/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
package org.apache.coyote;

import java.io.IOException;
import java.util.Iterator;
import java.util.Set;
import java.util.concurrent.CopyOnWriteArraySet;

import org.apache.juli.logging.Log;
import org.apache.tomcat.util.net.AbstractEndpoint.Handler.SocketState;
import org.apache.tomcat.util.net.DispatchType;
import org.apache.tomcat.util.net.SocketEvent;
import org.apache.tomcat.util.net.SocketWrapperBase;

This is a light-weight abstract processor implementation that is intended as
a basis for all Processor implementations from the light-weight upgrade
processors to the HTTP/AJP processors.
/**
 * This is a light-weight abstract processor implementation that is intended as
 * a basis for all Processor implementations from the light-weight upgrade
 * processors to the HTTP/AJP processors.
 */
public abstract class AbstractProcessorLight implements Processor {

    private Set<DispatchType> dispatches = new CopyOnWriteArraySet<>();


    @Override
    public SocketState process(SocketWrapperBase<?> socketWrapper, SocketEvent status)
            throws IOException {

        SocketState state = SocketState.CLOSED;
        Iterator<DispatchType> dispatches = null;
        do {
            if (dispatches != null) {
                DispatchType nextDispatch = dispatches.next();
                state = dispatch(nextDispatch.getSocketStatus());
            } else if (status == SocketEvent.DISCONNECT) {
                // Do nothing here, just wait for it to get recycled
            } else if (isAsync() || isUpgrade() || state == SocketState.ASYNC_END) {
                state = dispatch(status);
                if (state == SocketState.OPEN) {
                    // There may be pipe-lined data to read. If the data isn't
                    // processed now, execution will exit this loop and call
                    // release() which will recycle the processor (and input
                    // buffer) deleting any pipe-lined data. To avoid this,
                    // process it now.
                    state = service(socketWrapper);
                }
            } else if (status == SocketEvent.OPEN_WRITE) {
                // Extra write event likely after async, ignore
                state = SocketState.LONG;
            } else if (status == SocketEvent.OPEN_READ) {
                state = service(socketWrapper);
            } else if (status == SocketEvent.CONNECT_FAIL) {
                logAccess(socketWrapper);
            } else {
                // Default to closing the socket if the SocketEvent passed in
                // is not consistent with the current state of the Processor
                state = SocketState.CLOSED;
            }

            if (getLog().isDebugEnabled()) {
                getLog().debug("Socket: [" + socketWrapper +
                        "], Status in: [" + status +
                        "], State out: [" + state + "]");
            }

            if (state != SocketState.CLOSED && isAsync()) {
                state = asyncPostProcess();
                if (getLog().isDebugEnabled()) {
                    getLog().debug("Socket: [" + socketWrapper +
                            "], State after async post processing: [" + state + "]");
                }
            }

            if (dispatches == null || !dispatches.hasNext()) {
                // Only returns non-null iterator if there are
                // dispatches to process.
                dispatches = getIteratorAndClearDispatches();
            }
        } while (state == SocketState.ASYNC_END ||
                dispatches != null && state != SocketState.CLOSED);

        return state;
    }


    public void addDispatch(DispatchType dispatchType) {
        synchronized (dispatches) {
            dispatches.add(dispatchType);
        }
    }


    public Iterator<DispatchType> getIteratorAndClearDispatches() {
        // Note: Logic in AbstractProtocol depends on this method only returning
        // a non-null value if the iterator is non-empty. i.e. it should never
        // return an empty iterator.
        Iterator<DispatchType> result;
        synchronized (dispatches) {
            // Synchronized as the generation of the iterator and the clearing
            // of dispatches needs to be an atomic operation.
            result = dispatches.iterator();
            if (result.hasNext()) {
                dispatches.clear();
            } else {
                result = null;
            }
        }
        return result;
    }


    protected void clearDispatches() {
        synchronized (dispatches) {
            dispatches.clear();
        }
    }


    
Add an entry to the access log for a failed connection attempt.
Params:
socketWrapper – The connection to process
Throws:
IOException – If an I/O error occurs during the processing of the
        request/**
     * Add an entry to the access log for a failed connection attempt.
     *
     * @param socketWrapper The connection to process
     *
     * @throws IOException If an I/O error occurs during the processing of the
     *         request
     */
    protected void logAccess(SocketWrapperBase<?> socketWrapper) throws IOException {
        // NO-OP by default
    }


    
Service a 'standard' HTTP request. This method is called for both new requests and for requests that have partially read the HTTP request line or HTTP headers. Once the headers have been fully read this method is not called again until there is a new HTTP request to process. Note that the request type may change during processing which may result in one or more calls to dispatch(SocketEvent). Requests may be pipe-lined. 
Params:
socketWrapper – The connection to process
Throws:
IOException – If an I/O error occurs during the processing of the
        request
Returns:
The state the caller should put the socket in when this method
        returns/**
     * Service a 'standard' HTTP request. This method is called for both new
     * requests and for requests that have partially read the HTTP request line
     * or HTTP headers. Once the headers have been fully read this method is not
     * called again until there is a new HTTP request to process. Note that the
     * request type may change during processing which may result in one or more
     * calls to {@link #dispatch(SocketEvent)}. Requests may be pipe-lined.
     *
     * @param socketWrapper The connection to process
     *
     * @return The state the caller should put the socket in when this method
     *         returns
     *
     * @throws IOException If an I/O error occurs during the processing of the
     *         request
     */
    protected abstract SocketState service(SocketWrapperBase<?> socketWrapper) throws IOException;

    
Process an in-progress request that is not longer in standard HTTP mode.
Uses currently include Servlet 3.0 Async and HTTP upgrade connections.
Further uses may be added in the future. These will typically start as
HTTP requests.
Params:
status – The event to process
Throws:
IOException – If an I/O error occurs during the processing of the
        request
Returns:
The state the caller should put the socket in when this method
        returns/**
     * Process an in-progress request that is not longer in standard HTTP mode.
     * Uses currently include Servlet 3.0 Async and HTTP upgrade connections.
     * Further uses may be added in the future. These will typically start as
     * HTTP requests.
     *
     * @param status The event to process
     *
     * @return The state the caller should put the socket in when this method
     *         returns
     *
     * @throws IOException If an I/O error occurs during the processing of the
     *         request
     */
    protected abstract SocketState dispatch(SocketEvent status) throws IOException;

    protected abstract SocketState asyncPostProcess();

    protected abstract Log getLog();
}