Added NewStrictNullChecks option

Author: k163377

src/main/kotlin/com/fasterxml/jackson/module/kotlin/KotlinFeature.kt

@@ -1,5 +1,7 @@
 package com.fasterxml.jackson.module.kotlin
 
+import com.fasterxml.jackson.annotation.JsonSetter
+import com.fasterxml.jackson.databind.exc.InvalidNullException
 import java.util.BitSet
 
 /**
@@ -40,6 +42,11 @@ enum class KotlinFeature(internal val enabledByDefault: Boolean) {
      * may contain null values after deserialization.
      * Enabling it protects against this but has significant performance impact.
      */
+    @Deprecated(
+        level = DeprecationLevel.WARNING,
+        message = "This option will be migrated to the new backend in 2.21.",
+        replaceWith = ReplaceWith("NewStrictNullChecks")
+    )
     StrictNullChecks(enabledByDefault = false),
 
     /**
@@ -66,7 +73,23 @@ enum class KotlinFeature(internal val enabledByDefault: Boolean) {
      * `@JsonFormat` annotations need to be declared either on getter using `@get:JsonFormat` or field using `@field:JsonFormat`.
      * See [jackson-module-kotlin#651] for details.
      */
-    UseJavaDurationConversion(enabledByDefault = false);
+    UseJavaDurationConversion(enabledByDefault = false),
+
+    /**
+     * New [StrictNullChecks] feature with improved throughput.
+     * Internally, it will be the same as if [JsonSetter] (contentNulls = FAIL) had been granted.
+     * Benchmarks show that it can check for illegal nulls with throughput nearly identical to the default (see [jackson-module-kotlin#719]).
+     *
+     * Note that in the new backend, the exception thrown has changed from [MissingKotlinParameterException] to [InvalidNullException].
+     * The message will be changed accordingly.
+     * Since 2.19, the base class of [MissingKotlinParameterException] has also been changed to [InvalidNullException],
+     * so be careful when catching it.
+     *
+     * This is a temporary option for a phased backend migration,
+     * which will eventually be merged into [StrictNullChecks].
+     * Also, specifying both this and [StrictNullChecks] is not permitted.
+     */
+    NewStrictNullChecks(enabledByDefault = false);
 
     internal val bitSet: BitSet = (1 shl ordinal).toBitSet()
 

src/main/kotlin/com/fasterxml/jackson/module/kotlin/KotlinModule.kt

@@ -7,6 +7,7 @@ import com.fasterxml.jackson.module.kotlin.KotlinFeature.NullToEmptyCollection
 import com.fasterxml.jackson.module.kotlin.KotlinFeature.NullToEmptyMap
 import com.fasterxml.jackson.module.kotlin.KotlinFeature.SingletonSupport
 import com.fasterxml.jackson.module.kotlin.KotlinFeature.StrictNullChecks
+import com.fasterxml.jackson.module.kotlin.KotlinFeature.NewStrictNullChecks
 import com.fasterxml.jackson.module.kotlin.KotlinFeature.KotlinPropertyNameAsImplicitName
 import com.fasterxml.jackson.module.kotlin.KotlinFeature.UseJavaDurationConversion
 import java.util.*
@@ -42,9 +43,10 @@ class KotlinModule private constructor(
     val nullToEmptyMap: Boolean = NullToEmptyMap.enabledByDefault,
     val nullIsSameAsDefault: Boolean = NullIsSameAsDefault.enabledByDefault,
     val singletonSupport: Boolean = SingletonSupport.enabledByDefault,
-    val strictNullChecks: Boolean = StrictNullChecks.enabledByDefault,
+    strictNullChecks: Boolean = StrictNullChecks.enabledByDefault,
     val kotlinPropertyNameAsImplicitName: Boolean = KotlinPropertyNameAsImplicitName.enabledByDefault,
     val useJavaDurationConversion: Boolean = UseJavaDurationConversion.enabledByDefault,
+    private val newStrictNullChecks: Boolean = NewStrictNullChecks.enabledByDefault,
 ) : SimpleModule(KotlinModule::class.java.name, PackageVersion.VERSION) {
     /*
      * Prior to 2.18, an older Enum called SingletonSupport was used to manage feature.
@@ -64,6 +66,19 @@ class KotlinModule private constructor(
     )
     val enabledSingletonSupport: Boolean get() = singletonSupport
 
+    private val oldStrictNullChecks: Boolean = strictNullChecks
+
+    // To reduce the amount of destructive changes, no properties will be added to the public.
+    val strictNullChecks: Boolean = if (strictNullChecks) {
+        if (newStrictNullChecks) {
+            throw IllegalArgumentException("Enabling both StrictNullChecks and NewStrictNullChecks is not permitted.")
+        }
+
+        true
+    } else {
+        newStrictNullChecks
+    }
+
     companion object {
         // Increment when option is added
         private const val serialVersionUID = 3L
@@ -84,6 +99,7 @@ class KotlinModule private constructor(
         builder.isEnabled(StrictNullChecks),
         builder.isEnabled(KotlinPropertyNameAsImplicitName),
         builder.isEnabled(UseJavaDurationConversion),
+        builder.isEnabled(NewStrictNullChecks),
     )
 
     override fun setupModule(context: SetupContext) {
@@ -95,7 +111,7 @@ class KotlinModule private constructor(
 
         val cache = ReflectionCache(reflectionCacheSize)
 
-        context.addValueInstantiators(KotlinInstantiators(cache, nullToEmptyCollection, nullToEmptyMap, nullIsSameAsDefault, strictNullChecks))
+        context.addValueInstantiators(KotlinInstantiators(cache, nullToEmptyCollection, nullToEmptyMap, nullIsSameAsDefault, oldStrictNullChecks))
 
         if (singletonSupport) {
             context.addBeanDeserializerModifier(KotlinBeanDeserializerModifier)

src/test/kotlin/com/fasterxml/jackson/module/kotlin/DslTest.kt

@@ -6,7 +6,7 @@ import com.fasterxml.jackson.module.kotlin.KotlinFeature.NullIsSameAsDefault
 import com.fasterxml.jackson.module.kotlin.KotlinFeature.NullToEmptyCollection
 import com.fasterxml.jackson.module.kotlin.KotlinFeature.NullToEmptyMap
 import com.fasterxml.jackson.module.kotlin.KotlinFeature.SingletonSupport
-import com.fasterxml.jackson.module.kotlin.KotlinFeature.StrictNullChecks
+import com.fasterxml.jackson.module.kotlin.KotlinFeature.NewStrictNullChecks
 import org.junit.jupiter.api.Assertions.assertNotNull
 import org.junit.jupiter.api.Test
 import kotlin.test.assertEquals
@@ -35,7 +35,7 @@ class DslTest {
             enable(NullToEmptyMap)
             enable(NullIsSameAsDefault)
             enable(SingletonSupport)
-            enable(StrictNullChecks)
+            enable(NewStrictNullChecks)
         }
 
         assertNotNull(module)

src/test/kotlin/com/fasterxml/jackson/module/kotlin/KotlinModuleTest.kt

@@ -6,9 +6,24 @@ import org.junit.jupiter.api.Assertions.assertEquals
 import org.junit.jupiter.api.Assertions.assertFalse
 import org.junit.jupiter.api.Assertions.assertTrue
 import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.assertThrows
 import kotlin.test.assertNotNull
 
 class KotlinModuleTest {
+    // After the final migration is complete, this test will be removed.
+    @Test
+    fun strictNullChecksTests() {
+        assertTrue(kotlinModule { enable(StrictNullChecks) }.strictNullChecks)
+        assertTrue(kotlinModule { enable(NewStrictNullChecks) }.strictNullChecks)
+
+        assertThrows<IllegalArgumentException> {
+            kotlinModule {
+                enable(StrictNullChecks)
+                enable(NewStrictNullChecks)
+            }
+        }
+    }
+
     @Test
     fun builder_Defaults() {
         val module = KotlinModule.Builder().build()