runtime/monitor-inl.h

/*
 * Copyright (C) 2008 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_MONITOR_INL_H_
#define ART_RUNTIME_MONITOR_INL_H_

#include "monitor.h"

#include "gc_root-inl.h"
#include "obj_ptr-inl.h"

namespace art {

template<ReadBarrierOption kReadBarrierOption>
inline ObjPtr<mirror::Object> Monitor::GetObject() REQUIRES_SHARED(Locks::mutator_lock_) {
  return obj_.Read<kReadBarrierOption>();
}

// Check for request to set lock owner info.
void Monitor::CheckLockOwnerRequest(Thread* self) {
  DCHECK(self != nullptr);
  Thread* request_thread = lock_owner_request_.load(std::memory_order_relaxed);
  if (request_thread == self) {
    SetLockingMethod(self);
    // Only do this the first time after a request.
    lock_owner_request_.store(nullptr, std::memory_order_relaxed);
  }
}

uintptr_t Monitor::LockOwnerInfoChecksum(ArtMethod* m, uint32_t dex_pc, Thread* t) {
  uintptr_t dpc_and_thread = static_cast<uintptr_t>(dex_pc << 8) ^ reinterpret_cast<uintptr_t>(t);
  return reinterpret_cast<uintptr_t>(m) ^ dpc_and_thread
      ^ (dpc_and_thread << (/* ptr_size / 2 */ (sizeof m) << 2));
}

void Monitor::SetLockOwnerInfo(ArtMethod* method, uint32_t dex_pc, Thread* t) {
  lock_owner_method_.store(method, std::memory_order_relaxed);
  lock_owner_dex_pc_.store(dex_pc, std::memory_order_relaxed);
  lock_owner_.store(t, std::memory_order_relaxed);
  uintptr_t sum = LockOwnerInfoChecksum(method, dex_pc, t);
  lock_owner_sum_.store(sum, std::memory_order_relaxed);
}

void Monitor::GetLockOwnerInfo(/*out*/ArtMethod** method, /*out*/uint32_t* dex_pc,
                               Thread* t) {
  ArtMethod* owners_method;
  uint32_t owners_dex_pc;
  Thread* owner;
  uintptr_t owners_sum;
  DCHECK(t != nullptr);
  do {
    owner = lock_owner_.load(std::memory_order_relaxed);
    if (owner == nullptr) {
      break;
    }
    owners_method = lock_owner_method_.load(std::memory_order_relaxed);
    owners_dex_pc = lock_owner_dex_pc_.load(std::memory_order_relaxed);
    owners_sum = lock_owner_sum_.load(std::memory_order_relaxed);
  } while (owners_sum != LockOwnerInfoChecksum(owners_method, owners_dex_pc, owner));
  if (owner == t) {
    *method = owners_method;
    *dex_pc = owners_dex_pc;
  } else {
    *method = nullptr;
    *dex_pc = 0;
  }
}


}  // namespace art

#endif  // ART_RUNTIME_MONITOR_INL_H_