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/*
* Copyright (c) 2014-2015 VMware, Inc. All Rights Reserved.
*
* 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 com.vmware.xenon.services.common;
import java.net.URI;
import java.util.ArrayList;
import java.util.EnumSet;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import java.util.TreeMap;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
import com.vmware.xenon.common.Operation;
import com.vmware.xenon.common.Operation.CompletionHandler;
import com.vmware.xenon.common.Operation.OperationOption;
import com.vmware.xenon.common.Service;
import com.vmware.xenon.common.ServiceClient;
import com.vmware.xenon.common.ServiceDocument;
import com.vmware.xenon.common.ServiceDocument.DocumentRelationship;
import com.vmware.xenon.common.ServiceDocumentDescription;
import com.vmware.xenon.common.StatelessService;
import com.vmware.xenon.common.UriUtils;
import com.vmware.xenon.common.Utils;
public class NodeSelectorSynchronizationService extends StatelessService {
public static final String PROPERTY_NAME_SYNCHRONIZATION_LOGGING = Utils.PROPERTY_NAME_PREFIX
+ "NodeSelectorSynchronizationService.isDetailedLoggingEnabled";
public static class NodeGroupSynchronizationState extends ServiceDocument {
public Set inConflictLinks = new HashSet<>();
}
public static class SynchronizePeersRequest {
public static final String KIND = Utils.buildKind(SynchronizePeersRequest.class);
public static SynchronizePeersRequest create() {
SynchronizePeersRequest r = new SynchronizePeersRequest();
r.kind = KIND;
return r;
}
public String indexLink;
public ServiceDocument state;
public ServiceDocumentDescription stateDescription;
public EnumSet options;
public String factoryLink;
public String kind;
}
private Service parent;
private boolean isDetailedLoggingEnabled = Boolean
.getBoolean(PROPERTY_NAME_SYNCHRONIZATION_LOGGING);
public NodeSelectorSynchronizationService(Service parent) {
super(NodeGroupSynchronizationState.class);
super.toggleOption(ServiceOption.UTILITY, true);
this.parent = parent;
}
@Override
public void handleStart(Operation startPost) {
startPost.complete();
}
@Override
public void authorizeRequest(Operation op) {
op.complete();
}
@Override
public void handleRequest(Operation post) {
if (post.getAction() != Action.POST) {
post.fail(new IllegalArgumentException("Action not supported"));
return;
}
if (!post.hasBody()) {
post.fail(new IllegalArgumentException("Body is required"));
return;
}
SynchronizePeersRequest body = post.getBody(SynchronizePeersRequest.class);
if (body.kind == null) {
post.fail(new IllegalArgumentException("kind is required"));
return;
}
if (body.kind.equals(SynchronizePeersRequest.KIND)) {
handleSynchronizeRequest(post, body);
return;
}
post.fail(new IllegalArgumentException("kind is not supported: " + body.kind));
}
private void handleSynchronizeRequest(Operation post, SynchronizePeersRequest body) {
if (body.state == null) {
post.fail(new IllegalArgumentException("state is required"));
return;
}
if (body.state.documentSelfLink == null) {
post.fail(new IllegalArgumentException("state.documentSelfLink is required"));
return;
}
if (body.options == null || body.options.isEmpty()) {
post.fail(new IllegalArgumentException("options is required"));
return;
}
if (body.factoryLink == null || body.factoryLink.isEmpty()) {
post.fail(new IllegalArgumentException("factoryLink is required"));
return;
}
// we are going to broadcast a query (GET) to all peers, that should return
// a document with the specified self link
URI localQueryUri = UriUtils.buildDocumentQueryUri(
getHost(),
body.indexLink,
body.state.documentSelfLink,
false,
true,
body.options);
Operation remoteGet = Operation.createGet(localQueryUri)
.setReferer(getUri())
.setConnectionSharing(true)
.setConnectionTag(ServiceClient.CONNECTION_TAG_SYNCHRONIZATION)
.setExpiration(
Utils.fromNowMicrosUtc(NodeGroupService.PEER_REQUEST_TIMEOUT_MICROS))
.setCompletion((o, e) -> {
if (e != null) {
post.fail(e);
return;
}
NodeGroupBroadcastResponse rsp = o.getBody(NodeGroupBroadcastResponse.class);
handleBroadcastGetCompletion(rsp, post, body);
});
getHost().broadcastRequest(this.parent.getSelfLink(), body.state.documentSelfLink, true,
remoteGet);
}
private void handleBroadcastGetCompletion(NodeGroupBroadcastResponse rsp, Operation post,
SynchronizePeersRequest request) {
if (rsp.failures.size() > 0 && rsp.jsonResponses.isEmpty()) {
post.fail(new IllegalStateException("Failures received: " + Utils.toJsonHtml(rsp)));
return;
}
ServiceDocument bestPeerRsp = null;
TreeMap> syncRspsPerEpoch = new TreeMap<>();
Map peerStates = new HashMap<>();
for (Entry e : rsp.jsonResponses.entrySet()) {
ServiceDocument peerState = Utils.fromJson(e.getValue(),
request.state.getClass());
if (peerState.documentSelfLink == null
|| !peerState.documentSelfLink.equals(request.state.documentSelfLink)) {
logWarning("Invalid state from peer %s: %s", e.getKey(), e.getValue());
peerStates.put(e.getKey(), new ServiceDocument());
continue;
}
peerStates.put(e.getKey(), peerState);
if (peerState.documentEpoch == null) {
peerState.documentEpoch = 0L;
}
List statesForEpoch = syncRspsPerEpoch.get(peerState.documentEpoch);
if (statesForEpoch == null) {
statesForEpoch = new ArrayList<>();
syncRspsPerEpoch.put(peerState.documentEpoch, statesForEpoch);
}
statesForEpoch.add(peerState);
}
// As part of synchronization we need to detect what peer services do not have the best state.
// A peer might have been missing this service instance, or it might be unavailable. Either way,
// when we attempt to broadcast the best state, we will use this map to determine if a peer
// should receive the best state we found.
for (URI remotePeerService : rsp.receivers) {
if (peerStates.containsKey(remotePeerService)) {
continue;
}
if (this.isDetailedLoggingEnabled) {
logInfo("No peer response for %s from %s", request.state.documentSelfLink,
remotePeerService);
}
peerStates.put(remotePeerService, new ServiceDocument());
}
if (!syncRspsPerEpoch.isEmpty()) {
List statesForHighestEpoch = syncRspsPerEpoch.get(syncRspsPerEpoch
.lastKey());
long maxVersion = Long.MIN_VALUE;
for (ServiceDocument peerState : statesForHighestEpoch) {
if (peerState.documentVersion > maxVersion) {
bestPeerRsp = peerState;
maxVersion = peerState.documentVersion;
}
}
}
if (bestPeerRsp != null && bestPeerRsp.documentEpoch == null) {
bestPeerRsp.documentEpoch = 0L;
}
if (request.state.documentEpoch == null) {
request.state.documentEpoch = 0L;
}
EnumSet results = EnumSet.noneOf(DocumentRelationship.class);
if (bestPeerRsp == null) {
results.add(DocumentRelationship.PREFERRED);
} else if (request.state.documentEpoch.compareTo(bestPeerRsp.documentEpoch) > 0) {
// Local state is of higher epoch than all peers
results.add(DocumentRelationship.PREFERRED);
} else if (request.state.documentEpoch.equals(bestPeerRsp.documentEpoch)) {
// compare local state against peers only if they are in the same epoch
results = ServiceDocument.compare(request.state,
bestPeerRsp, request.stateDescription, Utils.getTimeComparisonEpsilonMicros());
}
if (bestPeerRsp == null && request.state.documentVersion == -1) {
// If we did not find any documents from peers for the provided self-link
// and the owner also did not provide a valid document, then we fail
// the request with 404 - NOT FOUND error.
// Note, documentVersion is set to -1 by the owner in
// ServiceSynchronizationTracker to indicate that the owner does not have
// a document for the self-link.
this.logWarning("Synch failed to find any documents for self-link %s",
request.state.documentSelfLink);
post.fail(Operation.STATUS_CODE_NOT_FOUND);
return;
}
if (results.contains(DocumentRelationship.IN_CONFLICT)) {
markServiceInConflict(request.state, bestPeerRsp);
// if we detect conflict, we will synchronize local service with selected peer state
} else if (results.contains(DocumentRelationship.PREFERRED)) {
// the local state is preferred
bestPeerRsp = request.state;
}
if (bestPeerRsp == null) {
bestPeerRsp = request.state;
}
if (bestPeerRsp.documentSelfLink == null
|| bestPeerRsp.documentVersion < 0
|| bestPeerRsp.documentEpoch == null
|| bestPeerRsp.documentEpoch < 0) {
post.fail(new IllegalStateException(
"Chosen state has invalid epoch or version: " + Utils.toJson(bestPeerRsp)));
return;
}
if (this.isDetailedLoggingEnabled) {
logInfo("Using best peer state %s", Utils.toJson(bestPeerRsp));
}
// Synchronization is always run from the owner node of the
// child-service. If the best state computed from peers does
// not mention the owner node as the owner, we increment the Epoch.
boolean incrementEpoch = (bestPeerRsp.documentOwner != null &&
!bestPeerRsp.documentOwner.equals(this.getHost().getId()));
bestPeerRsp.documentOwner = this.getHost().getId();
broadcastBestState(rsp.selectedNodes, peerStates, post, request, bestPeerRsp,
incrementEpoch);
}
private void broadcastBestState(Map selectedNodes,
Map peerStates,
Operation post, SynchronizePeersRequest request,
ServiceDocument bestPeerRsp,
boolean incrementEpoch) {
try {
post.setBodyNoCloning(null);
if (peerStates.isEmpty()) {
if (this.isDetailedLoggingEnabled) {
logInfo(") No peers available for %s", bestPeerRsp.documentSelfLink);
}
post.complete();
return;
}
final ServiceDocument bestState = bestPeerRsp;
boolean isServiceDeleted = Action.DELETE.toString().equals(
bestPeerRsp.documentUpdateAction);
if (isServiceDeleted) {
// The caller relies on the body being present to determine if a peer had a better
// state than local state. If the body is not present, it assumes all is OK, and proceeds
// with either service start, or completing pending requests. If we detect the state is
// deleted, we must set the body, so the caller aborts start, thus converging with peers
// that already have stopped this service
post.setBodyNoCloning(bestPeerRsp);
}
if (peerStates.isEmpty()) {
post.complete();
return;
}
AtomicInteger remaining = new AtomicInteger(peerStates.size());
CompletionHandler c = (o, e) -> {
int r = remaining.decrementAndGet();
if (e != null) {
logWarning("Peer update to %s:%d for %s failed with %s, remaining %d",
o.getUri().getHost(), o.getUri().getPort(),
bestPeerRsp.documentSelfLink,
e.toString(), r);
}
if (r != 0) {
return;
}
post.complete();
};
if (incrementEpoch) {
logInfo("Incrementing epoch from %d to %d for %s", bestPeerRsp.documentEpoch,
bestPeerRsp.documentEpoch + 1, bestPeerRsp.documentSelfLink);
bestPeerRsp.documentEpoch += 1;
bestPeerRsp.documentVersion++;
}
post.setBody(bestPeerRsp);
ServiceDocument clonedState = Utils.clone(bestPeerRsp);
for (Entry entry : peerStates.entrySet()) {
URI peer = entry.getKey();
ServiceDocument peerState = entry.getValue();
Operation peerOp = prepareSynchPostRequest(post, request, bestState,
isServiceDeleted, c, clonedState, peer);
boolean isVersionSame = ServiceDocument
.compare(bestPeerRsp, peerState, request.stateDescription, Utils.getTimeComparisonEpsilonMicros())
.contains(DocumentRelationship.EQUAL_VERSION);
if (!incrementEpoch && isVersionSame
&& bestPeerRsp.getClass().equals(peerState.getClass())
&& ServiceDocument.equals(request.stateDescription, bestPeerRsp, peerState)) {
skipSynchOrStartServiceOnPeer(peerOp, peerState.documentSelfLink, request);
continue;
}
if (this.isDetailedLoggingEnabled) {
logInfo("(remaining: %d) (last action: %s) Sending %s with best state for %s to %s (e:%d, v:%d)",
remaining.get(),
clonedState.documentUpdateAction,
peerOp.getAction(),
clonedState.documentSelfLink,
peerOp.getUri(),
clonedState.documentEpoch,
clonedState.documentVersion);
}
sendRequest(peerOp);
}
} catch (Exception e) {
logSevere(e);
post.fail(e);
}
}
/**
* The service state on the peer node is identical to best state. We should
* skip sending a synchronization POST, if the service is already started
*/
private void skipSynchOrStartServiceOnPeer(Operation peerOp, String link, SynchronizePeersRequest request) {
// If the service is an ON_DEMAND_LOAD service, we don't bother trying to
// start it on the peer host. It will get started on-demand when a request comes in.
if (request.options.contains(ServiceOption.ON_DEMAND_LOAD)) {
peerOp.complete();
return;
}
Operation checkGet = Operation.createGet(UriUtils.buildUri(peerOp.getUri(), link))
.addPragmaDirective(Operation.PRAGMA_DIRECTIVE_NO_FORWARDING)
.setConnectionSharing(true)
.setConnectionTag(ServiceClient.CONNECTION_TAG_SYNCHRONIZATION)
.setExpiration(Utils.fromNowMicrosUtc(TimeUnit.SECONDS.toMicros(2)))
.setCompletion((o, e) -> {
if (e == null) {
logInfo("Skipping %s , state identical with best state", o.getUri());
peerOp.complete();
return;
}
// service does not seem to exist, issue POST to start it
sendRequest(peerOp);
});
sendRequest(checkGet);
}
private Operation prepareSynchPostRequest(Operation post, SynchronizePeersRequest request,
final ServiceDocument bestState, boolean isServiceDeleted, CompletionHandler c,
ServiceDocument clonedState, URI peer) {
URI targetFactoryUri = UriUtils.buildUri(peer, request.factoryLink);
Operation peerOp = Operation.createPost(targetFactoryUri)
.transferRefererFrom(post)
.setCompletion(c);
peerOp.setRetryCount(0);
peerOp.setExpiration(
Utils.fromNowMicrosUtc(NodeGroupService.PEER_REQUEST_TIMEOUT_MICROS));
peerOp.toggleOption(OperationOption.CONNECTION_SHARING, true);
peerOp.setConnectionTag(ServiceClient.CONNECTION_TAG_SYNCHRONIZATION);
// Mark it as replicated so the remote factories do not try to replicate it again
peerOp.addPragmaDirective(Operation.PRAGMA_DIRECTIVE_REPLICATED);
// Request a version check to prevent restarting/recreating a service that might
// have been deleted
peerOp.addPragmaDirective(Operation.PRAGMA_DIRECTIVE_VERSION_CHECK);
// indicate this is a synchronization request.
peerOp.addPragmaDirective(Operation.PRAGMA_DIRECTIVE_SYNCH_PEER);
peerOp.addRequestHeader(Operation.REPLICATION_PHASE_HEADER,
Operation.REPLICATION_PHASE_COMMIT);
// must get started on peers, regardless if the index has it. Since only one node is doing
// synchronization, its responsible for starting the children on ALL nodes. If this is a synchronization
// due to a node joining or leaving and some peers have already started the service, the POST will
// automatically get converted to a PUT, if the factory is IDEMPOTENT. Otherwise, it will fail
clonedState.documentSelfLink = UriUtils.getLastPathSegment(bestState.documentSelfLink);
if (isServiceDeleted) {
peerOp.setAction(Action.DELETE);
// If this is a delete request, let's reset the uri to
// the actual documentSelfLink, both on the operation
// and the ServiceDocument.
peerOp.setUri(UriUtils.buildUri(peer, bestState.documentSelfLink));
clonedState.documentSelfLink = bestState.documentSelfLink;
}
peerOp.setBody(clonedState);
return peerOp;
}
private void markServiceInConflict(ServiceDocument state, ServiceDocument bestPeerRsp) {
logWarning("State in conflict. Local: %s, Among peers: %s",
Utils.toJsonHtml(state), Utils.toJsonHtml(bestPeerRsp));
}
}
