Jean-Baptiste Queru | d56b88a | 2012-11-07 07:48:57 -0800 | [diff] [blame^] | 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 | |
| 17 | package com.android.volley; |
| 18 | |
| 19 | import android.os.Handler; |
| 20 | import android.os.Looper; |
| 21 | |
| 22 | import java.util.ArrayList; |
| 23 | import java.util.HashMap; |
| 24 | import java.util.HashSet; |
| 25 | import java.util.LinkedList; |
| 26 | import java.util.List; |
| 27 | import java.util.Map; |
| 28 | import java.util.Queue; |
| 29 | import java.util.Set; |
| 30 | import java.util.concurrent.PriorityBlockingQueue; |
| 31 | import java.util.concurrent.atomic.AtomicInteger; |
| 32 | |
| 33 | /** |
| 34 | * A request dispatch queue with a thread pool of dispatchers. |
| 35 | * |
| 36 | * Calling {@link #add(Request)} will enqueue the given Request for dispatch, |
| 37 | * resolving from either cache or network on a worker thread, and then delivering |
| 38 | * a parsed response on the main thread. |
| 39 | */ |
| 40 | @SuppressWarnings("rawtypes") |
| 41 | public class RequestQueue { |
| 42 | |
| 43 | /** Used for generating monotonically-increasing sequence numbers for requests. */ |
| 44 | private static AtomicInteger sSequenceGenerator = new AtomicInteger(); |
| 45 | |
| 46 | /** |
| 47 | * Staging area for requests that already have a duplicate request in flight. |
| 48 | * |
| 49 | * <ul> |
| 50 | * <li>containsKey(cacheKey) indicates that there is a request in flight for the given cache |
| 51 | * key.</li> |
| 52 | * <li>get(cacheKey) returns waiting requests for the given cache key. The in flight request |
| 53 | * is <em>not</em> contained in that list. Is null if no requests are staged.</li> |
| 54 | * </ul> |
| 55 | */ |
| 56 | private final Map<String, Queue<Request>> mWaitingRequests = |
| 57 | new HashMap<String, Queue<Request>>(); |
| 58 | |
| 59 | /** |
| 60 | * The set of all requests currently being processed by this RequestQueue. A Request |
| 61 | * will be in this set if it is waiting in any queue or currently being processed by |
| 62 | * any dispatcher. |
| 63 | */ |
| 64 | private final Set<Request> mCurrentRequests = new HashSet<Request>(); |
| 65 | |
| 66 | /** The cache triage queue. */ |
| 67 | private final PriorityBlockingQueue<Request> mCacheQueue = |
| 68 | new PriorityBlockingQueue<Request>(); |
| 69 | |
| 70 | /** The queue of requests that are actually going out to the network. */ |
| 71 | private final PriorityBlockingQueue<Request> mNetworkQueue = |
| 72 | new PriorityBlockingQueue<Request>(); |
| 73 | |
| 74 | /** Number of network request dispatcher threads to start. */ |
| 75 | private static final int DEFAULT_NETWORK_THREAD_POOL_SIZE = 4; |
| 76 | |
| 77 | /** Cache interface for retrieving and storing respones. */ |
| 78 | private final Cache mCache; |
| 79 | |
| 80 | /** Network interface for performing requests. */ |
| 81 | private final Network mNetwork; |
| 82 | |
| 83 | /** Response delivery mechanism. */ |
| 84 | private final ResponseDelivery mDelivery; |
| 85 | |
| 86 | /** The network dispatchers. */ |
| 87 | private NetworkDispatcher[] mDispatchers; |
| 88 | |
| 89 | /** The cache dispatcher. */ |
| 90 | private CacheDispatcher mCacheDispatcher; |
| 91 | |
| 92 | /** |
| 93 | * Creates the worker pool. Processing will not begin until {@link #start()} is called. |
| 94 | * |
| 95 | * @param cache A Cache to use for persisting responses to disk |
| 96 | * @param network A Network interface for performing HTTP requests |
| 97 | * @param threadPoolSize Number of network dispatcher threads to create |
| 98 | * @param delivery A ResponseDelivery interface for posting responses and errors |
| 99 | */ |
| 100 | public RequestQueue(Cache cache, Network network, int threadPoolSize, |
| 101 | ResponseDelivery delivery) { |
| 102 | mCache = cache; |
| 103 | mNetwork = network; |
| 104 | mDispatchers = new NetworkDispatcher[threadPoolSize]; |
| 105 | mDelivery = delivery; |
| 106 | } |
| 107 | |
| 108 | /** |
| 109 | * Creates the worker pool. Processing will not begin until {@link #start()} is called. |
| 110 | * |
| 111 | * @param cache A Cache to use for persisting responses to disk |
| 112 | * @param network A Network interface for performing HTTP requests |
| 113 | * @param threadPoolSize Number of network dispatcher threads to create |
| 114 | */ |
| 115 | public RequestQueue(Cache cache, Network network, int threadPoolSize) { |
| 116 | this(cache, network, threadPoolSize, |
| 117 | new ExecutorDelivery(new Handler(Looper.getMainLooper()))); |
| 118 | } |
| 119 | |
| 120 | /** |
| 121 | * Creates the worker pool. Processing will not begin until {@link #start()} is called. |
| 122 | * |
| 123 | * @param cache A Cache to use for persisting responses to disk |
| 124 | * @param network A Network interface for performing HTTP requests |
| 125 | */ |
| 126 | public RequestQueue(Cache cache, Network network) { |
| 127 | this(cache, network, DEFAULT_NETWORK_THREAD_POOL_SIZE); |
| 128 | } |
| 129 | |
| 130 | /** |
| 131 | * Starts the dispatchers in this queue. |
| 132 | */ |
| 133 | public void start() { |
| 134 | stop(); // Make sure any currently running dispatchers are stopped. |
| 135 | // Create the cache dispatcher and start it. |
| 136 | mCacheDispatcher = new CacheDispatcher(mCacheQueue, mNetworkQueue, mCache, mDelivery); |
| 137 | mCacheDispatcher.start(); |
| 138 | |
| 139 | // Create network dispatchers (and corresponding threads) up to the pool size. |
| 140 | for (int i = 0; i < mDispatchers.length; i++) { |
| 141 | NetworkDispatcher networkDispatcher = new NetworkDispatcher(mNetworkQueue, mNetwork, |
| 142 | mCache, mDelivery); |
| 143 | mDispatchers[i] = networkDispatcher; |
| 144 | networkDispatcher.start(); |
| 145 | } |
| 146 | } |
| 147 | |
| 148 | /** |
| 149 | * Stops the cache and network dispatchers. |
| 150 | */ |
| 151 | public void stop() { |
| 152 | if (mCacheDispatcher != null) { |
| 153 | mCacheDispatcher.quit(); |
| 154 | } |
| 155 | for (int i = 0; i < mDispatchers.length; i++) { |
| 156 | if (mDispatchers[i] != null) { |
| 157 | mDispatchers[i].quit(); |
| 158 | } |
| 159 | } |
| 160 | } |
| 161 | |
| 162 | /** |
| 163 | * Gets a sequence number. |
| 164 | */ |
| 165 | public static int getSequenceNumber() { |
| 166 | return sSequenceGenerator.incrementAndGet(); |
| 167 | } |
| 168 | |
| 169 | /** |
| 170 | * A simple predicate or filter interface for Requests, for use by |
| 171 | * {@link RequestQueue#cancelAll(RequestFilter)}. |
| 172 | */ |
| 173 | public interface RequestFilter { |
| 174 | public boolean apply(Request<?> request); |
| 175 | } |
| 176 | |
| 177 | /** |
| 178 | * Cancels all requests in this queue for which the given filter applies. |
| 179 | * @param filter The filtering function to use |
| 180 | */ |
| 181 | public void cancelAll(RequestFilter filter) { |
| 182 | synchronized (mCurrentRequests) { |
| 183 | for (Request<?> request : mCurrentRequests) { |
| 184 | if (filter.apply(request)) { |
| 185 | request.cancel(); |
| 186 | } |
| 187 | } |
| 188 | } |
| 189 | } |
| 190 | |
| 191 | /** |
| 192 | * Cancels all requests in this queue with the given tag. Tag must be non-null |
| 193 | * and equality is by identity. |
| 194 | */ |
| 195 | public void cancelAll(final Object tag) { |
| 196 | if (tag == null) { |
| 197 | throw new IllegalArgumentException("Cannot cancelAll with a null tag"); |
| 198 | } |
| 199 | cancelAll(new RequestFilter() { |
| 200 | @Override |
| 201 | public boolean apply(Request<?> request) { |
| 202 | return request.getTag() == tag; |
| 203 | } |
| 204 | }); |
| 205 | } |
| 206 | |
| 207 | /** |
| 208 | * Drains this request queue. All requests currently being processed |
| 209 | * or waiting to be processed will be canceled, and no responses, success |
| 210 | * or error, will be delivered for them. |
| 211 | */ |
| 212 | @Deprecated |
| 213 | public void drain() { |
| 214 | drain(getSequenceNumber()); |
| 215 | } |
| 216 | |
| 217 | /** |
| 218 | * Drains this request queue. All requests currently being processed |
| 219 | * or waiting to be processed will be canceled, and no responses, success |
| 220 | * or error, will be delivered for them. |
| 221 | * @param sequenceNumber The sequence number of the drain request. Everything before this number |
| 222 | * will be drained. |
| 223 | */ |
| 224 | @Deprecated |
| 225 | public void drain(int sequenceNumber) { |
| 226 | // Cancel drainable requests. |
| 227 | cancelDrainable(mCacheQueue, sequenceNumber); |
| 228 | cancelDrainable(mNetworkQueue, sequenceNumber); |
| 229 | |
| 230 | // Tell the delivery to discard all requests with a sequence number below it. We can't stop |
| 231 | // requests that are already in flight, but this will suppress their responses |
| 232 | // from being delivered. |
| 233 | mDelivery.discardBefore(sequenceNumber); |
| 234 | if (VolleyLog.DEBUG) { |
| 235 | VolleyLog.v("Draining requests with sequence number below %s", sequenceNumber); |
| 236 | } |
| 237 | } |
| 238 | |
| 239 | /** |
| 240 | * Cancels all requests in the provided queue that return true from |
| 241 | * {@link Request#isDrainable()} and have a sequence number less than the |
| 242 | * provided one. |
| 243 | */ |
| 244 | @SuppressWarnings("deprecation") |
| 245 | private void cancelDrainable(PriorityBlockingQueue<Request> queue, int sequenceNumber) { |
| 246 | List<Request> pending = new ArrayList<Request>(); |
| 247 | // Remove all requests from the queue in order to work on them. |
| 248 | queue.drainTo(pending); |
| 249 | for (Request request : pending) { |
| 250 | if (request.isDrainable() && request.getSequence() < sequenceNumber) { |
| 251 | request.cancel(); |
| 252 | } |
| 253 | // Put the request back on the queue. If it is canceled, it |
| 254 | // will be discarded by one of the dispatchers or the delivery. |
| 255 | queue.add(request); |
| 256 | } |
| 257 | } |
| 258 | |
| 259 | /** |
| 260 | * Adds a Request to the dispatch queue. |
| 261 | * @param request The request to service |
| 262 | * @return The passed-in request |
| 263 | */ |
| 264 | public Request add(Request request) { |
| 265 | // Tag the request as belonging to this queue and add it to the set of current requests. |
| 266 | request.setRequestQueue(this); |
| 267 | synchronized (mCurrentRequests) { |
| 268 | mCurrentRequests.add(request); |
| 269 | } |
| 270 | |
| 271 | // Process requests in the order they are added. |
| 272 | request.setSequence(sSequenceGenerator.incrementAndGet()); |
| 273 | request.addMarker("add-to-queue"); |
| 274 | |
| 275 | // If the request is uncacheable, skip the cache queue and go straight to the network. |
| 276 | if (!request.shouldCache()) { |
| 277 | mNetworkQueue.add(request); |
| 278 | return request; |
| 279 | } |
| 280 | |
| 281 | // Insert request into stage if there's already a request with the same cache key in flight. |
| 282 | synchronized (mWaitingRequests) { |
| 283 | String cacheKey = request.getCacheKey(); |
| 284 | if (mWaitingRequests.containsKey(cacheKey)) { |
| 285 | // There is already a request in flight. Queue up. |
| 286 | Queue<Request> stagedRequests = mWaitingRequests.get(cacheKey); |
| 287 | if (stagedRequests == null) { |
| 288 | stagedRequests = new LinkedList<Request>(); |
| 289 | } |
| 290 | stagedRequests.add(request); |
| 291 | mWaitingRequests.put(cacheKey, stagedRequests); |
| 292 | if (VolleyLog.DEBUG) { |
| 293 | VolleyLog.v("Request for cacheKey=%s is in flight, putting on hold.", cacheKey); |
| 294 | } |
| 295 | } else { |
| 296 | // Insert 'null' queue for this cacheKey, indicating there is now a request in |
| 297 | // flight. |
| 298 | mWaitingRequests.put(cacheKey, null); |
| 299 | mCacheQueue.add(request); |
| 300 | } |
| 301 | return request; |
| 302 | } |
| 303 | } |
| 304 | |
| 305 | /** |
| 306 | * Called from {@link Request#finish(String)}, indicating that processing of the given request |
| 307 | * has finished. |
| 308 | * |
| 309 | * <p>Releases waiting requests for <code>request.getCacheKey()</code> if |
| 310 | * <code>request.shouldCache()</code>.</p> |
| 311 | */ |
| 312 | void finish(Request request) { |
| 313 | // Remove from the set of requests currently being processed. |
| 314 | synchronized (mCurrentRequests) { |
| 315 | mCurrentRequests.remove(request); |
| 316 | } |
| 317 | |
| 318 | if (request.shouldCache()) { |
| 319 | synchronized (mWaitingRequests) { |
| 320 | String cacheKey = request.getCacheKey(); |
| 321 | Queue<Request> waitingRequests = mWaitingRequests.remove(cacheKey); |
| 322 | if (waitingRequests != null) { |
| 323 | if (VolleyLog.DEBUG) { |
| 324 | VolleyLog.v("Releasing %d waiting requests for cacheKey=%s.", |
| 325 | waitingRequests.size(), cacheKey); |
| 326 | } |
| 327 | // Process all queued up requests. They won't be considered as in flight, but |
| 328 | // that's not a problem as the cache has been primed by 'request'. |
| 329 | mCacheQueue.addAll(waitingRequests); |
| 330 | } |
| 331 | } |
| 332 | } |
| 333 | } |
| 334 | } |