feat: Add code request generator dumper and an ability to run generator from dumped file

BUILD.bazel

@@ -8,6 +8,7 @@ load(
 package(default_visibility = ["//visibility:public"])
 
 JAVA_SRCS = [
+    "//src/main/java/com/google/api/generator/debug:debug_files",
     "//src/main/java/com/google/api/generator:generator_files",
     "//src/main/java/com/google/api/generator/engine:engine_files",
     "//src/main/java/com/google/api/generator/gapic:gapic_files",
@@ -47,6 +48,57 @@ java_binary(
     ],
 )
 
+# Request dumper binary, which dumps the CodeGeneratorRequest to a file on disk
+# which will be identical to the one passed to the protoc-gen-java_gapic during
+# normal execution. The dumped file then can be used to run this gapic-generator
+# directly (instead of relying on protoc to start the process), which would give
+# much greater flexibility in terms of debugging features, like attaching a
+# debugger, easier work with stdout and stderr etc.
+#
+# Usage example, via the rule in a corresponding BUILD.bazel file:
+#
+# load("@gapic_generator_java//rules_java_gapic:java_gapic.bzl", "java_generator_request_dump")
+# java_generator_request_dump(
+#     name = "compute_small_request_dump",
+#     srcs = [":compute_small_proto_with_info"],
+#     transport = "rest",
+# )
+#
+java_binary(
+    name = "protoc-gen-code_generator_request_dumper",
+    main_class = "com.google.api.generator.debug.CodeGeneratorRequestDumper",
+    runtime_deps = [
+        "//src/main/java/com/google/api/generator",
+        "//src/main/java/com/google/api/generator/debug",
+        "//src/main/java/com/google/api/generator/gapic",
+        "@com_google_googleapis//google/api:api_java_proto",
+        "@com_google_googleapis//google/longrunning:longrunning_java_proto",
+        "@com_google_guava_guava",
+        "@com_google_protobuf//:protobuf_java",
+    ],
+)
+
+# A binary similar to protoc-gen-java_gapic but reads the CodeGeneratorRequest
+# directly from a file instead of relying on protoc to pipe it in.
+#
+# Usage example:
+#
+# bazel run code_generator_request_file_to_gapic_main desc-dump.bin dump.jar
+#
+java_binary(
+    name = "code_generator_request_file_to_gapic_main",
+    main_class = "com.google.api.generator.debug.CodeGeneratorRequestFileToGapicMain",
+    runtime_deps = [
+        "//src/main/java/com/google/api/generator",
+        "//src/main/java/com/google/api/generator/debug",
+        "//src/main/java/com/google/api/generator/gapic",
+        "@com_google_googleapis//google/api:api_java_proto",
+        "@com_google_googleapis//google/longrunning:longrunning_java_proto",
+        "@com_google_guava_guava",
+        "@com_google_protobuf//:protobuf_java",
+    ],
+)
+
 # google-java-format
 java_binary(
     name = "google_java_format_binary",

rules_java_gapic/java_gapic.bzl

@@ -119,19 +119,18 @@ def _append_dep_without_duplicates(dest_deps, new_deps):
             dest_deps.append(new_deps[i])
     return dest_deps
 
-def java_gapic_library(
+def _java_gapic_srcjar(
         name,
         srcs,
-        grpc_service_config = None,
-        gapic_yaml = None,
-        service_yaml = None,
-        deps = [],
-        test_deps = [],
+        grpc_service_config,
+        gapic_yaml,
+        service_yaml,
         # possible values are: "grpc", "rest", "grpc+rest"
-        transport = None,
+        transport,
         # Can be used to provide a java_library with a customized generator,
         # like the one which dumps descriptor to a file for future debugging.
-        _java_generator_name = "java_gapic",
+        java_generator_name = "java_gapic",
+        output_suffix = ".srcjar",
         **kwargs):
     file_args_dict = {}
 
@@ -159,8 +158,6 @@ def java_gapic_library(
         else:
             fail("Service.yaml is no longer supported in the Java microgenerator")
 
-    srcjar_name = name + "_srcjar"
-    raw_srcjar_name = srcjar_name + "_raw"
     output_suffix = ".srcjar"
     opt_args = []
 
@@ -172,18 +169,43 @@ def java_gapic_library(
     plugin_args = ["metadata"]
 
     proto_custom_library(
-        name = raw_srcjar_name,
+        name = name,
         deps = srcs,
-        plugin = Label("@gapic_generator_java//:protoc-gen-%s" % _java_generator_name),
+        plugin = Label("@gapic_generator_java//:protoc-gen-%s" % java_generator_name),
         plugin_args = plugin_args,
         plugin_file_args = {},
         opt_file_args = file_args_dict,
-        output_type = _java_generator_name,
+        output_type = java_generator_name,
         output_suffix = output_suffix,
         opt_args = opt_args,
         **kwargs
     )
 
+def java_gapic_library(
+        name,
+        srcs,
+        grpc_service_config = None,
+        gapic_yaml = None,
+        service_yaml = None,
+        deps = [],
+        test_deps = [],
+        # possible values are: "grpc", "rest", "grpc+rest"
+        transport = None,
+        **kwargs):
+    srcjar_name = name + "_srcjar"
+    raw_srcjar_name = srcjar_name + "_raw"
+
+    _java_gapic_srcjar(
+        name = raw_srcjar_name,
+        srcs = srcs,
+        grpc_service_config = grpc_service_config,
+        gapic_yaml = gapic_yaml,
+        service_yaml = service_yaml,
+        transport = transport,
+        java_generator_name = "java_gapic",
+        **kwargs
+    )
+
     _java_gapic_postprocess_srcjar(
         name = srcjar_name,
         gapic_srcjar = "%s.srcjar" % raw_srcjar_name,
@@ -282,3 +304,26 @@ def java_gapic_test(name, runtime_deps, test_classes, **kwargs):
         tests = test_classes,
         **kwargs
     )
+
+# A debugging rule, to dump CodeGenereatorRequest from protoc as is to a file,
+# which then can be used to run gapic-generator directly instead of relying on
+# protoc to launch it. This would simplify attaching the debugger and/or
+# working with stdin/stderr.
+def java_generator_request_dump(
+        name,
+        srcs,
+        grpc_service_config = None,
+        gapic_yaml = None,
+        service_yaml = None,
+        transport = None,
+        **kwargs):
+    _java_gapic_srcjar(
+        name = name,
+        srcs = srcs,
+        grpc_service_config = grpc_service_config,
+        gapic_yaml = gapic_yaml,
+        service_yaml = service_yaml,
+        transport = transport,
+        java_generator_name = "code_generator_request_dumper",
+        **kwargs
+    )

src/main/java/com/google/api/generator/Main.java

@@ -14,34 +14,18 @@
 
 package com.google.api.generator;
 
-import com.google.api.AnnotationsProto;
-import com.google.api.ClientProto;
-import com.google.api.FieldBehaviorProto;
-import com.google.api.ResourceProto;
 import com.google.api.generator.gapic.Generator;
-import com.google.longrunning.OperationsProto;
-import com.google.protobuf.Descriptors.DescriptorValidationException;
 import com.google.protobuf.ExtensionRegistry;
 import com.google.protobuf.compiler.PluginProtos.CodeGeneratorRequest;
 import com.google.protobuf.compiler.PluginProtos.CodeGeneratorResponse;
 import java.io.IOException;
 
 public class Main {
-  public static void main(String[] args)
-      throws IOException, InterruptedException, DescriptorValidationException {
+  public static void main(String[] args) throws IOException {
     ExtensionRegistry registry = ExtensionRegistry.newInstance();
-    registerAllExtensions(registry);
+    ProtoRegistry.registerAllExtensions(registry);
     CodeGeneratorRequest request = CodeGeneratorRequest.parseFrom(System.in, registry);
     CodeGeneratorResponse response = Generator.generateGapic(request);
     response.writeTo(System.out);
   }
-
-  /** Register all extensions needed to process API protofiles. */
-  private static void registerAllExtensions(ExtensionRegistry extensionRegistry) {
-    OperationsProto.registerAllExtensions(extensionRegistry);
-    AnnotationsProto.registerAllExtensions(extensionRegistry);
-    ClientProto.registerAllExtensions(extensionRegistry);
-    ResourceProto.registerAllExtensions(extensionRegistry);
-    FieldBehaviorProto.registerAllExtensions(extensionRegistry);
-  }
 }

src/main/java/com/google/api/generator/ProtoRegistry.java

@@ -0,0 +1,33 @@
+// Copyright 2021 Google LLC
+//
+// 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.api.generator;
+
+import com.google.api.AnnotationsProto;
+import com.google.api.ClientProto;
+import com.google.api.FieldBehaviorProto;
+import com.google.api.ResourceProto;
+import com.google.longrunning.OperationsProto;
+import com.google.protobuf.ExtensionRegistry;
+
+public class ProtoRegistry {
+  /** Register all extensions needed to process API protofiles. */
+  public static void registerAllExtensions(ExtensionRegistry extensionRegistry) {
+    OperationsProto.registerAllExtensions(extensionRegistry);
+    AnnotationsProto.registerAllExtensions(extensionRegistry);
+    ClientProto.registerAllExtensions(extensionRegistry);
+    ResourceProto.registerAllExtensions(extensionRegistry);
+    FieldBehaviorProto.registerAllExtensions(extensionRegistry);
+  }
+}

src/main/java/com/google/api/generator/debug/BUILD.bazel

@@ -0,0 +1,27 @@
+load("@rules_java//java:defs.bzl", "java_library", "java_plugin")
+
+package(default_visibility = ["//visibility:public"])
+
+filegroup(
+    name = "debug_files",
+    srcs = glob(["*.java"]),
+)
+
+java_library(
+    name = "debug",
+    srcs = [
+        ":debug_files",
+    ],
+    deps = [
+        "//src/main/java/com/google/api/generator",
+        "//src/main/java/com/google/api/generator/engine",
+        "//src/main/java/com/google/api/generator/engine/ast",
+        "//src/main/java/com/google/api/generator/gapic",
+        "//src/main/java/com/google/api/generator/gapic/model",
+        "//src/main/java/com/google/api/generator/util",
+        "@com_google_googleapis//google/api:api_java_proto",
+        "@com_google_googleapis//google/longrunning:longrunning_java_proto",
+        "@com_google_guava_guava//jar",
+        "@com_google_protobuf//:protobuf_java",
+    ],
+)

src/main/java/com/google/api/generator/debug/CodeGeneratorRequestDumper.java

@@ -0,0 +1,42 @@
+// Copyright 2021 Google LLC
+//
+// 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.api.generator.debug;
+
+import com.google.api.generator.ProtoRegistry;
+import com.google.protobuf.ExtensionRegistry;
+import com.google.protobuf.compiler.PluginProtos.CodeGeneratorRequest;
+import com.google.protobuf.compiler.PluginProtos.CodeGeneratorResponse;
+import java.io.IOException;
+
+// Request dumper class, which dumps the CodeGeneratorRequest to a file on disk which will be
+// identical to the one passed to the Main class during normal execution. The dumped file then can
+// be used to run this gapic-generator directly (instead of relying on protoc to start the process),
+// which would give much greater flexibility in terms of debugging features, like attaching a
+// debugger, easier work with stdout and stderr etc.
+public class CodeGeneratorRequestDumper {
+  public static void main(String[] args) throws IOException {
+    ExtensionRegistry registry = ExtensionRegistry.newInstance();
+    ProtoRegistry.registerAllExtensions(registry);
+    CodeGeneratorRequest request = CodeGeneratorRequest.parseFrom(System.in, registry);
+
+    CodeGeneratorResponse.Builder response = CodeGeneratorResponse.newBuilder();
+    response
+        .setSupportedFeatures(CodeGeneratorResponse.Feature.FEATURE_PROTO3_OPTIONAL_VALUE)
+        .addFileBuilder()
+        .setName("desc-dump.bin")
+        .setContentBytes(request.toByteString());
+    response.build().writeTo(System.out);
+  }
+}

src/main/java/com/google/api/generator/debug/CodeGeneratorRequestFileToGapicMain.java

@@ -0,0 +1,45 @@
+// Copyright 2021 Google LLC
+//
+// 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.api.generator.debug;
+
+import com.google.api.generator.ProtoRegistry;
+import com.google.api.generator.gapic.Generator;
+import com.google.protobuf.ExtensionRegistry;
+import com.google.protobuf.compiler.PluginProtos.CodeGeneratorRequest;
+import com.google.protobuf.compiler.PluginProtos.CodeGeneratorResponse;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+
+// A generator entry point class, similar to Main but reads the CodeGeneratorRequest directly from a
+// file instead of relying on protoc to pipe it in.
+public class CodeGeneratorRequestFileToGapicMain {
+  public static void main(String[] args) throws IOException {
+    ExtensionRegistry registry = ExtensionRegistry.newInstance();
+    ProtoRegistry.registerAllExtensions(registry);
+
+    String inputFile = args[0];
+    String outputFile = args[1];
+
+    try (InputStream inputStream = new FileInputStream(inputFile);
+        OutputStream outputStream = new FileOutputStream(outputFile)) {
+      CodeGeneratorRequest request = CodeGeneratorRequest.parseFrom(inputStream, registry);
+      CodeGeneratorResponse response = Generator.generateGapic(request);
+      response.writeTo(outputStream);
+    }
+  }
+}