ConcurrentBufferInputStream.java

// ConcurrentBufferInputStream.java -- read bytes from blocking queue
// Copyright (c)2007 Christopher League <league@contrapunctus.net>

// This is free software, but it comes with ABSOLUTELY NO WARRANTY.
// GNU Lesser General Public License 2.1 or Common Public License 1.0

package net.contrapunctus.lzma;

import java.io.IOException;
import java.io.InputStream;
import java.io.InterruptedIOException;
import java.io.PrintStream;
import java.util.concurrent.ArrayBlockingQueue;

class ConcurrentBufferInputStream extends InputStream
{
    protected ArrayBlockingQueue<byte[]> q;
    protected byte[]                     buf  = null;
    protected int                        next = 0;
    protected boolean                    eof  = false;
    
    private static final PrintStream     dbg  = System.err;
    private static final boolean         DEBUG;
    
    static
    {
        String ds = null;
        try
        {
            ds = System.getProperty("DEBUG_ConcurrentBuffer");
        }
        catch (final SecurityException e)
        {
        }
        DEBUG = ds != null;
    }
    
    private ConcurrentBufferInputStream(ArrayBlockingQueue<byte[]> q)
    {
        if (DEBUG)
        {
            dbg.printf("%s << %s%n", this, q);
        }
        this.q = q;
        eof = false;
    }
    
    static InputStream create(ArrayBlockingQueue<byte[]> q)
    {
        final InputStream in = new ConcurrentBufferInputStream(q);
        return in;
    }
    
    protected byte[] guarded_take() throws IOException
    {
        try
        {
            return q.take();
        }
        catch (final InterruptedException exn)
        {
            throw new InterruptedIOException(exn.getMessage());
        }
    }
    
    protected boolean prepareAndCheckEOF() throws IOException
    {
        if (eof)
        {
            return true;
        }
        if (buf == null || next >= buf.length)
        {
            buf = guarded_take();
            next = 0;
            if (buf.length == 0)
            {
                eof = true;
                return true;
            }
        }
        return false;
    }
    
    
    public int read() throws IOException
    {
        if (prepareAndCheckEOF())
        {
            return -1;
        }
        final int x = buf[next];
        next++;
        return x & 0xff;
    }
    
    
    public int read(byte[] b, int off, int len) throws IOException
    {
        if (prepareAndCheckEOF())
        {
            return -1;
        }
        int k = buf.length - next;
        if (len < k)
        {
            k = len;
        }
        System.arraycopy(buf, next, b, off, k);
        next += k;
        return k;
    }
    
    
    public String toString()
    {
        return String.format("cbIn@%x", hashCode());
    }
}