Fix netty 'unknown' transactions

Author: obenkenobi

instrumentation/netty-4.1.16/src/main/java/com/agent/instrumentation/netty4116/NettyUtil.java

@@ -19,6 +19,13 @@
 
 public class NettyUtil {
 
+    // This config is added so customers can also start netty transactions at a lower level.
+    // However, this risks netty producing transactions with 'unknown' urls.
+    // Only use it if it provides the coverage you need for your application's use case.
+    public static Boolean START_HTTP2_FRAME_READ_LISTENER_TXN =
+            NewRelic.getAgent().getConfig().getValue("netty.http2.frame_read_listener.start_transaction", false);
+    public static Boolean START_HTTP2_FRAME_CODEC_TXN = !START_HTTP2_FRAME_READ_LISTENER_TXN;
+
     public static String getNettyVersion() {
         return "4.1.16";
     }

instrumentation/netty-4.1.16/src/main/java/io/netty/handler/codec/http2/FrameReadListener_Instrumentation.java

@@ -7,6 +7,7 @@
 
 package io.netty.handler.codec.http2;
 
+import com.agent.instrumentation.netty4116.NettyUtil;
 import com.newrelic.api.agent.weaver.MatchType;
 import com.newrelic.api.agent.weaver.Weave;
 import com.newrelic.api.agent.weaver.Weaver;
@@ -19,7 +20,7 @@ class FrameReadListener_Instrumentation {
     // Process HTTP/2 request headers and start txn
     public void onHeadersRead(ChannelHandlerContext_Instrumentation ctx, int streamId, Http2Headers headers, int streamDependency, short weight,
             boolean exclusive, int padding, boolean endOfStream) {
-        if (ctx.pipeline().token == null) {
+        if (NettyUtil.START_HTTP2_FRAME_CODEC_TXN && ctx.pipeline().token == null) {
             // NettyDispatcher class is usually initialized in AbstractBootstrap; however,
             // that code is not always invoked when using recent Netty versions (4.1.54)
             // so we check here and initialize if we haven't yet.

instrumentation/netty-4.1.16/src/main/java/io/netty/handler/codec/http2/Http2FrameCodec_Instrumentation.java

@@ -0,0 +1,52 @@
+/*
+ *
+ *  * Copyright 2024 New Relic Corporation. All rights reserved.
+ *  * SPDX-License-Identifier: Apache-2.0
+ *
+ */
+
+package io.netty.handler.codec.http2;
+
+import com.agent.instrumentation.netty4116.NettyUtil;
+import com.newrelic.api.agent.weaver.MatchType;
+import com.newrelic.api.agent.weaver.Weave;
+import com.newrelic.api.agent.weaver.Weaver;
+import io.netty.bootstrap.NettyDispatcher;
+import io.netty.channel.ChannelHandlerContext_Instrumentation;
+import io.netty.channel.ChannelPromise;
+
+@Weave(type = MatchType.BaseClass, originalName = "io.netty.handler.codec.http2.Http2FrameCodec")
+public class Http2FrameCodec_Instrumentation {
+
+    // Handle the incoming request. For HTTP/2 there is no HttpRequest object
+    // but rather a stream of Http2Frame objects that make up the full request.
+    void onHttp2Frame(ChannelHandlerContext_Instrumentation ctx, Http2Frame frame) {
+        if (!NettyUtil.START_HTTP2_FRAME_READ_LISTENER_TXN && frame instanceof Http2HeadersFrame && ctx.pipeline().token == null) {
+            Http2HeadersFrame msg = (Http2HeadersFrame) frame;
+            if (msg.isEndStream()) {
+                // NettyDispatcher class is usually initialized in AbstractBootstrap; however,
+                // that code is not always invoked when using recent Netty versions (4.1.54)
+                // so we check here and initialize if we haven't yet.
+                if (!NettyDispatcher.instrumented.get()) {
+                    NettyDispatcher.get();
+                }
+                NettyDispatcher.channelRead(ctx, msg.headers());
+            }
+        }
+        // Order matters here!!! Weaver.callOriginal() must come after the call to NettyDispatcher.channelRead.
+        Weaver.callOriginal();
+    }
+
+    // Handle the outgoing response. For HTTP/2 there is no HttpResponse object
+    // but rather a stream of Http2Frame objects that make up the full response.
+    public void write(ChannelHandlerContext_Instrumentation ctx, Object msg, ChannelPromise promise) {
+        if (msg instanceof Http2HeadersFrame) {
+            boolean expired = NettyUtil.processResponse(msg, ctx.pipeline().token);
+            if (expired) {
+                ctx.pipeline().token = null;
+            }
+        }
+        // Order matters here!!! Weaver.callOriginal() must come after the call to NettyUtil.processResponse.
+        Weaver.callOriginal();
+    }
+}