Github user cloud-fan commented on a diff in the pull request:
https://github.com/apache/spark/pull/17433#discussion_r108090394
--- 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
--- End diff --
shall we make it a method instead of returning a function?
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