/*
* Copyright 2012 Amazon.com, Inc. or its affiliates. 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.
* A copy of the License is located at
*
* http://aws.amazon.com/apache2.0
*
* 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.simpleworkflow.flow.worker;
import java.lang.management.ManagementFactory;
import java.util.Iterator;
import java.util.concurrent.TimeUnit;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import com.amazonaws.services.simpleworkflow.AmazonSimpleWorkflow;
import com.amazonaws.services.simpleworkflow.flow.common.WorkflowExecutionUtils;
import com.amazonaws.services.simpleworkflow.model.DecisionTask;
import com.amazonaws.services.simpleworkflow.model.PollForDecisionTaskRequest;
import com.amazonaws.services.simpleworkflow.model.RespondDecisionTaskCompletedRequest;
import com.amazonaws.services.simpleworkflow.model.TaskList;
public class DecisionTaskPoller implements TaskPoller {
private static final Log log = LogFactory.getLog(DecisionTaskPoller.class);
private static final Log decisionsLog = LogFactory.getLog(DecisionTaskPoller.class.getName() + ".decisions");
private class DecisionTaskIterator implements Iterator<DecisionTask> {
private final DecisionTask firstDecisionTask;
private DecisionTask next;
public DecisionTaskIterator() {
next = firstDecisionTask = poll(null);
}
@Override
public boolean hasNext() {
return next != null;
}
@Override
public DecisionTask next() {
if (!hasNext()) {
throw new IllegalStateException("hasNext() == false");
}
DecisionTask result = next;
if (next.getNextPageToken() == null) {
next = null;
}
else {
next = poll(next.getNextPageToken());
// Just to not keep around the history page
if (firstDecisionTask != result) {
firstDecisionTask.setEvents(null);
}
}
return result;
}
@Override
public void remove() {
throw new UnsupportedOperationException();
}
public DecisionTask getFirstDecisionTask() {
return firstDecisionTask;
}
}
private AmazonSimpleWorkflow service;
private String domain;
private String taskListToPoll;
private String identity;
private boolean validated;
private DecisionTaskHandler decisionTaskHandler;
public DecisionTaskPoller() {
identity = ManagementFactory.getRuntimeMXBean().getName();
}
public DecisionTaskPoller(AmazonSimpleWorkflow service, String domain, String taskListToPoll,
DecisionTaskHandler decisionTaskHandler) {
this.service = service;
this.domain = domain;
this.taskListToPoll = taskListToPoll;
this.decisionTaskHandler = decisionTaskHandler;
identity = ManagementFactory.getRuntimeMXBean().getName();
}
public String getIdentity() {
return identity;
}
public void setIdentity(String identity) {
validated = false;
this.identity = identity;
}
public AmazonSimpleWorkflow getService() {
return service;
}
public String getDomain() {
return domain;
}
public DecisionTaskHandler getDecisionTaskHandler() {
return decisionTaskHandler;
}
public void setDecisionTaskHandler(DecisionTaskHandler decisionTaskHandler) {
validated = false;
this.decisionTaskHandler = decisionTaskHandler;
}
public void setService(AmazonSimpleWorkflow service) {
validated = false;
this.service = service;
}
public void setDomain(String domain) {
this.domain = domain;
}
public String getTaskListToPoll() {
return taskListToPoll;
}
public void setTaskListToPoll(String pollTaskList) {
this.taskListToPoll = pollTaskList;
}
/**
* Poll for a task using {@link #getPollTimeoutInSeconds()}
*
* @param nextResultToken
*
* @return null if poll timed out
* @throws DeciderExecutorConfigurationException
*/
private DecisionTask poll(String nextResultToken) {
validate();
PollForDecisionTaskRequest pollRequest = new PollForDecisionTaskRequest();
pollRequest.setDomain(domain);
pollRequest.setIdentity(identity);
pollRequest.setNextPageToken(nextResultToken);
pollRequest.setTaskList(new TaskList().withName(taskListToPoll));
if (log.isDebugEnabled()) {
log.debug("poll request begin: " + pollRequest);
}
DecisionTask result = service.pollForDecisionTask(pollRequest);
if (log.isDebugEnabled()) {
log.debug("poll request returned decision task: workflowType=" + result.getWorkflowType() + ", workflowExecution="
+ result.getWorkflowExecution() + ", startedEventId=" + result.getStartedEventId() + ", previousStartedEventId=" + result.getPreviousStartedEventId());
}
if (result == null || result.getTaskToken() == null) {
return null;
}
return result;
}
/**
* Poll for a workflow task and call appropriate decider. This method might
* call the service multiple times to retrieve the whole history it it is
* paginated.
*
* @return true if task was polled and decided upon, false if poll timed out
* @throws Exception
* @throws DeciderConfigurationException
*/
@Override
public boolean pollAndProcessSingleTask() throws Exception {
DecisionTaskIterator tasks = null;
RespondDecisionTaskCompletedRequest taskCompletedRequest = null;
try {
tasks = new DecisionTaskIterator();
if (!tasks.hasNext()) {
return false;
}
taskCompletedRequest = decisionTaskHandler.handleDecisionTask(tasks);
if (decisionsLog.isTraceEnabled()) {
decisionsLog.trace(WorkflowExecutionUtils.prettyPrintDecisions(taskCompletedRequest.getDecisions()));
}
service.respondDecisionTaskCompleted(taskCompletedRequest);
}
catch (Exception e) {
if (tasks != null) {
DecisionTask firstTask = tasks.getFirstDecisionTask();
if (firstTask != null) {
if (log.isWarnEnabled()) {
log.warn("DecisionTask failure: taskId= " + firstTask.getStartedEventId() + ", workflowExecution="
+ firstTask.getWorkflowExecution(), e);
}
if (log.isDebugEnabled() && firstTask.getEvents() != null) {
log.debug("Failed taskId=" + firstTask.getStartedEventId() + " history: "
+ WorkflowExecutionUtils.prettyPrintHistory(firstTask.getEvents(), true));
}
}
if (taskCompletedRequest != null && decisionsLog.isWarnEnabled()) {
decisionsLog.warn("Failed taskId=" + firstTask.getStartedEventId() + " decisions="
+ WorkflowExecutionUtils.prettyPrintDecisions(taskCompletedRequest.getDecisions()));
}
}
throw e;
}
return true;
}
/**
* @param seconds
* @return
*/
private void validate() throws IllegalStateException {
if (validated) {
return;
}
checkFieldSet("decisionTaskHandler", decisionTaskHandler);
checkFieldSet("service", service);
checkFieldSet("identity", identity);
validated = true;
}
private void checkFieldSet(String fieldName, Object fieldValue) throws IllegalStateException {
if (fieldValue == null) {
throw new IllegalStateException("Required field " + fieldName + " is not set");
}
}
protected void checkFieldNotNegative(String fieldName, long fieldValue) throws IllegalStateException {
if (fieldValue < 0) {
throw new IllegalStateException("Field " + fieldName + " is negative");
}
}
@Override
public void shutdown() {
}
@Override
public void shutdownNow() {
}
@Override
public boolean awaitTermination(long left, TimeUnit milliseconds) throws InterruptedException {
//TODO: Waiting for all currently running pollAndProcessSingleTask to complete
return false;
}
}