com.netflix.concurrency.limits.servlet.ServletLimiterBuilder Maven / Gradle / Ivy

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/**
 * Copyright 2018 Netflix, Inc.
 *
 * Licensed 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 com.netflix.concurrency.limits.servlet;

import com.netflix.concurrency.limits.Limiter;
import com.netflix.concurrency.limits.limiter.AbstractPartitionedLimiter;

import javax.servlet.http.HttpServletRequest;
import java.security.Principal;
import java.util.Optional;
import java.util.function.Function;

/**
 * Builder to simplify creating a {@link Limiter} specific to a Servlet filter. By default,
 * the same concurrency limit is shared by all requests.  The limiter can be partitioned
 * based on one of many request attributes.  Only one type of partition may be specified.
 */
public final class ServletLimiterBuilder extends AbstractPartitionedLimiter.Builder {
    /**
     * Partition the limit by header
     * @return Chainable builder
     */
    public ServletLimiterBuilder partitionByHeader(String name) {
        return partitionResolver(request -> Optional.ofNullable(request.getHeader(name)).orElse(null));
    }
    
    /**
     * Partition the limit by {@link Principal}. Percentages of the limit are partitioned to named
     * groups.  Group membership is derived from the provided mapping function.
     * @param principalToGroup Mapping function from {@link Principal} to a named group.
     * @return Chainable builder
     */
    public ServletLimiterBuilder partitionByUserPrincipal(Function principalToGroup) {
        return partitionResolver(request -> Optional.ofNullable(request.getUserPrincipal()).map(principalToGroup).orElse(null));
    }
    
    /**
     * Partition the limit by request attribute
     * @return Chainable builder
     */
    public ServletLimiterBuilder partitionByAttribute(String name) {
        return partitionResolver(request -> Optional.ofNullable(request.getAttribute(name)).map(Object::toString).orElse(null));
    }
    
    /**
     * Partition the limit by request parameter
     * @return Chainable builder
     */
    public ServletLimiterBuilder partitionByParameter(String name) {
        return partitionResolver(request -> Optional.ofNullable(request.getParameter(name)).orElse(null));
    }
    
    /**
     * Partition the limit by the full path. Percentages of the limit are partitioned to named
     * groups.  Group membership is derived from the provided mapping function.
     * @param pathToGroup Mapping function from full path to a named group.
     * @return Chainable builder
     */
    public ServletLimiterBuilder partitionByPathInfo(Function pathToGroup) {
        return partitionResolver(request -> Optional.ofNullable(request.getPathInfo()).map(pathToGroup).orElse(null));
    }
    
    @Override
    protected ServletLimiterBuilder self() {
        return this;
    }
}