diff options
Diffstat (limited to 'runtime/gc')
| -rw-r--r-- | runtime/gc/reference_processor.cc | 32 |
1 files changed, 17 insertions, 15 deletions
diff --git a/runtime/gc/reference_processor.cc b/runtime/gc/reference_processor.cc index 188b6b3..2aba951 100644 --- a/runtime/gc/reference_processor.cc +++ b/runtime/gc/reference_processor.cc @@ -39,9 +39,6 @@ void ReferenceProcessor::EnableSlowPath() { void ReferenceProcessor::DisableSlowPath(Thread* self) { slow_path_enabled_ = false; - // Set to null so that GetReferent knows to not attempt to use the callback for seeing if - // referents are marked. - process_references_args_.is_marked_callback_ = nullptr; condition_.Broadcast(self); } @@ -57,13 +54,17 @@ mirror::Object* ReferenceProcessor::GetReferent(Thread* self, mirror::Reference* } MutexLock mu(self, lock_); while (slow_path_enabled_) { + mirror::Object* const referent = reference->GetReferent(); + // If the referent became cleared, return it. + if (referent == nullptr) { + return nullptr; + } // Try to see if the referent is already marked by using the is_marked_callback. We can return // it to the mutator as long as the GC is not preserving references. If the GC is // preserving references, the mutator could take a white field and move it somewhere else // in the heap causing corruption since this field would get swept. IsMarkedCallback* const is_marked_callback = process_references_args_.is_marked_callback_; if (!preserving_references_ && is_marked_callback != nullptr) { - mirror::Object* const referent = reference->GetReferent(); mirror::Object* const obj = is_marked_callback(referent, process_references_args_.arg_); // If it's null it means not marked, but it could become marked if the referent is reachable // by finalizer referents. So we can not return in this case and must block. @@ -107,14 +108,9 @@ void ReferenceProcessor::ProcessReferences(bool concurrent, TimingLogger* timing process_references_args_.is_marked_callback_ = is_marked_callback; process_references_args_.mark_callback_ = mark_object_callback; process_references_args_.arg_ = arg; + CHECK_EQ(slow_path_enabled_, concurrent) << "Slow path must be enabled iff concurrent"; } - if (concurrent) { - MutexLock mu(self, lock_); - CHECK(slow_path_enabled_) << "Slow path must be enabled for concurrent reference processing"; - timings->StartSplit("ProcessReferences"); - } else { - timings->StartSplit("(Paused)ProcessReferences"); - } + timings->StartSplit(concurrent ? "ProcessReferences" : "(Paused)ProcessReferences"); // Unless required to clear soft references with white references, preserve some white referents. if (!clear_soft_references) { TimingLogger::ScopedSplit split(concurrent ? "PreserveSomeSoftReferences" : @@ -125,7 +121,6 @@ void ReferenceProcessor::ProcessReferences(bool concurrent, TimingLogger* timing // References with a marked referent are removed from the list. soft_reference_queue_.PreserveSomeSoftReferences(&PreserveSoftReferenceCallback, &process_references_args_); - process_mark_stack_callback(arg); if (concurrent) { StopPreservingReferences(self); @@ -158,10 +153,17 @@ void ReferenceProcessor::ProcessReferences(bool concurrent, TimingLogger* timing DCHECK(weak_reference_queue_.IsEmpty()); DCHECK(finalizer_reference_queue_.IsEmpty()); DCHECK(phantom_reference_queue_.IsEmpty()); - if (concurrent) { + { MutexLock mu(self, lock_); - // Done processing, disable the slow path and broadcast to the waiters. - DisableSlowPath(self); + // Need to always do this since the next GC may be concurrent. Doing this for only concurrent + // could result in a stale is_marked_callback_ being called before the reference processing + // starts since there is a small window of time where slow_path_enabled_ is enabled but the + // callback isn't yet set. + process_references_args_.is_marked_callback_ = nullptr; + if (concurrent) { + // Done processing, disable the slow path and broadcast to the waiters. + DisableSlowPath(self); + } } timings->EndSplit(); } |