Warn on usage of Maps.transformValues

baseline-error-prone/src/main/java/com/palantir/baseline/errorprone/DangerousGuavaTransformValuesUsage.java

@@ -0,0 +1,57 @@
+/*
+ * (c) Copyright 2019 Palantir Technologies Inc. All rights reserved.
+ *
+ * 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 com.palantir.baseline.errorprone;
+
+import com.google.auto.service.AutoService;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.BugPattern.SeverityLevel;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.matchers.Matcher;
+import com.google.errorprone.matchers.method.MethodMatchers;
+import com.sun.source.tree.ExpressionTree;
+import com.sun.source.tree.MethodInvocationTree;
+
+@AutoService(BugChecker.class)
+@BugPattern(
+        link = "https://github.com/palantir/gradle-baseline#baseline-error-prone-checks",
+        linkType = BugPattern.LinkType.CUSTOM,
+        severity = SeverityLevel.ERROR,
+        summary = "Disallow usage of Guava Map's .transformValues().")
+public final class DangerousGuavaTransformValuesUsage extends BugChecker
+        implements BugChecker.MethodInvocationTreeMatcher {
+    private static final long serialVersionUID = 1L;
+    private static final String ERROR_MESSAGE = "The transformValues API of Guava Maps creates a lazily evaluated "
+            + "view of the source Map. Repeated access of the same key leads to repeated evaluations of the "
+            + "transformer function. This is often unintended and can cause severe performance degradation."
+            + "Where this is actually intended, suppress this warning.";
+
+    private static final Matcher<ExpressionTree> TRANSFORM_VALUES_CALL = MethodMatchers.instanceMethod()
+            .onExactClass("com.google.common.collect.Maps")
+            .named("transformValues");
+
+    @Override
+    public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
+        if (!TRANSFORM_VALUES_CALL.matches(tree, state)) {
+            return Description.NO_MATCH;
+        }
+
+        // Fail on any 'transformValues(...)' usage
+        return buildDescription(tree).setMessage(ERROR_MESSAGE).build();
+    }
+}

baseline-error-prone/src/test/java/com/palantir/baseline/errorprone/DangerousGuavaTransformValuesUsageUsageTest.java

@@ -0,0 +1,46 @@
+/*
+ * (c) Copyright 2022 Palantir Technologies Inc. All rights reserved.
+ *
+ * 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 com.palantir.baseline.errorprone;
+
+import com.google.errorprone.CompilationTestHelper;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+class DangerousGuavaTransformValuesUsageUsageTest {
+    private CompilationTestHelper compilationHelper;
+
+    @BeforeEach
+    public void before() {
+        compilationHelper = CompilationTestHelper.newInstance(DangerousGuavaTransformValuesUsage.class, getClass());
+    }
+
+    @Test
+    public void should_error_when_transforms_values_is_used() {
+        compilationHelper
+                .addSourceLines(
+                        "Test.java",
+                        "import java.util.Map;",
+                        "import com.google.common.collect.Maps;",
+                        "class Test {",
+                        "   public static final void main(String[] args) {",
+                        "       Map<Integer, Integer> map = Map.of(1, 2, 3, 4, 5, 6);",
+                        "       Maps.transformValues(map, value -> value + 1);",
+                        "   }",
+                        "}")
+                .doTest();
+    }
+}

changelog/@unreleased/pr-2518.v2.yml

@@ -0,0 +1,5 @@
+type: improvement
+improvement:
+  description: Warn on usage of Maps.transformValues
+  links:
+  - https://github.com/palantir/gradle-baseline/pull/2518