com.amazonaws.services.simpleworkflow.flow.worker.DecisionStateMachineBase Maven / Gradle / Ivy

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The Amazon Web Services SDK for Java provides Java APIs for building software on AWS' cost-effective, scalable, and reliable infrastructure products. The AWS Java SDK allows developers to code against APIs for all of Amazon's infrastructure web services (Amazon S3, Amazon EC2, Amazon SQS, Amazon Relational Database Service, Amazon AutoScaling, etc).
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/*
 * Copyright 2012-2014 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.util.ArrayList;
import java.util.List;

import com.amazonaws.services.simpleworkflow.model.HistoryEvent;

abstract class DecisionStateMachineBase implements DecisionStateMachine {

    protected DecisionState state = DecisionState.CREATED;

    protected List stateHistory = new ArrayList();

    private final DecisionId id;

    public DecisionStateMachineBase(DecisionId id) {
        this.id = id;
        stateHistory.add(state.toString());

    }

    /**
     * Used for unit testing.
     */
    protected DecisionStateMachineBase(DecisionId id, DecisionState state) {
        this.id = id;
        this.state = state;
        stateHistory.add(state.toString());
    }
    
    public DecisionState getState() {
        return state;
    }

    public DecisionId getId() {
        return id;
    }

    @Override
    public boolean isDone() {
        return state == DecisionState.COMPLETED || state == DecisionState.COMPLETED_AFTER_CANCELLATION_DECISION_SENT;
    }

    @Override
    public void handleDecisionTaskStartedEvent() {
        switch (state) {
        case CREATED:
            stateHistory.add("handleDecisionTaskStartedEvent");
            state = DecisionState.DECISION_SENT;
            stateHistory.add(state.toString());
            break;
        }
    }

    @Override
    public void cancel(Runnable immediateCancellationCallback) {
        stateHistory.add("cancel");
        switch (state) {
        case CREATED:
            state = DecisionState.COMPLETED;
            if (immediateCancellationCallback != null) {
                immediateCancellationCallback.run();
            }
            break;
        case DECISION_SENT:
            state = DecisionState.CANCELED_BEFORE_INITIATED;
            break;
        case INITIATED:
            state = DecisionState.CANCELED_AFTER_INITIATED;
            break;
        default:
            failStateTransition();
        }
        stateHistory.add(state.toString());
    }

    @Override
    public void handleInitiatedEvent(HistoryEvent event) {
        stateHistory.add("handleInitiatedEvent");
        switch (state) {
        case DECISION_SENT:
            state = DecisionState.INITIATED;
            break;
        case CANCELED_BEFORE_INITIATED:
            state = DecisionState.CANCELED_AFTER_INITIATED;
            break;
        default:
            failStateTransition();
        }
        stateHistory.add(state.toString());

    }

    @Override
    public void handleInitiationFailedEvent(HistoryEvent event) {
        stateHistory.add("handleInitiationFailedEvent");
        switch (state) {
        case DECISION_SENT:
        case CANCELED_BEFORE_INITIATED:
            state = DecisionState.COMPLETED;
            break;
        default:
            failStateTransition();
        }
        stateHistory.add(state.toString());

    }

    @Override
    public void handleStartedEvent(HistoryEvent event) {
        stateHistory.add("handleStartedEvent");
    }

    @Override
    public void handleCompletionEvent() {
        stateHistory.add("handleCompletionEvent");
        switch (state) {
        case CANCELED_AFTER_INITIATED:
        case INITIATED:
            state = DecisionState.COMPLETED;
            break;
        case CANCELLATION_DECISION_SENT:
            state = DecisionState.COMPLETED_AFTER_CANCELLATION_DECISION_SENT;
            break;
        default:
            failStateTransition();
        }
        stateHistory.add(state.toString());
    }

    @Override
    public void handleCancellationInitiatedEvent() {
        stateHistory.add("handleCancellationInitiatedEvent");
        switch (state) {
        case CANCELLATION_DECISION_SENT:
            // No state change
            break;
        default:
            failStateTransition();
        }
        stateHistory.add(state.toString());

    }

    @Override
    public void handleCancellationFailureEvent(HistoryEvent event) {
        stateHistory.add("handleCancellationFailureEvent");
        switch (state) {
        case COMPLETED_AFTER_CANCELLATION_DECISION_SENT:
            state = DecisionState.COMPLETED;
            break;
        default:
            failStateTransition();
        }
        stateHistory.add(state.toString());
    }

    @Override
    public void handleCancellationEvent() {
        stateHistory.add("handleCancellationEvent");
        switch (state) {
        case CANCELLATION_DECISION_SENT:
            state = DecisionState.COMPLETED;
            break;
        default:
            failStateTransition();
        }
        stateHistory.add(state.toString());

    }

    @Override
    public String toString() {
        return "DecisionStateMachineBase [id=" + id + ", state=" + state + ", isDone()=" + isDone() + ", stateHistory="
                + stateHistory + "]";
    }

    protected void failStateTransition() {
        throw new IllegalStateException("id=" + id + ", transitions=" + stateHistory);
    }

}