370 lines
13 KiB
Java
370 lines
13 KiB
Java
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/*
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* Copyright (C) 2014 The Android Open Source Project
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* Copyright (c) 1996, 2013, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package java.io;
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import libcore.io.IoUtils;
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/**
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* Piped character-input streams.
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*
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* @author Mark Reinhold
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* @since 1.1
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*/
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public class PipedReader extends Reader {
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boolean closedByWriter = false;
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boolean closedByReader = false;
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boolean connected = false;
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/* REMIND: identification of the read and write sides needs to be
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more sophisticated. Either using thread groups (but what about
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pipes within a thread?) or using finalization (but it may be a
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long time until the next GC). */
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Thread readSide;
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Thread writeSide;
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/**
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* The size of the pipe's circular input buffer.
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*/
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private static final int DEFAULT_PIPE_SIZE = 1024;
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/**
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* The circular buffer into which incoming data is placed.
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*/
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char buffer[];
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/**
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* The index of the position in the circular buffer at which the
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* next character of data will be stored when received from the connected
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* piped writer. <code>in<0</code> implies the buffer is empty,
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* <code>in==out</code> implies the buffer is full
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*/
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int in = -1;
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/**
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* The index of the position in the circular buffer at which the next
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* character of data will be read by this piped reader.
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*/
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int out = 0;
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/**
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* Creates a <code>PipedReader</code> so
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* that it is connected to the piped writer
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* <code>src</code>. Data written to <code>src</code>
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* will then be available as input from this stream.
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*
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* @param src the stream to connect to.
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* @exception IOException if an I/O error occurs.
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*/
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public PipedReader(PipedWriter src) throws IOException {
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this(src, DEFAULT_PIPE_SIZE);
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}
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/**
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* Creates a <code>PipedReader</code> so that it is connected
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* to the piped writer <code>src</code> and uses the specified
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* pipe size for the pipe's buffer. Data written to <code>src</code>
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* will then be available as input from this stream.
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* @param src the stream to connect to.
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* @param pipeSize the size of the pipe's buffer.
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* @exception IOException if an I/O error occurs.
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* @exception IllegalArgumentException if {@code pipeSize <= 0}.
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* @since 1.6
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*/
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public PipedReader(PipedWriter src, int pipeSize) throws IOException {
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initPipe(pipeSize);
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connect(src);
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}
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/**
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* Creates a <code>PipedReader</code> so
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* that it is not yet {@linkplain #connect(java.io.PipedWriter)
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* connected}. It must be {@linkplain java.io.PipedWriter#connect(
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* java.io.PipedReader) connected} to a <code>PipedWriter</code>
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* before being used.
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*/
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public PipedReader() {
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initPipe(DEFAULT_PIPE_SIZE);
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}
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/**
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* Creates a <code>PipedReader</code> so that it is not yet
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* {@link #connect(java.io.PipedWriter) connected} and uses
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* the specified pipe size for the pipe's buffer.
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* It must be {@linkplain java.io.PipedWriter#connect(
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* java.io.PipedReader) connected} to a <code>PipedWriter</code>
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* before being used.
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*
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* @param pipeSize the size of the pipe's buffer.
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* @exception IllegalArgumentException if {@code pipeSize <= 0}.
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* @since 1.6
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*/
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public PipedReader(int pipeSize) {
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initPipe(pipeSize);
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}
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private void initPipe(int pipeSize) {
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if (pipeSize <= 0) {
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throw new IllegalArgumentException("Pipe size <= 0");
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}
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buffer = new char[pipeSize];
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}
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/**
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* Causes this piped reader to be connected
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* to the piped writer <code>src</code>.
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* If this object is already connected to some
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* other piped writer, an <code>IOException</code>
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* is thrown.
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* <p>
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* If <code>src</code> is an
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* unconnected piped writer and <code>snk</code>
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* is an unconnected piped reader, they
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* may be connected by either the call:
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*
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* <pre><code>snk.connect(src)</code> </pre>
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* <p>
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* or the call:
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*
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* <pre><code>src.connect(snk)</code> </pre>
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* <p>
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* The two calls have the same effect.
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*
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* @param src The piped writer to connect to.
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* @exception IOException if an I/O error occurs.
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*/
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public void connect(PipedWriter src) throws IOException {
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src.connect(this);
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}
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/**
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* Receives a char of data. This method will block if no input is
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* available.
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*/
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synchronized void receive(int c) throws IOException {
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if (!connected) {
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throw new IOException("Pipe not connected");
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} else if (closedByWriter || closedByReader) {
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throw new IOException("Pipe closed");
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} else if (readSide != null && !readSide.isAlive()) {
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throw new IOException("Read end dead");
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}
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writeSide = Thread.currentThread();
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while (in == out) {
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if ((readSide != null) && !readSide.isAlive()) {
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throw new IOException("Pipe broken");
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}
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/* full: kick any waiting readers */
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notifyAll();
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try {
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wait(1000);
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} catch (InterruptedException ex) {
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// Android-changed: re-set the thread's interrupt status
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// throw new java.io.InterruptedIOException();
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IoUtils.throwInterruptedIoException();
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}
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}
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if (in < 0) {
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in = 0;
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out = 0;
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}
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buffer[in++] = (char) c;
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if (in >= buffer.length) {
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in = 0;
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}
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}
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/**
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* Receives data into an array of characters. This method will
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* block until some input is available.
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*/
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synchronized void receive(char c[], int off, int len) throws IOException {
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while (--len >= 0) {
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receive(c[off++]);
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}
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}
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/**
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* Notifies all waiting threads that the last character of data has been
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* received.
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*/
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synchronized void receivedLast() {
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closedByWriter = true;
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notifyAll();
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}
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/**
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* Reads the next character of data from this piped stream.
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* If no character is available because the end of the stream
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* has been reached, the value <code>-1</code> is returned.
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* This method blocks until input data is available, the end of
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* the stream is detected, or an exception is thrown.
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*
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* @return the next character of data, or <code>-1</code> if the end of the
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* stream is reached.
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* @exception IOException if the pipe is
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* <a href=PipedInputStream.html#BROKEN> <code>broken</code></a>,
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* {@link #connect(java.io.PipedWriter) unconnected}, closed,
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* or an I/O error occurs.
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*/
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public synchronized int read() throws IOException {
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if (!connected) {
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throw new IOException("Pipe not connected");
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} else if (closedByReader) {
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throw new IOException("Pipe closed");
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} else if (writeSide != null && !writeSide.isAlive()
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&& !closedByWriter && (in < 0)) {
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throw new IOException("Write end dead");
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}
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readSide = Thread.currentThread();
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int trials = 2;
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while (in < 0) {
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if (closedByWriter) {
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/* closed by writer, return EOF */
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return -1;
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}
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if ((writeSide != null) && (!writeSide.isAlive()) && (--trials < 0)) {
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throw new IOException("Pipe broken");
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}
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/* might be a writer waiting */
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notifyAll();
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try {
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wait(1000);
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} catch (InterruptedException ex) {
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// Android-changed: re-set the thread's interrupt status
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// throw new java.io.InterruptedIOException();
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IoUtils.throwInterruptedIoException();
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}
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}
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int ret = buffer[out++];
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if (out >= buffer.length) {
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out = 0;
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}
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if (in == out) {
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/* now empty */
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in = -1;
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}
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return ret;
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}
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/**
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* Reads up to <code>len</code> characters of data from this piped
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* stream into an array of characters. Less than <code>len</code> characters
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* will be read if the end of the data stream is reached or if
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* <code>len</code> exceeds the pipe's buffer size. This method
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* blocks until at least one character of input is available.
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*
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* @param cbuf the buffer into which the data is read.
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* @param off the start offset of the data.
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* @param len the maximum number of characters read.
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* @return the total number of characters read into the buffer, or
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* <code>-1</code> if there is no more data because the end of
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* the stream has been reached.
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* @exception IOException if the pipe is
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* <a href=PipedInputStream.html#BROKEN> <code>broken</code></a>,
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* {@link #connect(java.io.PipedWriter) unconnected}, closed,
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* or an I/O error occurs.
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* @exception IndexOutOfBoundsException {@inheritDoc}
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*/
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public synchronized int read(char cbuf[], int off, int len) throws IOException {
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if (!connected) {
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throw new IOException("Pipe not connected");
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} else if (closedByReader) {
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throw new IOException("Pipe closed");
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} else if (writeSide != null && !writeSide.isAlive()
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&& !closedByWriter && (in < 0)) {
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throw new IOException("Write end dead");
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}
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if ((off < 0) || (off > cbuf.length) || (len < 0) ||
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((off + len) > cbuf.length) || ((off + len) < 0)) {
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throw new IndexOutOfBoundsException();
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} else if (len == 0) {
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return 0;
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}
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/* possibly wait on the first character */
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int c = read();
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if (c < 0) {
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return -1;
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}
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cbuf[off] = (char)c;
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int rlen = 1;
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while ((in >= 0) && (--len > 0)) {
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cbuf[off + rlen] = buffer[out++];
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rlen++;
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if (out >= buffer.length) {
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out = 0;
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}
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if (in == out) {
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/* now empty */
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in = -1;
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}
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}
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return rlen;
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}
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/**
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* Tell whether this stream is ready to be read. A piped character
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* stream is ready if the circular buffer is not empty.
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*
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* @exception IOException if the pipe is
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* <a href=PipedInputStream.html#BROKEN> <code>broken</code></a>,
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* {@link #connect(java.io.PipedWriter) unconnected}, or closed.
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*/
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public synchronized boolean ready() throws IOException {
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if (!connected) {
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throw new IOException("Pipe not connected");
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} else if (closedByReader) {
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throw new IOException("Pipe closed");
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} else if (writeSide != null && !writeSide.isAlive()
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&& !closedByWriter && (in < 0)) {
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throw new IOException("Write end dead");
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}
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if (in < 0) {
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return false;
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} else {
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return true;
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}
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}
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/**
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* Closes this piped stream and releases any system resources
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* associated with the stream.
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*
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* @exception IOException if an I/O error occurs.
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*/
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public void close() throws IOException {
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in = -1;
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closedByReader = true;
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}
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}
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