atris commented on a change in pull request #1686: URL: https://github.com/apache/lucene-solr/pull/1686#discussion_r465515893
########## File path: solr/core/src/java/org/apache/solr/servlet/RateLimitManager.java ########## @@ -0,0 +1,148 @@ +/* + * 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.solr.servlet; + +import javax.servlet.FilterConfig; +import javax.servlet.http.HttpServletRequest; +import java.util.HashMap; +import java.util.Map; +import java.util.concurrent.ConcurrentHashMap; + +import org.apache.solr.client.solrj.SolrRequest; + +import static org.apache.solr.common.params.CommonParams.SOLR_REQUEST_CONTEXT_PARAM; +import static org.apache.solr.common.params.CommonParams.SOLR_REQUEST_TYPE_PARAM; + +/** + * This class is responsible for managing rate limiting per request type. Rate limiters + * can be registered with this class against a corresponding type. There can be only one + * rate limiter associated with a request type. + * + * The actual rate limiting and the limits should be implemented in the corresponding RequestRateLimiter + * implementation. RateLimitManager is responsible for the orchestration but not the specifics of how the + * rate limiting is being done for a specific request type. + */ +public class RateLimitManager { + public final static int DEFAULT_CONCURRENT_REQUESTS= (Runtime.getRuntime().availableProcessors()) * 3; + public final static long DEFAULT_SLOT_ACQUISITION_TIMEOUT_MS = -1; + private final Map<String, RequestRateLimiter> requestRateLimiterMap; + private final Map<HttpServletRequest, RequestRateLimiter> activeRequestsMap; + + public RateLimitManager() { + this.requestRateLimiterMap = new HashMap<>(); + this.activeRequestsMap = new ConcurrentHashMap<>(); + } + + // Handles an incoming request. The main orchestration code path, this method will + // identify which (if any) rate limiter can handle this request. Internal requests will not be + // rate limited + // Returns true if request is accepted for processing, false if it should be rejected + public boolean handleRequest(HttpServletRequest request) throws InterruptedException { + String requestContext = request.getHeader(SOLR_REQUEST_CONTEXT_PARAM); + String typeOfRequest = request.getHeader(SOLR_REQUEST_TYPE_PARAM); + + if (typeOfRequest == null) { + // Cannot determine if this request should be throttled + return true; + } + + // Do not throttle internal requests + if (requestContext != null && requestContext.equals(SolrRequest.SolrClientContext.SERVER.toString())) { + return true; + } + + RequestRateLimiter requestRateLimiter = requestRateLimiterMap.get(typeOfRequest); + + if (requestRateLimiter == null) { + // No request rate limiter for this request type + return true; + } + + if (requestRateLimiter.handleRequest()) { + activeRequestsMap.put(request, requestRateLimiter); + return true; + } + + requestRateLimiter = trySlotBorrowing(typeOfRequest); + + if (requestRateLimiter != null) { + activeRequestsMap.put(request, requestRateLimiter); + return true; + } + + return false; + } + + /* For a rejected request type, do the following: + * For each request rate limiter whose type that is not of the type of the request which got rejected, + * check if slot borrowing is enabled. If enabled, try to acquire a slot. + * If allotted, return else try next request type. + */ + private RequestRateLimiter trySlotBorrowing(String requestType) { + for (Map.Entry<String, RequestRateLimiter> currentEntry : requestRateLimiterMap.entrySet()) { + RequestRateLimiter requestRateLimiter = currentEntry.getValue(); + + if (requestRateLimiter.getRateLimiterConfig().requestType.equals(requestType)) { + continue; + } + + if (requestRateLimiter.getRateLimiterConfig().isSlotBorrowingEnabled && requestRateLimiter.allowSlotBorrowing()) { + return requestRateLimiter; + } + } + + return null; + } + + // Decrement the active requests in the rate limiter for the corresponding request type. + public void decrementActiveRequests(HttpServletRequest request) { Review comment: Discussed offline. Marking experimental and will follow up with a JIRA for rethinking the same. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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