src/main/java/org/apache/sling/engine/impl/filter/SlingFilterChainHelper.java

/*
 * 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.sling.engine.impl.filter;

import javax.servlet.Filter;

import java.util.Iterator;
import java.util.SortedSet;
import java.util.TreeSet;

/**
 * The <code>SlingFilterChainHelper</code> class is used by Sling to
 * support building lists of <code>Filter</code>s. To ensure filter
 * ordering, each filter is optionally registered with an ordering index. If
 * none is provided the default ordering index is Integer.MAX_VALUE to append
 * the filter to the end of the list.
 */
public class SlingFilterChainHelper {

    private static final FilterHandle[] EMPTY_FILTER_ARRAY = new FilterHandle[0];

    private final SortedSet<FilterHandle> filterList = new TreeSet<FilterHandle>();

    private volatile FilterHandle[] filters = EMPTY_FILTER_ARRAY;

    /**
     * Add a filter
     * @param filter The filter
     * @param pattern Optional pattern
     * @param filterId Id of the filter
     * @param order The order index
     * @param orderSource The source for the order
     * @param mbean MBean
     */
    public synchronized void addFilter(
            final Filter filter,
            FilterPredicate pattern,
            final long filterId,
            final int order,
            final String orderSource,
            FilterProcessorMBeanImpl mbean) {
        this.filterList.add(new FilterHandle(filter, pattern, filterId, order, orderSource, mbean));
        this.filters = getFiltersInternal();
    }

    public synchronized boolean removeFilterById(final long filterId) {
        for (Iterator<FilterHandle> fi = filterList.iterator(); fi.hasNext(); ) {
            final FilterHandle test = fi.next();
            if (test.getFilterId() == filterId) {
                fi.remove();
                this.filters = getFiltersInternal();
                return true;
            }
        }

        // no removed filter
        return false;
    }

    /**
     * Returns the list of {@code Filter}s added to this instance.
     * The array might be empty
     * This method doesn't need to be synced as the update is atomioc.
     * @return the filters
     */
    public FilterHandle[] getFilters() {
        return filters;
    }

    private FilterHandle[] getFiltersInternal() {
        if (filterList.isEmpty()) {
            return EMPTY_FILTER_ARRAY;
        }
        return filterList.toArray(new FilterHandle[filterList.size()]);
    }
}