Bug fix a race condition when Scope(useNullFieldInitialization = true) is set.

compiler/src/main/kotlin/motif/compiler/JavaCodeGenerator.kt

@@ -194,7 +194,8 @@ object JavaCodeGenerator {
           .add("Object $localFieldName = \$N;\n", cacheFieldName)
           .beginControlFlow("if (\$N == null)", localFieldName)
           .beginControlFlow("synchronized (this)")
-          .beginControlFlow("if (\$N == null)", cacheFieldName)
+          .add("\$N = \$N;\n", localFieldName, cacheFieldName)
+          .beginControlFlow("if (\$N == null)", localFieldName)
           .add("\$N = \$L;\n", localFieldName, instantiation.spec())
           .beginControlFlow("if (\$N == null)", localFieldName)
           .add(
@@ -203,7 +204,7 @@ object JavaCodeGenerator {
               "Factory method cannot return null",
           )
           .endControlFlow()
-          .add("\$N = \$L;\n", cacheFieldName, localFieldName)
+          .add("\$N = \$N;\n", cacheFieldName, localFieldName)
           .endControlFlow()
           .endControlFlow()
           .endControlFlow()

compiler/src/main/kotlin/motif/compiler/KotlinCodeGenerator.kt

@@ -231,7 +231,8 @@ object KotlinCodeGenerator {
               .addStatement("var $localFieldName = %N;\n", cacheFieldName)
               .beginControlFlow("if (%N == null)", localFieldName)
               .beginControlFlow("synchronized (this)")
-              .beginControlFlow("if (%N == null)", cacheFieldName)
+              .addStatement("%N = %N", localFieldName, cacheFieldName)
+              .beginControlFlow("if (%N == null)", localFieldName)
               .addStatement("%N = %L", localFieldName, instantiation.spec())
               .addStatement("%N = %N", cacheFieldName, localFieldName)
               .endControlFlow()

samples/sample/build.gradle

@@ -12,8 +12,8 @@ android {
     }
 
     compileOptions {
-        sourceCompatibility JavaVersion.VERSION_1_8
-        targetCompatibility JavaVersion.VERSION_1_8
+        sourceCompatibility JavaVersion.VERSION_11
+        targetCompatibility JavaVersion.VERSION_11
     }
 
     defaultConfig {

tests/src/main/java/testcases/KT009_use_null_field_concurrency_kotlin/GRAPH.txt

@@ -0,0 +1,32 @@
+########################################################################
+#                                                                      #
+# This file is auto-generated by running the Motif compiler tests and  #
+# serves a as validation of graph correctness. IntelliJ plugin tests   #
+# also rely on this file to ensure that the plugin graph understanding #
+# is equivalent to the compiler's.                                     #
+#                                                                      #
+# - Do not edit manually.                                              #
+# - Commit changes to source control.                                  #
+# - Since this file is autogenerated, code review changes carefully to #
+#   ensure correctness.                                                #
+#                                                                      #
+########################################################################
+
+ -------
+| Scope |
+ -------
+
+  ==== Required ====
+
+  ==== Provides ====
+
+    ---- Object | Objects.fooObject ----
+      [ Required ]
+      [ Consumed By ]
+        * Scope | Scope.fooObject()
+
+    ---- Scope | implicit ----
+      [ Required ]
+      [ Consumed By ]
+
+

tests/src/main/java/testcases/KT009_use_null_field_concurrency_kotlin/Scope.kt

@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2018-2019 Uber Technologies, Inc.
+ *
+ * Licensed 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 testcases.KT009_use_null_field_concurrency_kotlin
+
+import motif.Creatable
+
+@motif.Scope(useNullFieldInitialization = true)
+interface Scope : Creatable<Scope.Dependencies> {
+    fun fooObject(): Any
+
+    @motif.Objects
+    abstract class Objects {
+        fun fooObject(): Any {
+            return Any()
+        }
+    }
+
+    interface Dependencies
+}

tests/src/main/java/testcases/KT009_use_null_field_concurrency_kotlin/Test.java

@@ -0,0 +1,71 @@
+/*
+ * Copyright (c) 2018-2019 Uber Technologies, Inc.
+ *
+ * Licensed 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 testcases.KT009_use_null_field_concurrency_kotlin;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicInteger;
+
+
+public class Test {
+
+    /**
+     * This tests if the ScopeImpl synchronized blocks check and assign correct values
+     */
+    public static void run() {
+        Scope scope = new ScopeImpl();
+        int nThreads = 2;
+        ExecutorService executorService = Executors.newFixedThreadPool(nThreads);
+        CountDownLatch getFooObjectLatch = new CountDownLatch(nThreads);
+        CountDownLatch end = new CountDownLatch(nThreads);
+        AtomicBoolean isFooObjectNull = new AtomicBoolean(false);
+        try {
+            synchronized (scope) { // blocks the synchronized in scope.fooObject
+                for (int i = 0; i < nThreads; i++) {
+                    executorService.submit(() -> {
+                        getFooObjectLatch.countDown();
+                        try {
+                            Object fooObject = scope.fooObject();
+                            if(fooObject == null) {
+                                isFooObjectNull.set(true);
+                            }
+                        } catch (Exception e) {
+                            isFooObjectNull.set(true);
+                        }
+                        end.countDown();
+                    });
+                }
+                getFooObjectLatch.await(1000, TimeUnit.MILLISECONDS);
+            }
+            // at this point, the two threads will compete to create the fooObject
+
+            // Verify
+            if(end.await(1000, TimeUnit.MILLISECONDS)) {
+                assertThat(isFooObjectNull.get()).isFalse();
+            }
+        } catch (InterruptedException e) {
+            throw new RuntimeException(e);
+        }
+    }
+}

tests/src/main/java/testcases/T078_use_null_field_concurrency_java/GRAPH.txt

@@ -0,0 +1,32 @@
+########################################################################
+#                                                                      #
+# This file is auto-generated by running the Motif compiler tests and  #
+# serves a as validation of graph correctness. IntelliJ plugin tests   #
+# also rely on this file to ensure that the plugin graph understanding #
+# is equivalent to the compiler's.                                     #
+#                                                                      #
+# - Do not edit manually.                                              #
+# - Commit changes to source control.                                  #
+# - Since this file is autogenerated, code review changes carefully to #
+#   ensure correctness.                                                #
+#                                                                      #
+########################################################################
+
+ -------
+| Scope |
+ -------
+
+  ==== Required ====
+
+  ==== Provides ====
+
+    ---- Object | Objects.fooObject ----
+      [ Required ]
+      [ Consumed By ]
+        * Scope | Scope.fooObject()
+
+    ---- Scope | implicit ----
+      [ Required ]
+      [ Consumed By ]
+
+

tests/src/main/java/testcases/T078_use_null_field_concurrency_java/Scope.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright (c) 2018-2019 Uber Technologies, Inc.
+ *
+ * Licensed 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 testcases.T078_use_null_field_concurrency_java;
+
+import motif.Creatable;
+
+@motif.Scope(useNullFieldInitialization = true)
+public interface Scope extends Creatable<Scope.Dependencies> {
+
+    Object fooObject();
+
+    @motif.Objects
+    class Objects {
+
+        Object fooObject() {
+            return new Object();
+        }
+
+    }
+
+    interface Dependencies {}
+}

tests/src/main/java/testcases/T078_use_null_field_concurrency_java/Test.java

@@ -0,0 +1,65 @@
+/*
+ * Copyright (c) 2018-2019 Uber Technologies, Inc.
+ *
+ * Licensed 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 testcases.T078_use_null_field_concurrency_java;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+public class Test {
+
+    /**
+     * This tests if the ScopeImpl synchronized blocks check and assign correct values
+     */
+    public static void run() {
+        Scope scope = new ScopeImpl();
+        int nThreads = 2;
+        ExecutorService executorService = Executors.newFixedThreadPool(nThreads);
+        CountDownLatch getFooObjectLatch = new CountDownLatch(nThreads);
+        CountDownLatch end = new CountDownLatch(nThreads);
+        AtomicBoolean isFooObjectNull = new AtomicBoolean(false);
+        try {
+            synchronized (scope) { // blocks the synchronized in scope.fooObject
+                for (int i = 0; i < nThreads; i++) {
+                    executorService.submit(() -> {
+                        getFooObjectLatch.countDown();
+                        Object fooObject = scope.fooObject();
+                        if(fooObject == null) {
+                            isFooObjectNull.set(true);
+                        }
+                        end.countDown();
+                    });
+                }
+                getFooObjectLatch.await(1000, TimeUnit.MILLISECONDS);
+            }
+            // at this point, the two threads will compete to create the fooObject
+
+            // Verify
+            if(end.await(1000, TimeUnit.MILLISECONDS)) {
+                assertThat(isFooObjectNull.get()).isFalse();
+            }
+        } catch (InterruptedException e) {
+            throw new RuntimeException(e);
+        }
+    }
+}