src/sync.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_SRC_SYNC_H_
#define ART_SRC_SYNC_H_

#include <pthread.h>
#include <stdint.h>

#include "mutex.h"

namespace art {

/*
 * Monitor shape field. Used to distinguish thin locks from fat locks.
 */
#define LW_SHAPE_THIN 0
#define LW_SHAPE_FAT 1
#define LW_SHAPE_MASK 0x1
#define LW_SHAPE(x) ((x) & LW_SHAPE_MASK)

/*
 * Hash state field.  Used to signify that an object has had its
 * identity hash code exposed or relocated.
 */
#define LW_HASH_STATE_UNHASHED 0
#define LW_HASH_STATE_HASHED 1
#define LW_HASH_STATE_HASHED_AND_MOVED 3
#define LW_HASH_STATE_MASK 0x3
#define LW_HASH_STATE_SHIFT 1
#define LW_HASH_STATE(x) (((x) >> LW_HASH_STATE_SHIFT) & LW_HASH_STATE_MASK)

/*
 * Monitor accessor.  Extracts a monitor structure pointer from a fat
 * lock.  Performs no error checking.
 */
#define LW_MONITOR(x) \
  ((Monitor*)((x) & ~((LW_HASH_STATE_MASK << LW_HASH_STATE_SHIFT) | LW_SHAPE_MASK)))

/*
 * Lock owner field.  Contains the thread id of the thread currently
 * holding the lock.
 */
#define LW_LOCK_OWNER_MASK 0xffff
#define LW_LOCK_OWNER_SHIFT 3
#define LW_LOCK_OWNER(x) (((x) >> LW_LOCK_OWNER_SHIFT) & LW_LOCK_OWNER_MASK)

/*
 * Lock recursion count field.  Contains a count of the numer of times
 * a lock has been recursively acquired.
 */
#define LW_LOCK_COUNT_MASK 0x1fff
#define LW_LOCK_COUNT_SHIFT 19
#define LW_LOCK_COUNT(x) (((x) >> LW_LOCK_COUNT_SHIFT) & LW_LOCK_COUNT_MASK)

struct Object;
struct Thread;

class Monitor {
 public:
  ~Monitor();

  static uint32_t GetLockOwner(uint32_t raw_lock_word);

  static void MonitorEnter(Thread* thread, Object* obj);
  static bool MonitorExit(Thread* thread, Object* obj);

  static void Notify(Thread* self, Object* obj);
  static void NotifyAll(Thread* self, Object* obj);
  static void Wait(Thread* self, Object* obj, int64_t ms, int32_t ns, bool interruptShouldThrow);

  static void SweepMonitorList(bool (isUnmarkedObject)(void*));

  static void FreeMonitorList();

 private:
  Monitor(Object* obj);

  void AppendToWaitSet(Thread* thread);
  void RemoveFromWaitSet(Thread* thread);

  static void Inflate(Thread* self, Object* obj);

  void Lock(Thread* self);
  bool Unlock(Thread* thread);

  void Notify(Thread* self);
  void NotifyAll(Thread* self);

  void Wait(Thread* self, int64_t msec, int32_t nsec, bool interruptShouldThrow);

  /* Which thread currently owns the lock? */
  Thread* owner_;

  /* Owner's recursive lock depth */
  int lock_count_;

  /* What object are we part of (for debugging). */
  Object* obj_;

  /* Threads currently waiting on this monitor. */
  Thread* wait_set_;

  Mutex lock_;

  Monitor* next_;

  /*
   * Who last acquired this monitor, when lock sampling is enabled.
   * Even when enabled, ownerFileName may be NULL.
   */
  const char* owner_filename_;
  uint32_t owner_line_number_;

  friend class Object;
};

/*
 * Relative timed wait on condition
 */
int dvmRelativeCondWait(pthread_cond_t* cond, pthread_mutex_t* mutex, int64_t msec, int32_t nsec);

}  // namespace art

#endif  // ART_SRC_SYNC_H_