upload android base code part3

android/art/runtime/gc/system_weak.h

@@ -0,0 +1,98 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ART_RUNTIME_GC_SYSTEM_WEAK_H_
+#define ART_RUNTIME_GC_SYSTEM_WEAK_H_
+
+#include "base/mutex.h"
+#include "object_callbacks.h"
+#include "thread-inl.h"
+
+namespace art {
+namespace gc {
+
+class AbstractSystemWeakHolder {
+ public:
+  virtual ~AbstractSystemWeakHolder() {}
+
+  virtual void Allow() REQUIRES_SHARED(Locks::mutator_lock_) = 0;
+  virtual void Disallow() REQUIRES_SHARED(Locks::mutator_lock_) = 0;
+  // See Runtime::BroadcastForNewSystemWeaks for the broadcast_for_checkpoint definition.
+  virtual void Broadcast(bool broadcast_for_checkpoint) = 0;
+
+  virtual void Sweep(IsMarkedVisitor* visitor) REQUIRES_SHARED(Locks::mutator_lock_) = 0;
+};
+
+class SystemWeakHolder : public AbstractSystemWeakHolder {
+ public:
+  explicit SystemWeakHolder(LockLevel level)
+      : allow_disallow_lock_("SystemWeakHolder", level),
+        new_weak_condition_("SystemWeakHolder new condition", allow_disallow_lock_),
+        allow_new_system_weak_(true) {
+  }
+  virtual ~SystemWeakHolder() {}
+
+  void Allow() OVERRIDE
+      REQUIRES_SHARED(Locks::mutator_lock_)
+      REQUIRES(!allow_disallow_lock_) {
+    CHECK(!kUseReadBarrier);
+    MutexLock mu(Thread::Current(), allow_disallow_lock_);
+    allow_new_system_weak_ = true;
+    new_weak_condition_.Broadcast(Thread::Current());
+  }
+
+  void Disallow() OVERRIDE
+      REQUIRES_SHARED(Locks::mutator_lock_)
+      REQUIRES(!allow_disallow_lock_) {
+    CHECK(!kUseReadBarrier);
+    MutexLock mu(Thread::Current(), allow_disallow_lock_);
+    allow_new_system_weak_ = false;
+  }
+
+  void Broadcast(bool broadcast_for_checkpoint ATTRIBUTE_UNUSED) OVERRIDE
+      REQUIRES(!allow_disallow_lock_) {
+    MutexLock mu(Thread::Current(), allow_disallow_lock_);
+    new_weak_condition_.Broadcast(Thread::Current());
+  }
+
+  // WARNING: For lock annotations only.
+  Mutex* GetAllowDisallowLock() const RETURN_CAPABILITY(allow_disallow_lock_) {
+    return nullptr;
+  }
+
+ protected:
+  void Wait(Thread* self)
+      REQUIRES_SHARED(Locks::mutator_lock_)
+      REQUIRES(allow_disallow_lock_) {
+    // Wait for GC's sweeping to complete and allow new records
+    while (UNLIKELY((!kUseReadBarrier && !allow_new_system_weak_) ||
+                    (kUseReadBarrier && !self->GetWeakRefAccessEnabled()))) {
+      // Check and run the empty checkpoint before blocking so the empty checkpoint will work in the
+      // presence of threads blocking for weak ref access.
+      self->CheckEmptyCheckpointFromWeakRefAccess(&allow_disallow_lock_);
+      new_weak_condition_.WaitHoldingLocks(self);
+    }
+  }
+
+  Mutex allow_disallow_lock_;
+  ConditionVariable new_weak_condition_ GUARDED_BY(allow_disallow_lock_);
+  bool allow_new_system_weak_ GUARDED_BY(allow_disallow_lock_);
+};
+
+}  // namespace gc
+}  // namespace art
+
+#endif  // ART_RUNTIME_GC_SYSTEM_WEAK_H_