Mercurial > 510Connectbot
diff app/src/main/java/ch/ethz/ssh2/StreamGobbler.java @ 438:d29cce60f393
migrate from Eclipse to Android Studio
author | Carl Byington <carl@five-ten-sg.com> |
---|---|
date | Thu, 03 Dec 2015 11:23:55 -0800 |
parents | src/ch/ethz/ssh2/StreamGobbler.java@071eccdff8ea |
children |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/app/src/main/java/ch/ethz/ssh2/StreamGobbler.java Thu Dec 03 11:23:55 2015 -0800 @@ -0,0 +1,204 @@ +/* + * Copyright (c) 2006-2011 Christian Plattner. All rights reserved. + * Please refer to the LICENSE.txt for licensing details. + */ +package ch.ethz.ssh2; + +import java.io.IOException; +import java.io.InputStream; +import java.io.InterruptedIOException; + +/** + * A <code>StreamGobbler</code> is an InputStream that uses an internal worker + * thread to constantly consume input from another InputStream. It uses a buffer + * to store the consumed data. The buffer size is automatically adjusted, if needed. + * <p/> + * This class is sometimes very convenient - if you wrap a session's STDOUT and STDERR + * InputStreams with instances of this class, then you don't have to bother about + * the shared window of STDOUT and STDERR in the low level SSH-2 protocol, + * since all arriving data will be immediatelly consumed by the worker threads. + * Also, as a side effect, the streams will be buffered (e.g., single byte + * read() operations are faster). + * <p/> + * Other SSH for Java libraries include this functionality by default in + * their STDOUT and STDERR InputStream implementations, however, please be aware + * that this approach has also a downside: + * <p/> + * If you do not call the StreamGobbler's <code>read()</code> method often enough + * and the peer is constantly sending huge amounts of data, then you will sooner or later + * encounter a low memory situation due to the aggregated data (well, it also depends on the Java heap size). + * Joe Average will like this class anyway - a paranoid programmer would never use such an approach. + * <p/> + * The term "StreamGobbler" was taken from an article called "When Runtime.exec() won't", + * see http://www.javaworld.com/javaworld/jw-12-2000/jw-1229-traps.html. + * + * @author Christian Plattner + * @version 2.50, 03/15/10 + */ + +public class StreamGobbler extends InputStream { + class GobblerThread extends Thread { + @Override + public void run() { + byte[] buff = new byte[8192]; + + while (true) { + try { + int avail = is.read(buff); + + synchronized (synchronizer) { + if (avail <= 0) { + isEOF = true; + synchronizer.notifyAll(); + break; + } + + int space_available = buffer.length - write_pos; + + if (space_available < avail) { + /* compact/resize buffer */ + int unread_size = write_pos - read_pos; + int need_space = unread_size + avail; + byte[] new_buffer = buffer; + + if (need_space > buffer.length) { + int inc = need_space / 3; + inc = (inc < 256) ? 256 : inc; + inc = (inc > 8192) ? 8192 : inc; + new_buffer = new byte[need_space + inc]; + } + + if (unread_size > 0) + System.arraycopy(buffer, read_pos, new_buffer, 0, unread_size); + + buffer = new_buffer; + read_pos = 0; + write_pos = unread_size; + } + + System.arraycopy(buff, 0, buffer, write_pos, avail); + write_pos += avail; + synchronizer.notifyAll(); + } + } + catch (IOException e) { + synchronized (synchronizer) { + exception = e; + synchronizer.notifyAll(); + break; + } + } + } + } + } + + private InputStream is; + + private final Object synchronizer = new Object(); + + private boolean isEOF = false; + private boolean isClosed = false; + private IOException exception = null; + + private byte[] buffer = new byte[2048]; + private int read_pos = 0; + private int write_pos = 0; + + public StreamGobbler(InputStream is) { + this.is = is; + GobblerThread t = new GobblerThread(); + t.setDaemon(true); + t.start(); + } + + @Override + public int read() throws IOException { + synchronized (synchronizer) { + if (isClosed) + throw new IOException("This StreamGobbler is closed."); + + while (read_pos == write_pos) { + if (exception != null) + throw exception; + + if (isEOF) + return -1; + + try { + synchronizer.wait(); + } + catch (InterruptedException e) { + throw new InterruptedIOException(); + } + } + + return buffer[read_pos++] & 0xff; + } + } + + @Override + public int available() throws IOException { + synchronized (synchronizer) { + if (isClosed) + throw new IOException("This StreamGobbler is closed."); + + return write_pos - read_pos; + } + } + + @Override + public int read(byte[] b) throws IOException { + return read(b, 0, b.length); + } + + @Override + public void close() throws IOException { + synchronized (synchronizer) { + if (isClosed) + return; + + isClosed = true; + isEOF = true; + synchronizer.notifyAll(); + is.close(); + } + } + + @Override + public int read(byte[] b, int off, int len) throws IOException { + if (b == null) + throw new NullPointerException(); + + if ((off < 0) || (len < 0) || ((off + len) > b.length) || ((off + len) < 0) || (off > b.length)) + throw new IndexOutOfBoundsException(); + + if (len == 0) + return 0; + + synchronized (synchronizer) { + if (isClosed) + throw new IOException("This StreamGobbler is closed."); + + while (read_pos == write_pos) { + if (exception != null) + throw exception; + + if (isEOF) + return -1; + + try { + synchronizer.wait(); + } + catch (InterruptedException e) { + throw new InterruptedIOException(); + } + } + + int avail = write_pos - read_pos; + avail = (avail > len) ? len : avail; + System.arraycopy(buffer, read_pos, b, off, avail); + read_pos += avail; + return avail; + } + } +}