#811 Add read properties hash code as index key to avoid false cache

cobol-parser/src/main/scala/za/co/absa/cobrix/cobol/reader/VarLenNestedReader.scala

@@ -221,7 +221,10 @@ class VarLenNestedReader[T: ClassTag](copybookContents: Seq[String],
     if (isCompressed) {
       readerProperties.inputSplitSizeCompressedMB.orElse(Some(DEFAULT_INDEX_SIZE_COMPRESSED_FILES_MB))
     } else {
-      readerProperties.inputSplitSizeMB.orElse(readerProperties.fsDefaultBlockSize).map(_ * DEFAULT_FS_INDEX_SIZE_MULTIPLIER)
+      val defaultIndexSizeBofFsBlock = readerProperties.fsDefaultBlockSize.map { size =>
+        Math.min(size * DEFAULT_FS_INDEX_SIZE_MULTIPLIER, 256)
+      }
+      readerProperties.inputSplitSizeMB.orElse(defaultIndexSizeBofFsBlock)
     }
   }
 

spark-cobol/src/main/scala/za/co/absa/cobrix/spark/cobol/source/index/IndexBuilder.scala

@@ -32,9 +32,8 @@ import za.co.absa.cobrix.spark.cobol.source.SerializableConfiguration
 import za.co.absa.cobrix.spark.cobol.source.parameters.LocalityParameters
 import za.co.absa.cobrix.spark.cobol.source.streaming.FileStreamer
 import za.co.absa.cobrix.spark.cobol.source.types.FileWithOrder
-import za.co.absa.cobrix.spark.cobol.utils.{FileUtils, HDFSUtils, SparkUtils}
+import za.co.absa.cobrix.spark.cobol.utils.{FileUtils, HDFSUtils, LRUCache, SparkUtils}
 
-import java.util.concurrent.ConcurrentHashMap
 import scala.collection.mutable.ArrayBuffer
 
 /**
@@ -46,7 +45,9 @@ import scala.collection.mutable.ArrayBuffer
   * In a nutshell, ideally, there will be as many partitions as are there are indexes.
   */
 private[cobol] object IndexBuilder extends Logging {
-  private[cobol] val indexCache = new ConcurrentHashMap[String, Array[SparseIndexEntry]]()
+  private val maxCacheSize = 10000
+
+  private[cobol] val indexCache = new LRUCache[IndexKey, Array[SparseIndexEntry]](maxCacheSize)
 
   def buildIndex(filesList: Array[FileWithOrder],
                  cobolReader: Reader,
@@ -123,10 +124,11 @@ private[cobol] object IndexBuilder extends Logging {
                                                cachingAllowed: Boolean): RDD[SparseIndexEntry] = {
     val conf = sqlContext.sparkContext.hadoopConfiguration
     val sconf = new SerializableConfiguration(conf)
+    val readerOptionsHashCode = reader.getReaderProperties.hashCode()
 
     // Splitting between files for which indexes are cached and the list of files for which indexes are not cached
     val cachedFiles = if (cachingAllowed) {
-      filesList.filter(f => indexCache.containsKey(f.filePath))
+      filesList.filter(f => indexCache.containsKey(IndexKey(f.filePath, readerOptionsHashCode)))
     } else {
       Array.empty[FileWithOrder]
     }
@@ -157,15 +159,15 @@ private[cobol] object IndexBuilder extends Logging {
 
         filePathOpt.foreach { filePath =>
           logger.info(s"Index stored to cache for file: $filePath.")
-          indexCache.put(filePath, indexEntries.sortBy(_.offsetFrom))
+          indexCache.put(IndexKey(filePath, readerOptionsHashCode), indexEntries.sortBy(_.offsetFrom))
         }
       }
     }
 
     // Getting indexes for files for which indexes are in the cache
     val cachedIndexes = cachedFiles.flatMap { f =>
       logger.info("Index fetched from cache for file: " + f.filePath)
-      indexCache.get(f.filePath)
+      indexCache(IndexKey(f.filePath, readerOptionsHashCode))
         .map(ind => ind.copy(fileId = f.order))
     }
 

spark-cobol/src/main/scala/za/co/absa/cobrix/spark/cobol/source/index/IndexKey.scala

@@ -0,0 +1,19 @@
+/*
+ * Copyright 2018 ABSA Group 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.
+ */
+
+package za.co.absa.cobrix.spark.cobol.source.index
+
+case class IndexKey(fileName: String, optionsHashCode: Long)

spark-cobol/src/main/scala/za/co/absa/cobrix/spark/cobol/utils/LRUCache.scala

@@ -0,0 +1,49 @@
+/*
+ * Copyright 2018 ABSA Group 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.
+ */
+
+package za.co.absa.cobrix.spark.cobol.utils
+
+import scala.collection.JavaConverters._
+
+class LRUCache[K,V](maxSize: Int, loadFactor: Float = 0.75f) {
+  private val cache = new java.util.LinkedHashMap[K, V](16, loadFactor, true) {
+    override def removeEldestEntry(eldest: java.util.Map.Entry[K, V]): Boolean = size() > maxSize
+  }
+
+  def apply(key: K): V = synchronized {
+    cache.get(key)
+  }
+
+  def containsKey(key: K): Boolean = synchronized {
+    cache.containsKey(key)
+  }
+
+  def get(key: K): Option[V] = synchronized {
+    Option(cache.get(key))
+  }
+
+  def getMap: Map[K, V] = synchronized {
+    cache.asScala.toMap
+  }
+
+  def put(key: K, value: V): Unit = synchronized {
+    cache.put(key, value)
+  }
+
+  def remove(key: K): Unit = synchronized {
+    cache.remove(key)
+  }
+}

spark-cobol/src/test/scala/za/co/absa/cobrix/spark/cobol/source/integration/Test37RecordLengthMappingSpec.scala

@@ -197,8 +197,12 @@ class Test37RecordLengthMappingSpec extends AnyWordSpec with SparkTestBase with
 
         val pathNameAsCached = s"file:$tempFile"
 
-        assert(IndexBuilder.indexCache.get(pathNameAsCached) != null)
-        assert(IndexBuilder.indexCache.get(pathNameAsCached).length == 2)
+        val indexCacheSimplified = IndexBuilder.indexCache.getMap.map {
+          case (k, v) => (k.fileName, v)
+        }
+
+        assert(indexCacheSimplified.get(pathNameAsCached) != null)
+        assert(indexCacheSimplified(pathNameAsCached).length == 2)
 
         assert(actualInitial == expected)
         assert(actualCached == expected)

spark-cobol/src/test/scala/za/co/absa/cobrix/spark/cobol/source/utils/LRUCacheSuite.scala

@@ -0,0 +1,91 @@
+/*
+ * Copyright 2018 ABSA Group 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.
+ */
+
+package za.co.absa.cobrix.spark.cobol.source.utils
+
+import org.scalatest.wordspec.AnyWordSpec
+import za.co.absa.cobrix.spark.cobol.utils.LRUCache
+
+class LRUCacheSuite extends AnyWordSpec {
+  "LRUCache" should {
+    "remember items put there" in {
+      val cache = new LRUCache[Int, String](3)
+      cache.put(1, "one")
+      cache.put(2, "two")
+      cache.put(3, "three")
+      assert(cache.get(1).contains("one"))
+      assert(cache.get(2).contains("two"))
+      assert(cache.get(3).contains("three"))
+    }
+
+    "forget old items" in {
+      val cache = new LRUCache[Int, String](3)
+      cache.put(1, "one")
+      cache.put(2, "two")
+      cache.put(3, "three")
+      cache.put(4, "four")
+      assert(cache.get(1).isEmpty)
+      assert(cache(1) == null)
+      assert(cache.get(2).contains("two"))
+      assert(cache(2) == "two")
+      assert(cache.get(3).contains("three"))
+      assert(cache.get(4).contains("four"))
+    }
+
+    "remember frequently used items" in {
+      val cache = new LRUCache[Int, String](3)
+      cache.put(1, "one")
+      cache.put(2, "two")
+      cache.put(3, "three")
+      cache.get(1)
+      cache.get(3)
+      cache.put(4, "four")
+
+      assert(cache.get(1).contains("one"))
+      assert(cache.get(2).isEmpty)
+      assert(cache.get(3).contains("three"))
+      assert(cache.get(4).contains("four"))
+    }
+
+    "allow invalidating of values" in {
+      val cache = new LRUCache[Int, String](3)
+      cache.put(1, "one")
+      cache.put(2, "two")
+      cache.put(3, "three")
+      cache.remove(3)
+      cache.remove(4)
+      cache.get(1)
+      cache.get(3)
+      cache.put(4, "four")
+
+      assert(cache.containsKey(1))
+      assert(!cache.containsKey(8))
+      assert(cache(1) == "one")
+      assert(cache(2) == "two")
+      assert(cache(3) == null)
+      assert(cache(4) == "four")
+    }
+
+    "return the cache as a map" in {
+      val cache = new LRUCache[Int, String](3)
+      cache.put(1, "one")
+      cache.put(2, "two")
+      cache.put(3, "three")
+
+      assert(cache.getMap.size == 3)
+    }
+  }
+}