package Task2;

public class SolutionWithNoSynchronization implements MemoryWrapper{

    private MemorySegment _memory = null;
    private boolean writing = false;
    private int readers = 0, writers = 0;

    public SolutionWithNoSynchronization(){
	_memory = new MemorySegment();
    }

    public void read(Process p){
    	p.setState("wantread");
    	beforeRead();
    	p.setState("reading");
    	_memory.read();
    	p.setState("idle");
    	afterRead();
    }

    public void write(Process p){
    	p.setState("wantwrite");
    	beforeWrite();
    	p.setState("writing");
    	_memory.write();
    	p.setState("idle");
    	afterWrite();
    }

    private synchronized void beforeRead() {
    	while(!okToRead()) {
    		try {
				wait();
			} catch (InterruptedException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
    	}
    	readers++;
    }

   	private synchronized void afterRead() {
   		readers--;
   		notifyAll();
    }

    private synchronized void beforeWrite() {
    	while(!okToWrite()) {
    		try {
				wait();
			} catch (InterruptedException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
    	}
    	writing = true;
    }

    private synchronized void afterWrite() {
    	writing = false;
    	notifyAll();
    }

    private boolean okToRead() {
    	return !writing;
    }

    private boolean okToWrite() {
		return !writing && readers == 0;
	}
}