Github user tdas commented on a diff in the pull request:
https://github.com/apache/spark/pull/21739#discussion_r201597291
--- Diff:
sql/core/src/main/scala/org/apache/spark/sql/execution/streaming/state/FlatMapGroupsWithStateExecHelper.scala
---
@@ -0,0 +1,225 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 org.apache.spark.sql.execution.streaming.state
+
+import org.apache.spark.sql.catalyst.encoders.ExpressionEncoder
+import org.apache.spark.sql.catalyst.expressions._
+import org.apache.spark.sql.execution.ObjectOperator
+import org.apache.spark.sql.execution.streaming.GroupStateImpl
+import org.apache.spark.sql.execution.streaming.GroupStateImpl.NO_TIMESTAMP
+import org.apache.spark.sql.types._
+
+
+object FlatMapGroupsWithStateExecHelper {
+
+ val supportedVersions = Seq(1, 2)
+ val legacyVersion = 1
+
+ /**
+ * Class to capture deserialized state and timestamp return by the state
manager.
+ * This is intended for reuse.
+ */
+ case class StateData(
+ var keyRow: UnsafeRow = null,
+ var stateRow: UnsafeRow = null,
+ var stateObj: Any = null,
+ var timeoutTimestamp: Long = -1) {
+
+ private[FlatMapGroupsWithStateExecHelper] def withNew(
+ newKeyRow: UnsafeRow,
+ newStateRow: UnsafeRow,
+ newStateObj: Any,
+ newTimeout: Long): this.type = {
+ keyRow = newKeyRow
+ stateRow = newStateRow
+ stateObj = newStateObj
+ timeoutTimestamp = newTimeout
+ this
+ }
+ }
+
+ sealed trait StateManager extends Serializable {
+ def stateSchema: StructType
+ def getState(store: StateStore, keyRow: UnsafeRow): StateData
+ def putState(store: StateStore, keyRow: UnsafeRow, state: Any,
timeoutTimestamp: Long): Unit
+ def removeState(store: StateStore, keyRow: UnsafeRow): Unit
+ def getAllState(store: StateStore): Iterator[StateData]
+ def version: Int
+ }
+
+ def createStateManager(
+ stateEncoder: ExpressionEncoder[Any],
+ shouldStoreTimestamp: Boolean,
+ stateFormatVersion: Int): StateManager = {
+ stateFormatVersion match {
+ case 1 => new StateManagerImplV1(stateEncoder, shouldStoreTimestamp)
+ case 2 => new StateManagerImplV2(stateEncoder, shouldStoreTimestamp)
+ case _ => throw new IllegalArgumentException(s"Version
$stateFormatVersion is invalid")
+ }
+ }
+
+ //
===============================================================================================
+ // =========================== Private implementations of StateManager
===========================
+ //
===============================================================================================
+
+ private abstract class StateManagerImplBase(val version: Int,
shouldStoreTimestamp: Boolean)
+ extends StateManager {
+
+ protected def stateSerializerExprs: Seq[Expression]
+ protected def stateDeserializerExpr: Expression
+ protected def timeoutTimestampOrdinalInRow: Int
+
+ /** Get deserialized state and corresponding timeout timestamp for a
key */
+ override def getState(store: StateStore, keyRow: UnsafeRow): StateData
= {
+ val stateRow = store.get(keyRow)
+ stateDataForGets.withNew(keyRow, stateRow, getStateObject(stateRow),
getTimestamp(stateRow))
+ }
+
+ /** Put state and timeout timestamp for a key */
+ override def putState(store: StateStore, key: UnsafeRow, state: Any,
timestamp: Long): Unit = {
+ val stateRow = getStateRow(state)
+ setTimestamp(stateRow, timestamp)
+ store.put(key, stateRow)
+ }
+
+ override def removeState(store: StateStore, keyRow: UnsafeRow): Unit =
{
+ store.remove(keyRow)
+ }
+
+ override def getAllState(store: StateStore): Iterator[StateData] = {
+ val stateData = StateData()
+ store.getRange(None, None).map { p =>
+ stateData.withNew(p.key, p.value, getStateObject(p.value),
getTimestamp(p.value))
+ }
+ }
+
+ private lazy val stateSerializerFunc =
ObjectOperator.serializeObjectToRow(stateSerializerExprs)
+ private lazy val stateDeserializerFunc = {
+ ObjectOperator.deserializeRowToObject(stateDeserializerExpr,
stateSchema.toAttributes)
+ }
+ private lazy val stateDataForGets = StateData()
+
+ protected def getStateObject(row: UnsafeRow): Any = {
+ if (row != null) stateDeserializerFunc(row) else null
+ }
+
+ protected def getStateRow(obj: Any): UnsafeRow = {
+ stateSerializerFunc(obj)
+ }
+
+ /** Returns the timeout timestamp of a state row is set */
+ private def getTimestamp(stateRow: UnsafeRow): Long = {
+ if (shouldStoreTimestamp && stateRow != null) {
+ stateRow.getLong(timeoutTimestampOrdinalInRow)
+ } else NO_TIMESTAMP
+ }
+
+ /** Set the timestamp in a state row */
+ private def setTimestamp(stateRow: UnsafeRow, timeoutTimestamps:
Long): Unit = {
+ if (shouldStoreTimestamp)
stateRow.setLong(timeoutTimestampOrdinalInRow, timeoutTimestamps)
+ }
+ }
+
+
+ private class StateManagerImplV1(
+ stateEncoder: ExpressionEncoder[Any],
+ shouldStoreTimestamp: Boolean) extends StateManagerImplBase(1,
shouldStoreTimestamp) {
+
+ private val timestampTimeoutAttribute =
+ AttributeReference("timeoutTimestamp", dataType = IntegerType,
nullable = false)()
+
+ private val stateAttributes: Seq[Attribute] = {
+ val encSchemaAttribs = stateEncoder.schema.toAttributes
+ if (shouldStoreTimestamp) encSchemaAttribs :+
timestampTimeoutAttribute else encSchemaAttribs
+ }
+
+ override val stateSchema: StructType = stateAttributes.toStructType
+
+ override val timeoutTimestampOrdinalInRow: Int = {
+ stateAttributes.indexOf(timestampTimeoutAttribute)
+ }
+
+ override val stateSerializerExprs: Seq[Expression] = {
+ val encoderSerializer = stateEncoder.namedExpressions
+ if (shouldStoreTimestamp) {
+ encoderSerializer :+ Literal(GroupStateImpl.NO_TIMESTAMP)
+ } else {
+ encoderSerializer
+ }
+ }
+
+ override val stateDeserializerExpr: Expression = {
+ // Note that this must be done in the driver, as resolving and
binding of deserializer
+ // expressions to the encoded type can be safely done only in the
driver.
+ stateEncoder.resolveAndBind().deserializer
+ }
+
+ override protected def getStateRow(obj: Any): UnsafeRow = {
+ require(obj != null, "State object cannot be null")
+ super.getStateRow(obj)
+ }
+ }
+
+
+ private class StateManagerImplV2(
--- End diff --
Add docs explaining the state format
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