Move writeHeaders up to HttpStream and test HTTP/3 request trailers

Address review comments: pull the shared writeHeaders(MultiMap, boolean)
declaration up from HttpClientStream/HttpServerStream to HttpStream, drop
redundant comments, and mirror the HTTP/2 request trailer tests in
Http3ServerTest.

Author: jnbdz

vertx-core/src/main/java/io/vertx/core/http/impl/HttpClientStream.java

@@ -28,12 +28,6 @@ public interface HttpClientStream extends HttpStream {
 
   Future<Void> writeHead(HttpRequestHead request, boolean chunked, Buffer buf, boolean end, StreamPriority priority, boolean connect);
 
-  /**
-   * Writes a trailing header block, mirroring {@link HttpServerStream#writeHeaders(MultiMap, boolean)}.
-   * Only called after the request body has been written with {@code end == false}.
-   */
-  Future<Void> writeHeaders(MultiMap headers, boolean end);
-
   HttpClientStream headHandler(Handler<HttpResponseHead> handler);
   HttpClientStream resetHandler(Handler<Long> handler);
   HttpClientStream exceptionHandler(Handler<Throwable> handler);

vertx-core/src/main/java/io/vertx/core/http/impl/HttpServerRequestImpl.java

@@ -190,8 +190,6 @@ public void handleData(Buffer data) {
   public void handleTrailers(MultiMap trailers) {
     HttpEventHandler handler;
     synchronized (connection) {
-      // Setting the trailers must not race with trailers(), where the field can escape:
-      // if the user already obtained the empty map, update it in place instead.
       if (this.trailers == null) {
         this.trailers = trailers;
       } else if (this.trailers != trailers) {

vertx-core/src/main/java/io/vertx/core/http/impl/HttpServerStream.java

@@ -34,7 +34,6 @@ public interface HttpServerStream extends HttpStream {
   HttpServerConnection connection();
 
   Future<Void> writeHead(HttpResponseHead head, Buffer chunk, boolean end);
-  Future<Void> writeHeaders(MultiMap headers, boolean end);
 
   Future<HttpServerStream> sendPush(HostAndPort authority, HttpMethod method, MultiMap headers, String path, StreamPriority priority);
 

vertx-core/src/main/java/io/vertx/core/http/impl/HttpStream.java

@@ -42,6 +42,7 @@ public interface HttpStream {
   ContextInternal context();
 
   Future<Void> writeChunk(Buffer buf, boolean end);
+  Future<Void> writeHeaders(MultiMap headers, boolean end);
   Future<Void> writeFrame(int type, int flags, Buffer payload);
   Future<Void> writeReset(long code);
 

vertx-core/src/main/java/io/vertx/core/http/impl/http1/Http1ServerRequest.java

@@ -106,8 +106,6 @@ protected void handleMessage(Object elt) {
               if (elt == InboundBuffer.END_SENTINEL) {
                 onEnd();
               } else if (elt instanceof MultiMap) {
-                // Trailers travel through the queue so they cannot be observed before the
-                // preceding data has been delivered.
                 setTrailers((MultiMap) elt);
                 onEnd();
               } else {
@@ -185,8 +183,6 @@ private void handleEnd(InboundMessageQueue<Object> queue, Object end) {
 
   private void setTrailers(MultiMap trailers) {
     synchronized (conn) {
-      // Must not race with trailers(), where the field can escape: if the user already
-      // obtained the empty map, update it in place instead of replacing it.
       if (this.trailers == null) {
         this.trailers = trailers;
       } else if (this.trailers != trailers) {

vertx-core/src/test/java/io/vertx/tests/http/http3/Http3ServerTest.java

@@ -142,6 +142,54 @@ public void testTrailers() throws Exception{
     Assert.assertEquals("chunk", new String(stream.responseBody()));
   }
 
+  @Test
+  public void testRequestTrailers() throws Exception{
+
+    server.requestHandler(req -> {
+      req.handler(buff -> {});
+      req.endHandler(v -> {
+        Assert.assertEquals("chunky", req.getTrailer("x-trailer"));
+        Assert.assertEquals("other", req.getTrailer("x-other"));
+        Assert.assertEquals(2, req.trailers().size());
+        req.response().end("done");
+      });
+    });
+
+    server.listen(8443, "localhost").await();
+
+    Http3TestClient.Client.Connection connection = client.connect(new InetSocketAddress(NetUtil.LOCALHOST4, 8443));
+    Http3TestClient.Client.Stream stream = connection.stream();
+
+    stream.write(new DefaultHttp3Headers().method("POST").path("/"));
+    stream.write("hello".getBytes(StandardCharsets.UTF_8));
+    stream.end(new DefaultHttp3Headers().set("x-trailer", "chunky").set("x-other", "other"));
+
+    Assert.assertEquals("done", new String(stream.responseBody()));
+  }
+
+  @Test
+  public void testRequestNoTrailers() throws Exception{
+
+    server.requestHandler(req -> {
+      req.handler(buff -> {});
+      req.endHandler(v -> {
+        Assert.assertTrue(req.trailers().isEmpty());
+        Assert.assertNull(req.getTrailer("x-trailer"));
+        req.response().end("done");
+      });
+    });
+
+    server.listen(8443, "localhost").await();
+
+    Http3TestClient.Client.Connection connection = client.connect(new InetSocketAddress(NetUtil.LOCALHOST4, 8443));
+    Http3TestClient.Client.Stream stream = connection.stream();
+
+    stream.write(new DefaultHttp3Headers().method("POST").path("/"));
+    stream.end("hello".getBytes(StandardCharsets.UTF_8));
+
+    Assert.assertEquals("done", new String(stream.responseBody()));
+  }
+
   @Test
   public void testUnknownFrame() throws Exception{