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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.spark.streaming.receiver
import com.google.common.util.concurrent.{RateLimiter => GuavaRateLimiter}
import org.apache.spark.SparkConf
import org.apache.spark.internal.Logging
/**
* Provides waitToPush() method to limit the rate at which receivers consume data.
*
* waitToPush method will block the thread if too many messages have been pushed too quickly,
* and only return when a new message has been pushed. It assumes that only one message is
* pushed at a time.
*
* The spark configuration spark.streaming.receiver.maxRate gives the maximum number of messages
* per second that each receiver will accept.
*
* @param conf spark configuration
*/
private[receiver] abstract class RateLimiter(conf: SparkConf) extends Logging {
// treated as an upper limit
private val maxRateLimit = conf.getLong("spark.streaming.receiver.maxRate", Long.MaxValue)
private lazy val rateLimiter = GuavaRateLimiter.create(getInitialRateLimit().toDouble)
def waitToPush(): Unit = {
rateLimiter.acquire()
}
/**
* Return the current rate limit. If no limit has been set so far, it returns {{{Long.MaxValue}}}.
*/
def getCurrentLimit: Long = rateLimiter.getRate.toLong
/**
* Set the rate limit to `newRate`. The new rate will not exceed the maximum rate configured by
* {{{spark.streaming.receiver.maxRate}}}, even if `newRate` is higher than that.
*
* @param newRate A new rate in records per second. It has no effect if it's 0 or negative.
*/
private[receiver] def updateRate(newRate: Long): Unit =
if (newRate > 0) {
if (maxRateLimit > 0) {
rateLimiter.setRate(newRate.min(maxRateLimit))
} else {
rateLimiter.setRate(newRate)
}
}
/**
* Get the initial rateLimit to initial rateLimiter
*/
private def getInitialRateLimit(): Long = {
math.min(conf.getLong("spark.streaming.backpressure.initialRate", maxRateLimit), maxRateLimit)
}
}
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