[heap] Reland "Use RAIL mode for initial heap sizing"

src/isolate.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/isolate.h"
 
 #include <stdlib.h>
 
 #include <fstream>  // NOLINT(readability/streams)
 #include <sstream>
@@ skipping 2122 matching lines @@
       global_handles_(NULL),
       eternal_handles_(NULL),
       thread_manager_(NULL),
       regexp_stack_(NULL),
       date_cache_(NULL),
       call_descriptor_data_(NULL),
       // TODO(bmeurer) Initialized lazily because it depends on flags; can
       // be fixed once the default isolate cleanup is done.
       random_number_generator_(NULL),
       rail_mode_(PERFORMANCE_ANIMATION),
+      load_start_time_ms_(0),
       serializer_enabled_(enable_serializer),
       has_fatal_error_(false),
       initialized_from_snapshot_(false),
       is_promisehook_enabled_(false),
       is_tail_call_elimination_enabled_(true),
       is_isolate_in_background_(false),
       cpu_profiler_(NULL),
       heap_profiler_(NULL),
       code_event_dispatcher_(new CodeEventDispatcher()),
       function_entry_hook_(NULL),
@@ skipping 1335 matching lines @@
       }
     }
   }
   if (new_length == 0) {
     heap()->set_detached_contexts(heap()->empty_fixed_array());
   } else if (new_length < length) {
     heap()->RightTrimFixedArray(*detached_contexts, length - new_length);
   }
 }
 
+double Isolate::LoadStartTimeMs() {
+  base::LockGuard<base::Mutex> guard(&rail_mutex_);
+  return load_start_time_ms_;
+}
+
 void Isolate::SetRAILMode(RAILMode rail_mode) {
+  RAILMode old_rail_mode = rail_mode_.Value();
+  if (old_rail_mode != PERFORMANCE_LOAD && rail_mode == PERFORMANCE_LOAD) {
+    base::LockGuard<base::Mutex> guard(&rail_mutex_);
+    load_start_time_ms_ = heap()->MonotonicallyIncreasingTimeInMs();
+  }
   rail_mode_.SetValue(rail_mode);
+  if (old_rail_mode == PERFORMANCE_LOAD && rail_mode != PERFORMANCE_LOAD) {
+    heap()->incremental_marking()->incremental_marking_job()->ScheduleTask(
+        heap());
+  }
   if (FLAG_trace_rail) {
     PrintIsolate(this, "RAIL mode: %s\n", RAILModeName(rail_mode));
   }
 }
 
 void Isolate::IsolateInBackgroundNotification() {
   is_isolate_in_background_ = true;
   heap()->ActivateMemoryReducerIfNeeded();
 }
 
@@ skipping 48 matching lines @@
   // Then check whether this scope intercepts.
   if ((flag & intercept_mask_)) {
     intercepted_flags_ |= flag;
     return true;
   }
   return false;
 }
 
 }  // namespace internal
 }  // namespace v8