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.toolbox;
18
19import com.android.volley.Request;
20import com.android.volley.Response;
21import com.android.volley.VolleyError;
22
23import java.util.concurrent.ExecutionException;
24import java.util.concurrent.Future;
25import java.util.concurrent.TimeUnit;
26import java.util.concurrent.TimeoutException;
27
28/**
29 * A Future that represents a Volley request.
30 *
31 * Used by providing as your response and error listeners. For example:
32 * <pre>
33 * RequestFuture&lt;JSONObject&gt; future = RequestFuture.newFuture();
34 * MyRequest request = new MyRequest(URL, future, future);
35 *
36 * // If you want to be able to cancel the request:
37 * future.setRequest(requestQueue.add(request));
38 *
39 * // Otherwise:
40 * requestQueue.add(request);
41 *
42 * try {
43 *   JSONObject response = future.get();
44 *   // do something with response
45 * } catch (InterruptedException e) {
46 *   // handle the error
47 * } catch (ExecutionException e) {
48 *   // handle the error
49 * }
50 * </pre>
51 *
52 * @param <T> The type of parsed response this future expects.
53 */
54public class RequestFuture<T> implements Future<T>, Response.Listener<T>,
55       Response.ErrorListener {
56    private Request<?> mRequest;
57    private boolean mResultReceived = false;
58    private T mResult;
59    private VolleyError mException;
60
61    public static <E> RequestFuture<E> newFuture() {
62        return new RequestFuture<E>();
63    }
64
65    private RequestFuture() {}
66
67    public void setRequest(Request<?> request) {
68        mRequest = request;
69    }
70
71    @Override
72    public synchronized boolean cancel(boolean mayInterruptIfRunning) {
73        if (mRequest == null) {
74            return false;
75        }
76
77        if (!isDone()) {
78            mRequest.cancel();
79            return true;
80        } else {
81            return false;
82        }
83    }
84
85    @Override
86    public T get() throws InterruptedException, ExecutionException {
87        try {
88            return doGet(null);
89        } catch (TimeoutException e) {
90            throw new AssertionError(e);
91        }
92    }
93
94    @Override
95    public T get(long timeout, TimeUnit unit)
96            throws InterruptedException, ExecutionException, TimeoutException {
97        return doGet(TimeUnit.MILLISECONDS.convert(timeout, unit));
98    }
99
100    private synchronized T doGet(Long timeoutMs)
101            throws InterruptedException, ExecutionException, TimeoutException {
102        if (mException != null) {
103            throw new ExecutionException(mException);
104        }
105
106        if (mResultReceived) {
107            return mResult;
108        }
109
110        if (timeoutMs == null) {
111            wait(0);
112        } else if (timeoutMs > 0) {
113            wait(timeoutMs);
114        }
115
116        if (mException != null) {
117            throw new ExecutionException(mException);
118        }
119
120        if (!mResultReceived) {
121            throw new TimeoutException();
122        }
123
124        return mResult;
125    }
126
127    @Override
128    public boolean isCancelled() {
129        if (mRequest == null) {
130            return false;
131        }
132        return mRequest.isCanceled();
133    }
134
135    @Override
136    public synchronized boolean isDone() {
137        return mResultReceived || mException != null || isCancelled();
138    }
139
140    @Override
141    public synchronized void onResponse(T response) {
142        mResultReceived = true;
143        mResult = response;
144        notifyAll();
145    }
146
147    @Override
148    public synchronized void onErrorResponse(VolleyError error) {
149        mException = error;
150        notifyAll();
151    }
152}
153
154