com.threewks.thundr.deferred.DeferredTaskService.java Source code

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Here is the source code for com.threewks.thundr.deferred.DeferredTaskService.java

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/*
 * This file is a component of thundr, a software library from 3wks.
 * Read more: http://www.3wks.com.au/thundr
 * Copyright (C) 2013 3wks, <thundr@3wks.com.au>
 *
 * 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.threewks.thundr.deferred;

import java.util.List;

import org.apache.commons.lang3.exception.ExceptionUtils;

import com.threewks.thundr.deferred.provider.QueueProvider;
import com.threewks.thundr.deferred.serializer.JsonSerializer;
import com.threewks.thundr.deferred.serializer.TaskSerializer;
import com.threewks.thundr.deferred.task.DeferredTask;
import com.threewks.thundr.deferred.task.RetryableDeferredTask;
import com.threewks.thundr.logger.Logger;

public class DeferredTaskService {
    private final QueueProvider queueProvider;
    private final TaskSerializer serializer = new TaskSerializer(new JsonSerializer());

    public DeferredTaskService(QueueProvider queueProvider) {
        this.queueProvider = queueProvider;
    }

    public QueueProvider getQueueProvider() {
        return queueProvider;
    }

    public void defer(DeferredTask deferredTask) {
        String serialized = serializer.serialize(deferredTask);
        queueProvider.send(serialized);
    }

    public void processQueue() {
        List<String> messages = queueProvider.receive();
        for (String message : messages) {
            run(message);
        }
    }

    private void run(String message) {
        DeferredTask deferredTask = null;
        try {
            deferredTask = serializer.deserialize(message);
            deferredTask.run();
        } catch (ClassNotFoundException e) {
            String errorMessage = "Unable to deserialize task from queue. Class %s not found.";
            Logger.error(errorMessage, e.getMessage());
            throw new ThundrDeferredException(e, errorMessage, e.getMessage());
        } catch (Exception e) {
            Logger.error("Running deferred task failed. Cause: %s", ExceptionUtils.getStackTrace(e));
            if (deferredTask != null && deferredTask instanceof RetryableDeferredTask) {
                Logger.info("Task is retryable, attempting to schedule retry...", e.getMessage());
                attemptRetry(((RetryableDeferredTask) deferredTask));
            } else {
                Logger.warn("Task is not retryable. Giving up!");
                throw new ThundrDeferredException(e, "Running deferred task failed permanently. Reason: %s",
                        e.getMessage());
            }
        }
    }

    private void attemptRetry(RetryableDeferredTask task) {
        if (task.shouldRetry()) {
            Logger.info("Scheduling retry #%s for task.", task.retries() + 1);
            defer(task);
        } else {
            String message = "Max retries[%s] exceeded. Giving up!";
            Logger.error(message, task.maxRetries());
            throw new ThundrDeferredException(message, task.maxRetries());
        }
    }
}