Github user cloud-fan commented on a diff in the pull request: https://github.com/apache/spark/pull/17433#discussion_r108098422 --- Diff: sql/core/src/main/scala/org/apache/spark/sql/internal/SessionState.scala --- @@ -179,88 +132,295 @@ private[sql] class SessionState( } } - private[sql] object SessionState { + /** + * Create a new [[SessionState]] for the given session. + */ + def apply(session: SparkSession): SessionState = { + new SessionStateBuilder(session).build + } + + def newHadoopConf(hadoopConf: Configuration, sqlConf: SQLConf): Configuration = { + val newHadoopConf = new Configuration(hadoopConf) + sqlConf.getAllConfs.foreach { case (k, v) => if (v ne null) newHadoopConf.set(k, v) } + newHadoopConf + } +} + +/** + * Builder class that coordinates construction of a new [[SessionState]]. + * + * The builder explicitly defines all components needed by the session state, and creates a session + * state when `build` is called. Components should only be initialized once. This is not a problem + * for most components as they are only used in the `build` function. However some components + * (`conf`, `catalog`, `functionRegistry`, `experimentalMethods` & `sqlParser`) are as dependencies + * for other components and are shared as a result. These components are defined as lazy vals to + * make sure the component is created only once. + * + * A developer can modify the builder by providing custom versions of components, or by using the + * hooks provided for the analyzer, optimizer & planner. There are some dependencies between the + * components (they are documented per dependency), a developer should respect these when making + * modifications in order to prevent initialization problems. + * + * A parent [[SessionState]] can be used to initialize the new [[SessionState]]. The new session + * state will clone the parent sessions state's `conf`, `functionRegistry`, `experimentalMethods` + * and `catalog` fields. Note that the state is cloned when `build` is called, and not before. + */ +@Experimental +@InterfaceStability.Unstable +abstract class BaseSessionStateBuilder( + val session: SparkSession, + val parentState: Option[SessionState] = None) { + type NewBuilder = (SparkSession, Option[SessionState]) => BaseSessionStateBuilder - def apply(sparkSession: SparkSession): SessionState = { - apply(sparkSession, new SQLConf) + /** + * Extract entries from `SparkConf` and put them in the `SQLConf` + */ + protected def mergeSparkConf(sqlConf: SQLConf, sparkConf: SparkConf): Unit = { + sparkConf.getAll.foreach { case (k, v) => + sqlConf.setConfString(k, v) + } } - def apply(sparkSession: SparkSession, sqlConf: SQLConf): SessionState = { - val sparkContext = sparkSession.sparkContext + /** + * SQL-specific key-value configurations. + * + * These either get cloned from a pre-existing instance or newly created. The conf is always + * merged with its [[SparkConf]]. + */ + protected lazy val conf: SQLConf = { + val conf = parentState.map(_.conf.clone()).getOrElse(new SQLConf) + mergeSparkConf(conf, session.sparkContext.conf) + conf + } - // Automatically extract all entries and put them in our SQLConf - mergeSparkConf(sqlConf, sparkContext.getConf) + /** + * Internal catalog managing functions registered by the user. + * + * This either gets cloned from a pre-existing version or cloned from the build-in registry. + */ + protected lazy val functionRegistry: FunctionRegistry = { + parentState.map(_.functionRegistry).getOrElse(FunctionRegistry.builtin).clone() + } - val functionRegistry = FunctionRegistry.builtin.clone() + /** + * Experimental methods that can be used to define custom optimization rules and custom planning + * strategies. + * + * This either gets cloned from a pre-existing version or newly created. + */ + protected lazy val experimentalMethods: ExperimentalMethods = { + parentState.map(_.experimentalMethods.clone()).getOrElse(new ExperimentalMethods) + } - val sqlParser: ParserInterface = new SparkSqlParser(sqlConf) + /** + * Parser that extracts expressions, plans, table identifiers etc. from SQL texts. + * + * Note: this depends on the `conf` field. + */ + protected lazy val sqlParser: ParserInterface = new SparkSqlParser(conf) + /** + * Catalog for managing table and database states. If there is a pre-existing catalog, the state + * of that catalog (temp tables & current database) will be copied into the new catalog. + * + * Note: this depends on the `conf`, `functionRegistry` and `sqlParser` fields. + */ + protected lazy val catalog: SessionCatalog = { val catalog = new SessionCatalog( - sparkSession.sharedState.externalCatalog, - sparkSession.sharedState.globalTempViewManager, + session.sharedState.externalCatalog, + session.sharedState.globalTempViewManager, functionRegistry, - sqlConf, - newHadoopConf(sparkContext.hadoopConfiguration, sqlConf), - sqlParser) + conf, + SessionState.newHadoopConf(session.sparkContext.hadoopConfiguration, conf), + sqlParser, + new SessionFunctionResourceLoader(session)) + parentState.foreach(_.catalog.copyStateTo(catalog)) + catalog + } - val analyzer: Analyzer = createAnalyzer(sparkSession, catalog, sqlConf) + /** + * Logical query plan analyzer for resolving unresolved attributes and relations. + * + * Note: this depends on the `conf` and `catalog` field. + */ + protected def analyzer: Analyzer = new Analyzer(catalog, conf) { + override val extendedResolutionRules: Seq[Rule[LogicalPlan]] = + new FindDataSourceTable(session) +: + new ResolveSQLOnFile(session) +: + customResolutionRules + + override val postHocResolutionRules: Seq[Rule[LogicalPlan]] = + PreprocessTableCreation(session) +: + PreprocessTableInsertion(conf) +: + DataSourceAnalysis(conf) +: + customPostHocResolutionRules + + override val extendedCheckRules: Seq[LogicalPlan => Unit] = + PreWriteCheck +: + HiveOnlyCheck +: + customCheckRules + } - val streamingQueryManager: StreamingQueryManager = new StreamingQueryManager(sparkSession) + /** + * Custom resolution rules to add to the Analyzer. Prefer overriding this instead of creating + * your own Analyzer. + * + * Note that this may NOT depend on the `analyzer` function. + */ + protected def customResolutionRules: Seq[Rule[LogicalPlan]] = Nil - val queryExecutionCreator = (plan: LogicalPlan) => new QueryExecution(sparkSession, plan) + /** + * Custom post resolution rules to add to the Analyzer. Prefer overriding this instead of + * creating your own Analyzer. + * + * Note that this may NOT depend on the `analyzer` function. + */ + protected def customPostHocResolutionRules: Seq[Rule[LogicalPlan]] = Nil + + /** + * Custom check rules to add to the Analyzer. Prefer overriding this instead of creating + * your own Analyzer. + * + * Note that this may NOT depend on the `analyzer` function. + */ + protected def customCheckRules: Seq[LogicalPlan => Unit] = Nil + + /** + * Logical query plan optimizer. + * + * Note: this depends on the `conf`, `catalog` and `experimentalMethods` fields. + */ + protected def optimizer: Optimizer = { + new SparkOptimizer(catalog, conf, experimentalMethods) { + override def extendedOperatorOptimizationRules: Seq[Rule[LogicalPlan]] = + super.extendedOperatorOptimizationRules ++ customOperatorOptimizationRules + } + } + + /** + * Custom operator optimization rules to add to the Optimizer. Prefer overriding this instead + * of creating your own Optimizer. + * + * Note that this may NOT depend on the `optimizer` function. + */ + protected def customOperatorOptimizationRules: Seq[Rule[LogicalPlan]] = Nil - val sessionState = new SessionState( - sparkContext, - sparkSession.sharedState, - sqlConf, - new ExperimentalMethods, + /** + * Planner that converts optimized logical plans to physical plans. + * + * Note: this depends on the `conf` and `experimentalMethods` fields. + */ + protected def planner: SparkPlanner = { + new SparkPlanner(session.sparkContext, conf, experimentalMethods) { + override def extraPlanningStrategies: Seq[Strategy] = + super.extraPlanningStrategies ++ customPlanningStrategies + } + } + + /** + * Custom strategies to add to the planner. Prefer overriding this instead of creating + * your own Planner. + * + * Note that this may NOT depend on the `planner` function. + */ + protected def customPlanningStrategies: Seq[Strategy] = Nil + + /** + * Create a query execution object. + */ + protected def createQueryExecution: LogicalPlan => QueryExecution = { plan => + new QueryExecution(session, plan) + } + + /** + * Interface to start and stop streaming queries. + */ + protected def streamingQueryManager: StreamingQueryManager = new StreamingQueryManager(session) + + /** + * Function that produces a new instance of the SessionStateBuilder. This is used by the + * [[SessionState]]'s clone functionality. Make sure to override this when implementing your own + * [[SessionStateBuilder]]. + */ + protected def newBuilder: NewBuilder + + /** + * Function used to make clones of the session state. + */ + protected def createClone: (SparkSession, SessionState) => SessionState = { + val createBuilder = newBuilder + (session, state) => createBuilder(session, Option(state)).build + } + + /** + * Build the [[SessionState]]. + */ + def build: SessionState = { + new SessionState( + session.sparkContext, + session.sharedState, + conf, + experimentalMethods, functionRegistry, catalog, sqlParser, analyzer, + optimizer, + planner, streamingQueryManager, - queryExecutionCreator) - // functionResourceLoader needs to access SessionState.addJar, so it cannot be created before - // creating SessionState. Setting `catalog.functionResourceLoader` here is safe since the caller - // cannot use SessionCatalog before we return SessionState. - catalog.functionResourceLoader = sessionState.functionResourceLoader - sessionState + createQueryExecution, + createClone) } +} - def newHadoopConf(hadoopConf: Configuration, sqlConf: SQLConf): Configuration = { - val newHadoopConf = new Configuration(hadoopConf) - sqlConf.getAllConfs.foreach { case (k, v) => if (v ne null) newHadoopConf.set(k, v) } - newHadoopConf - } +/** + * Concrete implementation of a [[SessionStateBuilder]]. + */ +@Experimental +@InterfaceStability.Unstable +class SessionStateBuilder( + session: SparkSession, + state: Option[SessionState] = None) + extends BaseSessionStateBuilder(session, state) { + override protected def newBuilder: NewBuilder = new SessionStateBuilder(_, _) +} - /** - * Create an logical query plan `Analyzer` with rules specific to a non-Hive `SessionState`. - */ - private def createAnalyzer( - sparkSession: SparkSession, - catalog: SessionCatalog, - sqlConf: SQLConf): Analyzer = { - new Analyzer(catalog, sqlConf) { - override val extendedResolutionRules: Seq[Rule[LogicalPlan]] = - new FindDataSourceTable(sparkSession) :: - new ResolveSQLOnFile(sparkSession) :: Nil - - override val postHocResolutionRules: Seq[Rule[LogicalPlan]] = - PreprocessTableCreation(sparkSession) :: - PreprocessTableInsertion(sqlConf) :: - DataSourceAnalysis(sqlConf) :: Nil - - override val extendedCheckRules = Seq(PreWriteCheck, HiveOnlyCheck) +/** + * Helper class for using SessionStateBuilders during tests. + */ +private[sql] trait WithTestConf { self: BaseSessionStateBuilder => --- End diff -- if it's only used in test, shall we move this class to test?
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