}
Map realtimeNodeMemory = realtimeTasksMemoryPerNode.get(node.getNodeIdentifier());
Set nodeFulfilledAcquires = fulfilledAcquiresByNode.get(node.getNodeIdentifier());
long nodeUsedMemoryRuntimeAdjusted = 0;
for (BinPackingNodeLease lease : nodeFulfilledAcquires) {
long realtimeTaskMemory = 0;
if (lease.getAttachedTaskId().isPresent()) {
realtimeTaskMemory = realtimeNodeMemory.getOrDefault(lease.getAttachedTaskId().get().toString(), 0L);
realtimeTaskMemory += taskRuntimeMemoryEstimationOverhead.toBytes();
}
long reservedTaskMemory = lease.getMemoryLease();
nodeUsedMemoryRuntimeAdjusted += max(realtimeTaskMemory, reservedTaskMemory);
}
// if globally reported memory usage of node is greater than computed one lets use that.
// it can be greater if there are tasks executed on cluster which do not have task retries enabled.
nodeUsedMemoryRuntimeAdjusted = max(nodeUsedMemoryRuntimeAdjusted, memoryPoolInfo.getReservedBytes());
nodesRemainingMemoryRuntimeAdjusted.put(node.getNodeIdentifier(), max(memoryPoolInfo.getMaxBytes() + nodeMemoryOvercommit.toBytes() - nodeUsedMemoryRuntimeAdjusted, 0L));
}
}
public ReserveResult tryReserve(PendingAcquire acquire)
{
NodeRequirements requirements = acquire.getNodeRequirements();
Optional> catalogNodes = requirements.getCatalogHandle().map(nodesSnapshot::getConnectorNodes);
List candidates = allNodesSorted.stream()
.filter(node -> catalogNodes.isEmpty() || catalogNodes.get().contains(node))
.filter(node -> {
// Allow using coordinator if explicitly requested
if (requirements.getAddresses().contains(node.getHostAndPort())) {
return true;
}
if (requirements.getAddresses().isEmpty()) {
return scheduleOnCoordinator || !node.isCoordinator();
}
return false;
})
.collect(toImmutableList());
if (candidates.isEmpty()) {
return ReserveResult.NONE_MATCHING;
}
Comparator comparator = comparing(node -> nodesRemainingMemoryRuntimeAdjusted.get(node.getNodeIdentifier()));
if (ignoreAcquiredSpeculative) {
comparator = resolveTiesWithSpeculativeMemory(comparator);
}
InternalNode selectedNode = candidates.stream()
.max(comparator)
.orElseThrow();
// result of acquire.getMemoryLease() can change; store memory as a variable, so we have consistent value through this method.
long memoryRequirements = acquire.getMemoryLease();
if (nodesRemainingMemoryRuntimeAdjusted.get(selectedNode.getNodeIdentifier()) >= memoryRequirements || isNodeEmpty(selectedNode.getNodeIdentifier())) {
// there is enough unreserved memory on the node
// OR
// there is not enough memory available on the node but the node is empty so we cannot to better anyway
// todo: currant logic does not handle heterogenous clusters best. There is a chance that there is a larger node in the cluster but
// with less memory available right now, hence that one was not selected as a candidate.
// mark memory reservation
subtractFromRemainingMemory(selectedNode.getNodeIdentifier(), memoryRequirements);
return ReserveResult.reserved(selectedNode);
}
// If selected node cannot be used right now, select best one ignoring runtime memory usage and reserve space there
// for later use. This is important from algorithm liveliness perspective. If we did not reserve space for a task which
// is too big to be scheduled right now, it could be starved by smaller tasks coming later.
Comparator fallbackComparator = comparing(node -> nodesRemainingMemory.get(node.getNodeIdentifier()));
if (ignoreAcquiredSpeculative) {
fallbackComparator = resolveTiesWithSpeculativeMemory(fallbackComparator);
}
InternalNode fallbackNode = candidates.stream()
.max(fallbackComparator)
.orElseThrow();
subtractFromRemainingMemory(fallbackNode.getNodeIdentifier(), memoryRequirements);
return ReserveResult.NOT_ENOUGH_RESOURCES_NOW;
}
private Comparator resolveTiesWithSpeculativeMemory(Comparator comparator)
{
return comparator.thenComparing(node -> -speculativeMemoryReserved.getOrDefault(node.getNodeIdentifier(), 0L));
}
private void subtractFromRemainingMemory(String nodeIdentifier, long memoryLease)
{
nodesRemainingMemoryRuntimeAdjusted.compute(
nodeIdentifier,
(key, free) -> max(free - memoryLease, 0));
nodesRemainingMemory.compute(
nodeIdentifier,
(key, free) -> max(free - memoryLease, 0));
}
private boolean isNodeEmpty(String nodeIdentifier)
{
return nodeMemoryPoolInfos.containsKey(nodeIdentifier)
&& nodesRemainingMemory.get(nodeIdentifier).equals(nodeMemoryPoolInfos.get(nodeIdentifier).getMaxBytes());
}
public enum ReservationStatus
{
NONE_MATCHING,
NOT_ENOUGH_RESOURCES_NOW,
RESERVED
}
public static class ReserveResult
{
public static final ReserveResult NONE_MATCHING = new ReserveResult(ReservationStatus.NONE_MATCHING, Optional.empty());
public static final ReserveResult NOT_ENOUGH_RESOURCES_NOW = new ReserveResult(ReservationStatus.NOT_ENOUGH_RESOURCES_NOW, Optional.empty());
public static ReserveResult reserved(InternalNode node)
{
return new ReserveResult(ReservationStatus.RESERVED, Optional.of(node));
}
private final ReservationStatus status;
private final Optional node;
private ReserveResult(ReservationStatus status, Optional node)
{
this.status = requireNonNull(status, "status is null");
this.node = requireNonNull(node, "node is null");
checkArgument(node.isPresent() == (status == ReservationStatus.RESERVED), "node must be set iff status is RESERVED");
}
public ReservationStatus getStatus()
{
return status;
}
public InternalNode getNode()
{
return node.orElseThrow(() -> new IllegalStateException("node not set"));
}
}
}
}
