1 /*
   2  * Copyright (c) 2016, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package jdk.management.jfr;
  27 
  28 import java.io.BufferedInputStream;
  29 import java.io.Closeable;
  30 import java.io.IOException;
  31 import java.io.InputStream;
  32 
  33 final class Stream implements Closeable {
  34 
  35     private final long identifier;
  36     private final BufferedInputStream inputStream;
  37     private final byte[] buffer;
  38 
  39     private volatile long time;
  40 
  41     Stream(InputStream is, long identifier, int blockSize) {
  42         this.inputStream = new BufferedInputStream(is, 50000);
  43         this.identifier = identifier;
  44         this.buffer = new byte[blockSize];
  45     }
  46 
  47     private void touch() {
  48         time = System.currentTimeMillis();
  49     }
  50 
  51     public long getLastTouched() {
  52         return time;
  53     }
  54 
  55     public byte[] read() throws IOException {
  56         // OK to reuse buffer since this
  57         // is only used for serialization
  58         touch();
  59         int read = inputStream.read(buffer);
  60         if (read == -1) {
  61             // null indicate no more data
  62             return null;
  63         }
  64         if (read != buffer.length) {
  65             byte[] smallerBuffer = new byte[read];
  66             System.arraycopy(buffer, 0, smallerBuffer, 0, read);
  67             return smallerBuffer;
  68         }
  69 
  70         return buffer;
  71     }
  72 
  73     @Override
  74     public void close() throws IOException {
  75         inputStream.close();
  76     }
  77 
  78     public long getId() {
  79         return identifier;
  80     }
  81 }