Make empty checkpoint work while weak ref access is disabled.
Fix a potential race on PushOntoMarkStack for CC by running an empty
checkpoint (while weak ref access is disabled).
Bug: 32508093
Bug: 12687968
Test: test-art-host with CC/CMS, libartd boot with N9, Ritz EAAC.
Change-Id: I3749bb525e7734804307ee16262355f3fc730312
diff --git a/runtime/thread_list.h b/runtime/thread_list.h
index b455e31..133d430 100644
--- a/runtime/thread_list.h
+++ b/runtime/thread_list.h
@@ -17,6 +17,7 @@
#ifndef ART_RUNTIME_THREAD_LIST_H_
#define ART_RUNTIME_THREAD_LIST_H_
+#include "barrier.h"
#include "base/histogram.h"
#include "base/mutex.h"
#include "base/value_object.h"
@@ -100,6 +101,14 @@
size_t RunCheckpoint(Closure* checkpoint_function, Closure* callback = nullptr)
REQUIRES(!Locks::thread_list_lock_, !Locks::thread_suspend_count_lock_);
+ // Run an empty checkpoint on threads. Wait until threads pass the next suspend point or are
+ // suspended. This is used to ensure that the threads finish or aren't in the middle of an
+ // in-flight mutator heap access (eg. a read barrier.) Runnable threads will respond by
+ // decrementing the empty checkpoint barrier count. This works even when the weak ref access is
+ // disabled. Only one concurrent use is currently supported.
+ size_t RunEmptyCheckpoint()
+ REQUIRES(!Locks::thread_list_lock_, !Locks::thread_suspend_count_lock_);
+
size_t RunCheckpointOnRunnableThreads(Closure* checkpoint_function)
REQUIRES(!Locks::thread_list_lock_, !Locks::thread_suspend_count_lock_);
@@ -158,6 +167,10 @@
void DumpNativeStacks(std::ostream& os)
REQUIRES(!Locks::thread_list_lock_);
+ Barrier* EmptyCheckpointBarrier() {
+ return empty_checkpoint_barrier_.get();
+ }
+
private:
uint32_t AllocThreadId(Thread* self);
void ReleaseThreadId(Thread* self, uint32_t id) REQUIRES(!Locks::allocated_thread_ids_lock_);
@@ -203,6 +216,8 @@
// Whether or not the current thread suspension is long.
bool long_suspend_;
+ std::unique_ptr<Barrier> empty_checkpoint_barrier_;
+
friend class Thread;
DISALLOW_COPY_AND_ASSIGN(ThreadList);