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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.Arrays;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.function.Consumer;
import com.vmware.xenon.common.FactoryService;
import com.vmware.xenon.common.Operation;
import com.vmware.xenon.common.Service;
import com.vmware.xenon.common.ServiceStats.ServiceStat;
import com.vmware.xenon.common.ServiceSubscriptionState.ServiceSubscriber;
import com.vmware.xenon.common.TaskState;
import com.vmware.xenon.common.TaskState.TaskStage;
import com.vmware.xenon.common.Utils;
import com.vmware.xenon.services.common.TaskService.TaskServiceState;
/**
* Default implementation of a task factory service that handles indirect to direct task
* processing. The factory will special case a POST request to create a child task, that has
* taskInfo.isDirect=true. Using a subscription, it will delay completion of the POST,
* and only complete it when it receives a notification that the child task has reached a final
* state
*/
public class TaskFactoryService extends FactoryService {
public static final String STAT_NAME_ACTIVE_SUBSCRIPTION_COUNT = "subscriptionCount";
public TaskFactoryService(Class stateClass) {
super(stateClass);
}
@SuppressWarnings("unchecked")
public static FactoryService create(Class childServiceType,
ServiceOption... options) {
try {
Service s = childServiceType.newInstance();
Class childServiceDocumentType =
(Class) s.getStateType();
FactoryService fs = new TaskFactoryService(childServiceDocumentType) {
@Override
public Service createServiceInstance() throws Throwable {
return childServiceType.newInstance();
}
};
Arrays.stream(options).forEach(option -> fs.toggleOption(option, true));
return fs;
} catch (Exception e) {
Utils.logWarning("Failure creating factory for %s: %s", childServiceType,
Utils.toString(e));
return null;
}
}
@Override
public void handleRequest(Operation op, OperationProcessingStage opProcessingStage) {
opProcessingStage = OperationProcessingStage.EXECUTING_SERVICE_HANDLER;
boolean isIdempotentPut = (op.getAction() == Action.PUT) &&
op.hasPragmaDirective(Operation.PRAGMA_DIRECTIVE_POST_TO_PUT);
if (op.getAction() != Action.POST && !isIdempotentPut) {
super.handleRequest(op, opProcessingStage);
return;
}
if (!op.hasBody()) {
op.fail(new IllegalArgumentException("body is required"));
return;
}
TaskServiceState initState = (TaskServiceState) op.getBody(super.getStateType());
if (initState.taskInfo == null || !initState.taskInfo.isDirect) {
super.handleRequest(op, opProcessingStage);
return;
}
// handle only direct request from a client, not forwarded or replicated requests, to avoid
// duplicate processing
if (op.isFromReplication() || op.isForwarded()) {
super.handleRequest(op, opProcessingStage);
return;
}
handleDirectTaskPost(op, initState);
}
private void handleDirectTaskPost(Operation post, TaskServiceState initState) {
// Direct task handling. We want to keep the task service simple and unaware of the
// pending POST from the client. This keeps the child task a true finite state machine that
// can PATCH itself, etc
if (initState.taskInfo.stage == null) {
initState.taskInfo.stage = TaskStage.CREATED;
}
Operation clonedPost = post.clone();
clonedPost.setCompletion((o, e) -> {
if (e != null) {
post.setStatusCode(o.getStatusCode())
.setBodyNoCloning(o.getBodyRaw())
.fail(e);
return;
}
subscribeToChildTask(o, post);
});
clonedPost.setConnectionSharing(true);
super.handleRequest(clonedPost, OperationProcessingStage.EXECUTING_SERVICE_HANDLER);
}
private void subscribeToChildTask(Operation o, Operation post) {
// Its possible to unsubscribe multiple times given multiple notifications from a task
// in a terminal state. We need to fix up our *approximate* accounting of active subscriptions
ServiceStat st = getStat(STAT_NAME_ACTIVE_SUBSCRIPTION_COUNT);
if (st != null && st.latestValue < 0) {
setStat(STAT_NAME_ACTIVE_SUBSCRIPTION_COUNT, 0);
}
TaskServiceState initState = (TaskServiceState) o.getBody(super.getStateType());
Operation subscribe = Operation.createPost(this, initState.documentSelfLink)
.transferRefererFrom(post)
.setCompletion((so, e) -> {
if (e == null) {
adjustStat(STAT_NAME_ACTIVE_SUBSCRIPTION_COUNT, 1);
return;
}
post.setStatusCode(so.getStatusCode())
.setBodyNoCloning(so.getBodyRaw())
.fail(e);
});
AtomicBoolean taskComplete = new AtomicBoolean();
long expiration = initState.documentExpirationTimeMicros;
ServiceSubscriber sr = ServiceSubscriber.create(true).setUsePublicUri(true)
.setReplayState(true)
.setExpiration(expiration);
Consumer notifyC = (nOp) -> {
nOp.complete();
switch (nOp.getAction()) {
case PUT:
case PATCH:
TaskServiceState task = (TaskServiceState) nOp.getBody(super.getStateType());
if (task.taskInfo == null || TaskState.isInProgress(task.taskInfo)) {
return;
}
if (taskComplete.compareAndSet(false, true)) {
// task is in final state (failed, or completed), complete original post
post.setBodyNoCloning(task).complete();
stopInDirectTaskSubscription(subscribe, nOp.getUri());
}
return;
case DELETE:
if (Utils.getSystemNowMicrosUtc() >= expiration) {
// the task might have expired and self deleted, fail the client post
post.setStatusCode(Operation.STATUS_CODE_TIMEOUT)
.fail(new IllegalStateException("Task expired"));
stopInDirectTaskSubscription(subscribe, nOp.getUri());
} else {
// this is a self DELETE, the task is done
post.complete();
// subscription stop will happen on the PATCH/PUT for the terminal state
}
return;
default:
break;
}
};
// Only if this is an owner-selected service, we create a reliable subscription.
// Otherwise for non-replicated services, we just create a normal subscription.
if (this.hasChildOption(ServiceOption.OWNER_SELECTION)) {
ReliableSubscriptionService notificationTarget = ReliableSubscriptionService.create(
subscribe, sr, notifyC);
getHost().startSubscriptionService(subscribe, notificationTarget, sr);
} else {
getHost().startSubscriptionService(subscribe, notifyC, sr);
}
}
private void stopInDirectTaskSubscription(Operation sub, URI notificationTarget) {
getHost().stopSubscriptionService(
sub.clone().setAction(Action.DELETE).setCompletion((o, e) -> {
if (e != null) {
return;
}
adjustStat(STAT_NAME_ACTIVE_SUBSCRIPTION_COUNT, -1);
}), notificationTarget);
}
@Override
public Service createServiceInstance() throws Throwable {
return null;
}
}
