Byte FIFO
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
public class ByteFIFOTest extends Object {
private ByteFIFO fifo;
private byte[] srcData;
public ByteFIFOTest() throws IOException {
fifo = new ByteFIFO(20);
makeSrcData();
System.out.println("srcData.length=" + srcData.length);
Runnable srcRunnable = new Runnable() {
public void run() {
src();
}
};
Thread srcThread = new Thread(srcRunnable);
srcThread.start();
Runnable dstRunnable = new Runnable() {
public void run() {
dst();
}
};
Thread dstThread = new Thread(dstRunnable);
dstThread.start();
}
private void makeSrcData() throws IOException {
String[] list = {
"The first string is right here",
"The second string is a bit longer and also right here",
"The third string",
"ABCDEFGHIJKLMNOPQRSTUVWXYZ",
"0123456789",
"The last string in the list"
};
ByteArrayOutputStream baos = new ByteArrayOutputStream();
ObjectOutputStream oos = new ObjectOutputStream(baos);
oos.writeObject(list);
oos.flush();
oos.close();
srcData = baos.toByteArray();
}
private void src() {
try {
boolean justAddOne = true;
int count = 0;
while ( count < srcData.length ) {
if ( !justAddOne ) {
int writeSize = (int) ( 40.0 * Math.random() );
writeSize = Math.min(writeSize, srcData.length - count);
byte[] buf = new byte[writeSize];
System.arraycopy(srcData, count, buf, 0, writeSize);
fifo.add(buf);
count += writeSize;
System.out.println("just added " + writeSize + " bytes");
} else {
fifo.add(srcData[count]);
count++;
System.out.println("just added exactly 1 byte");
}
justAddOne = !justAddOne;
}
} catch ( InterruptedException x ) {
x.printStackTrace();
}
}
private void dst() {
try {
boolean justAddOne = true;
int count = 0;
byte[] dstData = new byte[srcData.length];
while ( count < dstData.length ) {
if ( !justAddOne ) {
byte[] buf = fifo.removeAll();
if ( buf.length > 0 ) {
System.arraycopy(buf, 0, dstData, count, buf.length);
count += buf.length;
}
System.out.println(
"just removed " + buf.length + " bytes");
} else {
byte b = fifo.remove();
dstData[count] = b;
count++;
System.out.println(
"just removed exactly 1 byte");
}
justAddOne = !justAddOne;
}
System.out.println("received all data, count=" + count);
ObjectInputStream ois = new ObjectInputStream(
new ByteArrayInputStream(dstData));
String[] line = (String[]) ois.readObject();
for ( int i = 0; i < line.length; i++ ) {
System.out.println("line[" + i + "]=" + line[i]);
}
} catch ( ClassNotFoundException x1 ) {
x1.printStackTrace();
} catch ( IOException iox ) {
iox.printStackTrace();
} catch ( InterruptedException x ) {
x.printStackTrace();
}
}
public static void main(String[] args) {
try {
new ByteFIFOTest();
} catch ( IOException iox ) {
iox.printStackTrace();
}
}
}
class ByteFIFO extends Object {
private byte[] queue;
private int capacity;
private int size;
private int head;
private int tail;
public ByteFIFO(int cap) {
capacity = ( cap > 0 ) ? cap : 1; // at least 1
queue = new byte[capacity];
head = 0;
tail = 0;
size = 0;
}
public int getCapacity() {
return capacity;
}
public synchronized int getSize() {
return size;
}
public synchronized boolean isEmpty() {
return ( size == 0 );
}
public synchronized boolean isFull() {
return ( size == capacity );
}
public synchronized void add(byte b)
throws InterruptedException {
waitWhileFull();
queue[head] = b;
head = ( head + 1 ) % capacity;
size++;
notifyAll(); // let any waiting threads know about change
}
public synchronized void add(byte[] list)
throws InterruptedException {
// For efficiency, the bytes are copied in blocks
// instead of one at a time. As space becomes available,
// more bytes are copied until all of them have been
// added.
int ptr = 0;
while ( ptr < list.length ) {
// If full, the lock will be released to allow
// another thread to come in and remove bytes.
waitWhileFull();
int space = capacity - size;
int distToEnd = capacity - head;
int blockLen = Math.min(space, distToEnd);
int bytesRemaining = list.length - ptr;
int copyLen = Math.min(blockLen, bytesRemaining);
System.arraycopy(list, ptr, queue, head, copyLen);
head = ( head + copyLen ) % capacity;
size += copyLen;
ptr += copyLen;
// Keep the lock, but let any waiting threads
// know that something has changed.
notifyAll();
}
}
public synchronized byte remove()
throws InterruptedException {
waitWhileEmpty();
byte b = queue[tail];
tail = ( tail + 1 ) % capacity;
size--;
notifyAll(); // let any waiting threads know about change
return b;
}
public synchronized byte[] removeAll() {
// For efficiency, the bytes are copied in blocks
// instead of one at a time.
if ( isEmpty() ) {
// Nothing to remove, return a zero-length
// array and do not bother with notification
// since nothing was removed.
return new byte[0];
}
// based on the current size
byte[] list = new byte[size];
// copy in the block from tail to the end
int distToEnd = capacity - tail;
int copyLen = Math.min(size, distToEnd);
System.arraycopy(queue, tail, list, 0, copyLen);
// If data wraps around, copy the remaining data
// from the front of the array.
if ( size > copyLen ) {
System.arraycopy(
queue, 0, list, copyLen, size - copyLen);
}
tail = ( tail + size ) % capacity;
size = 0; // everything has been removed
// Signal any and all waiting threads that
// something has changed.
notifyAll();
return list;
}
public synchronized byte[] removeAtLeastOne()
throws InterruptedException {
waitWhileEmpty(); // wait for a least one to be in FIFO
return removeAll();
}
public synchronized boolean waitUntilEmpty(long msTimeout)
throws InterruptedException {
if ( msTimeout == 0L ) {
waitUntilEmpty(); // use other method
return true;
}
// wait only for the specified amount of time
long endTime = System.currentTimeMillis() + msTimeout;
long msRemaining = msTimeout;
while ( !isEmpty() && ( msRemaining > 0L ) ) {
wait(msRemaining);
msRemaining = endTime - System.currentTimeMillis();
}
// May have timed out, or may have met condition,
// calc return value.
return isEmpty();
}
public synchronized void waitUntilEmpty()
throws InterruptedException {
while ( !isEmpty() ) {
wait();
}
}
public synchronized void waitWhileEmpty()
throws InterruptedException {
while ( isEmpty() ) {
wait();
}
}
public synchronized void waitUntilFull()
throws InterruptedException {
while ( !isFull() ) {
wait();
}
}
public synchronized void waitWhileFull()
throws InterruptedException {
while ( isFull() ) {
wait();
}
}
}
Related examples in the same category
