Thread and Timeline fixes for Mojo.

runtime/vm/dart_api_impl.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 "include/dart_api.h"
 #include "include/dart_mirrors_api.h"
 #include "include/dart_native_api.h"
 
 #include "platform/assert.h"
 #include "vm/class_finalizer.h"
@@ skipping 1271 matching lines @@
 }
 
 
 DART_EXPORT Dart_Handle Dart_DebugName() {
   DARTSCOPE(Thread::Current());
   Isolate* I = T->isolate();
   return Api::NewHandle(T, String::New(I->name()));
 }
 
 
-
 DART_EXPORT void Dart_EnterIsolate(Dart_Isolate isolate) {
   CHECK_NO_ISOLATE(Isolate::Current());
   // TODO(16615): Validate isolate parameter.
   Isolate* iso = reinterpret_cast<Isolate*>(isolate);
   if (iso->HasMutatorThread()) {
     FATAL("Multiple mutators within one isolate is not supported.");
   }
   Thread::EnterIsolate(iso);
 }
 
@@ skipping 4418 matching lines @@
   Timeline::ReclaimCachedBlocksFromThreads();
   JSONStream js;
   IsolateTimelineEventFilter filter(isolate->main_port());
   timeline_recorder->PrintTraceEvent(&js, &filter);
   return StreamTraceEvents(consumer, user_data, &js);
 }
 
 
 DART_EXPORT bool Dart_GlobalTimelineGetTrace(Dart_StreamConsumer consumer,
                                              void* user_data) {
+  // To support various embedders, it must be possible to call this function
+  // from a thread for which we have not entered an Isolate and set up a Thread
+  // TLS object. Therefore, a Zone may not be available, a StackZone cannot be
+  // created, and no ZoneAllocated objects can be allocated.
   if (consumer == NULL) {
     return false;
   }
   TimelineEventRecorder* timeline_recorder = Timeline::recorder();
   if (timeline_recorder == NULL) {
     // Nothing has been recorded.
     return false;
   }
-  Thread* T = Thread::Current();
-  StackZone zone(T);
   Timeline::ReclaimCachedBlocksFromThreads();
   JSONStream js;
   TimelineEventFilter filter;
   timeline_recorder->PrintTraceEvent(&js, &filter);
   return StreamTraceEvents(consumer, user_data, &js);
 }
 
 
 DART_EXPORT Dart_Handle Dart_TimelineDuration(const char* label,
                                               int64_t start_micros,
@@ skipping 167 matching lines @@
                                    ApiReallocate);
   writer.WriteFullSnapshot();
   *vm_isolate_snapshot_size = writer.VmIsolateSnapshotSize();
   *isolate_snapshot_size = writer.IsolateSnapshotSize();
   *instructions_snapshot_size = writer.InstructionsSnapshotSize();
 
   return Api::Success();
 }
 
 }  // namespace dart