// ThrottledOutputStream - output stream with throttling
//
// Copyright (C)1996,1998 by Jef Poskanzer <jef@acme.com>. All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
// 1. Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
// OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
// HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
// OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
// SUCH DAMAGE.
//
// Visit the ACME Labs Java page for up-to-date versions of this and other
// fine Java utilities: http://www.acme.com/java/
package Acme.Serve;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.OutputStream;
/// Output stream with throttling.
// <P>
// Restricts output to a specified rate. Also includes a static utility
// routine for parsing a file of throttle settings.
// <P>
// <A HREF="/resources/classes/Acme/Serve/ThrottledOutputStream.java">Fetch the software.</A><BR>
// <A HREF="/resources/classes/Acme.tar.Z">Fetch the entire Acme package.</A>
public class ThrottledOutputStream extends FilterOutputStream {
// / Parses a standard throttle file.
// <P>
// A throttle file lets you set maximum byte rates on filename patterns.
// The format of the throttle file is very simple. A # starts a
// comment, and the rest of the line is ignored. Blank lines are ignored.
// The rest of the lines should consist of a pattern, whitespace, and a
// number. The pattern is a simple shell-style filename pattern, using
// ? and *, or multiple such patterns separated by |.
// <P>
// The numbers in the file are byte rates, specified in units of bytes
// per second. For comparison, a v.32b/v.42b modem gives about
// 1500/2000 B/s depending on compression, a double-B-channel ISDN line
// about 12800 B/s, and a T1 line is about 150000 B/s.
// <P>
// Example:
// <BLOCKQUOTE><PRE>
// # throttle file for www.acme.com
// * 100000 # limit total web usage to 2/3 of our T1
// *.jpg|*.gif 50000 # limit images to 1/3 of our T1
// *.mpg 20000 # and movies to even less
// jef/* 20000 # jef's pages are too popular
// </PRE></BLOCKQUOTE>
// <P>
// The routine returns a WildcardDictionary. Do a lookup in this
// dictionary using a filename, and you'll get back a ThrottleItem
// containing the corresponding byte rate.
public static Acme.WildcardDictionary parseThrottleFile(String filename) throws IOException {
Acme.WildcardDictionary wcd = new Acme.WildcardDictionary();
File thFile = new File(filename);
if (thFile.isAbsolute() == false)
thFile = new File(System.getProperty("user.dir", "."), thFile.getName());
BufferedReader br = new BufferedReader(new FileReader(thFile));
while (true) {
String line = br.readLine();
if (line == null)
break;
int i = line.indexOf('#');
if (i != -1)
line = line.substring(0, i);
line = line.trim();
if (line.length() == 0)
continue;
String[] words = Acme.Utils.splitStr(line);
if (words.length != 2)
throw new IOException("malformed throttle line: " + line);
try {
wcd.put(words[0], new ThrottleItem(Long.parseLong(words[1])));
} catch (NumberFormatException e) {
throw new IOException("malformed number in throttle line: " + line);
}
}
br.close();
return wcd;
}
private long maxBps;
private long bytes;
private long start;
// / Constructor.
public ThrottledOutputStream(OutputStream out, long maxBps) {
super(out);
this.maxBps = maxBps;
bytes = 0;
start = System.currentTimeMillis();
}
private byte[] oneByte = new byte[1];
// / Writes a byte. This method will block until the byte is actually
// written.
// @param b the byte to be written
// @exception IOException if an I/O error has occurred
public void write(int b) throws IOException {
oneByte[0] = (byte) b;
write(oneByte, 0, 1);
}
// / Writes a subarray of bytes.
// @param b the data to be written
// @param off the start offset in the data
// @param len the number of bytes that are written
// @exception IOException if an I/O error has occurred
public void write(byte b[], int off, int len) throws IOException {
// Check the throttle.
bytes += len;
long elapsed = Math.max(System.currentTimeMillis() - start, 1);
long bps = bytes * 1000L / elapsed;
if (bps > maxBps) {
// Oops, sending too fast.
long wakeElapsed = bytes * 1000L / maxBps;
try {
Thread.sleep(wakeElapsed - elapsed);
} catch (InterruptedException ignore) {
}
}
// Write the bytes.
out.write(b, off, len);
}
}