Improve create object performance for QueryDslImpl & ReactiveQueryDslImpl (#50)

* Improve create object performance for QueryDslImpl & ReactiveQueryDslImpl

Author: Hyunsik Kang

build.gradle.kts

@@ -13,7 +13,7 @@ plugins {
 
 allprojects {
     group = "com.linecorp.kotlin-jdsl"
-    version = "2.0.0.RELEASE"
+    version = "2.0.1.RELEASE"
 
     repositories {
         mavenCentral()

core/src/main/kotlin/com/linecorp/kotlinjdsl/querydsl/QueryDslImpl.kt

@@ -45,23 +45,33 @@ import javax.persistence.criteria.JoinType
  *
  * Don't use this directly because it's an <string>INTERNAL</strong> class.
  * It does not support backward compatibility.
+ * This class should be used with the understanding that it is not thread safe and therefore not suitable for parallel processing.
  */
 open class QueryDslImpl<T>(
     private val returnType: Class<T>,
 ) : CriteriaQueryDsl<T>, SubqueryDsl<T>, CriteriaUpdateQueryDsl, CriteriaDeleteQueryDsl {
     private var singleSelectClause: SingleSelectClause<T>? = null
     private var multiSelectClause: MultiSelectClause<T>? = null
     private var fromClause: FromClause<*>? = null
-    private var joins: MutableList<JoinSpec<*>> = mutableListOf()
-    private var wheres: MutableList<PredicateSpec> = mutableListOf()
-    private var groupBys: MutableList<ExpressionSpec<*>> = mutableListOf()
-    private var havings: MutableList<PredicateSpec> = mutableListOf()
-    private var orderBys: MutableList<OrderSpec> = mutableListOf()
+    private var joins: MutableList<JoinSpec<*>>? = null
+    private var wheres: MutableList<PredicateSpec>? = null
+    private var groupBys: MutableList<ExpressionSpec<*>>? = null
+    private var havings: MutableList<PredicateSpec>? = null
+    private var orderBys: MutableList<OrderSpec>? = null
     private var offset: Int? = null
     private var maxResults: Int? = null
-    private var sqlHints: MutableList<String> = mutableListOf()
-    private var jpaHints: MutableMap<String, Any> = mutableMapOf()
-    private var params: MutableMap<ColumnSpec<*>, Any?> = mutableMapOf()
+    private var sqlHints: MutableList<String>? = null
+    private var jpaHints: MutableMap<String, Any>? = null
+    private var params: MutableMap<ColumnSpec<*>, Any?>? = null
+
+    private fun lazyJoins() = (joins ?: mutableListOf<JoinSpec<*>>().apply { joins = this })
+    private fun lazyWheres() = (wheres ?: mutableListOf<PredicateSpec>().apply { wheres = this })
+    private fun lazyGroupBys() = (groupBys ?: mutableListOf<ExpressionSpec<*>>().apply { groupBys = this })
+    private fun lazyHavings() = (havings ?: mutableListOf<PredicateSpec>().apply { havings = this })
+    private fun lazyOrderBys() = (orderBys ?: mutableListOf<OrderSpec>().apply { orderBys = this })
+    private fun lazySqlHints() = (sqlHints ?: mutableListOf<String>().apply { sqlHints = this })
+    private fun lazyJpaHints() = (jpaHints ?: mutableMapOf<String, Any>().apply { jpaHints = this })
+    private fun lazyParams() = (params ?: mutableMapOf<ColumnSpec<*>, Any?>().apply { params = this })
 
     override fun select(distinct: Boolean, expression: ExpressionSpec<T>): SingleSelectClause<T> {
         return SingleSelectClause(
@@ -84,12 +94,12 @@ open class QueryDslImpl<T>(
     }
 
     override fun <T, R> join(left: EntitySpec<T>, right: EntitySpec<R>, relation: Relation<T, R?>, joinType: JoinType) {
-        joins.add(SimpleJoinSpec(left = left, right = right, path = relation.path, joinType = joinType))
+        lazyJoins().add(SimpleJoinSpec(left = left, right = right, path = relation.path, joinType = joinType))
     }
 
     override fun <T> join(entity: EntitySpec<T>, predicate: PredicateSpec) {
-        joins.add(CrossJoinSpec(entity))
-        wheres.add(predicate)
+        lazyJoins().add(CrossJoinSpec(entity))
+        lazyWheres().add(predicate)
     }
 
     override fun <T, R> associate(
@@ -98,7 +108,7 @@ open class QueryDslImpl<T>(
         relation: Relation<T, R?>,
         joinType: JoinType
     ) {
-        joins.add(SimpleAssociatedJoinSpec(left = left, right = right, path = relation.path))
+        lazyJoins().add(SimpleAssociatedJoinSpec(left = left, right = right, path = relation.path))
     }
 
     override fun <T, R> fetch(
@@ -107,23 +117,23 @@ open class QueryDslImpl<T>(
         relation: Relation<T, R?>,
         joinType: JoinType
     ) {
-        joins.add(FetchJoinSpec(left = left, right = right, path = relation.path, joinType = joinType))
+        lazyJoins().add(FetchJoinSpec(left = left, right = right, path = relation.path, joinType = joinType))
     }
 
     override fun where(predicate: PredicateSpec) {
-        wheres.add(predicate)
+        lazyWheres().add(predicate)
     }
 
     override fun groupBy(columns: List<ExpressionSpec<*>>) {
-        groupBys.addAll(columns)
+        lazyGroupBys().addAll(columns)
     }
 
     override fun having(predicate: PredicateSpec) {
-        havings.add(predicate)
+        lazyHavings().add(predicate)
     }
 
     override fun orderBy(orders: List<OrderSpec>) {
-        orderBys.addAll(orders)
+        lazyOrderBys().addAll(orders)
     }
 
     override fun offset(offset: Int) {
@@ -135,19 +145,19 @@ open class QueryDslImpl<T>(
     }
 
     override fun sqlHints(hints: List<String>) {
-        sqlHints.addAll(hints)
+        lazySqlHints().addAll(hints)
     }
 
     override fun hints(hints: Map<String, Any>) {
-        jpaHints.putAll(hints)
+        lazyJpaHints().putAll(hints)
     }
 
     override fun setParams(params: Map<ColumnSpec<*>, Any?>) {
-        this.params.putAll(params)
+        lazyParams().putAll(params)
     }
 
     override fun set(column: ColumnSpec<*>, value: Any?) {
-        params[column] = value
+        lazyParams()[column] = value
     }
 
     fun createCriteriaQuerySpec(): CriteriaQuerySpec<T, TypedQuery<T>> {
@@ -174,10 +184,13 @@ open class QueryDslImpl<T>(
             where = getWhereClause(),
             sqlHint = getSqlQueryHintClause(),
             jpaHint = getJpaQueryHintClause(),
-            set = SetClause(params)
+            set = getSetClause()
         )
     }
 
+    @Suppress("MemberVisibilityCanBePrivate")
+    protected fun getSetClause() = SetClause(params.orEmpty())
+
     @Suppress("UNCHECKED_CAST")
     fun createCriteriaDeleteQuerySpec(): CriteriaDeleteQuerySpec<T, Query> {
         return CriteriaDeleteQuerySpecImpl(
@@ -224,30 +237,32 @@ open class QueryDslImpl<T>(
 
     @Suppress("MemberVisibilityCanBePrivate")
     protected fun getJoinClause(): JoinClause {
-        return JoinClause(joins)
+        return JoinClause(joins.orEmpty())
     }
 
     @Suppress("MemberVisibilityCanBePrivate")
     protected fun getJoinClauseDoesNotHaveFetch(): JoinClause {
-        mustBe(joins.filterIsInstance<FetchJoinSpec<*, *>>().isEmpty()) { "This query does not support fetch" }
+        mustBe(joins.orEmpty().filterIsInstance<FetchJoinSpec<*, *>>().isEmpty()) { "This query does not support fetch" }
 
         return getJoinClause()
     }
 
+    @Suppress("MemberVisibilityCanBePrivate")
     protected fun getSimpleAssociatedJoinClauseOnly(): SimpleAssociatedJoinClause {
+        val joins = joins.orEmpty()
         return joins.filterIsInstance<SimpleAssociatedJoinSpec<*, *>>().let {
             mustBe(it.size == joins.size) { "This query only support associate" }
             SimpleAssociatedJoinClause(it)
         }
     }
 
     protected fun getWhereClause(): WhereClause {
-        return WhereClause(wheres.merge())
+        return WhereClause(wheres.orEmpty().merge())
     }
 
     @Suppress("MemberVisibilityCanBePrivate")
     protected fun getGroupByClause(): GroupByClause {
-        return GroupByClause(groupBys)
+        return GroupByClause(groupBys.orEmpty())
     }
 
     protected fun getEmptyGroupByClause(): GroupByClause {
@@ -256,7 +271,7 @@ open class QueryDslImpl<T>(
 
     @Suppress("MemberVisibilityCanBePrivate")
     protected fun getHavingClause(): HavingClause {
-        return HavingClause(havings.merge())
+        return HavingClause(havings.orEmpty().merge())
     }
 
     protected fun getEmptyHavingClause(): HavingClause {
@@ -265,7 +280,7 @@ open class QueryDslImpl<T>(
 
     @Suppress("MemberVisibilityCanBePrivate")
     protected fun getOrderByClause(): CriteriaQueryOrderByClause {
-        return OrderByClause(orderBys)
+        return OrderByClause(orderBys.orEmpty())
     }
 
     protected fun getEmptyOrderByClause(): CriteriaQueryOrderByClause {
@@ -282,12 +297,12 @@ open class QueryDslImpl<T>(
     }
 
     protected fun <Q : Query> getJpaQueryHintClause(): JpaQueryHintClause<Q> {
-        return JpaQueryHintClauseImpl(jpaHints)
+        return JpaQueryHintClauseImpl(jpaHints.orEmpty())
     }
 
     @Suppress("UNCHECKED_CAST")
     protected fun <Q : Query> getSqlQueryHintClause(): SqlQueryHintClause<Q> {
-        return SqlQueryHintClauseProvider.provide(sqlHints) as SqlQueryHintClause<Q>
+        return SqlQueryHintClauseProvider.provide(sqlHints.orEmpty()) as SqlQueryHintClause<Q>
     }
 
     @Suppress("MemberVisibilityCanBePrivate")