1 files changed, 342 insertions, 0 deletions
diff --git a/core/src/main/java/com/android/volley/RequestQueue.java b/core/src/main/java/com/android/volley/RequestQueue.java
new file mode 100644
index 0000000..6db0b1c
--- /dev/null
+++ b/core/src/main/java/com/android/volley/RequestQueue.java
@@ -0,0 +1,342 @@
+/*
+ * 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.os.Handler;
+import android.os.Looper;
+import androidx.annotation.IntDef;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.concurrent.PriorityBlockingQueue;
+import java.util.concurrent.atomic.AtomicInteger;
+
+/**
+ * A request dispatch queue with a thread pool of dispatchers.
+ *
+ * <p>Calling {@link #add(Request)} will enqueue the given Request for dispatch, resolving from
+ * either cache or network on a worker thread, and then delivering a parsed response on the main
+ * thread.
+ */
+public class RequestQueue {
+
+    /** Callback interface for completed requests. */
+    // TODO: This should not be a generic class, because the request type can't be determined at
+    // compile time, so all calls to onRequestFinished are unsafe. However, changing this would be
+    // an API-breaking change. See also: https://github.com/google/volley/pull/109
+    @Deprecated // Use RequestEventListener instead.
+    public interface RequestFinishedListener<T> {
+        /** Called when a request has finished processing. */
+        void onRequestFinished(Request<T> request);
+    }
+
+    /** Request event types the listeners {@link RequestEventListener} will be notified about. */
+    @Retention(RetentionPolicy.SOURCE)
+    @IntDef({
+        RequestEvent.REQUEST_QUEUED,
+        RequestEvent.REQUEST_CACHE_LOOKUP_STARTED,
+        RequestEvent.REQUEST_CACHE_LOOKUP_FINISHED,
+        RequestEvent.REQUEST_NETWORK_DISPATCH_STARTED,
+        RequestEvent.REQUEST_NETWORK_DISPATCH_FINISHED,
+        RequestEvent.REQUEST_FINISHED
+    })
+    public @interface RequestEvent {
+        /** The request was added to the queue. */
+        public static final int REQUEST_QUEUED = 0;
+        /** Cache lookup started for the request. */
+        public static final int REQUEST_CACHE_LOOKUP_STARTED = 1;
+        /**
+         * Cache lookup finished for the request and cached response is delivered or request is
+         * queued for network dispatching.
+         */
+        public static final int REQUEST_CACHE_LOOKUP_FINISHED = 2;
+        /** Network dispatch started for the request. */
+        public static final int REQUEST_NETWORK_DISPATCH_STARTED = 3;
+        /** The network dispatch finished for the request and response (if any) is delivered. */
+        public static final int REQUEST_NETWORK_DISPATCH_FINISHED = 4;
+        /**
+         * All the work associated with the request is finished and request is removed from all the
+         * queues.
+         */
+        public static final int REQUEST_FINISHED = 5;
+    }
+
+    /** Callback interface for request life cycle events. */
+    public interface RequestEventListener {
+        /**
+         * Called on every request lifecycle event. Can be called from different threads. The call
+         * is blocking request processing, so any processing should be kept at minimum or moved to
+         * another thread.
+         */
+        void onRequestEvent(Request<?> request, @RequestEvent int event);
+    }
+
+    /** Used for generating monotonically-increasing sequence numbers for requests. */
+    private final AtomicInteger mSequenceGenerator = new AtomicInteger();
+
+    /**
+     * The set of all requests currently being processed by this RequestQueue. A Request will be in
+     * this set if it is waiting in any queue or currently being processed by any dispatcher.
+     */
+    private final Set<Request<?>> mCurrentRequests = new HashSet<>();
+
+    /** The cache triage queue. */
+    private final PriorityBlockingQueue<Request<?>> mCacheQueue = new PriorityBlockingQueue<>();
+
+    /** The queue of requests that are actually going out to the network. */
+    private final PriorityBlockingQueue<Request<?>> mNetworkQueue = new PriorityBlockingQueue<>();
+
+    /** Number of network request dispatcher threads to start. */
+    private static final int DEFAULT_NETWORK_THREAD_POOL_SIZE = 4;
+
+    /** Cache interface for retrieving and storing responses. */
+    private final Cache mCache;
+
+    /** Network interface for performing requests. */
+    private final Network mNetwork;
+
+    /** Response delivery mechanism. */
+    private final ResponseDelivery mDelivery;
+
+    /** The network dispatchers. */
+    private final NetworkDispatcher[] mDispatchers;
+
+    /** The cache dispatcher. */
+    private CacheDispatcher mCacheDispatcher;
+
+    private final List<RequestFinishedListener> mFinishedListeners = new ArrayList<>();
+
+    /** Collection of listeners for request life cycle events. */
+    private final List<RequestEventListener> mEventListeners = new ArrayList<>();
+
+    /**
+     * Creates the worker pool. Processing will not begin until {@link #start()} is called.
+     *
+     * @param cache A Cache to use for persisting responses to disk
+     * @param network A Network interface for performing HTTP requests
+     * @param threadPoolSize Number of network dispatcher threads to create
+     * @param delivery A ResponseDelivery interface for posting responses and errors
+     */
+    public RequestQueue(
+            Cache cache, Network network, int threadPoolSize, ResponseDelivery delivery) {
+        mCache = cache;
+        mNetwork = network;
+        mDispatchers = new NetworkDispatcher[threadPoolSize];
+        mDelivery = delivery;
+    }
+
+    /**
+     * Creates the worker pool. Processing will not begin until {@link #start()} is called.
+     *
+     * @param cache A Cache to use for persisting responses to disk
+     * @param network A Network interface for performing HTTP requests
+     * @param threadPoolSize Number of network dispatcher threads to create
+     */
+    public RequestQueue(Cache cache, Network network, int threadPoolSize) {
+        this(
+                cache,
+                network,
+                threadPoolSize,
+                new ExecutorDelivery(new Handler(Looper.getMainLooper())));
+    }
+
+    /**
+     * Creates the worker pool. Processing will not begin until {@link #start()} is called.
+     *
+     * @param cache A Cache to use for persisting responses to disk
+     * @param network A Network interface for performing HTTP requests
+     */
+    public RequestQueue(Cache cache, Network network) {
+        this(cache, network, DEFAULT_NETWORK_THREAD_POOL_SIZE);
+    }
+
+    /** Starts the dispatchers in this queue. */
+    public void start() {
+        stop(); // Make sure any currently running dispatchers are stopped.
+        // Create the cache dispatcher and start it.
+        mCacheDispatcher = new CacheDispatcher(mCacheQueue, mNetworkQueue, mCache, mDelivery);
+        mCacheDispatcher.start();
+
+        // Create network dispatchers (and corresponding threads) up to the pool size.
+        for (int i = 0; i < mDispatchers.length; i++) {
+            NetworkDispatcher networkDispatcher =
+                    new NetworkDispatcher(mNetworkQueue, mNetwork, mCache, mDelivery);
+            mDispatchers[i] = networkDispatcher;
+            networkDispatcher.start();
+        }
+    }
+
+    /** Stops the cache and network dispatchers. */
+    public void stop() {
+        if (mCacheDispatcher != null) {
+            mCacheDispatcher.quit();
+        }
+        for (final NetworkDispatcher mDispatcher : mDispatchers) {
+            if (mDispatcher != null) {
+                mDispatcher.quit();
+            }
+        }
+    }
+
+    /** Gets a sequence number. */
+    public int getSequenceNumber() {
+        return mSequenceGenerator.incrementAndGet();
+    }
+
+    /** Gets the {@link Cache} instance being used. */
+    public Cache getCache() {
+        return mCache;
+    }
+
+    /**
+     * A simple predicate or filter interface for Requests, for use by {@link
+     * RequestQueue#cancelAll(RequestFilter)}.
+     */
+    public interface RequestFilter {
+        boolean apply(Request<?> request);
+    }
+
+    /**
+     * Cancels all requests in this queue for which the given filter applies.
+     *
+     * @param filter The filtering function to use
+     */
+    public void cancelAll(RequestFilter filter) {
+        synchronized (mCurrentRequests) {
+            for (Request<?> request : mCurrentRequests) {
+                if (filter.apply(request)) {
+                    request.cancel();
+                }
+            }
+        }
+    }
+
+    /**
+     * Cancels all requests in this queue with the given tag. Tag must be non-null and equality is
+     * by identity.
+     */
+    public void cancelAll(final Object tag) {
+        if (tag == null) {
+            throw new IllegalArgumentException("Cannot cancelAll with a null tag");
+        }
+        cancelAll(
+                new RequestFilter() {
+                    @Override
+                    public boolean apply(Request<?> request) {
+                        return request.getTag() == tag;
+                    }
+                });
+    }
+
+    /**
+     * Adds a Request to the dispatch queue.
+     *
+     * @param request The request to service
+     * @return The passed-in request
+     */
+    public <T> Request<T> add(Request<T> request) {
+        // Tag the request as belonging to this queue and add it to the set of current requests.
+        request.setRequestQueue(this);
+        synchronized (mCurrentRequests) {
+            mCurrentRequests.add(request);
+        }
+
+        // Process requests in the order they are added.
+        request.setSequence(getSequenceNumber());
+        request.addMarker("add-to-queue");
+        sendRequestEvent(request, RequestEvent.REQUEST_QUEUED);
+
+        beginRequest(request);
+        return request;
+    }
+
+    <T> void beginRequest(Request<T> request) {
+        // If the request is uncacheable, skip the cache queue and go straight to the network.
+        if (!request.shouldCache()) {
+            sendRequestOverNetwork(request);
+        } else {
+            mCacheQueue.add(request);
+        }
+    }
+
+    /**
+     * Called from {@link Request#finish(String)}, indicating that processing of the given request
+     * has finished.
+     */
+    @SuppressWarnings("unchecked") // see above note on RequestFinishedListener
+    <T> void finish(Request<T> request) {
+        // Remove from the set of requests currently being processed.
+        synchronized (mCurrentRequests) {
+            mCurrentRequests.remove(request);
+        }
+        synchronized (mFinishedListeners) {
+            for (RequestFinishedListener<T> listener : mFinishedListeners) {
+                listener.onRequestFinished(request);
+            }
+        }
+        sendRequestEvent(request, RequestEvent.REQUEST_FINISHED);
+    }
+
+    /** Sends a request life cycle event to the listeners. */
+    void sendRequestEvent(Request<?> request, @RequestEvent int event) {
+        synchronized (mEventListeners) {
+            for (RequestEventListener listener : mEventListeners) {
+                listener.onRequestEvent(request, event);
+            }
+        }
+    }
+
+    /** Add a listener for request life cycle events. */
+    public void addRequestEventListener(RequestEventListener listener) {
+        synchronized (mEventListeners) {
+            mEventListeners.add(listener);
+        }
+    }
+
+    /** Remove a listener for request life cycle events. */
+    public void removeRequestEventListener(RequestEventListener listener) {
+        synchronized (mEventListeners) {
+            mEventListeners.remove(listener);
+        }
+    }
+
+    @Deprecated // Use RequestEventListener instead.
+    public <T> void addRequestFinishedListener(RequestFinishedListener<T> listener) {
+        synchronized (mFinishedListeners) {
+            mFinishedListeners.add(listener);
+        }
+    }
+
+    /** Remove a RequestFinishedListener. Has no effect if listener was not previously added. */
+    @Deprecated // Use RequestEventListener instead.
+    public <T> void removeRequestFinishedListener(RequestFinishedListener<T> listener) {
+        synchronized (mFinishedListeners) {
+            mFinishedListeners.remove(listener);
+        }
+    }
+
+    public ResponseDelivery getResponseDelivery() {
+        return mDelivery;
+    }
+
+    <T> void sendRequestOverNetwork(Request<T> request) {
+        mNetworkQueue.add(request);
+    }
+}