Sharing: yes we can

error-prone-contrib/pom.xml

@@ -39,6 +39,11 @@
             <artifactId>error_prone_test_helpers</artifactId>
             <scope>test</scope>
         </dependency>
+        <!-- XXX: dubious. -->
+        <dependency>
+            <groupId>${project.groupId}</groupId>
+            <artifactId>plexus-compiler-javac-caching</artifactId>
+        </dependency>
         <dependency>
             <groupId>${project.groupId}</groupId>
             <artifactId>refaster-compiler</artifactId>

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/RefasterCheck.java

@@ -43,9 +43,11 @@ import java.util.List;
 import java.util.Map;
 import java.util.NoSuchElementException;
 import java.util.Optional;
+import java.util.concurrent.ConcurrentMap;
 import java.util.function.Supplier;
 import java.util.regex.Pattern;
 import java.util.stream.Stream;
+import tech.picnic.errorprone.plexus.compiler.javac.caching.CachingJavacCompiler;
 
 /**
  * A {@link BugChecker} which flags code which can be simplified using Refaster templates located on
@@ -89,6 +91,16 @@ public final class RefasterCheck extends BugChecker implements CompilationUnitTr
 
   @Override
   public Description matchCompilationUnit(CompilationUnitTree tree, VisitorState state) {
+    System.out.println("XXXX :" + CachingJavacCompiler.class.toString());
+    ConcurrentMap<String, Integer> cache = state.context.get(ConcurrentMap.class);
+    System.err.printf("XXX %s%n", cache);
+    if (cache != null) {
+      cache.compute("x", (a, b) -> b == null ? 1 : b + 1);
+    } else {
+      // We're not using the hacked compiler
+      System.err.printf("XXX NOP!%n");
+    }
+
     /* First, collect all matches. */
     List<Description> matches = new ArrayList<>();
     try {

plexus-compiler-javac-caching/pom.xml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
 
     <parent>
@@ -14,6 +14,11 @@
     <description>Caching Javac compiler Plexus Compiler component.</description>
 
     <dependencies>
+        <dependency>
+            <groupId>com.google.errorprone</groupId>
+            <artifactId>javac</artifactId>
+            <scope>provided</scope>
+        </dependency>
         <dependency>
             <groupId>org.codehaus.plexus</groupId>
             <artifactId>plexus-compiler-api</artifactId>

plexus-compiler-javac-caching/src/main/java/tech/picnic/errorprone/plexus/compiler/javac/caching/CachingJavacCompiler.java

@@ -1,7 +1,21 @@
 package tech.picnic.errorprone.plexus.compiler.javac.caching;
 
+import com.sun.tools.javac.api.JavacTool;
+import com.sun.tools.javac.util.Context;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.io.Writer;
+import java.nio.charset.Charset;
+import java.util.Locale;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+import javax.lang.model.SourceVersion;
+import javax.tools.DiagnosticListener;
 import javax.tools.JavaCompiler;
-import javax.tools.ToolProvider;
+import javax.tools.JavaFileManager;
+import javax.tools.JavaFileObject;
+import javax.tools.StandardJavaFileManager;
 import org.codehaus.plexus.compiler.CompilerConfiguration;
 import org.codehaus.plexus.compiler.CompilerException;
 import org.codehaus.plexus.compiler.CompilerResult;
@@ -13,7 +27,10 @@ public final class CachingJavacCompiler extends JavaxToolsCompiler {
   @Override
   protected JavaCompiler newJavaCompiler() {
     // XXX: Tweak!
-    return ToolProvider.getSystemJavaCompiler();
+    // XXX: Could we instead simply provide another `JavaCompiler` to be service-loaded? Would
+    // certainly be simpler.
+    //    return ToolProvider.getSystemJavaCompiler();
+    return new XxxJavaCompiler(JavacTool.create());
   }
 
   // XXX: Drop?
@@ -23,4 +40,53 @@ public final class CachingJavacCompiler extends JavaxToolsCompiler {
     getLogger().error("XXXX I'm invoked!");
     return super.compileInProcess(args, config, sourceFiles);
   }
+
+  // XXX: Name!
+  private static final class XxxJavaCompiler implements JavaCompiler {
+    private final ConcurrentHashMap<?, ?> cache = new ConcurrentHashMap<>();
+    private final JavacTool delegate;
+
+    private XxxJavaCompiler(JavacTool delegate) {
+      this.delegate = delegate;
+    }
+
+    @Override
+    public CompilationTask getTask(
+        Writer out,
+        JavaFileManager fileManager,
+        DiagnosticListener<? super JavaFileObject> diagnosticListener,
+        Iterable<String> options,
+        Iterable<String> classes,
+        Iterable<? extends JavaFileObject> compilationUnits) {
+      System.out.println("XXXX I'm invoked!");
+      Context context = new Context();
+      // XXX: Explain.
+      context.put(ConcurrentMap.class, cache);
+      return delegate.getTask(
+          out, fileManager, diagnosticListener, options, classes, compilationUnits, context);
+    }
+
+    @Override
+    public StandardJavaFileManager getStandardFileManager(
+        DiagnosticListener<? super JavaFileObject> diagnosticListener,
+        Locale locale,
+        Charset charset) {
+      return delegate.getStandardFileManager(diagnosticListener, locale, charset);
+    }
+
+    @Override
+    public int isSupportedOption(String option) {
+      return delegate.isSupportedOption(option);
+    }
+
+    @Override
+    public int run(InputStream in, OutputStream out, OutputStream err, String... arguments) {
+      return delegate.run(in, out, err, arguments);
+    }
+
+    @Override
+    public Set<SourceVersion> getSourceVersions() {
+      return delegate.getSourceVersions();
+    }
+  }
 }

plexus-compiler-javac-caching/src/main/resources/META-INF/plexus/components.xml

@@ -1,26 +1,26 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <component-set>
-  <components>
-    <component>
-      <role>org.codehaus.plexus.compiler.Compiler</role>
-      <role-hint>javac-with-caching</role-hint>
-      <implementation>org.codehaus.plexus.compiler.javac.JavacCompiler</implementation>
-      <description />
-      <isolated-realm>false</isolated-realm>
-      <requirements>
-        <requirement>
-          <role>org.codehaus.plexus.compiler.javac.InProcessCompiler</role>
-           <role-hint>javac-with-caching</role-hint>
-          <field-name>inProcessCompiler</field-name>
-        </requirement>
-      </requirements>
-    </component>
-    <component>
-      <role>org.codehaus.plexus.compiler.javac.InProcessCompiler</role>
-      <role-hint>javac-with-caching</role-hint>
-      <implementation>tech.picnic.errorprone.plexus.compiler.javac.caching.CachingJavacCompiler</implementation>
-      <description />
-      <isolated-realm>false</isolated-realm>
-    </component>
-  </components>
+    <components>
+        <component>
+            <role>org.codehaus.plexus.compiler.Compiler</role>
+            <role-hint>javac-with-caching</role-hint>
+            <implementation>org.codehaus.plexus.compiler.javac.JavacCompiler</implementation>
+            <description/>
+            <isolated-realm>false</isolated-realm>
+            <requirements>
+                <requirement>
+                    <role>org.codehaus.plexus.compiler.javac.InProcessCompiler</role>
+                    <role-hint>javac-with-caching</role-hint>
+                    <field-name>inProcessCompiler</field-name>
+                </requirement>
+            </requirements>
+        </component>
+        <component>
+            <role>org.codehaus.plexus.compiler.javac.InProcessCompiler</role>
+            <role-hint>javac-with-caching</role-hint>
+            <implementation>tech.picnic.errorprone.plexus.compiler.javac.caching.CachingJavacCompiler</implementation>
+            <description/>
+            <isolated-realm>false</isolated-realm>
+        </component>
+    </components>
 </component-set>

pom.xml

@@ -185,6 +185,11 @@
                 <artifactId>error_prone_test_helpers</artifactId>
                 <version>${version.error-prone}</version>
             </dependency>
+            <dependency>
+                <groupId>${project.groupId}</groupId>
+                <artifactId>plexus-compiler-javac-caching</artifactId>
+                <version>${project.version}</version>
+            </dependency>
             <dependency>
                 <groupId>${project.groupId}</groupId>
                 <artifactId>refaster-compiler</artifactId>