Subversion Repositories SmartDukaan

/*

 * Copyright (C) 2011 The Android Open Source Project

 *

 * 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.android.volley;

import android.annotation.TargetApi;

import android.net.TrafficStats;

import android.os.Build;

import android.os.Process;

import android.os.SystemClock;

import java.util.concurrent.BlockingQueue;

/**

 * Provides a thread for performing network dispatch from a queue of requests.

 *

 * Requests added to the specified queue are processed from the network via a

 * specified {@link Network} interface. Responses are committed to cache, if

 * eligible, using a specified {@link Cache} interface. Valid responses and

 * errors are posted back to the caller via a {@link ResponseDelivery}.

 */

public class NetworkDispatcher extends Thread {

    /** The queue of requests to service. */

    private final BlockingQueue<Request<?>> mQueue;

    /** The network interface for processing requests. */

    private final Network mNetwork;

    /** The cache to write to. */

    private final Cache mCache;

    /** For posting responses and errors. */

    private final ResponseDelivery mDelivery;

    /** Used for telling us to die. */

    private volatile boolean mQuit = false;

    /**

     * Creates a new network dispatcher thread.  You must call {@link #start()}

     * in order to begin processing.

     *

     * @param queue Queue of incoming requests for triage

     * @param network Network interface to use for performing requests

     * @param cache Cache interface to use for writing responses to cache

     * @param delivery Delivery interface to use for posting responses

     */

    public NetworkDispatcher(BlockingQueue<Request<?>> queue,

            Network network, Cache cache,

            ResponseDelivery delivery) {

        mQueue = queue;

        mNetwork = network;

        mCache = cache;

        mDelivery = delivery;

    }

    /**

     * Forces this dispatcher to quit immediately.  If any requests are still in

     * the queue, they are not guaranteed to be processed.

     */

    public void quit() {

        mQuit = true;

        interrupt();

    }

    @TargetApi(Build.VERSION_CODES.ICE_CREAM_SANDWICH)

    private void addTrafficStatsTag(Request<?> request) {

        // Tag the request (if API >= 14)

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) {

            TrafficStats.setThreadStatsTag(request.getTrafficStatsTag());

        }

    }

    @Override

    public void run() {

        Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND);

        while (true) {

            long startTimeMs = SystemClock.elapsedRealtime();

            Request<?> request;

            try {

                // Take a request from the queue.

                request = mQueue.take();

            } catch (InterruptedException e) {

                // We may have been interrupted because it was time to quit.

                if (mQuit) {

                    return;

                }

                continue;

            }

            try {

                request.addMarker("network-queue-take");

                // If the request was cancelled already, do not perform the

                // network request.

                if (request.isCanceled()) {

                    request.finish("network-discard-cancelled");

                    continue;

                }

                addTrafficStatsTag(request);

                // Perform the network request.

                NetworkResponse networkResponse = mNetwork.performRequest(request);

                request.addMarker("network-http-complete");

                // If the server returned 304 AND we delivered a response already,

                // we're done -- don't deliver a second identical response.

                if (networkResponse.notModified && request.hasHadResponseDelivered()) {

                    request.finish("not-modified");

                    continue;

                }

                // Parse the response here on the worker thread.

                Response<?> response = request.parseNetworkResponse(networkResponse);

                request.addMarker("network-parse-complete");

                // Write to cache if applicable.

                // TODO: Only update cache metadata instead of entire record for 304s.

                if (request.shouldCache() && response.cacheEntry != null) {

                    mCache.put(request.getCacheKey(), response.cacheEntry);

                    request.addMarker("network-cache-written");

                }

                // Post the response back.

                request.markDelivered();

                mDelivery.postResponse(request, response);

            } catch (VolleyError volleyError) {

                volleyError.setNetworkTimeMs(SystemClock.elapsedRealtime() - startTimeMs);

                parseAndDeliverNetworkError(request, volleyError);

            } catch (Exception e) {

                VolleyLog.e(e, "Unhandled exception %s", e.toString());

                VolleyError volleyError = new VolleyError(e);

                volleyError.setNetworkTimeMs(SystemClock.elapsedRealtime() - startTimeMs);

                mDelivery.postError(request, volleyError);

            }

        }

    }

    private void parseAndDeliverNetworkError(Request<?> request, VolleyError error) {

        error = request.parseNetworkError(error);

        mDelivery.postError(request, error);

    }

}