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/*******************************************************************************
* ============LICENSE_START=======================================================
* slice-analysis-ms
* ================================================================================
* Copyright (C) 2022 Huawei Canada Limited.
* ==============================================================================
* 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.
* ============LICENSE_END=========================================================
*
*******************************************************************************/
package org.onap.slice.analysis.ms.service;
/**
* A simple rate-limiter; make sure bandwidth adjustment requests don't swarm underlying network controller
*/
class RateLimiter {
private int MAX_TOKENS;
private long lastRequestTime = System.currentTimeMillis();
private long possibleTokens = 0;
private long interval = 1000;
/**
* Constructor for rate limiter (simple token bucket filter)
* @param maxTokens max number of token allowed
* @param interval interval(ms) between received new token
*/
public RateLimiter(int maxTokens, int interval){
MAX_TOKENS = maxTokens;
this.interval = interval;
}
/**
* Trying to get a new token for execution, if no token left, stall for interval ms.
* @throws InterruptedException
*/
synchronized public void getToken() throws InterruptedException {
possibleTokens += (System.currentTimeMillis() - lastRequestTime) / interval;
if (possibleTokens > MAX_TOKENS){
possibleTokens = MAX_TOKENS;
}
if (possibleTokens == 0){
Thread.sleep(interval);
} else {
possibleTokens--;
}
// granting token
lastRequestTime = System.currentTimeMillis();
}
}
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