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/*
* 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.catalina.util;
import jakarta.servlet.FilterConfig;
public interface RateLimiter {
/**
* @return the actual duration of a time window in seconds
*/
int getDuration();
/**
* Sets the configured duration value in seconds.
*
* @param duration The duration of the time window in seconds
*/
void setDuration(int duration);
/**
* @return the maximum number of requests allowed per time window
*/
int getRequests();
/**
* Sets the configured number of requests allowed per time window.
*
* @param requests The number of requests per time window
*/
void setRequests(int requests);
/**
* Increments the number of requests by the given identifier in the current time window.
*
* @param identifier the identifier for which the number of associated requests should be incremented
*
* @return the new value after incrementing
*/
int increment(String identifier);
/**
* Cleanup no longer needed resources.
*/
void destroy();
/**
* Pass the FilterConfig to configure the filter.
*
* @param filterConfig The FilterConfig used to configure the associated filter
*/
void setFilterConfig(FilterConfig filterConfig);
/**
* @return name of RateLimit policy
*/
String getPolicyName();
/**
* Sets the policy name, otherwise an auto-generated name is used.
*
* @param name of rate limit policy
*/
void setPolicyName(String name);
/**
* @return full representation of current policy
*
* @see <a href="https://datatracker.ietf.org/doc/draft-ietf-httpapi-ratelimit-headers">RateLimit header fields for
* HTTP (draft)</a>
*/
default String getPolicy() {
// enclose policy name with double quotes. e.g. "fixed-01";q=3000;w=60
return "\"" + getPolicyName() + "\";q=" + getRequests() + ";w=" + getDuration();
}
/**
* Provide the quota header for this rate limit for a given request count within the current time window.
*
* @param requestCount The request count within the current time window
*
* @return the quota header for the given value of request count
*
* @see <a href="https://datatracker.ietf.org/doc/draft-ietf-httpapi-ratelimit-headers">RateLimit header fields for
* HTTP (draft)</a>
*/
default String getQuota(int requestCount) {
// Local copy to ensure consistency
int maxRequests = getRequests();
int remaining = (requestCount < 0 || requestCount > maxRequests) ? 0 : (maxRequests - requestCount);
return "\"" + getPolicyName() + "\";r=" + remaining;
}
}
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