Display isolate message queue in Observatory debugger

runtime/vm/service.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 "vm/service.h"
 
 #include "include/dart_api.h"
 #include "platform/globals.h"
 
 #include "vm/compiler.h"
@@ skipping 715 matching lines @@
 };
 
 
 static bool GetStack(Isolate* isolate, JSONStream* js) {
   DebuggerStackTrace* stack = isolate->debugger()->StackTrace();
   // Do we want the complete script object and complete local variable objects?
   // This is true for dump requests.
   const bool full = BoolParameter::Parse(js->LookupParam("full"), false);
   JSONObject jsobj(js);
   jsobj.AddProperty("type", "Stack");
-  JSONArray jsarr(&jsobj, "frames");
+  {
+    JSONArray jsarr(&jsobj, "frames");
 
-  intptr_t num_frames = stack->Length();
-  for (intptr_t i = 0; i < num_frames; i++) {
-    ActivationFrame* frame = stack->FrameAt(i);
-    JSONObject jsobj(&jsarr);
-    frame->PrintToJSONObject(&jsobj, full);
-    // TODO(turnidge): Implement depth differently -- differentiate
-    // inlined frames.
-    jsobj.AddProperty("depth", i);
+    intptr_t num_frames = stack->Length();
+    for (intptr_t i = 0; i < num_frames; i++) {
+      ActivationFrame* frame = stack->FrameAt(i);
+      JSONObject jsobj(&jsarr);
+      frame->PrintToJSONObject(&jsobj, full);
+      // TODO(turnidge): Implement depth differently -- differentiate
+      // inlined frames.
+      jsobj.AddProperty("depth", i);
+    }
   }
+
+  {
+    MessageHandler::AcquiredQueues aq;
+    isolate->message_handler()->AcquireQueues(&aq);
+    jsobj.AddProperty("messages", aq.queue());
+  }
+
   return true;
 }
 
 
 static bool HandleCommonEcho(JSONObject* jsobj, JSONStream* js) {
   jsobj->AddProperty("type", "_EchoResponse");
   if (js->HasParam("text")) {
     jsobj->AddProperty("text", js->LookupParam("text"));
   }
   return true;
@@ skipping 417 matching lines @@
     intptr_t bpt_id = 0;
     SourceBreakpoint* bpt = NULL;
     if (GetIntegerId(rest, &bpt_id)) {
       bpt = isolate->debugger()->GetBreakpointById(bpt_id);
     }
     return bpt;
   }
   return NULL;
 }
 
 

[turnidge, 2015/05/04 17:47:13]

Maybe a short function-level comment.

[Cutch, 2015/05/04 19:56:51]

Done.

+static bool PrintMessage(JSONStream* js, Isolate* isolate, const char* id) {
+  size_t end_pos = strcspn(id, "/");
+  const char* rest = NULL;
+  if (end_pos < strlen(id)) {
+    rest = id + end_pos + 1;  // +1 for '/'.
+  }
+  if (strncmp("messages", id, end_pos) == 0) {
+    if (rest == NULL) {
+      return false;
+    }

[turnidge, 2015/05/04 17:47:13]

I see that this code is very similar to code I wrote in LookupBreakpoint, above.
 I don't understand why I waiting to check for (rest == NULL) until after the
strncmp test.  it's kind of weird.  I'm guessing this code used to be embedded
in a larger control flow and then got abstracted into a function.

Once we hoist the "rest check" up, does it turn into something like this?:

size_t end_pos = strcspn(id, "/");
if (end_pos == strlen(id)) {
  return false;
}
const char* rest = id + end_pos + 1;    // +1 for '/'.

Do you mind fixing LookupBreakpoint as well, if you agree that the code is
weird?

[Cutch, 2015/05/04 19:56:51]

Done.

+    intptr_t message_id = 0;
+    if (GetIntegerId(rest, &message_id, 16)) {
+      MessageHandler::AcquiredQueues aq;
+      isolate->message_handler()->AcquireQueues(&aq);
+      Message* message = aq.queue()->FindMessageById(message_id);
+      if (message == NULL) {
+        // Not found.
+        return false;
+      }
+      SnapshotReader reader(message->data(),
+                            message->len(),
+                            Snapshot::kMessage,
+                            isolate,
+                            isolate->current_zone());
+      const Object& msg_obj = Object::Handle(reader.ReadObject());
+      msg_obj.PrintJSON(js);
+      return true;
+    }
+  }
+  return false;
+}
 
 
 static bool PrintInboundReferences(Isolate* isolate,
                                    Object* target,
                                    intptr_t limit,
                                    JSONStream* js) {
   ObjectGraph graph(isolate);
   Array& path = Array::Handle(Array::New(limit * 2));
   intptr_t length = graph.InboundReferences(target, path);
   JSONObject jsobj(js);
@@ skipping 1129 matching lines @@
     return true;
   }
 
   // Handle non-heap objects.
   SourceBreakpoint* bpt = LookupBreakpoint(isolate, id);
   if (bpt != NULL) {
     bpt->PrintJSON(js);
     return true;
   }
 
+  if (PrintMessage(js, isolate, id)) {
+    return true;
+  }
+
   PrintError(js, "Unrecognized object id: %s\n", id);
   return true;
 }
 
 
 static const MethodParameter* get_class_list_params[] = {
   ISOLATE_PARAMETER,
   NULL,
 };
 
@@ skipping 238 matching lines @@
     ServiceMethodDescriptor& method = service_methods_[i];
     if (strcmp(method_name, method.name) == 0) {
       return &method;
     }
   }
   return NULL;
 }
 
 
 }  // namespace dart