Add spark session extension for Hyperspace (#504)

src/main/scala/com/microsoft/hyperspace/HyperspaceSparkSessionExtension.scala

@@ -0,0 +1,69 @@
+/*
+ * Copyright (2020) The Hyperspace Project Authors.
+ *
+ * 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 com.microsoft.hyperspace
+
+import org.apache.spark.sql.{SparkSession, SparkSessionExtensions}
+import org.apache.spark.sql.catalyst.plans.logical.LogicalPlan
+import org.apache.spark.sql.catalyst.rules.Rule
+
+import com.microsoft.hyperspace.index.execution.BucketUnionStrategy
+import com.microsoft.hyperspace.index.rules.ApplyHyperspace
+
+/**
+ * An extension for Spark SQL to activate Hyperspace.
+ *
+ * Example to run a `spark-submit` with Hyperspace enabled:
+ * {{{
+ *   spark-submit -c spark.sql.extensions=com.microsoft.hyperspace.HyperspaceSparkSessionExtension
+ * }}}
+ *
+ * Example to create a `SparkSession` with Hyperspace enabled:
+ * {{{
+ *    val spark = SparkSession
+ *       .builder()
+ *       .appName("...")
+ *       .master("...")
+ *       .config("spark.sql.extensions", "com.microsoft.hyperspace.HyperspaceSparkSessionExtension")
+ *       .getOrCreate()
+ * }}}
+ */
+class HyperspaceSparkSessionExtension extends (SparkSessionExtensions => Unit) {
+
+  /**
+   * If HyperspaceRule is injected directly to OptimizerRule with HyperspaceExtension,
+   * the order of applying rule is different from without HyperspaceExtension
+   * (i.e., explicitly calling enableHyperspace). To make behavior consistently,
+   * current implementation of HyperspaceExtension uses a trick to call enableHyperspace
+   * before rule is applied. Since the interface of injectOptimizerRule should return rule builder,
+   * it returns a dummy rule that does nothing. It may increase overhead slightly
+   * because enableHyperspace is called once for each evaluation of spark plan.
+   */
+  private case object DummyRule extends Rule[LogicalPlan] {
+    override def apply(plan: LogicalPlan): LogicalPlan = {
+      plan
+    }
+  }
+
+  override def apply(extensions: SparkSessionExtensions): Unit = {
+    extensions.injectOptimizerRule { sparkSession =>
+      // Enable Hyperspace to leverage indexes.
+      sparkSession.addOptimizationsIfNeeded()
+      // Return a dummy rule to fit in interface of injectOptimizerRule
+      DummyRule
+    }
+  }
+}

src/main/scala/com/microsoft/hyperspace/index/IndexConstants.scala

@@ -19,6 +19,10 @@ package com.microsoft.hyperspace.index
 import org.apache.spark.sql.internal.SQLConf
 
 object IndexConstants {
+  // If it is set as false, Hyperspace will not be applied.
+  val HYPERSPACE_APPLY_ENABLED = "spark.hyperspace.apply.enabled"
+  val HYPERSPACE_APPLY_ENABLED_DEFAULT = "true"
+
   val INDEXES_DIR = "indexes"
 
   // Config used for setting the system path, which is considered as a "root" path for Hyperspace;

src/main/scala/com/microsoft/hyperspace/index/rules/ApplyHyperspace.scala

@@ -24,6 +24,7 @@ import com.microsoft.hyperspace.{ActiveSparkSession, Hyperspace}
 import com.microsoft.hyperspace.actions.Constants
 import com.microsoft.hyperspace.index.IndexLogEntry
 import com.microsoft.hyperspace.telemetry.HyperspaceEventLogging
+import com.microsoft.hyperspace.util.HyperspaceConf
 
 /**
  * Transform the given plan to use Hyperspace indexes.
@@ -42,7 +43,7 @@ object ApplyHyperspace
   private[hyperspace] val disableForIndexMaintenance = new ThreadLocal[Boolean]
 
   override def apply(plan: LogicalPlan): LogicalPlan = {
-    if (disableForIndexMaintenance.get) {
+    if (!HyperspaceConf.hyperspaceApplyEnabled(spark) || disableForIndexMaintenance.get) {
       return plan
     }
 

src/main/scala/com/microsoft/hyperspace/package.scala

@@ -18,8 +18,10 @@ package com.microsoft
 
 import org.apache.spark.sql.SparkSession
 
+import com.microsoft.hyperspace.HyperspaceSparkSessionExtension
 import com.microsoft.hyperspace.index.execution.BucketUnionStrategy
 import com.microsoft.hyperspace.index.rules.ApplyHyperspace
+import com.microsoft.hyperspace.util.HyperspaceConf
 
 package object hyperspace {
 
@@ -29,42 +31,65 @@ package object hyperspace {
   implicit class Implicits(sparkSession: SparkSession) {
 
     /**
-     * Plug in Hyperspace-specific rules.
+     * Enable Hyperspace indexes.
+     *
+     * Plug in Hyperspace-specific rules and set `IndexConstants.HYPERSPACE_APPLY_ENABLED` as true.
      *
      * @return a spark session that contains Hyperspace-specific rules.
      */
     def enableHyperspace(): SparkSession = {
-      disableHyperspace
-      sparkSession.sessionState.experimentalMethods.extraOptimizations ++=
-        ApplyHyperspace :: Nil
-      sparkSession.sessionState.experimentalMethods.extraStrategies ++=
-        BucketUnionStrategy :: Nil
+      HyperspaceConf.setHyperspaceApplyEnabled(sparkSession, true)
+      addOptimizationsIfNeeded()
       sparkSession
     }
 
     /**
-     * Plug out Hyperspace-specific rules.
+     * Disable Hyperspace indexes.
      *
-     * @return a spark session that does not contain Hyperspace-specific rules.
+     * Set `IndexConstants.HYPERSPACE_APPLY_ENABLED` as false
+     * to stop applying Hyperspace indexes.
+     *
+     * @return a spark session that `IndexConstants.HYPERSPACE_APPLY_ENABLED` is set as false.
      */
     def disableHyperspace(): SparkSession = {
-      val experimentalMethods = sparkSession.sessionState.experimentalMethods
-      experimentalMethods.extraOptimizations =
-        experimentalMethods.extraOptimizations.filterNot(ApplyHyperspace.equals)
-      experimentalMethods.extraStrategies =
-        experimentalMethods.extraStrategies.filterNot(BucketUnionStrategy.equals)
+      HyperspaceConf.setHyperspaceApplyEnabled(sparkSession, false)
       sparkSession
     }
 
     /**
      * Checks if Hyperspace is enabled or not.
      *
+     * Note that Hyperspace is enabled when:
+     * 1) `ApplyHyperspace` exists in extraOptimization
+     * 2) `BucketUnionStrate` exists in extraStrategies and
+     * 3) `IndexConstants.HYPERSPACE_APPLY_ENABLED` is true.
+     *
      * @return true if Hyperspace is enabled or false otherwise.
      */
     def isHyperspaceEnabled(): Boolean = {
       val experimentalMethods = sparkSession.sessionState.experimentalMethods
       experimentalMethods.extraOptimizations.contains(ApplyHyperspace) &&
-      experimentalMethods.extraStrategies.contains(BucketUnionStrategy)
+      experimentalMethods.extraStrategies.contains(BucketUnionStrategy) &&
+      HyperspaceConf.hyperspaceApplyEnabled(sparkSession)
+    }
+
+    /**
+     * Add ApplyHyperspace and BucketUnionStrategy into extraOptimization
+     * and extraStrategies, respectively, to make Spark can use Hyperspace.
+     *
+     * @param sparkSession Spark session that will use Hyperspace
+     */
+    private[hyperspace] def addOptimizationsIfNeeded(): Unit = {
+      if (!sparkSession.sessionState.experimentalMethods.extraOptimizations.contains(
+          ApplyHyperspace)) {
+        sparkSession.sessionState.experimentalMethods.extraOptimizations ++=
+          ApplyHyperspace :: Nil
+      }
+      if (!sparkSession.sessionState.experimentalMethods.extraStrategies.contains(
+          BucketUnionStrategy)) {
+        sparkSession.sessionState.experimentalMethods.extraStrategies ++=
+          BucketUnionStrategy :: Nil
+      }
     }
   }
 }

src/main/scala/com/microsoft/hyperspace/util/HyperspaceConf.scala

@@ -25,6 +25,22 @@ import com.microsoft.hyperspace.index.IndexConstants
  * Helper class to extract Hyperspace-related configs from SparkSession.
  */
 object HyperspaceConf {
+
+  /**
+   * Returns the config value whether hyperspace is enabled or not.
+   */
+  def hyperspaceApplyEnabled(spark: SparkSession): Boolean = {
+    spark.conf
+      .get(
+        IndexConstants.HYPERSPACE_APPLY_ENABLED,
+        IndexConstants.HYPERSPACE_APPLY_ENABLED_DEFAULT)
+      .toBoolean
+  }
+
+  def setHyperspaceApplyEnabled(spark: SparkSession, apply: Boolean): Unit = {
+    spark.conf.set(IndexConstants.HYPERSPACE_APPLY_ENABLED, apply.toString)
+  }
+
   def hybridScanEnabled(spark: SparkSession): Boolean = {
     spark.conf
       .get(

src/test/scala/com/microsoft/hyperspace/HyperspaceExtensionTest.scala

@@ -0,0 +1,198 @@
+/*
+ * Copyright (2020) The Hyperspace Project Authors.
+ *
+ * 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 com.microsoft.hyperspace
+
+import org.apache.hadoop.conf.Configuration
+import org.apache.hadoop.fs.Path
+import org.apache.spark.sql.{DataFrame, Row, SparkSession}
+import org.apache.spark.sql.catalyst.plans.logical.LogicalPlan
+import org.apache.spark.sql.execution.datasources.{HadoopFsRelation, InMemoryFileIndex, LogicalRelation}
+
+import com.microsoft.hyperspace.index.{Content, FileIdTracker, HyperspaceSuite, IndexConfig, IndexConstants}
+import com.microsoft.hyperspace.telemetry.Constants.HYPERSPACE_EVENT_LOGGER_CLASS_KEY
+import com.microsoft.hyperspace.util.FileUtils
+
+class HyperspaceExtensionTest extends HyperspaceSuite {
+  private val sampleDeptDataLocation = inTempDir("dept")
+  private val sampleEmpDataLocation = inTempDir("emp")
+
+  private val departments = Seq(
+    (10, "Accounting", "New York"),
+    (20, "Research", "Dallas"),
+    (30, "Sales", "Chicago"),
+    (40, "Operations", "Boston"))
+
+  private val employees = Seq(
+    (7369, "SMITH", 20),
+    (7499, "ALLEN", 30),
+    (7521, "WARD", 30),
+    (7566, "JONES", 20),
+    (7698, "BLAKE", 30),
+    (7782, "CLARK", 10),
+    (7788, "SCOTT", 20),
+    (7839, "KING", 10),
+    (7844, "TURNER", 30),
+    (7876, "ADAMS", 20),
+    (7900, "JAMES", 30),
+    (7934, "MILLER", 10),
+    (7902, "FORD", 20),
+    (7654, "MARTIN", 30))
+
+  override protected lazy val spark: SparkSession = SparkSession
+    .builder()
+    .master(s"local[$numParallelism]")
+    .config(HYPERSPACE_EVENT_LOGGER_CLASS_KEY, "com.microsoft.hyperspace.MockEventLogger")
+    .config("delta.log.cacheSize", "3")
+    .config("spark.databricks.delta.snapshotPartitions", "2")
+    .config("spark.driver.bindAddress", "127.0.0.1")
+    .config("spark.sql.catalog.spark_catalog", "org.apache.spark.sql.delta.catalog.DeltaCatalog")
+    .config(
+      "spark.sql.extensions",
+      "io.delta.sql.DeltaSparkSessionExtension," +
+        "com.microsoft.hyperspace.HyperspaceSparkSessionExtension")
+    .config("spark.sql.shuffle.partitions", "5")
+    .config("spark.sql.sources.parallelPartitionDiscovery.parallelism", "5")
+    .config("spark.ui.enabled", "false")
+    .config("spark.ui.showConsoleProgress", "false")
+    .appName(suiteName)
+    .getOrCreate()
+
+  override def beforeAll(): Unit = {
+    super.beforeAll()
+
+    val sparkSession = spark
+    import sparkSession.implicits._
+    FileUtils.delete(new Path(sampleDeptDataLocation))
+    FileUtils.delete(new Path(sampleEmpDataLocation))
+
+    departments
+      .toDF("deptId", "deptName", "location")
+      .write
+      .mode("overwrite")
+      .parquet(sampleDeptDataLocation)
+
+    employees
+      .toDF("empId", "empName", "deptId")
+      .write
+      .mode("overwrite")
+      .parquet(sampleEmpDataLocation)
+  }
+
+  override def afterAll(): Unit = {
+    FileUtils.delete(new Path(sampleDeptDataLocation))
+    FileUtils.delete(new Path(sampleEmpDataLocation))
+    super.beforeAll()
+  }
+
+  test("Verify ApplyHyperspace is used with hyperspace extension session") {
+    MockEventLogger.reset()
+
+    val deptDF = spark.read.parquet(sampleDeptDataLocation)
+    val empDF = spark.read.parquet(sampleEmpDataLocation)
+
+    val deptIndexConfig = IndexConfig("deptIndex", Seq("deptId"), Seq("deptName"))
+    val empIndexConfig = IndexConfig("empIndex", Seq("deptId"), Seq("empName"))
+
+    // Create Hyperspace indexes.
+    val hs = new Hyperspace(spark)
+    hs.createIndex(deptDF, deptIndexConfig)
+    hs.createIndex(empDF, empIndexConfig)
+
+    // Make sure new index is available to all.
+    assert(Hyperspace.getContext(spark).indexCollectionManager.indexes.count == 2)
+
+    def filterQuery(): DataFrame = deptDF.filter("deptId == '30'").select("deptId", "deptName")
+
+    verifyIndexUsage(filterQuery, getIndexFilesPath(deptIndexConfig.indexName))
+
+    def eqJoinQuery(): DataFrame =
+      empDF
+        .join(deptDF, empDF("deptId") === deptDF("deptId"))
+        .select(empDF("empName"), deptDF("deptName"))
+
+    verifyIndexUsage(
+      eqJoinQuery,
+      getIndexFilesPath(deptIndexConfig.indexName) ++ getIndexFilesPath(empIndexConfig.indexName))
+  }
+
+  /**
+   * Verify that the query plan has the expected rootPaths.
+   *
+   * @param optimizedPlan the optimized query plan.
+   * @param expectedPaths the expected paths in the query plan.
+   */
+  private def verifyQueryPlanHasExpectedRootPaths(
+      optimizedPlan: LogicalPlan,
+      expectedPaths: Seq[Path]): Unit = {
+    assert(getAllRootPaths(optimizedPlan).sortBy(_.getName) === expectedPaths.sortBy(_.getName))
+  }
+
+  /**
+   * Get all rootPaths from a query plan.
+   *
+   * @param optimizedPlan the optimized query plan.
+   * @return a sequence of [[Path]].
+   */
+  private def getAllRootPaths(optimizedPlan: LogicalPlan): Seq[Path] = {
+    optimizedPlan.collect {
+      case LogicalRelation(
+            HadoopFsRelation(location: InMemoryFileIndex, _, _, _, _, _),
+            _,
+            _,
+            _) =>
+        location.rootPaths
+    }.flatten
+  }
+
+  private def getIndexFilesPath(indexName: String, versions: Seq[Int] = Seq(0)): Seq[Path] = {
+    versions.flatMap { v =>
+      Content
+        .fromDirectory(
+          new Path(systemPath, s"$indexName/${IndexConstants.INDEX_VERSION_DIRECTORY_PREFIX}=$v"),
+          new FileIdTracker,
+          new Configuration)
+        .files
+    }
+  }
+
+  /**
+   * Gets the sorted rows from the given dataframe to make it easy to compare with
+   * other dataframe.
+   *
+   * @param df dataframe to collect rows from.
+   * @return sorted rows.
+   */
+  private def getSortedRows(df: DataFrame): Array[Row] = {
+    df.orderBy(df.columns.head, df.columns.tail: _*).collect()
+  }
+
+  private def verifyIndexUsage(f: () => DataFrame, expectedRootPaths: Seq[Path]): Unit = {
+    spark.disableHyperspace()
+    val dfWithHyperspaceDisabled = f()
+    val schemaWithHyperspaceDisabled = dfWithHyperspaceDisabled.schema
+    val sortedRowsWithHyperspaceDisabled = getSortedRows(dfWithHyperspaceDisabled)
+
+    spark.enableHyperspace()
+    val dfWithHyperspaceEnabled = f()
+
+    verifyQueryPlanHasExpectedRootPaths(
+      dfWithHyperspaceEnabled.queryExecution.optimizedPlan,
+      expectedRootPaths)
+
+    assert(schemaWithHyperspaceDisabled.equals(dfWithHyperspaceEnabled.schema))
+    assert(sortedRowsWithHyperspaceDisabled.sameElements(getSortedRows(dfWithHyperspaceEnabled)))
+  }
+}

src/test/scala/com/microsoft/hyperspace/index/E2EHyperspaceRulesTest.scala

@@ -33,7 +33,7 @@ import com.microsoft.hyperspace.index.dataskipping.DataSkippingIndexConfig
 import com.microsoft.hyperspace.index.dataskipping.sketches.MinMaxSketch
 import com.microsoft.hyperspace.index.execution.BucketUnionStrategy
 import com.microsoft.hyperspace.index.rules.{ApplyHyperspace, CandidateIndexCollector}
-import com.microsoft.hyperspace.util.PathUtils
+import com.microsoft.hyperspace.util.{HyperspaceConf, PathUtils}
 
 class E2EHyperspaceRulesTest extends QueryTest with HyperspaceSuite {
   private val testDir = inTempDir("e2eTests")
@@ -91,12 +91,16 @@ class E2EHyperspaceRulesTest extends QueryTest with HyperspaceSuite {
       spark.sessionState.experimentalMethods.extraStrategies
         .containsSlice(expectedOptimizationStrategy))
 
+    // Since applyHyperspace is called before, extraOptimization contains ApplyHyperspace
+    // This behavior has changed according to following discussion:
+    // https://github.com/microsoft/hyperspace/pull/504/files#r740278070
     spark.disableHyperspace()
+    assert(!HyperspaceConf.hyperspaceApplyEnabled(spark))
     assert(
-      !spark.sessionState.experimentalMethods.extraOptimizations
+      spark.sessionState.experimentalMethods.extraOptimizations
         .containsSlice(expectedOptimizationRuleBatch))
     assert(
-      !spark.sessionState.experimentalMethods.extraStrategies
+      spark.sessionState.experimentalMethods.extraStrategies
         .containsSlice(expectedOptimizationStrategy))
   }