protobuf{,lite,nano}: make more classes final

- Split anonymous classes in named and final classes
- Fix some Javadocs and annotate when things were added.

protobuf-lite/src/main/java/io/grpc/protobuf/lite/ProtoInputStream.java

@@ -30,7 +30,7 @@ import javax.annotation.Nullable;
 /**
  * An {@link InputStream} backed by a protobuf.
  */
-class ProtoInputStream extends InputStream implements Drainable, KnownLength {
+final class ProtoInputStream extends InputStream implements Drainable, KnownLength {
 
   // ProtoInputStream is first initialized with a *message*. *partial* is initially null.
   // Once there has been a read operation on this stream, *message* is serialized to *partial* and
@@ -39,7 +39,7 @@ class ProtoInputStream extends InputStream implements Drainable, KnownLength {
   private final Parser<?> parser;
   @Nullable private ByteArrayInputStream partial;
 
-  public ProtoInputStream(MessageLite message, Parser<?> parser) {
+  ProtoInputStream(MessageLite message, Parser<?> parser) {
     this.message = message;
     this.parser = parser;
   }
@@ -103,7 +103,7 @@ class ProtoInputStream extends InputStream implements Drainable, KnownLength {
   }
 
   @Override
-  public int available() throws IOException {
+  public int available() {
     if (message != null) {
       return message.getSerializedSize();
     } else if (partial != null) {

protobuf-lite/src/main/java/io/grpc/protobuf/lite/ProtoLiteUtils.java

@@ -40,9 +40,10 @@ import java.lang.ref.WeakReference;
  * Utility methods for using protobuf with grpc.
  */
 @ExperimentalApi("Experimental until Lite is stable in protobuf")
-public class ProtoLiteUtils {
+public final class ProtoLiteUtils {
 
-  private static volatile ExtensionRegistryLite globalRegistry =
+  // default visibility to avoid synthetic accessors
+  static volatile ExtensionRegistryLite globalRegistry =
       ExtensionRegistryLite.getEmptyRegistry();
 
   private static final int BUF_SIZE = 8192;
@@ -66,26 +67,68 @@ public class ProtoLiteUtils {
    * <p>If you need custom parsing behavior for protos, you will need to make your own
    * {@code MethodDescriptor.Marshaller} for the time being.
    *
+   * @since 1.0.0
    */
   @ExperimentalApi("https://github.com/grpc/grpc-java/issues/1787")
   public static void setExtensionRegistry(ExtensionRegistryLite newRegistry) {
     globalRegistry = checkNotNull(newRegistry, "newRegistry");
   }
 
-  private static final ThreadLocal<Reference<byte[]>> bufs = new ThreadLocal<Reference<byte[]>>() {
-
-    @Override
-    protected Reference<byte[]> initialValue() {
-      return new WeakReference<byte[]>(new byte[4096]); // Picked at random.
-    }
-  };
-
-  /** Create a {@code Marshaller} for protos of the same type as {@code defaultInstance}. */
-  public static <T extends MessageLite> Marshaller<T> marshaller(final T defaultInstance) {
-    @SuppressWarnings("unchecked")
-    final Parser<T> parser = (Parser<T>) defaultInstance.getParserForType();
+  /**
+   * Creates a {@link Marshaller} for protos of the same type as {@code defaultInstance}.
+   *
+   * @since 1.0.0
+   */
+  public static <T extends MessageLite> Marshaller<T> marshaller(T defaultInstance) {
     // TODO(ejona): consider changing return type to PrototypeMarshaller (assuming ABI safe)
-    return new PrototypeMarshaller<T>() {
+    return new MessageMarshaller<T>(defaultInstance);
+  }
+
+  /**
+   * Produce a metadata marshaller for a protobuf type.
+   *
+   * @since 1.0.0
+   */
+  public static <T extends MessageLite> Metadata.BinaryMarshaller<T> metadataMarshaller(
+      T defaultInstance) {
+    return new MetadataMarshaller<T>(defaultInstance);
+  }
+
+  /** Copies the data from input stream to output stream. */
+  static long copy(InputStream from, OutputStream to) throws IOException {
+    // Copied from guava com.google.common.io.ByteStreams because its API is unstable (beta)
+    checkNotNull(from);
+    checkNotNull(to);
+    byte[] buf = new byte[BUF_SIZE];
+    long total = 0;
+    while (true) {
+      int r = from.read(buf);
+      if (r == -1) {
+        break;
+      }
+      to.write(buf, 0, r);
+      total += r;
+    }
+    return total;
+  }
+
+  private ProtoLiteUtils() {
+  }
+
+  private static final class MessageMarshaller<T extends MessageLite>
+      implements PrototypeMarshaller<T> {
+    private static final ThreadLocal<Reference<byte[]>> bufs = new ThreadLocal<Reference<byte[]>>();
+
+    private final Parser<T> parser;
+    private final T defaultInstance;
+
+    @SuppressWarnings("unchecked")
+    MessageMarshaller(T defaultInstance) {
+      this.defaultInstance = defaultInstance;
+      parser = (Parser<T>) defaultInstance.getParserForType();
+    }
+
+
     @SuppressWarnings("unchecked")
     @Override
     public Class<T> getMessageClass() {
@@ -131,9 +174,10 @@ public class ProtoLiteUtils {
         if (stream instanceof KnownLength) {
           int size = stream.available();
           if (size > 0 && size <= DEFAULT_MAX_MESSAGE_SIZE) {
+            Reference<byte[]> ref;
             // buf should not be used after this method has returned.
-              byte[] buf = bufs.get().get();
-              if (buf == null || buf.length < size) {
+            byte[] buf;
+            if ((ref = bufs.get()) == null || (buf = ref.get()) == null || buf.length < size) {
               buf = new byte[size];
               bufs.set(new WeakReference<byte[]>(buf));
             }
@@ -185,15 +229,17 @@ public class ProtoLiteUtils {
         throw e;
       }
     }
-    };
   }
 
-  /**
-   * Produce a metadata marshaller for a protobuf type.
-   */
-  public static <T extends MessageLite> Metadata.BinaryMarshaller<T> metadataMarshaller(
-      final T instance) {
-    return new Metadata.BinaryMarshaller<T>() {
+  private static final class MetadataMarshaller<T extends MessageLite>
+      implements Metadata.BinaryMarshaller<T> {
+
+    private final T defaultInstance;
+
+    MetadataMarshaller(T defaultInstance) {
+      this.defaultInstance = defaultInstance;
+    }
+
     @Override
     public byte[] toBytes(T value) {
       return value.toByteArray();
@@ -203,32 +249,10 @@ public class ProtoLiteUtils {
     @SuppressWarnings("unchecked")
     public T parseBytes(byte[] serialized) {
       try {
-          return (T) instance.getParserForType().parseFrom(serialized, globalRegistry);
+        return (T) defaultInstance.getParserForType().parseFrom(serialized, globalRegistry);
       } catch (InvalidProtocolBufferException ipbe) {
         throw new IllegalArgumentException(ipbe);
       }
     }
-    };
-  }
-
-  /** Copies the data from input stream to output stream. */
-  static long copy(InputStream from, OutputStream to) throws IOException {
-    // Copied from guava com.google.common.io.ByteStreams because its API is unstable (beta)
-    checkNotNull(from);
-    checkNotNull(to);
-    byte[] buf = new byte[BUF_SIZE];
-    long total = 0;
-    while (true) {
-      int r = from.read(buf);
-      if (r == -1) {
-        break;
-      }
-      to.write(buf, 0, r);
-      total += r;
-    }
-    return total;
-  }
-
-  private ProtoLiteUtils() {
   }
 }

protobuf-nano/src/main/java/io/grpc/protobuf/nano/MessageNanoFactory.java

@@ -22,6 +22,8 @@ import com.google.protobuf.nano.MessageNano;
  * Produce new message instances. Used by a marshaller to deserialize incoming messages.
  *
  * <p>Should be implemented by generated code.
+ *
+ * @since 1.0.0
  */
 public interface MessageNanoFactory<T extends MessageNano> {
   T newInstance();

protobuf-nano/src/main/java/io/grpc/protobuf/nano/NanoProtoInputStream.java

@@ -27,7 +27,7 @@ import javax.annotation.Nullable;
 /**
  * An {@link InputStream} backed by a nano proto.
  */
-class NanoProtoInputStream extends InputStream implements KnownLength {
+final class NanoProtoInputStream extends InputStream implements KnownLength {
 
   // NanoProtoInputStream is first initialized with a *message*. *partial* is initially null.
   // Once there has been a read operation on this stream, *message* is serialized to *partial* and
@@ -35,7 +35,7 @@ class NanoProtoInputStream extends InputStream implements KnownLength {
   @Nullable private MessageNano message;
   @Nullable private ByteArrayInputStream partial;
 
-  public NanoProtoInputStream(MessageNano message) {
+  NanoProtoInputStream(MessageNano message) {
     this.message = message;
   }
 
@@ -84,7 +84,7 @@ class NanoProtoInputStream extends InputStream implements KnownLength {
   }
 
   @Override
-  public int available() throws IOException {
+  public int available() {
     if (message != null) {
       return message.getSerializedSize();
     } else if (partial != null) {

protobuf-nano/src/main/java/io/grpc/protobuf/nano/NanoUtils.java

@@ -30,16 +30,28 @@ import java.io.OutputStream;
 /**
  * Utility methods for using nano proto with grpc.
  */
-public class NanoUtils {
-
-  private static final int BUF_SIZE = 8192;
+public final class NanoUtils {
 
   private NanoUtils() {}
 
-  /** Adapt {@code parser} to a {@code Marshaller}. */
-  public static <T extends MessageNano> Marshaller<T> marshaller(
-      final MessageNanoFactory<T> factory) {
-    return new Marshaller<T>() {
+  /**
+   * Adapt {@code parser} to a {@link Marshaller}.
+   *
+   * @since 1.0.0
+   */
+  public static <T extends MessageNano> Marshaller<T> marshaller(MessageNanoFactory<T> factory) {
+    return new MessageMarshaller<T>(factory);
+  }
+
+  private static final class MessageMarshaller<T extends MessageNano> implements Marshaller<T> {
+    private static final int BUF_SIZE = 8192;
+
+    private final MessageNanoFactory<T> factory;
+
+    MessageMarshaller(MessageNanoFactory<T> factory) {
+      this.factory = factory;
+    }
+
     @Override
     public InputStream stream(T value) {
       return new NanoProtoInputStream(value);
@@ -60,8 +72,6 @@ public class NanoUtils {
             .asRuntimeException();
       }
     }
-    };
-  }
 
     // Copied from guava com.google.common.io.ByteStreams because its API is unstable (beta)
     private static byte[] toByteArray(InputStream in) throws IOException {
@@ -86,4 +96,5 @@ public class NanoUtils {
       }
       return total;
     }
+  }
 }

protobuf/src/main/java/io/grpc/protobuf/ProtoFileDescriptorSupplier.java

@@ -20,6 +20,8 @@ import com.google.protobuf.Descriptors.FileDescriptor;
 
 /**
  * Provides access to the underlying proto file descriptor.
+ *
+ * @since 1.1.0
  */
 public interface ProtoFileDescriptorSupplier {
   /**

protobuf/src/main/java/io/grpc/protobuf/ProtoUtils.java

@@ -25,15 +25,21 @@ import io.grpc.protobuf.lite.ProtoLiteUtils;
 /**
  * Utility methods for using protobuf with grpc.
  */
-public class ProtoUtils {
+public final class ProtoUtils {
 
-  /** Create a {@code Marshaller} for protos of the same type as {@code defaultInstance}. */
+  /**
+   * Create a {@link Marshaller} for protos of the same type as {@code defaultInstance}.
+   *
+   * @since 1.0.0
+   */
   public static <T extends Message> Marshaller<T> marshaller(final T defaultInstance) {
     return ProtoLiteUtils.marshaller(defaultInstance);
   }
 
   /**
    * Produce a metadata key for a generated protobuf type.
+   *
+   * @since 1.0.0
    */
   public static <T extends Message> Metadata.Key<T> keyForProto(T instance) {
     return Metadata.Key.of(