Initial isolate reload support

runtime/vm/isolate.h

Index: runtime/vm/isolate.h
diff --git a/runtime/vm/isolate.h b/runtime/vm/isolate.h
index c2fc95554d71e231affe824e2d343fce1bd32818..b418fd6fec65f34c19cb88c74d6a6411a11fd56c 100644
--- a/runtime/vm/isolate.h
+++ b/runtime/vm/isolate.h
@@ -35,6 +35,7 @@ class HandleVisitor;
 class Heap;
 class ICData;
 class IsolateProfilerData;
+class IsolateReloadContext;
 class IsolateSpawnState;
 class Log;
 class MessageHandler;
@@ -47,12 +48,12 @@ class RawInstance;
 class RawArray;
 class RawContext;
 class RawDouble;
+class RawError;
+class RawField;
 class RawGrowableObjectArray;
 class RawMint;
 class RawObject;
 class RawInteger;
-class RawError;
-class RawField;
 class RawFloat32x4;
 class RawInt32x4;
 class RawUserTag;
@@ -91,6 +92,18 @@ class NoOOBMessageScope : public StackResource {
 };
 
 
+// Disallow isolate reload.
+class NoReloadScope : public StackResource {
+ public:
+  NoReloadScope(Isolate* isolate, Thread* thread);
+  ~NoReloadScope();
+
+ private:
+  Isolate* isolate_;
+  DISALLOW_COPY_AND_ASSIGN(NoReloadScope);
+};
+
+
 class Isolate : public BaseIsolate {
  public:
   // Keep both these enums in sync with isolate_patch.dart.
@@ -150,6 +163,9 @@ class Isolate : public BaseIsolate {
     return OFFSET_OF(Isolate, class_table_);
   }
 
+  // Prefers old classes when we are in the middle of a reload.
+  RawClass* GetClassForHeapWalkAt(intptr_t cid);
+
   static intptr_t ic_miss_code_offset() {
     return OFFSET_OF(Isolate, ic_miss_code_);
   }
@@ -237,6 +253,10 @@ class Isolate : public BaseIsolate {
 
   // Marks all libraries as loaded.
   void DoneLoading();
+  void DoneFinalizing();
+
+  void OnStackReload();
+  void ReloadSources(bool test_mode = false);
 
   bool MakeRunnable();
   void Run();
@@ -388,6 +408,22 @@ class Isolate : public BaseIsolate {
     background_compiler_ = value;
   }
 
+  void enable_background_compiler() {
+    background_compiler_disabled_depth_--;
+    if (background_compiler_disabled_depth_ < 0) {
+      FATAL("Mismatched number of calls to disable_background_compiler and "
+            "enable_background_compiler.");
+    }
+  }
+
+  void disable_background_compiler() {
+    background_compiler_disabled_depth_++;
+  }
+
+  bool is_background_compiler_disabled() const {
+    return background_compiler_disabled_depth_ > 0;
+  }
+
   void UpdateLastAllocationProfileAccumulatorResetTimestamp() {
     last_allocationprofile_accumulator_reset_timestamp_ =
         OS::GetCurrentTimeMillis();
@@ -432,6 +468,22 @@ class Isolate : public BaseIsolate {
     return &vm_tag_counters_;
   }
 
+  bool IsReloading() const {
+    return reload_context_ != NULL;
+  }
+
+  IsolateReloadContext* reload_context() {
+    return reload_context_;
+  }
+
+  bool HasAttemptedReload() const {
+    return has_attempted_reload_;
+  }
+
+  bool CanReload() const;
+
+  void ReportReloadError(const Error& error);
+
   uword user_tag() const {
     return user_tag_;
   }
@@ -717,6 +769,7 @@ class Isolate : public BaseIsolate {
 
   // Background compilation.
   BackgroundCompiler* background_compiler_;
+  intptr_t background_compiler_disabled_depth_;
 
   // We use 6 list entries for each pending service extension calls.
   enum {
@@ -769,6 +822,11 @@ class Isolate : public BaseIsolate {
   Monitor* spawn_count_monitor_;
   intptr_t spawn_count_;
 
+  // Has a reload ever been attempted?
+  bool has_attempted_reload_;
+  intptr_t no_reload_scope_depth_;  // we can only reload when this is 0.
+  IsolateReloadContext* reload_context_;
+
 #define ISOLATE_METRIC_VARIABLE(type, variable, name, unit)                    \
   type metric_##variable##_;
   ISOLATE_METRIC_LIST(ISOLATE_METRIC_VARIABLE);
@@ -795,12 +853,15 @@ class Isolate : public BaseIsolate {
 REUSABLE_HANDLE_LIST(REUSABLE_FRIEND_DECLARATION)
 #undef REUSABLE_FRIEND_DECLARATION
 
+  friend class Become;  // VisitObjectPointers
   friend class GCMarker;  // VisitObjectPointers
   friend class SafepointHandler;
   friend class Scavenger;  // VisitObjectPointers
   friend class ServiceIsolate;
   friend class Thread;
   friend class Timeline;
+  friend class NoReloadScope;  // reload_block
+
 
   DISALLOW_COPY_AND_ASSIGN(Isolate);
 };