package org.apache.coyote;
import java.util.ArrayDeque;
import java.util.Deque;

import org.apache.coyote.AbstractProtocol.ConnectionHandler;
import org.apache.tomcat.util.collections.SynchronizedStack;

	protected static class RecycledProcessors {

        private final transient ConnectionHandler<?> handler;
        private final Deque<Processor> queue = new ArrayDeque<>(SynchronizedStack.DEFAULT_SIZE);

        public RecycledProcessors(ConnectionHandler<?> handler) {
            this.handler = handler;
        }

        @SuppressWarnings("sync-override") // Size may exceed cache size a bit
        public boolean push(Processor processor) {
        	synchronized (queue) {
        		if ( queue.contains(processor) ) {
        			return true;
        		}
        	}
            int cacheSize = handler.getProtocol().getProcessorCache();
            boolean offer = true;
            if ( cacheSize != -1 ) {
            	synchronized (queue) {
            		offer = queue.size() < cacheSize;
            	}
            }
            //avoid over growing our cache or add after we have stopped
            boolean result = false;
            if (offer) {
            	synchronized (queue) {
            		result = queue.offerLast(processor);
            	}
            }
            if (!result) handler.unregister(processor);
            return result;
        }

        @SuppressWarnings("sync-override") // OK if size is too big briefly
        public Processor pop() {
        	synchronized (queue) {
        		return queue.pollLast();
        	}
        }

        public void clear() {
        	synchronized (queue) {
        		Processor next = pop();
        		while (next != null) {
        			handler.unregister(next);
        			next = pop();
        		}
        	}
        }
    }