Partially revert "core: change serverimpl,servercallimpl's internalcl…

…ose to cancel stream (#4038)"

This partially reverts commit 48ca452.
It leaves the changes to ServerCallImpl and test.

This also partially reverts "Lint fixes" commit
3002a23 which removed unused variables
which are now necessary again.

This is reverted for the combined result of two issues:
* Some users are testing that they get UNKNOWN when the service throws.
  That's not unreasonable given the behavior was well-publicised when it
  changed in v1.5. We should probably keep the UNKNOWN in some common
  cases (like the service threw immediately, before sending anything).
* The client could see CANCELLED instead of INTERNAL as had been
  intended. It's unclear as to why (I didn't investigate heavily). This
  behavior is visible in MoreInProcessTest and was overlooked during
  review.

core/src/main/java/io/grpc/internal/ServerImpl.java

@@ -655,7 +655,8 @@ void setListener(ServerStreamListener listener) {
      * Like {@link ServerCall#close(Status, Metadata)}, but thread-safe for internal use.
      */
     private void internalClose() {
-      stream.cancel(Status.INTERNAL);
+      // TODO(ejona86): this is not thread-safe :)
+      stream.close(Status.UNKNOWN, new Metadata());
     }
 
     @Override

core/src/test/java/io/grpc/internal/ServerImplTest.java

@@ -1110,7 +1110,7 @@ public void messageRead_errorCancelsCall() throws Exception {
       fail("Expected exception");
     } catch (TestError t) {
       assertSame(expectedT, t);
-      ensureServerStateIsCancelled();
+      ensureServerStateNotLeaked();
     }
   }
 
@@ -1135,7 +1135,7 @@ public void messageRead_runtimeExceptionCancelsCall() throws Exception {
       fail("Expected exception");
     } catch (RuntimeException t) {
       assertSame(expectedT, t);
-      ensureServerStateIsCancelled();
+      ensureServerStateNotLeaked();
     }
   }
 
@@ -1158,7 +1158,7 @@ public void halfClosed_errorCancelsCall() {
       fail("Expected exception");
     } catch (TestError t) {
       assertSame(expectedT, t);
-      ensureServerStateIsCancelled();
+      ensureServerStateNotLeaked();
     }
   }
 
@@ -1181,7 +1181,7 @@ public void halfClosed_runtimeExceptionCancelsCall() {
       fail("Expected exception");
     } catch (RuntimeException t) {
       assertSame(expectedT, t);
-      ensureServerStateIsCancelled();
+      ensureServerStateNotLeaked();
     }
   }
 
@@ -1204,7 +1204,7 @@ public void onReady_errorCancelsCall() {
       fail("Expected exception");
     } catch (TestError t) {
       assertSame(expectedT, t);
-      ensureServerStateIsCancelled();
+      ensureServerStateNotLeaked();
     }
   }
 
@@ -1227,7 +1227,7 @@ public void onReady_runtimeExceptionCancelsCall() {
       fail("Expected exception");
     } catch (RuntimeException t) {
       assertSame(expectedT, t);
-      ensureServerStateIsCancelled();
+      ensureServerStateNotLeaked();
     }
   }
 
@@ -1430,10 +1430,11 @@ private void verifyExecutorsReturned() {
     verifyNoMoreInteractions(executorPool);
   }
 
-  private void ensureServerStateIsCancelled() {
-    verify(stream).cancel(statusCaptor.capture());
-    assertEquals(Status.INTERNAL, statusCaptor.getValue());
+  private void ensureServerStateNotLeaked() {
+    verify(stream).close(statusCaptor.capture(), metadataCaptor.capture());
+    assertEquals(Status.UNKNOWN, statusCaptor.getValue());
     assertNull(statusCaptor.getValue().getCause());
+    assertTrue(metadataCaptor.getValue().keys().isEmpty());
   }
 
   private static class SimpleServer implements io.grpc.internal.InternalServer {

interop-testing/src/test/java/io/grpc/testing/integration/MoreInProcessTest.java

@@ -247,7 +247,7 @@ public void onCompleted() {
         .onNext(StreamingInputCallRequest.getDefaultInstance());
 
     assertTrue(finishLatch.await(900, TimeUnit.MILLISECONDS));
-    assertEquals(Status.CANCELLED.getCode(), Status.fromThrowable(throwableRef.get()).getCode());
+    assertEquals(Status.UNKNOWN, Status.fromThrowable(throwableRef.get()));
     assertNull(responseRef.get());
   }
 }

netty/src/main/java/io/grpc/netty/NettyServerHandler.java

@@ -651,13 +651,8 @@ private void cancelStream(ChannelHandlerContext ctx, CancelServerStreamCommand c
       ChannelPromise promise) {
     // Notify the listener if we haven't already.
     cmd.stream().transportReportStatus(cmd.reason());
-    Http2Error http2Error = Http2Error.INTERNAL_ERROR;
-    if (Status.DEADLINE_EXCEEDED.getCode().equals(cmd.reason().getCode()) || Status.CANCELLED
-        .getCode().equals(cmd.reason().getCode())) {
-      http2Error = Http2Error.CANCEL;
-    }
     // Terminate the stream.
-    encoder().writeRstStream(ctx, cmd.stream().id(), http2Error.code(), promise);
+    encoder().writeRstStream(ctx, cmd.stream().id(), Http2Error.CANCEL.code(), promise);
   }
 
   private void forcefulClose(final ChannelHandlerContext ctx, final ForcefulCloseCommand msg,