Github user HeartSaVioR commented on a diff in the pull request:
https://github.com/apache/spark/pull/22138#discussion_r214909826
--- Diff:
external/kafka-0-10-sql/src/main/scala/org/apache/spark/sql/kafka010/FetchedDataPool.scala
---
@@ -0,0 +1,160 @@
+/*
+ * 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.sql.kafka010
+
+import java.{util => ju}
+import java.util.concurrent.TimeUnit
+
+import scala.collection.mutable
+
+import org.apache.kafka.clients.consumer.ConsumerRecord
+
+import org.apache.spark.SparkEnv
+import org.apache.spark.sql.kafka010.KafkaDataConsumer.{CacheKey,
UNKNOWN_OFFSET}
+import org.apache.spark.util.ThreadUtils
+
+/**
+ * Provides object pool for [[FetchedData]] which is grouped by
[[CacheKey]].
+ *
+ * Along with CacheKey, it receives desired start offset to find cached
FetchedData which
+ * may be stored from previous batch. If it can't find one to match, it
will create
+ * a new FetchedData.
+ */
+private[kafka010] class FetchedDataPool {
+ import FetchedDataPool._
+
+ private[kafka010] case class CachedFetchedData(fetchedData: FetchedData)
{
+ var lastReleasedTimestamp: Long = Long.MaxValue
+ var lastAcquiredTimestamp: Long = Long.MinValue
+ var inUse: Boolean = false
+
+ def getObject: FetchedData = fetchedData
+ }
+
+ private object CachedFetchedData {
+ def empty(): CachedFetchedData = {
+ val emptyData = FetchedData(
+ ju.Collections.emptyListIterator[ConsumerRecord[Array[Byte],
Array[Byte]]],
+ UNKNOWN_OFFSET,
+ UNKNOWN_OFFSET)
+
+ CachedFetchedData(emptyData)
+ }
+ }
+
+ private type CachedFetchedDataList =
mutable.ListBuffer[CachedFetchedData]
+
+ private val cache: mutable.Map[CacheKey, CachedFetchedDataList] =
mutable.HashMap.empty
+
+ /** Retrieve internal cache. This method is only for testing. */
+ private[kafka010] def getCache: mutable.Map[CacheKey,
CachedFetchedDataList] = cache
+
+ private val (minEvictableIdleTimeMillis,
evictorThreadRunIntervalMillis): (Long, Long) = {
+ val conf = SparkEnv.get.conf
+
+ val minEvictIdleTime =
conf.getLong(CONFIG_NAME_MIN_EVICTABLE_IDLE_TIME_MILLIS,
+ DEFAULT_VALUE_MIN_EVICTABLE_IDLE_TIME_MILLIS)
+
+ val evictorThreadInterval = conf.getLong(
+ CONFIG_NAME_EVICTOR_THREAD_RUN_INTERVAL_MILLIS,
+ DEFAULT_VALUE_EVICTOR_THREAD_RUN_INTERVAL_MILLIS)
+
+ (minEvictIdleTime, evictorThreadInterval)
+ }
+
+ private val executorService =
ThreadUtils.newDaemonSingleThreadScheduledExecutor(
+ "kafka-fetched-data--cache-evictor")
+
+ private def startEvictorThread(): Unit = {
+ executorService.scheduleAtFixedRate(new Runnable() {
+ override def run(): Unit = {
+ removeIdleFetchedData()
+ }
+ }, 0, evictorThreadRunIntervalMillis, TimeUnit.MILLISECONDS)
+ }
+
+ startEvictorThread()
+
+ def acquire(key: CacheKey, desiredStartOffset: Long): FetchedData =
synchronized {
+ val fetchedDataList = cache.getOrElseUpdate(key, new
CachedFetchedDataList())
+
+ val cachedFetchedDataOption = fetchedDataList.find { p =>
+ !p.inUse && p.getObject.nextOffsetInFetchedData == desiredStartOffset
+ }
+
+ var cachedFetchedData: CachedFetchedData = null
+ if (cachedFetchedDataOption.isDefined) {
+ cachedFetchedData = cachedFetchedDataOption.get
+ } else {
+ cachedFetchedData = CachedFetchedData.empty()
+ fetchedDataList += cachedFetchedData
+ }
+
+ cachedFetchedData.lastAcquiredTimestamp = System.currentTimeMillis()
+ cachedFetchedData.inUse = true
+
+ cachedFetchedData.getObject
+ }
+
+ def invalidate(key: CacheKey): Unit = synchronized {
+ cache.remove(key)
+ }
+
+ def release(key: CacheKey, fetchedData: FetchedData): Unit =
synchronized {
+ cache.get(key) match {
+ case Some(fetchedDataList) =>
+ val cachedFetchedDataOption = fetchedDataList.find { p =>
+ p.inUse && p.getObject == fetchedData
+ }
+
+ if (cachedFetchedDataOption.isDefined) {
+ val cachedFetchedData = cachedFetchedDataOption.get
+ cachedFetchedData.inUse = false
+ cachedFetchedData.lastReleasedTimestamp =
System.currentTimeMillis()
+ }
+
+ case None =>
--- End diff --
Yeah sometimes yes and sometimes ignorable thing, I intended to avoid the
situation which end users are confused with false-negative, but I'm also open
to add log message for that.
Let me add some warning message, and if some reviewer stated the level or
removing log, we can revisit it later.
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