[GitHub] [incubator-zipkin] trustin commented on a change in pull request #2563: Add a netty scribe server.

[GitBox <gi...@apache.org>]

trustin commented on a change in pull request #2563: Add a netty scribe server.
URL: https://github.com/apache/incubator-zipkin/pull/2563#discussion_r281954029
 
 

 ##########
 File path: zipkin-collector/scribe/src/main/java/zipkin2/collector/scribe/ScribeInboundHandler.java
 ##########
 @@ -0,0 +1,187 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package zipkin2.collector.scribe;
+
+import com.linecorp.armeria.common.HttpData;
+import com.linecorp.armeria.common.HttpHeaderNames;
+import com.linecorp.armeria.common.HttpHeaders;
+import com.linecorp.armeria.common.HttpMethod;
+import com.linecorp.armeria.common.HttpRequest;
+import com.linecorp.armeria.common.HttpResponse;
+import com.linecorp.armeria.server.ServiceRequestContext;
+import com.linecorp.armeria.server.ServiceRequestContextBuilder;
+import com.linecorp.armeria.server.thrift.THttpService;
+import com.linecorp.armeria.unsafe.ByteBufHttpData;
+import io.netty.buffer.ByteBuf;
+import io.netty.buffer.ByteBufHolder;
+import io.netty.buffer.CompositeByteBuf;
+import io.netty.buffer.Unpooled;
+import io.netty.channel.Channel;
+import io.netty.channel.ChannelFutureListener;
+import io.netty.channel.ChannelHandlerContext;
+import io.netty.channel.ChannelInboundHandlerAdapter;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+class ScribeInboundHandler extends ChannelInboundHandlerAdapter {
+
+  static final Logger logger = LoggerFactory.getLogger(ScribeInboundHandler.class);
+
+  // Headers mostly copied from https://github.com/apache/thrift/blob/master/lib/javame/src/org/apache/thrift/transport/THttpClient.java#L130
+  static final HttpHeaders THRIFT_HEADERS = HttpHeaders.of(
+    HttpMethod.POST, "/internal/zipkin-thriftrpc")
+    .set(HttpHeaderNames.CONTENT_TYPE, "application/x-thrift")
+    .set(HttpHeaderNames.ACCEPT, "application/x-thrift")
+    .set(HttpHeaderNames.USER_AGENT, "Zipkin/ScribeInboundHandler")
+    .asImmutable();
+
+  final THttpService scribeService;
+
+  ScribeInboundHandler(ScribeSpanConsumer scribe) {
+    scribeService = THttpService.of(scribe);
+  }
+
+  enum ReadState {
+    HEADER,
+    PAYLOAD
+  }
+
+  CompositeByteBuf pending;
+  ReadState state;
+  int nextFrameSize;
+
+  @Override
+  public void channelActive(ChannelHandlerContext ctx) throws Exception {
+    pending = ctx.alloc().compositeBuffer();
+    state = ReadState.HEADER;
+  }
+
+  @Override
+  public void channelRead(final ChannelHandlerContext ctx, Object msg) {
+    if (pending == null) {
+      // Already closed (probably due to an exception).
+      return;
+    }
+
+    assert msg instanceof ByteBuf;
+    ByteBuf buf = (ByteBuf) msg;
+    pending.addComponent(true, buf);
+
+    switch (state) {
+      case HEADER:
+        maybeReadHeader(ctx);
+        break;
+      case PAYLOAD:
+        maybeReadPayload(ctx);
+        break;
+    }
+  }
+
+  @Override
+  public void channelInactive(ChannelHandlerContext ctx) {
+    release();
+  }
+
+  @Override
+  public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
+    logger.warn("Unexpected error handling connection.", cause);
+
+    release();
+    closeOnFlush(ctx.channel());
+  }
+
+  void maybeReadHeader(ChannelHandlerContext ctx) {
+    if (pending.readableBytes() < 4) {
+      return;
+    }
+    nextFrameSize = pending.readInt();
+    state = ReadState.PAYLOAD;
+    maybeReadPayload(ctx);
+  }
+
+  void maybeReadPayload(ChannelHandlerContext ctx) {
+    if (pending.readableBytes() < nextFrameSize) {
+      return;
+    }
+
+    ByteBuf payload = ctx.alloc().buffer(nextFrameSize);
+    pending.readBytes(payload, nextFrameSize);
+
+    state = ReadState.HEADER;
+
+    HttpRequest request = HttpRequest.of(
+      THRIFT_HEADERS.toMutable(),
+      new ByteBufHttpData(payload, true));
+    ServiceRequestContext requestContext = ServiceRequestContextBuilder.of(request)
+      .service(scribeService)
+      .build();
+
+    final HttpResponse response;
+    try {
+      response = scribeService.serve(requestContext, request);
+    } catch (Exception e) {
+      logger.warn("Unexpected exception servicing thrift request. "
+        + "This usually indicates a bug in armeria's thrift implementation.", e);
+      exceptionCaught(ctx, e);
+      return;
+    }
+
+    response.aggregateWithPooledObjects(ctx.executor(), ctx.alloc()).handle((msg, t) -> {
+      if (t != null) {
+        logger.warn("Unexpected exception reading thrift response. "
+          + "This usually indicates a bug in armeria's thrift implementation.", t);
 
 Review comment:
   Hmm, really? I think aggregation may fail on other cases such as OOME.

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