[SPARK-529][SQL] Modify SQLConf to use new config API from core.

Because SQL keeps track of all known configs, some customization was
needed in SQLConf to allow that, since the core API does not have that
feature.

Tested via existing (and slightly updated) unit tests.

Author: Marcelo Vanzin <vanzin@cloudera.com>

Closes #11570 from vanzin/SPARK-529-sql.

2 files changed, 55 insertions, 33 deletions

diff --git a/core/src/main/scala/org/apache/spark/internal/config/ConfigBuilder.scala b/core/src/main/scala/org/apache/spark/internal/config/ConfigBuilder.scala
index 770b43697a..5d50e3851a 100644
--- a/core/src/main/scala/org/apache/spark/internal/config/ConfigBuilder.scala
+++ b/core/src/main/scala/org/apache/spark/internal/config/ConfigBuilder.scala
@@ -85,10 +85,12 @@ private[spark] class TypedConfigBuilder[T](
     this(parent, converter, Option(_).map(_.toString).orNull)
   }
 
+  /** Apply a transformation to the user-provided values of the config entry. */
   def transform(fn: T => T): TypedConfigBuilder[T] = {
     new TypedConfigBuilder(parent, s => fn(converter(s)), stringConverter)
   }
 
+  /** Check that user-provided values for the config match a pre-defined set. */
   def checkValues(validValues: Set[T]): TypedConfigBuilder[T] = {
     transform { v =>
       if (!validValues.contains(v)) {
@@ -99,30 +101,38 @@ private[spark] class TypedConfigBuilder[T](
     }
   }
 
+  /** Turns the config entry into a sequence of values of the underlying type. */
   def toSequence: TypedConfigBuilder[Seq[T]] = {
     new TypedConfigBuilder(parent, stringToSeq(_, converter), seqToString(_, stringConverter))
   }
 
-  /** Creates a [[ConfigEntry]] that does not require a default value. */
-  def optional: OptionalConfigEntry[T] = {
-    new OptionalConfigEntry[T](parent.key, converter, stringConverter, parent._doc, parent._public)
+  /** Creates a [[ConfigEntry]] that does not have a default value. */
+  def createOptional: OptionalConfigEntry[T] = {
+    val entry = new OptionalConfigEntry[T](parent.key, converter, stringConverter, parent._doc,
+      parent._public)
+    parent._onCreate.foreach(_(entry))
+    entry
   }
 
   /** Creates a [[ConfigEntry]] that has a default value. */
-  def withDefault(default: T): ConfigEntry[T] = {
+  def createWithDefault(default: T): ConfigEntry[T] = {
     val transformedDefault = converter(stringConverter(default))
-    new ConfigEntryWithDefault[T](parent.key, transformedDefault, converter, stringConverter,
-      parent._doc, parent._public)
+    val entry = new ConfigEntryWithDefault[T](parent.key, transformedDefault, converter,
+      stringConverter, parent._doc, parent._public)
+    parent._onCreate.foreach(_(entry))
+    entry
   }
 
   /**
    * Creates a [[ConfigEntry]] that has a default value. The default value is provided as a
    * [[String]] and must be a valid value for the entry.
    */
-  def withDefaultString(default: String): ConfigEntry[T] = {
+  def createWithDefaultString(default: String): ConfigEntry[T] = {
     val typedDefault = converter(default)
-    new ConfigEntryWithDefault[T](parent.key, typedDefault, converter, stringConverter, parent._doc,
-      parent._public)
+    val entry = new ConfigEntryWithDefault[T](parent.key, typedDefault, converter, stringConverter,
+      parent._doc, parent._public)
+    parent._onCreate.foreach(_(entry))
+    entry
   }
 
 }
@@ -136,10 +146,11 @@ private[spark] case class ConfigBuilder(key: String) {
 
   import ConfigHelpers._
 
-  var _public = true
-  var _doc = ""
+  private[config] var _public = true
+  private[config] var _doc = ""
+  private[config] var _onCreate: Option[ConfigEntry[_] => Unit] = None
 
-  def internal: ConfigBuilder = {
+  def internal(): ConfigBuilder = {
     _public = false
     this
   }
@@ -149,6 +160,15 @@ private[spark] case class ConfigBuilder(key: String) {
     this
   }
 
+  /**
+   * Registers a callback for when the config entry is finally instantiated. Currently used by
+   * SQLConf to keep track of SQL configuration entries.
+   */
+  def onCreate(callback: ConfigEntry[_] => Unit): ConfigBuilder = {
+    _onCreate = Option(callback)
+    this
+  }
+
   def intConf: TypedConfigBuilder[Int] = {
     new TypedConfigBuilder(this, toNumber(_, _.toInt, key, "int"))
   }
diff --git a/core/src/main/scala/org/apache/spark/internal/config/package.scala b/core/src/main/scala/org/apache/spark/internal/config/package.scala
index 968c5192ac..94b50ee065 100644
--- a/core/src/main/scala/org/apache/spark/internal/config/package.scala
+++ b/core/src/main/scala/org/apache/spark/internal/config/package.scala
@@ -23,68 +23,70 @@ import org.apache.spark.network.util.ByteUnit
 package object config {
 
   private[spark] val DRIVER_CLASS_PATH =
-    ConfigBuilder(SparkLauncher.DRIVER_EXTRA_CLASSPATH).stringConf.optional
+    ConfigBuilder(SparkLauncher.DRIVER_EXTRA_CLASSPATH).stringConf.createOptional
 
   private[spark] val DRIVER_JAVA_OPTIONS =
-    ConfigBuilder(SparkLauncher.DRIVER_EXTRA_JAVA_OPTIONS).stringConf.optional
+    ConfigBuilder(SparkLauncher.DRIVER_EXTRA_JAVA_OPTIONS).stringConf.createOptional
 
   private[spark] val DRIVER_LIBRARY_PATH =
-    ConfigBuilder(SparkLauncher.DRIVER_EXTRA_LIBRARY_PATH).stringConf.optional
+    ConfigBuilder(SparkLauncher.DRIVER_EXTRA_LIBRARY_PATH).stringConf.createOptional
 
   private[spark] val DRIVER_USER_CLASS_PATH_FIRST =
-    ConfigBuilder("spark.driver.userClassPathFirst").booleanConf.withDefault(false)
+    ConfigBuilder("spark.driver.userClassPathFirst").booleanConf.createWithDefault(false)
 
   private[spark] val DRIVER_MEMORY = ConfigBuilder("spark.driver.memory")
     .bytesConf(ByteUnit.MiB)
-    .withDefaultString("1g")
+    .createWithDefaultString("1g")
 
   private[spark] val EXECUTOR_CLASS_PATH =
-    ConfigBuilder(SparkLauncher.EXECUTOR_EXTRA_CLASSPATH).stringConf.optional
+    ConfigBuilder(SparkLauncher.EXECUTOR_EXTRA_CLASSPATH).stringConf.createOptional
 
   private[spark] val EXECUTOR_JAVA_OPTIONS =
-    ConfigBuilder(SparkLauncher.EXECUTOR_EXTRA_JAVA_OPTIONS).stringConf.optional
+    ConfigBuilder(SparkLauncher.EXECUTOR_EXTRA_JAVA_OPTIONS).stringConf.createOptional
 
   private[spark] val EXECUTOR_LIBRARY_PATH =
-    ConfigBuilder(SparkLauncher.EXECUTOR_EXTRA_LIBRARY_PATH).stringConf.optional
+    ConfigBuilder(SparkLauncher.EXECUTOR_EXTRA_LIBRARY_PATH).stringConf.createOptional
 
   private[spark] val EXECUTOR_USER_CLASS_PATH_FIRST =
-    ConfigBuilder("spark.executor.userClassPathFirst").booleanConf.withDefault(false)
+    ConfigBuilder("spark.executor.userClassPathFirst").booleanConf.createWithDefault(false)
 
   private[spark] val EXECUTOR_MEMORY = ConfigBuilder("spark.executor.memory")
     .bytesConf(ByteUnit.MiB)
-    .withDefaultString("1g")
+    .createWithDefaultString("1g")
 
-  private[spark] val IS_PYTHON_APP = ConfigBuilder("spark.yarn.isPython").internal
-    .booleanConf.withDefault(false)
+  private[spark] val IS_PYTHON_APP = ConfigBuilder("spark.yarn.isPython").internal()
+    .booleanConf.createWithDefault(false)
 
-  private[spark] val CPUS_PER_TASK = ConfigBuilder("spark.task.cpus").intConf.withDefault(1)
+  private[spark] val CPUS_PER_TASK = ConfigBuilder("spark.task.cpus").intConf.createWithDefault(1)
 
   private[spark] val DYN_ALLOCATION_MIN_EXECUTORS =
-    ConfigBuilder("spark.dynamicAllocation.minExecutors").intConf.withDefault(0)
+    ConfigBuilder("spark.dynamicAllocation.minExecutors").intConf.createWithDefault(0)
 
   private[spark] val DYN_ALLOCATION_INITIAL_EXECUTORS =
     ConfigBuilder("spark.dynamicAllocation.initialExecutors")
       .fallbackConf(DYN_ALLOCATION_MIN_EXECUTORS)
 
   private[spark] val DYN_ALLOCATION_MAX_EXECUTORS =
-    ConfigBuilder("spark.dynamicAllocation.maxExecutors").intConf.withDefault(Int.MaxValue)
+    ConfigBuilder("spark.dynamicAllocation.maxExecutors").intConf.createWithDefault(Int.MaxValue)
 
   private[spark] val SHUFFLE_SERVICE_ENABLED =
-    ConfigBuilder("spark.shuffle.service.enabled").booleanConf.withDefault(false)
+    ConfigBuilder("spark.shuffle.service.enabled").booleanConf.createWithDefault(false)
 
   private[spark] val KEYTAB = ConfigBuilder("spark.yarn.keytab")
     .doc("Location of user's keytab.")
-    .stringConf.optional
+    .stringConf.createOptional
 
   private[spark] val PRINCIPAL = ConfigBuilder("spark.yarn.principal")
     .doc("Name of the Kerberos principal.")
-    .stringConf.optional
+    .stringConf.createOptional
 
-  private[spark] val EXECUTOR_INSTANCES = ConfigBuilder("spark.executor.instances").intConf.optional
+  private[spark] val EXECUTOR_INSTANCES = ConfigBuilder("spark.executor.instances")
+    .intConf
+    .createOptional
 
   private[spark] val PY_FILES = ConfigBuilder("spark.submit.pyFiles")
-    .internal
+    .internal()
     .stringConf
     .toSequence
-    .withDefault(Nil)
+    .createWithDefault(Nil)
 }