Recipe to migrate from Math.random to ThreadLocalRandom (#543)

* Recipe to migrate from Math.random to ThreadLocalRandom

* Update src/main/java/org/openrewrite/java/migrate/util/ReplaceMathRandomWithThreadLocalRandom.java

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

* Revert "Update src/main/java/org/openrewrite/java/migrate/util/ReplaceMathRandomWithThreadLocalRandom.java"

This reverts commit 527c48c.

* tweak imports

* Minor polish and include with Java 7 upgrades

---------

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Tim te Beek <[email protected]>

src/main/java/org/openrewrite/java/migrate/util/ReplaceMathRandomWithThreadLocalRandom.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2024 the original author or authors.
+ * <p>
+ * 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
+ * <p>
+ * https://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * 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.openrewrite.java.migrate.util;
+
+import com.google.errorprone.refaster.annotation.AfterTemplate;
+import com.google.errorprone.refaster.annotation.BeforeTemplate;
+import org.openrewrite.java.template.RecipeDescriptor;
+
+import java.util.concurrent.ThreadLocalRandom;
+
+@RecipeDescriptor(
+        name = "Replace `java.lang.Math random()` with `ThreadLocalRandom nextDouble()`",
+        description = "Replace `java.lang.Math random()` with `ThreadLocalRandom nextDouble()` to reduce contention."
+)
+public class ReplaceMathRandomWithThreadLocalRandom {
+    @BeforeTemplate
+    double javaMathRandom() {
+        return Math.random();
+    }
+
+    @AfterTemplate
+    double threadLocalRandomNextDouble() {
+        return ThreadLocalRandom.current().nextDouble();
+    }
+}

src/main/resources/META-INF/rewrite/java-version-7.yml

@@ -26,6 +26,7 @@ recipeList:
   - org.openrewrite.java.migrate.UpgradeToJava6
   - org.openrewrite.java.migrate.JREJdbcInterfaceNewMethods
   - org.openrewrite.java.migrate.JREThrowableFinalMethods
+  - org.openrewrite.java.migrate.util.ReplaceMathRandomWithThreadLocalRandomRecipe
 ---
 type: specs.openrewrite.org/v1beta/recipe
 name: org.openrewrite.java.migrate.JREJdbcInterfaceNewMethods

src/test/java/org/openrewrite/java/migrate/util/ReplaceMathRandomWithThreadLocalRandomRecipeTest.java

@@ -0,0 +1,57 @@
+/*
+ * Copyright 2024 the original author or authors.
+ * <p>
+ * 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
+ * <p>
+ * https://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * 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.openrewrite.java.migrate.util;
+
+import org.junit.jupiter.api.Test;
+import org.openrewrite.DocumentExample;
+import org.openrewrite.test.RecipeSpec;
+import org.openrewrite.test.RewriteTest;
+
+import static org.openrewrite.java.Assertions.java;
+
+class ReplaceMathRandomWithThreadLocalRandomRecipeTest implements RewriteTest {
+
+    @Override
+    public void defaults(RecipeSpec spec) {
+        spec.recipe(new ReplaceMathRandomWithThreadLocalRandomRecipe());
+    }
+
+    @Test
+    @DocumentExample
+    void replacesMathRandom() {
+        rewriteRun(
+          //language=java
+          java(
+            """
+              class Example {
+                  double test() {
+                      return Math.random();
+                  }
+              }
+              """,
+            """
+              import java.util.concurrent.ThreadLocalRandom;
+              
+              class Example {
+                  double test() {
+                      return ThreadLocalRandom.current().nextDouble();
+                  }
+              }
+              """
+          )
+        );
+    }
+}