Do not JSON encode the 'result' of a service rpc.

runtime/vm/json_stream.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "platform/assert.h"
 
 #include "vm/dart_entry.h"
 #include "vm/debugger.h"
 #include "vm/json_stream.h"
 #include "vm/message.h"
 #include "vm/metrics.h"
 #include "vm/object.h"
 #include "vm/service_event.h"
 #include "vm/unicode.h"
 
 
 namespace dart {
 
 DECLARE_FLAG(bool, trace_service);
 
 JSONStream::JSONStream(intptr_t buf_size)
     : open_objects_(0),
       buffer_(buf_size),
       reply_port_(ILLEGAL_PORT),
+      seq_(""),
       method_(""),
       param_keys_(NULL),
       param_values_(NULL),
       num_params_(0) {
 }
 
 
 JSONStream::~JSONStream() {
 }
 
 
 void JSONStream::Setup(Zone* zone,
                        Dart_Port reply_port,
+                       const String& seq,
                        const String& method,
                        const Array& param_keys,
                        const Array& param_values) {
   set_reply_port(reply_port);
+  seq_ = seq.ToCString();
   method_ = method.ToCString();
 
   String& string_iterator = String::Handle();
   if (param_keys.Length() > 0) {
     ASSERT(param_keys.Length() == param_values.Length());
     const char** param_keys_native =
         zone->Alloc<const char*>(param_keys.Length());
     const char** param_values_native =
         zone->Alloc<const char*>(param_keys.Length());
     for (intptr_t i = 0; i < param_keys.Length(); i++) {
       string_iterator ^= param_keys.At(i);
       param_keys_native[i] =
           zone->MakeCopyOfString(string_iterator.ToCString());
       string_iterator ^= param_values.At(i);
       param_values_native[i] =
           zone->MakeCopyOfString(string_iterator.ToCString());
     }
     SetParams(param_keys_native, param_values_native, param_keys.Length());
   }
   if (FLAG_trace_service) {
     Isolate* isolate = Isolate::Current();
     ASSERT(isolate != NULL);
     const char* isolate_name = isolate->name();
     OS::Print("Isolate %s processing service request %s\n",
               isolate_name, method_);
     setup_time_micros_ = OS::GetCurrentTimeMicros();
   }
+  buffer_.Printf("{\"result\":");
 }
 
 
+void JSONStream::SetupError() {
+  buffer_.Clear();
+  buffer_.Printf("{\"error\":");
+}
+
+
 static uint8_t* allocator(uint8_t* ptr, intptr_t old_size, intptr_t new_size) {
   void* new_ptr = realloc(reinterpret_cast<void*>(ptr), new_size);
   return reinterpret_cast<uint8_t*>(new_ptr);
 }
 
 
 void JSONStream::PostReply() {
   Dart_Port port = reply_port();
   ASSERT(port != ILLEGAL_PORT);
   set_reply_port(ILLEGAL_PORT);  // Prevent double replies.
   int64_t process_delta_micros = 0;
   if (FLAG_trace_service) {
     process_delta_micros = OS::GetCurrentTimeMicros() - setup_time_micros_;
   }
+  // TODO(turnidge): Handle non-string sequence numbers.
+  buffer_.Printf(", \"id\":\"%s\"}", seq());
   const String& reply = String::Handle(String::New(ToCString()));
   ASSERT(!reply.IsNull());
 
   uint8_t* data = NULL;
   MessageWriter writer(&data, &allocator, false);
   writer.WriteMessage(reply);
   bool result = PortMap::PostMessage(new Message(port, data,
                                                  writer.BytesWritten(),
                                                  Message::kNormalPriority));
   if (FLAG_trace_service) {
@@ skipping 389 matching lines @@
   intptr_t len2 = OS::VSNPrint(p, len+1, format, args);
   va_end(args);
   ASSERT(len == len2);
   stream_->buffer_.AddChar('"');
   stream_->AddEscapedUTF8String(p);
   stream_->buffer_.AddChar('"');
   free(p);
 }
 
 }  // namespace dart