1 files changed, 18 insertions, 8 deletions
diff --git a/runtime/instrumentation.h b/runtime/instrumentation.h
index 612ca14cf5..726cf1b461 100644
--- a/runtime/instrumentation.h
+++ b/runtime/instrumentation.h
@@ -397,6 +397,11 @@ class Instrumentation {
       SHARED_REQUIRES(Locks::mutator_lock_)
       REQUIRES(!Locks::thread_list_lock_);
 
+  static size_t ComputeFrameId(Thread* self,
+                               size_t frame_depth,
+                               size_t inlined_frames_before_frame)
+      SHARED_REQUIRES(Locks::mutator_lock_);
+
  private:
   InstrumentationLevel GetCurrentInstrumentationLevel() const;
 
@@ -512,20 +517,25 @@ class Instrumentation {
   InstrumentationLevelTable requested_instrumentation_levels_ GUARDED_BY(Locks::mutator_lock_);
 
   // The event listeners, written to with the mutator_lock_ exclusively held.
+  // Mutators must be able to iterate over these lists concurrently, that is, with listeners being
+  // added or removed while iterating. The modifying thread holds exclusive lock,
+  // so other threads cannot iterate (i.e. read the data of the list) at the same time but they
+  // do keep iterators that need to remain valid. This is the reason these listeners are std::list
+  // and not for example std::vector: the existing storage for a std::list does not move.
+  // Note that mutators cannot make a copy of these lists before iterating, as the instrumentation
+  // listeners can also be deleted concurrently.
+  // As a result, these lists are never trimmed. That's acceptable given the low number of
+  // listeners we have.
   std::list<InstrumentationListener*> method_entry_listeners_ GUARDED_BY(Locks::mutator_lock_);
   std::list<InstrumentationListener*> method_exit_listeners_ GUARDED_BY(Locks::mutator_lock_);
   std::list<InstrumentationListener*> method_unwind_listeners_ GUARDED_BY(Locks::mutator_lock_);
   std::list<InstrumentationListener*> backward_branch_listeners_ GUARDED_BY(Locks::mutator_lock_);
   std::list<InstrumentationListener*> invoke_virtual_or_interface_listeners_
       GUARDED_BY(Locks::mutator_lock_);
-  std::shared_ptr<std::list<InstrumentationListener*>> dex_pc_listeners_
-      GUARDED_BY(Locks::mutator_lock_);
-  std::shared_ptr<std::list<InstrumentationListener*>> field_read_listeners_
-      GUARDED_BY(Locks::mutator_lock_);
-  std::shared_ptr<std::list<InstrumentationListener*>> field_write_listeners_
-      GUARDED_BY(Locks::mutator_lock_);
-  std::shared_ptr<std::list<InstrumentationListener*>> exception_caught_listeners_
-      GUARDED_BY(Locks::mutator_lock_);
+  std::list<InstrumentationListener*> dex_pc_listeners_ GUARDED_BY(Locks::mutator_lock_);
+  std::list<InstrumentationListener*> field_read_listeners_ GUARDED_BY(Locks::mutator_lock_);
+  std::list<InstrumentationListener*> field_write_listeners_ GUARDED_BY(Locks::mutator_lock_);
+  std::list<InstrumentationListener*> exception_caught_listeners_ GUARDED_BY(Locks::mutator_lock_);
 
   // The set of methods being deoptimized (by the debugger) which must be executed with interpreter
   // only.