Add a cache around ASTHelpers.isInherited

This is called quite often, and with a very small number of distinct
arguments. I'd like to speed up the actual implementation, or avoid
calling it so often, but for starters introducing a cache speeds up
the method by around 80%, shaving 2% off of the entire javac action.

This adds a new dependency on Caffeine; I considered using a Guava
Cache since we already depend on Guava, but Caffeine's version is 3
times as fast for this use case.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=259064453

check_api/pom.xml

@@ -15,7 +15,9 @@
   limitations under the License.
   -->
 
-<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
   <modelVersion>4.0.0</modelVersion>
 
   <!-- Added this because the JSR 305 dependency wouldn't download from the
@@ -139,6 +141,12 @@
       <artifactId>software-and-algorithms</artifactId>
       <version>1.0</version>
     </dependency>
+    <dependency>
+      <!-- Apache 2.0 -->
+      <groupId>com.github.ben-manes.caffeine</groupId>
+      <artifactId>caffeine</artifactId>
+      <version>2.2.6</version>
+    </dependency>
   </dependencies>
 
 </project>

check_api/src/main/java/com/google/errorprone/util/ASTHelpers.java

@@ -22,6 +22,8 @@
 import static com.sun.tools.javac.code.Scope.LookupKind.NON_RECURSIVE;
 import static java.util.Objects.requireNonNull;
 
+import com.github.benmanes.caffeine.cache.Cache;
+import com.github.benmanes.caffeine.cache.Caffeine;
 import com.google.auto.value.AutoValue;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.CharMatcher;
@@ -677,19 +679,27 @@ public static boolean hasAnnotation(Symbol sym, String annotationClass, VisitorS
     return false;
   }
 
+  private static final Cache<String, Boolean> inheritedAnnotationCache =
+      Caffeine.newBuilder().maximumSize(1000).build();
+
+  @SuppressWarnings("ConstantConditions") // IntelliJ worries unboxing our Boolean may throw NPE.
   private static boolean isInherited(VisitorState state, String annotationName) {
-    Symbol annotationSym = state.getSymbolFromString(annotationName);
-    if (annotationSym == null) {
-      return false;
-    }
-    try {
-      annotationSym.complete();
-    } catch (CompletionFailure e) {
-      // @Inherited won't work if the annotation isn't on the classpath, but we can still check
-      // if it's present directly
-    }
-    Symbol inheritedSym = state.getSymtab().inheritedType.tsym;
-    return annotationSym.attribute(inheritedSym) != null;
+    return inheritedAnnotationCache.get(
+        annotationName,
+        name -> {
+          Symbol annotationSym = state.getSymbolFromString(name);
+          if (annotationSym == null) {
+            return false;
+          }
+          try {
+            annotationSym.complete();
+          } catch (CompletionFailure e) {
+            /* @Inherited won't work if the annotation isn't on the classpath, but we can still
+            check if it's present directly */
+          }
+          Symbol inheritedSym = state.getSymtab().inheritedType.tsym;
+          return annotationSym.attribute(inheritedSym) != null;
+        });
   }
 
   private static boolean hasAttribute(Symbol sym, Name annotationName) {