public CyclicBuffer(int maxSize) throws IllegalArgumentException 
{
    if(maxSize <  1) {
      throw new IllegalArgumentException("The maxSize argument ("+maxSize+
			    ") is not a positive integer.");
    }
    this.maxSize = maxSize;
    ea = new LoggingEvent[maxSize];
    first = 0;
    last = 0;
    numElems = 0;
}

Instantiate a new CyclicBuffer of at most maxSize events. The maxSize argument must a positive integer.

Parameters:

maxSize - The maximum number of elements in the buffer.

 public  void add(LoggingEvent event) 
{
    
    ea[last] = event;    
    if(++last == maxSize)
      last = 0;
    if(numElems <  maxSize)
      numElems++;
    else if(++first == maxSize)
      first = 0;
}

Add an event as the last event in the buffer.

 public LoggingEvent get() 
{
    LoggingEvent r = null;
    if(numElems  > 0) {
      numElems--;
      r = ea[first];
      ea[first] = null;
      if(++first == maxSize)
	first = 0;
    } 
    return r;
}

Get the oldest (first) element in the buffer. The oldest element is removed from the buffer.

 public LoggingEvent get(int i) 
{
    if(i <  0 || i  >= numElems)
      return null;
    return ea[(first + i) % maxSize];
}

Get the ith oldest event currently in the buffer. If i is outside the range 0 to the number of elements currently in the buffer, then null is returned.

 public int getMaxSize() 
{
    return maxSize;
}

 public int length() 
{
    return numElems;
}

Get the number of elements in the buffer. This number is guaranteed to be in the range 0 to maxSize (inclusive).

 public  void resize(int newSize) 
{
    if(newSize <  0) {
      throw new IllegalArgumentException("Negative array size ["+newSize+
					 "] not allowed.");
    }
    if(newSize == numElems)
      return; // nothing to do
    LoggingEvent[] temp = new  LoggingEvent[newSize];
    int loopLen = newSize <  numElems ? newSize : numElems;
    for(int i = 0; i <  loopLen; i++) {
      temp[i] = ea[first];
      ea[first] = null;
      if(++first == numElems) 
	first = 0;
    }
    ea = temp;
    first = 0;
    numElems = loopLen;
    maxSize = newSize;
    if (loopLen == newSize) {
      last = 0;
    } else {
      last = loopLen;
    }
}

Resize the cyclic buffer to newSize.