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      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 libcore.io;
     18 
     19 import java.io.FileDescriptor;
     20 
     21 /**
     22  * Corresponds to C's {@code struct pollfd} from
     23  * <a href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/poll.h.html">&lt;poll.h&gt;</a>
     24  */
     25 public final class StructPollfd {
     26     /** The file descriptor to poll. */
     27     public FileDescriptor fd;
     28 
     29     /**
     30      * The events we're interested in. POLLIN corresponds to being in select(2)'s read fd set,
     31      * POLLOUT to the write fd set.
     32      */
     33     public short events;
     34 
     35     /** The events that actually happened. */
     36     public short revents;
     37 
     38     /**
     39      * A non-standard extension that lets callers conveniently map back to the object
     40      * their fd belongs to. This is used by Selector, for example, to associate each
     41      * FileDescriptor with the corresponding SelectionKey.
     42      */
     43     public Object userData;
     44 
     45     @Override public String toString() {
     46         return "StructPollfd[fd=" + fd + ",events=" + events + ",revents=" + revents + "]";
     47     }
     48 }
     49