Adds call type to MethodDescriptor as some transports need to know whether

the call is unary or streaming when starting the call.

-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=71867037

core/src/main/java/com/google/net/stubby/MethodDescriptor.java

@@ -19,6 +19,14 @@ import javax.inject.Provider;
 @Immutable
 public class MethodDescriptor<RequestT, ResponseT> {
 
+  public enum Type {
+    UNARY,
+    CLIENT_STREAMING,
+    SERVER_STREAMING,
+    DUPLEX_STREAMING,
+    UNKNOWN
+  }
+
   private  static final Function<Provider<String>,String> HEADER_SNAPSHOT =
       new Function<Provider<String>, String>() {
     @Override
@@ -27,6 +35,7 @@ public class MethodDescriptor<RequestT, ResponseT> {
     }
   };
 
+  private final Type type;
   private final String name;
   private final Marshaller<RequestT> requestMarshaller;
   private final Marshaller<ResponseT> responseMarshaller;
@@ -34,18 +43,19 @@ public class MethodDescriptor<RequestT, ResponseT> {
   private final ImmutableMap<String, Provider<String>> headers;
 
   public static <RequestT, ResponseT> MethodDescriptor<RequestT, ResponseT> create(
-      String name, long timeout, TimeUnit timeoutUnit,
+      Type type, String name, long timeout, TimeUnit timeoutUnit,
       Marshaller<RequestT> requestMarshaller,
       Marshaller<ResponseT> responseMarshaller) {
     return new MethodDescriptor<RequestT, ResponseT>(
-        name, timeoutUnit.toMicros(timeout), requestMarshaller, responseMarshaller,
+        type, name, timeoutUnit.toMicros(timeout), requestMarshaller, responseMarshaller,
         ImmutableMap.<String, Provider<String>>of());
   }
 
-  private MethodDescriptor(String name, long timeoutMicros,
+  private MethodDescriptor(Type type, String name, long timeoutMicros,
                            Marshaller<RequestT> requestMarshaller,
                            Marshaller<ResponseT> responseMarshaller,
                            ImmutableMap<String, Provider<String>> headers) {
+    this.type = Preconditions.checkNotNull(type);
     this.name = name;
     Preconditions.checkArgument(timeoutMicros > 0);
     this.timeoutMicros = timeoutMicros;
@@ -54,6 +64,13 @@ public class MethodDescriptor<RequestT, ResponseT> {
     this.headers = headers;
   }
 
+  /**
+   * The call type of the method.
+   */
+  public Type getType() {
+    return type;
+  }
+
   /**
    * The fully qualified name of the method
    */
@@ -96,7 +113,7 @@ public class MethodDescriptor<RequestT, ResponseT> {
    * Create a new descriptor with a different timeout
    */
   public MethodDescriptor withTimeout(long timeout, TimeUnit unit) {
-    return new MethodDescriptor<RequestT, ResponseT>(name, unit.toMicros(timeout),
+    return new MethodDescriptor<RequestT, ResponseT>(type, name, unit.toMicros(timeout),
         requestMarshaller, responseMarshaller, headers);
   }
 
@@ -104,7 +121,7 @@ public class MethodDescriptor<RequestT, ResponseT> {
    * Create a new descriptor with an additional bound header.
    */
   public MethodDescriptor withHeader(String headerName, Provider<String> headerValueProvider) {
-    return new MethodDescriptor<RequestT, ResponseT>(name, timeoutMicros,
+    return new MethodDescriptor<RequestT, ResponseT>(type, name, timeoutMicros,
         requestMarshaller, responseMarshaller,
         ImmutableMap.<String, Provider<String>>builder().
             putAll(headers).put(headerName, headerValueProvider).build());