Introduce GsonGrpcJsonMarshaller and catch JsonMarshaller initialization failure

grpc/src/main/java/com/linecorp/armeria/common/grpc/GrpcJsonMarshaller.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2020 LINE Corporation
+ * Copyright 2022 LINE Corporation
  *
  * LINE Corporation licenses this file to you under the Apache License,
  * version 2.0 (the "License"); you may not use this file except in compliance
@@ -39,19 +39,62 @@ public interface GrpcJsonMarshaller {
 
     /**
      * Returns a newly-created {@link GrpcJsonMarshaller} which serializes and deserializes a {@link Message}
-     * served by the {@linkplain ServiceDescriptor service}.
+     * served by the {@linkplain ServiceDescriptor service}. This implementation internally uses
+     * <a href="https://github.com/curioswitch/protobuf-jackson">protobuf-jackson</a>
+     * to serialize and deserialize messages.
      */
     static GrpcJsonMarshaller of(ServiceDescriptor serviceDescriptor) {
-        return builder().build(serviceDescriptor);
+        return ofJackson(serviceDescriptor);
     }
 
     /**
-     * Returns a new {@link GrpcJsonMarshallerBuilder}.
+     * Returns a new {@link GrpcJsonMarshallerBuilder}. This implementation internally uses
+     * <a href="https://github.com/curioswitch/protobuf-jackson">protobuf-jackson</a>
+     * to serialize and deserialize messages.
      */
     static GrpcJsonMarshallerBuilder builder() {
+        return builderForJackson();
+    }
+
+    /**
+     * Returns a newly-created {@link GrpcJsonMarshaller} which serializes and deserializes a {@link Message}
+     * served by the {@linkplain ServiceDescriptor service}. This implementation internally uses
+     * <a href="https://github.com/curioswitch/protobuf-jackson">protobuf-jackson</a>
+     * to serialize and deserialize messages.
+     */
+    static GrpcJsonMarshaller ofJackson(ServiceDescriptor serviceDescriptor) {
+        return builderForJackson().build(serviceDescriptor);
+    }
+
+    /**
+     * Returns a new {@link GrpcJsonMarshallerBuilder}.  This implementation internally uses
+     * <a href="https://github.com/curioswitch/protobuf-jackson">protobuf-jackson</a>
+     * to serialize and deserialize messages.
+     */
+    static GrpcJsonMarshallerBuilder builderForJackson() {
         return new GrpcJsonMarshallerBuilder();
     }
 
+    /**
+     * Returns a newly-created {@link GrpcJsonMarshaller} which serializes and deserializes {@link Message}.
+     * This implementation internally uses
+     * <a href="https://developers.google.com/protocol-buffers/docs/reference/java/com/google/protobuf/util/JsonFormat">JsonFormat</a>
+     * and {@code Gson} to serialize and deserialize messages.
+     */
+    static GrpcJsonMarshaller ofGson() {
+        return builderForGson().build();
+    }
+
+    /**
+     * Returns a new {@link GrpcJsonMarshallerBuilder}.
+     * This implementation internally uses
+     * <a href="https://developers.google.com/protocol-buffers/docs/reference/java/com/google/protobuf/util/JsonFormat">JsonFormat</a>
+     * and {@code Gson} to serialize and deserialize messages.
+     */
+    static GsonGrpcJsonMarshallerBuilder builderForGson() {
+        return new GsonGrpcJsonMarshallerBuilder();
+    }
+
     /**
      * Serializes a gRPC message into JSON.
      */

grpc/src/main/java/com/linecorp/armeria/common/grpc/GrpcJsonUtil.java

@@ -20,6 +20,8 @@
 import java.util.function.Consumer;
 
 import org.curioswitch.common.protobuf.json.MessageMarshaller;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import com.google.protobuf.Message;
 
@@ -34,6 +36,8 @@
  */
 final class GrpcJsonUtil {
 
+    private static final Logger logger = LoggerFactory.getLogger(GrpcJsonUtil.class);
+
     /**
      * Returns a {@link MessageMarshaller} with the request/response {@link Message}s of all the {@code methods}
      * registered.
@@ -59,7 +63,13 @@ public static MessageMarshaller jsonMarshaller(
             jsonMarshallerCustomizer.accept(builder);
         }
 
-        return builder.build();
+        try {
+            return builder.build();
+        } catch (RuntimeException e) {
+            logger.warn("Failed to instantiate a json marshaller for {}." +
+                        " Consider using GrpcJsonMarshaller.ofGson instead.", methods);
+            throw e;
+        }
     }
 
     @Nullable

grpc/src/main/java/com/linecorp/armeria/common/grpc/GsonGrpcJsonMarshaller.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright 2022 LINE Corporation
+ *
+ * LINE Corporation licenses this file to you 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:
+ *
+ *   https://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.linecorp.armeria.common.grpc;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.io.OutputStream;
+import java.nio.charset.StandardCharsets;
+
+import com.google.protobuf.Message;
+import com.google.protobuf.MessageOrBuilder;
+import com.google.protobuf.util.JsonFormat;
+
+import io.grpc.MethodDescriptor.Marshaller;
+import io.grpc.MethodDescriptor.PrototypeMarshaller;
+
+final class GsonGrpcJsonMarshaller implements GrpcJsonMarshaller {
+
+    final JsonFormat.Printer printer;
+    final JsonFormat.Parser parser;
+
+    GsonGrpcJsonMarshaller(JsonFormat.Printer printer, JsonFormat.Parser parser) {
+        this.printer = printer;
+        this.parser = parser;
+    }
+
+    @Override
+    public <T> void serializeMessage(Marshaller<T> marshaller, T message, OutputStream os) throws IOException {
+        os.write(printer.print((MessageOrBuilder) message).getBytes(StandardCharsets.UTF_8));
+    }
+
+    @Override
+    public <T> T deserializeMessage(Marshaller<T> marshaller, InputStream is) throws IOException {
+        final PrototypeMarshaller<T> prototypeMarshaller = (PrototypeMarshaller<T>) marshaller;
+        final Message prototype = (Message) prototypeMarshaller.getMessagePrototype();
+        assert prototype != null;
+        final Message.Builder builder = prototype.newBuilderForType();
+        parser.merge(new InputStreamReader(is, StandardCharsets.UTF_8), builder);
+        @SuppressWarnings("unchecked")
+        final T cast = (T) builder.build();
+        return cast;
+    }
+}

grpc/src/main/java/com/linecorp/armeria/common/grpc/GsonGrpcJsonMarshallerBuilder.java

@@ -0,0 +1,91 @@
+/*
+ * Copyright 2020 LINE Corporation
+ *
+ * LINE Corporation licenses this file to you 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:
+ *
+ *   https://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.linecorp.armeria.common.grpc;
+
+import static java.util.Objects.requireNonNull;
+
+import java.util.function.Consumer;
+
+import com.google.protobuf.Message;
+import com.google.protobuf.util.JsonFormat;
+
+import com.linecorp.armeria.common.annotation.Nullable;
+
+/**
+ * A builder for creating a new {@link GrpcJsonMarshaller} that serializes and deserializes a {@link Message}
+ * to and from JSON.
+ */
+public final class GsonGrpcJsonMarshallerBuilder {
+
+    @Nullable
+    private Consumer<JsonFormat.Parser> jsonParserCustomizer;
+
+    @Nullable
+    private Consumer<JsonFormat.Printer> jsonPrinterCustomizer;
+
+    GsonGrpcJsonMarshallerBuilder() {}
+
+    /**
+     * Adds a {@link Consumer} that can customize the {@link JsonFormat.Parser}
+     * used when deserializing a JSON payload into a {@link Message}.
+     */
+    public GsonGrpcJsonMarshallerBuilder jsonParserCustomizer(
+            Consumer<? super JsonFormat.Parser> jsonParserCustomizer) {
+        requireNonNull(jsonParserCustomizer, "jsonParserCustomizer");
+        if (this.jsonParserCustomizer == null) {
+            @SuppressWarnings("unchecked")
+            final Consumer<JsonFormat.Parser> cast = (Consumer<JsonFormat.Parser>) jsonParserCustomizer;
+            this.jsonParserCustomizer = cast;
+        } else {
+            this.jsonParserCustomizer = this.jsonParserCustomizer.andThen(jsonParserCustomizer);
+        }
+        return this;
+    }
+
+    /**
+     * Adds a {@link Consumer} that can customize the {@link JsonFormat.Printer}
+     * used when serializing a {@link Message} into a JSON payload.
+     */
+    public GsonGrpcJsonMarshallerBuilder jsonPrinterCustomizer(
+            Consumer<? super JsonFormat.Printer> jsonPrinterCustomizer) {
+        requireNonNull(jsonPrinterCustomizer, "jsonPrinterCustomizer");
+        if (this.jsonPrinterCustomizer == null) {
+            @SuppressWarnings("unchecked")
+            final Consumer<JsonFormat.Printer> cast = (Consumer<JsonFormat.Printer>) jsonPrinterCustomizer;
+            this.jsonPrinterCustomizer = cast;
+        } else {
+            this.jsonPrinterCustomizer = this.jsonPrinterCustomizer.andThen(jsonPrinterCustomizer);
+        }
+        return this;
+    }
+
+    /**
+     * Returns a newly-created {@link GrpcJsonMarshaller}.
+     */
+    public GrpcJsonMarshaller build() {
+        final JsonFormat.Printer printer = JsonFormat.printer().omittingInsignificantWhitespace();
+        if (jsonPrinterCustomizer != null) {
+            jsonPrinterCustomizer.accept(printer);
+        }
+
+        final JsonFormat.Parser parser = JsonFormat.parser().ignoringUnknownFields();
+        if (jsonParserCustomizer != null) {
+            jsonParserCustomizer.accept(parser);
+        }
+        return new GsonGrpcJsonMarshaller(printer, parser);
+    }
+}