1/* 2 * Copyright (C) 2011 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17package com.android.volley; 18 19import android.annotation.TargetApi; 20import android.net.TrafficStats; 21import android.os.Build; 22import android.os.Process; 23import android.os.SystemClock; 24 25import java.util.concurrent.BlockingQueue; 26 27/** 28 * Provides a thread for performing network dispatch from a queue of requests. 29 * 30 * Requests added to the specified queue are processed from the network via a 31 * specified {@link Network} interface. Responses are committed to cache, if 32 * eligible, using a specified {@link Cache} interface. Valid responses and 33 * errors are posted back to the caller via a {@link ResponseDelivery}. 34 */ 35public class NetworkDispatcher extends Thread { 36 /** The queue of requests to service. */ 37 private final BlockingQueue<Request<?>> mQueue; 38 /** The network interface for processing requests. */ 39 private final Network mNetwork; 40 /** The cache to write to. */ 41 private final Cache mCache; 42 /** For posting responses and errors. */ 43 private final ResponseDelivery mDelivery; 44 /** Used for telling us to die. */ 45 private volatile boolean mQuit = false; 46 47 /** 48 * Creates a new network dispatcher thread. You must call {@link #start()} 49 * in order to begin processing. 50 * 51 * @param queue Queue of incoming requests for triage 52 * @param network Network interface to use for performing requests 53 * @param cache Cache interface to use for writing responses to cache 54 * @param delivery Delivery interface to use for posting responses 55 */ 56 public NetworkDispatcher(BlockingQueue<Request<?>> queue, 57 Network network, Cache cache, 58 ResponseDelivery delivery) { 59 mQueue = queue; 60 mNetwork = network; 61 mCache = cache; 62 mDelivery = delivery; 63 } 64 65 /** 66 * Forces this dispatcher to quit immediately. If any requests are still in 67 * the queue, they are not guaranteed to be processed. 68 */ 69 public void quit() { 70 mQuit = true; 71 interrupt(); 72 } 73 74 @TargetApi(Build.VERSION_CODES.ICE_CREAM_SANDWICH) 75 private void addTrafficStatsTag(Request<?> request) { 76 // Tag the request (if API >= 14) 77 if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) { 78 TrafficStats.setThreadStatsTag(request.getTrafficStatsTag()); 79 } 80 } 81 82 @Override 83 public void run() { 84 Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND); 85 while (true) { 86 long startTimeMs = SystemClock.elapsedRealtime(); 87 Request<?> request; 88 try { 89 // Take a request from the queue. 90 request = mQueue.take(); 91 } catch (InterruptedException e) { 92 // We may have been interrupted because it was time to quit. 93 if (mQuit) { 94 return; 95 } 96 continue; 97 } 98 99 try { 100 request.addMarker("network-queue-take"); 101 102 // If the request was cancelled already, do not perform the 103 // network request. 104 if (request.isCanceled()) { 105 request.finish("network-discard-cancelled"); 106 continue; 107 } 108 109 addTrafficStatsTag(request); 110 111 // Perform the network request. 112 NetworkResponse networkResponse = mNetwork.performRequest(request); 113 request.addMarker("network-http-complete"); 114 115 // If the server returned 304 AND we delivered a response already, 116 // we're done -- don't deliver a second identical response. 117 if (networkResponse.notModified && request.hasHadResponseDelivered()) { 118 request.finish("not-modified"); 119 continue; 120 } 121 122 // Parse the response here on the worker thread. 123 Response<?> response = request.parseNetworkResponse(networkResponse); 124 request.addMarker("network-parse-complete"); 125 126 // Write to cache if applicable. 127 // TODO: Only update cache metadata instead of entire record for 304s. 128 if (request.shouldCache() && response.cacheEntry != null) { 129 mCache.put(request.getCacheKey(), response.cacheEntry); 130 request.addMarker("network-cache-written"); 131 } 132 133 // Post the response back. 134 request.markDelivered(); 135 mDelivery.postResponse(request, response); 136 } catch (VolleyError volleyError) { 137 volleyError.setNetworkTimeMs(SystemClock.elapsedRealtime() - startTimeMs); 138 parseAndDeliverNetworkError(request, volleyError); 139 } catch (Exception e) { 140 VolleyLog.e(e, "Unhandled exception %s", e.toString()); 141 VolleyError volleyError = new VolleyError(e); 142 volleyError.setNetworkTimeMs(SystemClock.elapsedRealtime() - startTimeMs); 143 mDelivery.postError(request, volleyError); 144 } 145 } 146 } 147 148 private void parseAndDeliverNetworkError(Request<?> request, VolleyError error) { 149 error = request.parseNetworkError(error); 150 mDelivery.postError(request, error); 151 } 152} 153