Benchmark part 1: generate java code for build

--
PiperOrigin-RevId: 145524911
MOS_MIGRATED_REVID=145524911

11 files changed, 1141 insertions, 0 deletions

diff --git a/src/BUILD b/src/BUILD
index 2739232951..bca7c98a15 100644
--- a/src/BUILD
+++ b/src/BUILD
@@ -321,6 +321,7 @@ filegroup(
         "//src/test/java/com/google/devtools/common/options:srcs",
         "//src/test/shell:srcs",
         "//src/tools/android/java/com/google/devtools/build/android:srcs",
+        "//src/tools/benchmark:srcs",
         "//src/tools/generate_workspace:srcs",
         "//src/tools/xcode/actoolwrapper:srcs",
         "//src/tools/xcode/environment:srcs",
diff --git a/src/tools/benchmark/BUILD b/src/tools/benchmark/BUILD
new file mode 100644
index 0000000000..c2678f81ce
--- /dev/null
+++ b/src/tools/benchmark/BUILD
@@ -0,0 +1,8 @@
+filegroup(
+    name = "srcs",
+    srcs = glob(["**"]) + [
+        "//src/tools/benchmark/java/com/google/devtools/build/benchmark/codegenerator:srcs",
+        "//src/tools/benchmark/javatests/com/google/devtools/build/benchmark/codegenerator:srcs",
+    ],
+    visibility = ["//src:__pkg__"],
+)
diff --git a/src/tools/benchmark/java/com/google/devtools/build/benchmark/codegenerator/BUILD b/src/tools/benchmark/java/com/google/devtools/build/benchmark/codegenerator/BUILD
new file mode 100644
index 0000000000..4285252bd8
--- /dev/null
+++ b/src/tools/benchmark/java/com/google/devtools/build/benchmark/codegenerator/BUILD
@@ -0,0 +1,28 @@
+package(default_visibility = ["//src/tools/benchmark:__subpackages__"])
+
+java_binary(
+    name = "codegenerator",
+    srcs = glob(["*.java"]),
+    main_class = "com.google.devtools.build.benchmark.codegenerator.Main",
+    deps = [
+        "//src/main/java/com/google/devtools/common/options",
+        "//third_party:guava",
+        "//third_party/java/javapoet",
+    ],
+)
+
+java_library(
+    name = "codegenerator_lib",
+    srcs = glob(["*.java"]),
+    deps = [
+        "//src/main/java/com/google/devtools/common/options",
+        "//third_party:guava",
+        "//third_party/java/javapoet",
+    ],
+)
+
+filegroup(
+    name = "srcs",
+    srcs = glob(["**"]),
+    visibility = ["//src:__pkg__"],
+)
diff --git a/src/tools/benchmark/java/com/google/devtools/build/benchmark/codegenerator/GeneratorOptions.java b/src/tools/benchmark/java/com/google/devtools/build/benchmark/codegenerator/GeneratorOptions.java
new file mode 100644
index 0000000000..dd3d79346b
--- /dev/null
+++ b/src/tools/benchmark/java/com/google/devtools/build/benchmark/codegenerator/GeneratorOptions.java
@@ -0,0 +1,71 @@
+// Copyright 2017 The Bazel Authors. 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.google.devtools.build.benchmark.codegenerator;
+
+import com.google.devtools.common.options.Option;
+import com.google.devtools.common.options.OptionsBase;
+
+/** Class that contains arguments for the java files generator. */
+public class GeneratorOptions extends OptionsBase {
+
+  @Option(
+    name = "modify",
+    defaultValue = "false",
+    category = "generator",
+    help = "if we modify the existing code (or generate new code)."
+  )
+  public boolean modificationMode;
+
+  @Option(
+    name = "output_dir",
+    defaultValue = "",
+    category = "generator",
+    valueHelp = "path",
+    help = "directory where we put generated code or modify the existing code."
+  )
+  public String outputDir;
+
+  @Option(
+    name = "a_few_files",
+    defaultValue = "false",
+    category = "generator",
+    help = "if we generate a package with a few files."
+  )
+  public boolean aFewFiles;
+
+  @Option(
+    name = "many_files",
+    defaultValue = "false",
+    category = "generator",
+    help = "if we generate a package with many files."
+  )
+  public boolean manyFiles;
+
+  @Option(
+    name = "long_chained_deps",
+    defaultValue = "false",
+    category = "generator",
+    help = "if we generate a package with long chained dependencies."
+  )
+  public boolean longChainedDeps;
+
+  @Option(
+    name = "parallel_deps",
+    defaultValue = "false",
+    category = "generator",
+    help = "if we generate a package with parallel dependencies."
+  )
+  public boolean parallelDeps;
+}
diff --git a/src/tools/benchmark/java/com/google/devtools/build/benchmark/codegenerator/JavaCodeGenerator.java b/src/tools/benchmark/java/com/google/devtools/build/benchmark/codegenerator/JavaCodeGenerator.java
new file mode 100644
index 0000000000..f1ba3a6eed
--- /dev/null
+++ b/src/tools/benchmark/java/com/google/devtools/build/benchmark/codegenerator/JavaCodeGenerator.java
@@ -0,0 +1,230 @@
+// Copyright 2017 The Bazel Authors. 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.google.devtools.build.benchmark.codegenerator;
+
+import com.google.common.annotations.VisibleForTesting;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+
+/** Create 4 types of Java project, or modify existing ones. */
+public class JavaCodeGenerator {
+
+  @VisibleForTesting static final String TARGET_A_FEW_FILES = "AFewFiles";
+  @VisibleForTesting static final int SIZE_A_FEW_FILES = 10;
+
+  @VisibleForTesting static final String TARGET_MANY_FILES = "ManyFiles";
+  @VisibleForTesting static final int SIZE_MANY_FILES = 1000;
+
+  @VisibleForTesting static final String TARGET_LONG_CHAINED_DEPS = "LongChainedDeps";
+  @VisibleForTesting static final int SIZE_LONG_CHAINED_DEPS = 20;
+
+  @VisibleForTesting static final String TARGET_PARALLEL_DEPS = "ParallelDeps";
+  @VisibleForTesting static final int SIZE_PARALLEL_DEPS = 20;
+
+  public static void generateNewProject(
+      String outputDir,
+      boolean aFewFiles,
+      boolean manyFiles,
+      boolean longChainedDeps,
+      boolean parallelDeps) {
+    Path dir = Paths.get(outputDir);
+    if (aFewFiles) {
+      createTargetWithSomeFiles(dir.resolve(TARGET_A_FEW_FILES), SIZE_A_FEW_FILES);
+    }
+    if (manyFiles) {
+      createTargetWithSomeFiles(dir.resolve(TARGET_MANY_FILES), SIZE_MANY_FILES);
+    }
+    if (longChainedDeps) {
+      createTargetWithLongChainedDeps(dir.resolve(TARGET_LONG_CHAINED_DEPS));
+    }
+    if (parallelDeps) {
+      createTargetWithParallelDeps(dir.resolve(TARGET_PARALLEL_DEPS));
+    }
+  }
+
+  public static void modifyExistingProject(
+      String outputDir,
+      boolean aFewFiles,
+      boolean manyFiles,
+      boolean longChainedDeps,
+      boolean parallelDeps) {
+    Path dir = Paths.get(outputDir);
+    if (aFewFiles) {
+      modifyTargetWithSomeFiles(dir.resolve(TARGET_A_FEW_FILES));
+    }
+    if (manyFiles) {
+      modifyTargetWithSomeFiles(dir.resolve(TARGET_MANY_FILES));
+    }
+    if (longChainedDeps) {
+      modifyTargetWithLongChainedDeps(dir.resolve(TARGET_LONG_CHAINED_DEPS));
+    }
+    if (parallelDeps) {
+      modifyTargetWithParallelDeps(dir.resolve(TARGET_PARALLEL_DEPS));
+    }
+  }
+
+  /** Target type 1/2: Create targets with some files */
+  private static void createTargetWithSomeFiles(Path projectPath, int numberOfFiles) {
+    if (pathExists(projectPath)) {
+      return;
+    }
+
+    try {
+      Files.createDirectories(projectPath);
+
+      for (int i = 0; i < numberOfFiles; ++i) {
+        JavaCodeGeneratorHelper.writeRandomClassToDir(
+            /* addExtraMethod = */ false, "RandomClass" + i, "com.example.generated", projectPath);
+      }
+
+      JavaCodeGeneratorHelper.writeMainClassToDir("com.example.generated", projectPath);
+      JavaCodeGeneratorHelper.buildFileWithMainClass(TARGET_A_FEW_FILES, "", projectPath);
+    } catch (IOException e) {
+      System.err.println("Error creating target with some files: " + e.getMessage());
+    }
+  }
+
+  /** Target type 1/2: Modify targets with some files */
+  private static void modifyTargetWithSomeFiles(Path projectPath) {
+    File dir = projectPath.toFile();
+    if (directoryExists(dir)) {
+      System.err.format(
+          "Project dir (%s) does not contain code for modification.\n", projectPath.toString());
+      return;
+    }
+    try {
+      JavaCodeGeneratorHelper.writeRandomClassToDir(
+          /* addExtraMethod = */ true, "RandomClass0", "com.example.generated", projectPath);
+    } catch (IOException e) {
+      System.err.println("Error modifying targets some files: " + e.getMessage());
+    }
+  }
+
+  /** Target type 3: Create targets with a few long chained dependencies (A -> B -> C -> … -> Z) */
+  private static void createTargetWithLongChainedDeps(Path projectPath) {
+    if (pathExists(projectPath)) {
+      return;
+    }
+
+    try {
+      Files.createDirectories(projectPath);
+
+      int count = SIZE_LONG_CHAINED_DEPS;
+
+      // Call next one for 0..(count-2)
+      for (int i = 0; i < count - 1; ++i) {
+        JavaCodeGeneratorHelper.targetWithNextHelper(i, true, projectPath);
+        JavaCodeGeneratorHelper.buildFileWithNextDeps(
+            i, "    deps=[ \":Deps" + (i + 1) + "\" ],\n", projectPath);
+      }
+      // Don't call next one for (count-1)
+      JavaCodeGeneratorHelper.targetWithNextHelper(count - 1, false, projectPath);
+      JavaCodeGeneratorHelper.buildFileWithNextDeps(count - 1, "", projectPath);
+
+      JavaCodeGeneratorHelper.writeMainClassToDir("com.example.generated", projectPath);
+
+      String deps = "    deps=[ \":Deps0\" ],\n";
+      JavaCodeGeneratorHelper.buildFileWithMainClass(TARGET_LONG_CHAINED_DEPS, deps, projectPath);
+    } catch (IOException e) {
+      System.err.println(
+          "Error creating targets with a few long chained dependencies: " + e.getMessage());
+    }
+  }
+
+  /** Target type 3: Modify targets with a few long chained dependencies (A -> B -> C -> … -> Z) */
+  private static void modifyTargetWithLongChainedDeps(Path projectPath) {
+    File dir = projectPath.toFile();
+    if (directoryExists(dir)) {
+      System.err.format(
+          "Project dir (%s) does not contain code for modification.\n", projectPath.toString());
+      return;
+    }
+    try {
+      JavaCodeGeneratorHelper.targetWithNextExtraHelper(
+          (SIZE_LONG_CHAINED_DEPS + 1) >> 1, true, projectPath);
+    } catch (IOException e) {
+      System.err.println(
+          "Error modifying targets with a few long chained dependencies: " + e.getMessage());
+    }
+  }
+
+  /** Target type 4: Create targets with lots of parallel dependencies (A -> B, C, D, E, F, G, H) */
+  private static void createTargetWithParallelDeps(Path projectPath) {
+    if (pathExists(projectPath)) {
+      return;
+    }
+
+    try {
+      Files.createDirectories(projectPath);
+
+      int count = SIZE_PARALLEL_DEPS;
+
+      // parallel dependencies B~Z
+      for (int i = 1; i < count; ++i) {
+        JavaCodeGeneratorHelper.writeRandomClassToDir(
+            false, "Deps" + i, "com.example.deps" + i, projectPath);
+        JavaCodeGeneratorHelper.buildFileWithNextDeps(i, "", projectPath);
+      }
+
+      // A(Main)
+      JavaCodeGeneratorHelper.parallelDepsMainClassHelper(count, projectPath);
+
+      String deps = "    deps=[ ";
+      for (int i = 1; i < count; ++i) {
+        deps += "\":Deps" + i + "\", ";
+      }
+      deps += "], \n";
+      JavaCodeGeneratorHelper.buildFileWithMainClass(TARGET_PARALLEL_DEPS, deps, projectPath);
+    } catch (IOException e) {
+      System.err.println(
+          "Error creating targets with lots of parallel dependencies: " + e.getMessage());
+    }
+  }
+
+  /** Target type 4: Modify targets with lots of parallel dependencies (A -> B, C, D, E, F, G, H) */
+  private static void modifyTargetWithParallelDeps(Path projectPath) {
+    File dir = projectPath.toFile();
+    if (directoryExists(dir)) {
+      System.err.format(
+          "Project dir (%s) does not contain code for modification.\n", projectPath.toString());
+      return;
+    }
+    try {
+      JavaCodeGeneratorHelper.writeRandomClassToDir(
+          true, "Deps1", "com.example.deps1", projectPath);
+    } catch (IOException e) {
+      System.err.println(
+          "Error creating targets with lots of parallel dependencies: " + e.getMessage());
+    }
+  }
+
+  private static boolean pathExists(Path path) {
+    File dir = path.toFile();
+    if (dir.exists()) {
+      System.err.println("File or directory exists, not rewriting it: " + path);
+      return true;
+    }
+
+    return false;
+  }
+
+  private static boolean directoryExists(File file) {
+    return !(file.exists() && file.isDirectory());
+  }
+}
diff --git a/src/tools/benchmark/java/com/google/devtools/build/benchmark/codegenerator/JavaCodeGeneratorHelper.java b/src/tools/benchmark/java/com/google/devtools/build/benchmark/codegenerator/JavaCodeGeneratorHelper.java
new file mode 100644
index 0000000000..82a0c48c1a
--- /dev/null
+++ b/src/tools/benchmark/java/com/google/devtools/build/benchmark/codegenerator/JavaCodeGeneratorHelper.java
@@ -0,0 +1,225 @@
+// Copyright 2017 The Bazel Authors. 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.google.devtools.build.benchmark.codegenerator;
+
+import static java.nio.charset.StandardCharsets.UTF_8;
+
+import com.google.common.base.Joiner;
+import com.squareup.javapoet.ClassName;
+import com.squareup.javapoet.JavaFile;
+import com.squareup.javapoet.MethodSpec;
+import com.squareup.javapoet.TypeSpec;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.StandardOpenOption;
+import java.util.Random;
+import javax.lang.model.element.Modifier;
+
+/** Helper class of {@link JavaCodeGenerator} */
+class JavaCodeGeneratorHelper {
+
+  private static final Joiner JOINER = Joiner.on("\n");
+  private static final MethodSpec randomMethod = genRandomMethod("PrintSth");
+  private static final MethodSpec somethingElseMethod = genRandomMethod("PrintSthElse");
+
+  /**
+   * Writes a class file {@code Deps(index).java} to the directory
+   * {@code projectPath/com/example/deps(index)}
+   *
+   * @param callNext if we should call the method from {@code Deps(index+1).java}
+   */
+  static void targetWithNextHelper(int index, boolean callNext, Path projectPath)
+      throws IOException {
+    ClassName nextClass = ClassName.get("com.example.deps" + (index + 1), "Deps" + (index + 1));
+
+    MethodSpec callNextMethod =
+        MethodSpec.methodBuilder("CallNext")
+            .addModifiers(Modifier.PUBLIC, Modifier.STATIC)
+            .returns(void.class)
+            .addStatement("$T.PrintSth()", nextClass)
+            .build();
+
+    TypeSpec.Builder klassBuilder =
+        TypeSpec.classBuilder("Deps" + index)
+            .addModifiers(Modifier.PUBLIC, Modifier.FINAL)
+            .addMethod(randomMethod);
+    if (callNext) {
+      klassBuilder.addMethod(callNextMethod);
+    }
+    TypeSpec klass = klassBuilder.build();
+
+    writeClassToDir(klass, "com.example.deps" + index, projectPath);
+  }
+
+  /**
+   * Writes a class file {@code Deps(index).java} with extra method {@code printSthElse()}
+   * to the directory {@code projectPath/com/example/deps(index)}
+   *
+   * @param callNext if we should call the method from {@code Deps(index+1).java}
+   */
+  static void targetWithNextExtraHelper(int index, boolean callNext, Path projectPath)
+      throws IOException {
+    ClassName nextClass = ClassName.get("com.example.deps" + (index + 1), "Deps" + (index + 1));
+
+    MethodSpec callNextMethod =
+        MethodSpec.methodBuilder("CallNext")
+            .addModifiers(Modifier.PUBLIC, Modifier.STATIC)
+            .returns(void.class)
+            .addStatement("$T.PrintSth()", nextClass)
+            .build();
+
+    TypeSpec.Builder klassBuilder =
+        TypeSpec.classBuilder("Deps" + index)
+            .addModifiers(Modifier.PUBLIC, Modifier.FINAL)
+            .addMethod(randomMethod)
+            .addMethod(somethingElseMethod);
+    if (callNext) {
+      klassBuilder.addMethod(callNextMethod);
+    }
+    TypeSpec klass = klassBuilder.build();
+
+    writeClassToDir(klass, "com.example.deps" + index, projectPath);
+  }
+
+  /**
+   * Writes {@code count-1} class files to the directory {@code projectPath/com/example/deps(index)}
+   * and one main class.
+   */
+  static void parallelDepsMainClassHelper(int count, Path projectPath) throws IOException {
+    MethodSpec.Builder callDepsBuilder =
+        MethodSpec.methodBuilder("main")
+            .addModifiers(Modifier.PUBLIC, Modifier.STATIC)
+            .addParameter(String[].class, "args")
+            .returns(void.class);
+    for (int i = 1; i < count; ++i) {
+      ClassName callingClass = ClassName.get("com.example.deps" + i, "Deps" + i);
+      callDepsBuilder.addStatement("$T.PrintSth()", callingClass);
+    }
+    MethodSpec callDeps = callDepsBuilder.build();
+    TypeSpec klass =
+        TypeSpec.classBuilder("Main")
+            .addModifiers(Modifier.PUBLIC, Modifier.FINAL)
+            .addMethod(callDeps)
+            .build();
+    writeClassToDir(klass, "com.example.generated", projectPath);
+  }
+
+  static void writeRandomClassToDir(
+      boolean addExtraMethod, String className, String packageName, Path projectPath)
+      throws IOException {
+    TypeSpec klass = genRandomClass(addExtraMethod, className);
+    writeClassToDir(klass, packageName, projectPath);
+  }
+
+  static void writeMainClassToDir(String packageName, Path projectPath) throws IOException {
+    TypeSpec main = genMainClass();
+    writeClassToDir(main, packageName, projectPath);
+  }
+
+  static void buildFileWithNextDeps(int index, String deps, Path projectPath) throws IOException {
+    Path buildFilePath = projectPath.resolve("BUILD");
+
+    String buildFileContent =
+        String.format(
+            JOINER
+                .join(
+                    "java_library(",
+                    "    name = 'Deps%d',",
+                    "    srcs = glob([ 'com/example/deps%d/*.java' ]),",
+                    "%s",
+                    "    visibility = [ '//visibility:public' ],",
+                    ")"),
+            index,
+            index,
+            deps);
+
+    createAndAppendFile(buildFilePath, buildFileContent);
+  }
+
+  static void buildFileWithMainClass(String targetName, String deps, Path projectPath)
+      throws IOException {
+    Path buildFilePath = projectPath.resolve("BUILD");
+
+    String buildFileContent =
+        String.format(
+            JOINER
+                .join(
+                    "java_binary(",
+                    "    name = '%s',",
+                    "    srcs = glob([ 'com/example/generated/*.java' ]),",
+                    "    main_class = 'com.example.generated.Main',",
+                    "%s",
+                    ")"),
+            targetName,
+            deps);
+
+    createAndAppendFile(buildFilePath, buildFileContent);
+  }
+
+  private static MethodSpec genRandomMethod(String methodName) {
+    return MethodSpec.methodBuilder(methodName)
+        .addModifiers(Modifier.PUBLIC, Modifier.STATIC)
+        .returns(void.class)
+        .addStatement("$T rand = new Random()", Random.class)
+        .addStatement("int n = rand.nextInt(100)")
+        .addStatement(
+            "$T.out.format($S, $S, $L)",
+            System.class,
+            "This is method(%s) with random number(%d)\n",
+            methodName,
+            "n")
+        .build();
+  }
+
+  private static TypeSpec genRandomClass(boolean addExtraMethod, String className) {
+
+    TypeSpec.Builder klassBuilder =
+        TypeSpec.classBuilder(className)
+            .addModifiers(Modifier.PUBLIC, Modifier.FINAL)
+            .addMethod(randomMethod);
+
+    if (addExtraMethod) {
+      klassBuilder.addMethod(somethingElseMethod);
+    }
+
+    return klassBuilder.build();
+  }
+
+  private static TypeSpec genMainClass() {
+    MethodSpec method =
+        MethodSpec.methodBuilder("main")
+            .addModifiers(Modifier.PUBLIC, Modifier.STATIC)
+            .returns(void.class)
+            .addParameter(String[].class, "args")
+            .build();
+
+    return TypeSpec.classBuilder("Main").addModifiers(Modifier.PUBLIC).addMethod(method).build();
+  }
+
+  private static void writeClassToDir(TypeSpec klass, String packageName, Path path)
+      throws IOException {
+    JavaFile javaFile = JavaFile.builder(packageName, klass).build();
+    javaFile.writeTo(path);
+  }
+
+  private static void createAndAppendFile(Path path, String content) throws IOException {
+    if (!Files.exists(path)) {
+      Files.createFile(path);
+    }
+    Files.write(path, content.getBytes(UTF_8), StandardOpenOption.APPEND);
+  }
+
+}
diff --git a/src/tools/benchmark/java/com/google/devtools/build/benchmark/codegenerator/Main.java b/src/tools/benchmark/java/com/google/devtools/build/benchmark/codegenerator/Main.java
new file mode 100644
index 0000000000..f251701545
--- /dev/null
+++ b/src/tools/benchmark/java/com/google/devtools/build/benchmark/codegenerator/Main.java
@@ -0,0 +1,71 @@
+// Copyright 2017 The Bazel Authors. 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.google.devtools.build.benchmark.codegenerator;
+
+import com.google.devtools.common.options.Options;
+import com.google.devtools.common.options.OptionsParsingException;
+import java.io.File;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+/** Main class for generating code. */
+public class Main {
+
+  private static final Logger logger = Logger.getLogger(Main.class.getName());
+
+  public static void main(String[] args) {
+    GeneratorOptions opt = null;
+    try {
+      opt = parseArgs(args);
+    } catch (Exception e) {
+      if (!e.getMessage().isEmpty()) {
+        logger.log(Level.SEVERE, e.getMessage());
+      }
+      System.exit(1);
+    }
+
+    // Generate or modify Java code
+    if (opt.modificationMode) {
+      JavaCodeGenerator.modifyExistingProject(
+          opt.outputDir, opt.aFewFiles, opt.manyFiles, opt.longChainedDeps, opt.parallelDeps);
+    } else {
+      JavaCodeGenerator.generateNewProject(
+          opt.outputDir, opt.aFewFiles, opt.manyFiles, opt.longChainedDeps, opt.parallelDeps);
+    }
+  }
+
+  public static GeneratorOptions parseArgs(String[] args) throws OptionsParsingException {
+    GeneratorOptions opt = Options.parse(GeneratorOptions.class, args).getOptions();
+
+    // Check output_dir argument
+    if (opt.outputDir.isEmpty()) {
+      throw new IllegalArgumentException("--output_dir should not be empty.");
+    }
+    if (opt.modificationMode) {
+      File dir = new File(opt.outputDir);
+      if (!(dir.exists() && dir.isDirectory())) {
+        throw new IllegalArgumentException(
+            "--output_dir (" + opt.outputDir + ") does not contain code for modification.");
+      }
+    }
+    // Check at least one type of package will be generated
+    if (!(opt.aFewFiles || opt.manyFiles || opt.longChainedDeps || opt.parallelDeps)) {
+      System.err.println(Options.getUsage(GeneratorOptions.class));
+      throw new IllegalArgumentException("No type of package is specified.");
+    }
+
+    return opt;
+  }
+}
diff --git a/src/tools/benchmark/javatests/com/google/devtools/build/benchmark/codegenerator/BUILD b/src/tools/benchmark/javatests/com/google/devtools/build/benchmark/codegenerator/BUILD
new file mode 100644
index 0000000000..6982009058
--- /dev/null
+++ b/src/tools/benchmark/javatests/com/google/devtools/build/benchmark/codegenerator/BUILD
@@ -0,0 +1,36 @@
+java_test(
+    name = "JavaCodeGeneratorHelperTest",
+    srcs = ["JavaCodeGeneratorHelperTest.java"],
+    deps = [
+        "//src/tools/benchmark/java/com/google/devtools/build/benchmark/codegenerator:codegenerator_lib",
+        "//third_party:guava",
+        "//third_party:junit4",
+    ],
+)
+
+java_test(
+    name = "JavaCodeGeneratorTest",
+    srcs = ["JavaCodeGeneratorTest.java"],
+    deps = [
+        "//src/tools/benchmark/java/com/google/devtools/build/benchmark/codegenerator:codegenerator_lib",
+        "//third_party:guava",
+        "//third_party:junit4",
+        "//third_party:truth",
+    ],
+)
+
+java_test(
+    name = "MainTest",
+    srcs = ["MainTest.java"],
+    deps = [
+        "//src/main/java/com/google/devtools/common/options",
+        "//src/tools/benchmark/java/com/google/devtools/build/benchmark/codegenerator:codegenerator_lib",
+        "//third_party:junit4",
+    ],
+)
+
+filegroup(
+    name = "srcs",
+    srcs = glob(["**"]),
+    visibility = ["//src:__pkg__"],
+)
diff --git a/src/tools/benchmark/javatests/com/google/devtools/build/benchmark/codegenerator/JavaCodeGeneratorHelperTest.java b/src/tools/benchmark/javatests/com/google/devtools/build/benchmark/codegenerator/JavaCodeGeneratorHelperTest.java
new file mode 100644
index 0000000000..15f41b30a5
--- /dev/null
+++ b/src/tools/benchmark/javatests/com/google/devtools/build/benchmark/codegenerator/JavaCodeGeneratorHelperTest.java
@@ -0,0 +1,255 @@
+// Copyright 2017 The Bazel Authors. 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.google.devtools.build.benchmark.codegenerator;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+import com.google.common.base.Joiner;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Scanner;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+/** Test for {@link JavaCodeGeneratorHelper}. */
+@RunWith(JUnit4.class)
+public class JavaCodeGeneratorHelperTest {
+
+  private static final String RANDOM_CLASS_CONTENT = joinLines(
+      "package com.package.name;",
+      "",
+      "import java.lang.System;",
+      "import java.util.Random;",
+      "",
+      "public final class ClassName {",
+      "  public static void PrintSth() {",
+      "    Random rand = new Random();",
+      "    int n = rand.nextInt(100);",
+      "    System.out.format(\"This is method(%s) with random number(%d)\\n\", \"PrintSth\", n);",
+      "  }",
+      "}");
+
+  private static final String RANDOM_CLASS_EXTRA_CONTENT = joinLines(
+      "package com.package.name;",
+      "",
+      "import java.lang.System;",
+      "import java.util.Random;",
+      "",
+      "public final class ClassNameExtra {",
+      "  public static void PrintSth() {",
+      "    Random rand = new Random();",
+      "    int n = rand.nextInt(100);",
+      "    System.out.format(\"This is method(%s) with random number(%d)\\n\", \"PrintSth\", n);",
+      "  }",
+      "",
+      "  public static void PrintSthElse() {",
+      "    Random rand = new Random();",
+      "    int n = rand.nextInt(100);",
+      "    System.out.format(\"This is method(%s) with random number(%d)\\n\","
+          + " \"PrintSthElse\", n);",
+      "  }",
+      "}");
+
+  private static final String MAIN_CLASS_CONTENT = joinLines(
+      "package com.package.name;",
+      "",
+      "import java.lang.String;",
+      "",
+      "public class Main {",
+      "  public static void main(String[] args) {",
+      "  }",
+      "}");
+
+  private static final String DEPS_BUILD_FILE_CONTENT = joinLines(
+      "java_library(",
+      "    name = 'Deps42',",
+      "    srcs = glob([ 'com/example/deps42/*.java' ]),",
+      "<this is deps>",
+      "    visibility = [ '//visibility:public' ],",
+      ")");
+
+  private static final String TARGET_BUILD_FILE_CONTENT = joinLines(
+      "java_binary(",
+      "    name = 'Target',",
+      "    srcs = glob([ 'com/example/generated/*.java' ]),",
+      "    main_class = 'com.example.generated.Main',",
+      "<this is deps>",
+      ")");
+
+  private static final String DEPS_CLASS_CONTENT = joinLines(
+      "package com.example.deps42;",
+      "",
+      "import com.example.deps43.Deps43;",
+      "import java.lang.System;",
+      "import java.util.Random;",
+      "",
+      "public final class Deps42 {",
+      "  public static void PrintSth() {",
+      "    Random rand = new Random();",
+      "    int n = rand.nextInt(100);",
+      "    System.out.format(\"This is method(%s) with random number(%d)\\n\", \"PrintSth\", n);",
+      "  }",
+      "",
+      "  public static void CallNext() {",
+      "    Deps43.PrintSth();",
+      "  }",
+      "}");
+
+  private static final String DEPS_CLASS_EXTRA_CONTENT = joinLines(
+      "package com.example.deps42;",
+      "",
+      "import java.lang.System;",
+      "import java.util.Random;",
+      "",
+      "public final class Deps42 {",
+      "  public static void PrintSth() {",
+      "    Random rand = new Random();",
+      "    int n = rand.nextInt(100);",
+      "    System.out.format(\"This is method(%s) with random number(%d)\\n\", \"PrintSth\", n);",
+      "  }",
+      "",
+      "  public static void PrintSthElse() {",
+      "    Random rand = new Random();",
+      "    int n = rand.nextInt(100);",
+      "    System.out.format(\"This is method(%s) with random number(%d)\\n\","
+          + " \"PrintSthElse\", n);",
+      "  }",
+      "}");
+
+  private static final String MAIN_CLASS_WITH_DEPS_CONTENT = joinLines(
+      "package com.example.generated;",
+      "",
+      "import com.example.deps1.Deps1;",
+      "import com.example.deps2.Deps2;",
+      "import com.example.deps3.Deps3;",
+      "import java.lang.String;",
+      "",
+      "public final class Main {",
+      "  public static void main(String[] args) {",
+      "    Deps1.PrintSth();",
+      "    Deps2.PrintSth();",
+      "    Deps3.PrintSth();",
+      "  }",
+      "}");
+
+  @Rule public TemporaryFolder folder = new TemporaryFolder();
+
+  @Test
+  public void testWriteRandomClassToDir() throws IOException {
+    Path dir = folder.newFolder("WriteRandomClassToDir").toPath();
+    JavaCodeGeneratorHelper.writeRandomClassToDir(false, "ClassName", "com.package.name", dir);
+
+    Path javaFile = dir.resolve("com/package/name/ClassName.java");
+    assertTrue(javaFile.toFile().exists());
+
+    String content = new Scanner(javaFile).useDelimiter("\\Z").next();
+    assertEquals(RANDOM_CLASS_CONTENT, content);
+  }
+
+  @Test
+  public void testWriteRandomClassToDirExtraMethod() throws IOException {
+    Path dir = folder.newFolder("WriteRandomClassToDirExtraMethod").toPath();
+    JavaCodeGeneratorHelper.writeRandomClassToDir(true, "ClassNameExtra", "com.package.name", dir);
+
+    Path javaFile = dir.resolve("com/package/name/ClassNameExtra.java");
+    assertTrue(javaFile.toFile().exists());
+
+    String content = new Scanner(javaFile).useDelimiter("\\Z").next();
+    assertEquals(RANDOM_CLASS_EXTRA_CONTENT, content);
+  }
+
+  @Test
+  public void testWriteMainClassToDir() throws IOException {
+    Path dir = folder.newFolder("WriteMainClassToDir").toPath();
+    JavaCodeGeneratorHelper.writeMainClassToDir("com.package.name", dir);
+
+    Path javaFile = dir.resolve("com/package/name/Main.java");
+    assertTrue(javaFile.toFile().exists());
+
+    String content = new Scanner(javaFile).useDelimiter("\\Z").next();
+    assertEquals(MAIN_CLASS_CONTENT, content);
+  }
+
+  @Test
+  public void testBuildFileWithNextDeps() throws IOException {
+    Path dir = folder.newFolder("BuildFileWithNextDeps").toPath();
+    Files.createDirectories(dir);
+    JavaCodeGeneratorHelper.buildFileWithNextDeps(42, "<this is deps>", dir);
+
+    Path buildFile = dir.resolve("BUILD");
+    assertTrue(buildFile.toFile().exists());
+
+    String content = new Scanner(buildFile).useDelimiter("\\Z").next();
+    assertEquals(DEPS_BUILD_FILE_CONTENT, content);
+  }
+
+  @Test
+  public void testBuildFileWithMainClass() throws IOException {
+    Path dir = folder.newFolder("BuildFileWithMainClass").toPath();
+    Files.createDirectories(dir);
+    JavaCodeGeneratorHelper.buildFileWithMainClass("Target", "<this is deps>", dir);
+
+    Path buildFile = dir.resolve("BUILD");
+    assertTrue(buildFile.toFile().exists());
+
+    String content = new Scanner(buildFile).useDelimiter("\\Z").next();
+    assertEquals(TARGET_BUILD_FILE_CONTENT, content);
+  }
+
+  @Test
+  public void testTargetWithNextHelper() throws IOException {
+    Path dir = folder.newFolder("TargetWithNextHelper").toPath();
+    JavaCodeGeneratorHelper.targetWithNextHelper(42, true, dir);
+
+    Path javaFile = dir.resolve("com/example/deps42/Deps42.java");
+    assertTrue(javaFile.toFile().exists());
+
+    String content = new Scanner(javaFile).useDelimiter("\\Z").next();
+    assertEquals(DEPS_CLASS_CONTENT, content);
+  }
+
+  @Test
+  public void testTargetWithNextExtraHelper() throws IOException {
+    Path dir = folder.newFolder("TargetWithNextHelperExtra").toPath();
+    JavaCodeGeneratorHelper.targetWithNextExtraHelper(42, false, dir);
+
+    Path javaFile = dir.resolve("com/example/deps42/Deps42.java");
+    assertTrue(javaFile.toFile().exists());
+
+    String content = new Scanner(javaFile).useDelimiter("\\Z").next();
+    assertEquals(DEPS_CLASS_EXTRA_CONTENT, content);
+  }
+
+  @Test
+  public void testParallelDepsMainClassHelper() throws IOException {
+    Path dir = folder.newFolder("ParallelDepsMainClassHelper").toPath();
+    JavaCodeGeneratorHelper.parallelDepsMainClassHelper(4, dir);
+
+    Path javaFile = dir.resolve("com/example/generated/Main.java");
+    assertTrue(javaFile.toFile().exists());
+
+    String content = new Scanner(javaFile).useDelimiter("\\Z").next();
+    assertEquals(MAIN_CLASS_WITH_DEPS_CONTENT, content);
+  }
+
+  private static String joinLines(String... lines) {
+    return Joiner.on("\n").join(lines);
+  }
+}
diff --git a/src/tools/benchmark/javatests/com/google/devtools/build/benchmark/codegenerator/JavaCodeGeneratorTest.java b/src/tools/benchmark/javatests/com/google/devtools/build/benchmark/codegenerator/JavaCodeGeneratorTest.java
new file mode 100644
index 0000000000..f135b1fb77
--- /dev/null
+++ b/src/tools/benchmark/javatests/com/google/devtools/build/benchmark/codegenerator/JavaCodeGeneratorTest.java
@@ -0,0 +1,124 @@
+// Copyright 2017 The Bazel Authors. 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.google.devtools.build.benchmark.codegenerator;
+
+import static com.google.common.truth.Truth.assertThat;
+import static org.junit.Assert.assertNotNull;
+
+import com.google.common.collect.ImmutableSet;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Path;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+/** Test for {@link JavaCodeGenerator}. */
+@RunWith(JUnit4.class)
+public class JavaCodeGeneratorTest {
+
+  @Rule public TemporaryFolder folder = new TemporaryFolder();
+
+  @Test
+  public void testGenerateNewProject() throws IOException {
+    File createdFolder = folder.newFolder("GenerateNewProject");
+    Path dir = createdFolder.toPath();
+    JavaCodeGenerator.generateNewProject(dir.toString(), true, true, true, true);
+
+    // Check dir contains 4 project directories
+    File[] filesList = dir.toFile().listFiles();
+    assertNotNull(filesList);
+    ImmutableSet<String> filenames = fileArrayToImmutableSet(filesList);
+    assertThat(filenames).containsExactly(
+        JavaCodeGenerator.TARGET_A_FEW_FILES,
+        JavaCodeGenerator.TARGET_LONG_CHAINED_DEPS,
+        JavaCodeGenerator.TARGET_MANY_FILES,
+        JavaCodeGenerator.TARGET_PARALLEL_DEPS);
+
+    // Target 1: a few files
+    checkProjectPathContains(dir, JavaCodeGenerator.TARGET_A_FEW_FILES);
+    checkSimpleTarget(
+        dir, JavaCodeGenerator.TARGET_A_FEW_FILES, JavaCodeGenerator.SIZE_A_FEW_FILES);
+
+    // Target 2: many files
+    checkProjectPathContains(dir, JavaCodeGenerator.TARGET_MANY_FILES);
+    checkSimpleTarget(dir, JavaCodeGenerator.TARGET_MANY_FILES, JavaCodeGenerator.SIZE_MANY_FILES);
+
+    // Target 3: long chained deps
+    checkProjectPathContains(dir, JavaCodeGenerator.TARGET_LONG_CHAINED_DEPS);
+    checkDepsTarget(
+        dir, JavaCodeGenerator.TARGET_LONG_CHAINED_DEPS, JavaCodeGenerator.SIZE_LONG_CHAINED_DEPS);
+
+    // Target 4: parallel deps
+    checkProjectPathContains(dir, JavaCodeGenerator.TARGET_PARALLEL_DEPS);
+    checkDepsTarget(
+        dir, JavaCodeGenerator.TARGET_PARALLEL_DEPS, JavaCodeGenerator.SIZE_PARALLEL_DEPS);
+  }
+
+  private static ImmutableSet<String> fileArrayToImmutableSet(File[] files) {
+    ImmutableSet.Builder<String> builder = ImmutableSet.builder();
+    for (File file : files) {
+      builder.add(file.getName());
+    }
+    return builder.build();
+  }
+
+  private static void checkProjectPathContains(Path root, String targetName) {
+    // Check project dir contains BUILD and com
+    File[] filesList = root.resolve(targetName).toFile().listFiles();
+    assertNotNull(filesList);
+    ImmutableSet<String> filenames = fileArrayToImmutableSet(filesList);
+    assertThat(filenames).containsExactly("BUILD", "com");
+
+    // Check project dir contains com/example
+    filesList = root.resolve(targetName).resolve("com").toFile().listFiles();
+    assertNotNull(filesList);
+    filenames = fileArrayToImmutableSet(filesList);
+    assertThat(filenames).containsExactly("example");
+  }
+
+  private static void checkSimpleTarget(Path root, String targetName, int targetSize) {
+    // Check Java files
+    File[] filesList =
+        root.resolve(targetName).resolve("com/example/generated").toFile().listFiles();
+    assertNotNull(filesList);
+    ImmutableSet<String> filenames = fileArrayToImmutableSet(filesList);
+    ImmutableSet.Builder<String> randomClassNames = ImmutableSet.builder();
+    randomClassNames.add("Main.java");
+    for (int i = 0; i < targetSize; ++i) {
+      randomClassNames.add("RandomClass" + i + ".java");
+    }
+    assertThat(filenames).containsExactlyElementsIn(randomClassNames.build());
+  }
+
+  private static void checkDepsTarget(Path root, String targetName, int targetSize) {
+    // Check Java files
+    for (int i = 1; i < targetSize; ++i) {
+      File[] filesList =
+          root.resolve(targetName).resolve("com/example/deps" + i).toFile().listFiles();
+      assertNotNull(filesList);
+      ImmutableSet<String> filenames = fileArrayToImmutableSet(filesList);
+      assertThat(filenames).containsExactly("Deps" + i + ".java");
+    }
+    File[] filesList =
+        root.resolve(targetName).resolve("com/example/generated").toFile().listFiles();
+    assertNotNull(filesList);
+    ImmutableSet<String> filenames = fileArrayToImmutableSet(filesList);
+    assertThat(filenames).containsExactly("Main.java");
+  }
+}
diff --git a/src/tools/benchmark/javatests/com/google/devtools/build/benchmark/codegenerator/MainTest.java b/src/tools/benchmark/javatests/com/google/devtools/build/benchmark/codegenerator/MainTest.java
new file mode 100644
index 0000000000..ef47492dbb
--- /dev/null
+++ b/src/tools/benchmark/javatests/com/google/devtools/build/benchmark/codegenerator/MainTest.java
@@ -0,0 +1,92 @@
+// Copyright 2017 The Bazel Authors. 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.google.devtools.build.benchmark.codegenerator;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.fail;
+
+import com.google.devtools.common.options.OptionsParsingException;
+import java.io.IOException;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+/** Test for {@link Main}. */
+@RunWith(JUnit4.class)
+public class MainTest {
+
+  @Test
+  public void testParseArgsEmpty() throws OptionsParsingException, IOException {
+    try {
+      Main.parseArgs(new String[]{});
+      fail("Should throw IllegalArgumentException");
+    } catch (IllegalArgumentException e) {
+      assertEquals("--output_dir should not be empty.", e.getMessage());
+    }
+  }
+
+  @Test
+  public void testParseArgsWrongMode() throws IOException {
+    try {
+      Main.parseArgs(new String[]{"--modify=mango"});
+      fail("Should throw OptionsParsingException");
+    } catch (OptionsParsingException e) {
+      assertEquals(
+          "While parsing option --modify=mango: 'mango' is not a boolean", e.getMessage());
+    }
+  }
+
+  @Test
+  public void testParseArgsNoOutputDir() throws OptionsParsingException, IOException {
+    try {
+      Main.parseArgs(new String[]{"--modify"});
+      fail("Should throw IllegalArgumentException");
+    } catch (IllegalArgumentException e) {
+      assertEquals("--output_dir should not be empty.", e.getMessage());
+    }
+  }
+
+  @Test
+  public void testParseArgsOutputDirNonExists() throws OptionsParsingException, IOException {
+    try {
+      Main.parseArgs(new String[]{"--modify", "--output_dir=mango"});
+      fail("Should throw IllegalArgumentException");
+    } catch (IllegalArgumentException e) {
+      assertEquals("--output_dir (mango) does not contain code for modification.", e.getMessage());
+    }
+  }
+
+  @Test
+  public void testParseArgsNoType() throws OptionsParsingException, IOException {
+    try {
+      Main.parseArgs(new String[]{"--output_dir=mango"});
+      fail("Should throw IllegalArgumentException");
+    } catch (IllegalArgumentException e) {
+      assertEquals("No type of package is specified.", e.getMessage());
+    }
+  }
+
+  @Test
+  public void testParseArgsCorrect() throws OptionsParsingException, IOException {
+    GeneratorOptions opt = Main.parseArgs(
+        new String[]{"--modify=false", "--output_dir=mango", "--a_few_files", "--parallel_deps"});
+    assertEquals(opt.modificationMode, false);
+    assertEquals(opt.outputDir, "mango");
+    assertEquals(opt.aFewFiles, true);
+    assertEquals(opt.manyFiles, false);
+    assertEquals(opt.longChainedDeps, false);
+    assertEquals(opt.parallelDeps, true);
+  }
+}