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 android.system;
18 
19 import java.io.FileDescriptor;
20 import libcore.util.Objects;
21 
22 /**
23  * Used as an in/out parameter to {@link Os#poll}.
24  * Corresponds to C's {@code struct pollfd} from {@code <poll.h>}.
25  */
26 public final class StructPollfd {
27     /** The file descriptor to poll. */
28     public FileDescriptor fd;
29 
30     /**
31      * The events we're interested in. POLLIN corresponds to being in select(2)'s read fd set,
32      * POLLOUT to the write fd set.
33      */
34     public short events;
35 
36     /** The events that actually happened. */
37     public short revents;
38 
39     /**
40      * A non-standard extension that lets callers conveniently map back to the object
41      * their fd belongs to. This is used by Selector, for example, to associate each
42      * FileDescriptor with the corresponding SelectionKey.
43      */
44     public Object userData;
45 
toString()46     @Override public String toString() {
47         return Objects.toString(this);
48     }
49 }
50