Feature/interceptors

demos/grpc-java-contrib-demo/pom.xml

@@ -44,7 +44,8 @@
             <dependency>
                 <groupId>org.slf4j</groupId>
                 <artifactId>slf4j-api</artifactId>
-                <version>1.7.21</version>
+                <version>${slf4j.version}</version>
+                <scope>compile</scope>
             </dependency>
         </dependencies>
     </dependencyManagement>

grpc-contrib/pom.xml

@@ -35,6 +35,16 @@
             <groupId>io.grpc</groupId>
             <artifactId>grpc-context</artifactId>
         </dependency>
+        <dependency>
+            <groupId>com.google.code.gson</groupId>
+            <artifactId>gson</artifactId>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-api</artifactId>
+            <scope>provided</scope>
+        </dependency>
         <dependency>
             <groupId>io.grpc</groupId>
             <artifactId>grpc-testing</artifactId>
@@ -60,6 +70,11 @@
             <artifactId>mockito-core</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>io.grpc</groupId>
+            <artifactId>grpc-netty</artifactId>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 
     <build>

grpc-contrib/src/main/java/com/salesforce/grpc/contrib/MoreFutures.java

@@ -202,7 +202,7 @@ public boolean completeExceptionally(Throwable ex) {
             } catch (RuntimeException | Error ex) { // the ListenableFuture failed with a REALLY BAD exception
                 completableFuture.completeExceptionally(ex);
             } catch (InterruptedException ex) {
-                completableFuture.completeExceptionally(ex); // Won't happen since get() only called after completion
+                completableFuture.completeExceptionally(ex); // Won't happen since current() only called after completion
             }
         };
         listenableFuture.addListener(callbackRunnable, MoreExecutors.directExecutor());

grpc-contrib/src/main/java/com/salesforce/grpc/contrib/MoreMetadata.java

@@ -0,0 +1,167 @@
+/*
+ *  Copyright (c) 2017, salesforce.com, inc.
+ *  All rights reserved.
+ *  Licensed under the BSD 3-Clause license.
+ *  For full license text, see LICENSE.txt file in the repo root  or https://opensource.org/licenses/BSD-3-Clause
+ */
+
+package com.salesforce.grpc.contrib;
+
+import com.google.common.reflect.TypeToken;
+import com.google.gson.Gson;
+import com.google.protobuf.GeneratedMessageV3;
+import com.google.protobuf.InvalidProtocolBufferException;
+import io.grpc.Metadata;
+
+import java.io.IOException;
+import java.io.StringWriter;
+import java.io.Writer;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+
+/**
+ * {@code MoreMetadata} provides additional utilities for working with gRPC {@code Metadata}.
+ */
+//CHECKSTYLE:OFF: MethodName
+public final class MoreMetadata {
+    private MoreMetadata() { }
+
+    /**
+     * A metadata marshaller that encodes objects as JSON using the google-gson library.
+     *
+     * <p>All non-ascii characters are unicode escaped to comply with {@code AsciiMarshaller}'s character range
+     * requirements.
+     *
+     * @param clazz the type to serialize
+     * @param <T>
+     */
+    public static final <T> Metadata.AsciiMarshaller<T> JSON_MARSHALLER(Class<T> clazz) {
+        return new Metadata.AsciiMarshaller<T>() {
+            TypeToken<T> typeToken = TypeToken.of(clazz);
+            private Gson gson = new Gson();
+
+            @Override
+            public String toAsciiString(T value) {
+                try {
+                    try (StringWriter sw = new StringWriter()) {
+                        gson.toJson(value, typeToken.getType(), new UnicodeEscapingAsciiWriter(sw));
+                        return sw.toString();
+                    }
+                } catch (IOException e) {
+                    throw new IllegalArgumentException(e);
+                }
+            }
+
+            @Override
+            public T parseAsciiString(String serialized) {
+                return gson.fromJson(serialized, typeToken.getType());
+            }
+        };
+    }
+
+    /**
+     * See: https://github.com/google/gson/issues/388.
+     */
+    private static final class UnicodeEscapingAsciiWriter extends Writer {
+        private final Writer out;
+
+        private UnicodeEscapingAsciiWriter(Writer out) {
+            this.out = out;
+        }
+
+        @Override public void write(char[] buffer, int offset, int count) throws IOException {
+            for (int i = 0; i < count; i++) {
+                char c = buffer[i + offset];
+                if (c >= ' ' && c <= '~') {
+                    out.write(c);
+                } else {
+                    out.write(String.format("\\u%04x", (int) c));
+                }
+            }
+        }
+
+        @Override public void flush() throws IOException {
+            out.flush();
+        }
+
+        @Override public void close() throws IOException {
+            out.close();
+        }
+    }
+
+    /**
+     * A metadata marshaller that encodes objects as protobuf according to their proto IDL specification.
+     *
+     * @param clazz the type to serialize
+     * @param <T>
+     */
+    public static <T extends GeneratedMessageV3> Metadata.BinaryMarshaller<T> PROTOBUF_MARSHALLER(Class<T> clazz) {
+        try {
+            Method defaultInstance = clazz.getMethod("getDefaultInstance");
+            GeneratedMessageV3 instance = (GeneratedMessageV3) defaultInstance.invoke(null);
+
+            return new Metadata.BinaryMarshaller<T>() {
+                @Override
+                public byte[] toBytes(T value) {
+                    return value.toByteArray();
+                }
+
+                @Override
+                public T parseBytes(byte[] serialized) {
+                    try {
+                        return (T) instance.getParserForType().parseFrom(serialized);
+                    } catch (InvalidProtocolBufferException ipbe) {
+                        throw new IllegalArgumentException(ipbe);
+                    }
+                }
+            };
+        } catch (NoSuchMethodException | IllegalAccessException | InvocationTargetException ex) {
+            throw new IllegalStateException(ex);
+        }
+    }
+
+    /**
+     * A metadata marshaller that encodes boolean values.
+     */
+    public static final Metadata.AsciiMarshaller<Boolean> BOOLEAN_MARSHALLER = new Metadata.AsciiMarshaller<Boolean>() {
+        @Override
+        public String toAsciiString(Boolean value) {
+            return value.toString();
+        }
+
+        @Override
+        public Boolean parseAsciiString(String serialized) {
+            return Boolean.parseBoolean(serialized);
+        }
+    };
+
+    /**
+     * A metadata marshaller that encodes integer-type values.
+     */
+    public static final Metadata.AsciiMarshaller<Long> LONG_MARSHALLER = new Metadata.AsciiMarshaller<Long>() {
+        @Override
+        public String toAsciiString(Long value) {
+            return value.toString();
+        }
+
+        @Override
+        public Long parseAsciiString(String serialized) {
+            return Long.parseLong(serialized);
+        }
+    };
+
+    /**
+     * A metadata marshaller that encodes floating-point-type values.
+     */
+    public static final Metadata.AsciiMarshaller<Double> DOUBLE_MARSHALLER = new Metadata.AsciiMarshaller<Double>() {
+        @Override
+        public String toAsciiString(Double value) {
+            return value.toString();
+        }
+
+        @Override
+        public Double parseAsciiString(String serialized) {
+            return Double.parseDouble(serialized);
+        }
+    };
+}