logs JSON-RPC request and responses in TRACE mode (#4395)

Signed-off-by: Pedro Novais <jpvnovais@gmail.com>
Co-authored-by: Antony Denyer <git@antonydenyer.co.uk>
Co-authored-by: Simon Dudley <simon.dudley@consensys.net>

ethereum/api/src/main/java/org/hyperledger/besu/ethereum/api/handlers/JsonRpcExecutorHandler.java

@@ -52,9 +52,11 @@ public class JsonRpcExecutorHandler {
   private static final Logger LOG = LoggerFactory.getLogger(JsonRpcExecutorHandler.class);
   private static final String SPAN_CONTEXT = "span_context";
   private static final String APPLICATION_JSON = "application/json";
-  private static final ObjectWriter JSON_OBJECT_WRITER =
+  private static final ObjectMapper JSON_OBJECT_MAPPER =
       new ObjectMapper()
-          .registerModule(new Jdk8Module()) // Handle JDK8 Optionals (de)serialization
+          .registerModule(new Jdk8Module()); // Handle JDK8 Optionals (de)serialization
+  private static final ObjectWriter JSON_OBJECT_WRITER =
+      JSON_OBJECT_MAPPER
           .writerWithDefaultPrettyPrinter()
           .without(JsonGenerator.Feature.FLUSH_PASSED_TO_STREAM)
           .with(JsonGenerator.Feature.AUTO_CLOSE_TARGET);
@@ -72,6 +74,7 @@ public class JsonRpcExecutorHandler {
 
         if (ctx.data().containsKey(ContextKey.REQUEST_BODY_AS_JSON_OBJECT.name())) {
           JsonObject jsonRequest = ctx.get(ContextKey.REQUEST_BODY_AS_JSON_OBJECT.name());
+          lazyTraceLogger(jsonRequest::toString);
           JsonRpcResponse jsonRpcResponse =
               jsonRpcExecutor.execute(
                   user,
@@ -87,23 +90,24 @@ public class JsonRpcExecutorHandler {
             try (final JsonResponseStreamer streamer =
                 new JsonResponseStreamer(response, ctx.request().remoteAddress())) {
               // underlying output stream lifecycle is managed by the json object writer
+              lazyTraceLogger(() -> JSON_OBJECT_MAPPER.writeValueAsString(jsonRpcResponse));
               JSON_OBJECT_WRITER.writeValue(streamer, jsonRpcResponse);
             }
           }
         } else if (ctx.data().containsKey(ContextKey.REQUEST_BODY_AS_JSON_ARRAY.name())) {
           JsonArray batchJsonRequest = ctx.get(ContextKey.REQUEST_BODY_AS_JSON_ARRAY.name());
-          List<JsonRpcResponse> jsonRpcBatchResponse;
+          lazyTraceLogger(batchJsonRequest::toString);
+          List<JsonRpcResponse> jsonRpcBatchResponses = new ArrayList<>();
           try {
-            List<JsonRpcResponse> responses = new ArrayList<>();
             for (int i = 0; i < batchJsonRequest.size(); i++) {
               final JsonObject jsonRequest;
               try {
                 jsonRequest = batchJsonRequest.getJsonObject(i);
               } catch (ClassCastException e) {
-                responses.add(new JsonRpcErrorResponse(null, INVALID_REQUEST));
+                jsonRpcBatchResponses.add(new JsonRpcErrorResponse(null, INVALID_REQUEST));
                 continue;
               }
-              responses.add(
+              jsonRpcBatchResponses.add(
                   jsonRpcExecutor.execute(
                       user,
                       tracer,
@@ -112,18 +116,18 @@ public class JsonRpcExecutorHandler {
                       jsonRequest,
                       req -> req.mapTo(JsonRpcRequest.class)));
             }
-            jsonRpcBatchResponse = responses;
           } catch (RuntimeException e) {
             response.setStatusCode(HttpResponseStatus.BAD_REQUEST.code()).end();
             return;
           }
           final JsonRpcResponse[] completed =
-              jsonRpcBatchResponse.stream()
+              jsonRpcBatchResponses.stream()
                   .filter(jsonRpcResponse -> jsonRpcResponse.getType() != JsonRpcResponseType.NONE)
                   .toArray(JsonRpcResponse[]::new);
           try (final JsonResponseStreamer streamer =
               new JsonResponseStreamer(response, ctx.request().remoteAddress())) {
             // underlying output stream lifecycle is managed by the json object writer
+            lazyTraceLogger(() -> JSON_OBJECT_MAPPER.writeValueAsString(completed));
             JSON_OBJECT_WRITER.writeValue(streamer, completed);
           }
         } else {
@@ -170,4 +174,19 @@ public class JsonRpcExecutorHandler {
         return HttpResponseStatus.OK;
     }
   }
+
+  @FunctionalInterface
+  private interface ExceptionThrowingSupplier<T> {
+    T get() throws Exception;
+  }
+
+  private static void lazyTraceLogger(final ExceptionThrowingSupplier<String> logMessageSupplier) {
+    if (LOG.isTraceEnabled()) {
+      try {
+        LOG.trace(logMessageSupplier.get());
+      } catch (Exception e) {
+        throw new RuntimeException(e);
+      }
+    }
+  }
 }