/*

 * Copyright (c) 1998, 2007, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

class ObjectMonitor;

class ObjectSynchronizer : AllStatic {

  friend class VMStructs;

 public:

  typedef enum {

    owner_self,

    owner_none,

    owner_other

  } LockOwnership;

  // exit must be implemented non-blocking, since the compiler cannot easily handle

  // deoptimization at monitor exit. Hence, it does not take a Handle argument.

  // This is full version of monitor enter and exit. I choose not

  // to use enter() and exit() in order to make sure user be ware

  // of the performance and semantics difference. They are normally

  // used by ObjectLocker etc. The interpreter and compiler use

  // assembly copies of these routines. Please keep them synchornized.

  //

  // attempt_rebias flag is used by UseBiasedLocking implementation

  static void fast_enter  (Handle obj, BasicLock* lock, bool attempt_rebias, TRAPS);

  static void fast_exit   (oop obj,    BasicLock* lock, Thread* THREAD);

  // WARNING: They are ONLY used to handle the slow cases. They should

  // only be used when the fast cases failed. Use of these functions

  // without previous fast case check may cause fatal error.

  static void slow_enter  (Handle obj, BasicLock* lock, TRAPS);

  static void slow_exit   (oop obj,    BasicLock* lock, Thread* THREAD);

  // Used only to handle jni locks or other unmatched monitor enter/exit

  // Internally they will use heavy weight monitor.

  static void jni_enter   (Handle obj, TRAPS);

  static bool jni_try_enter(Handle obj, Thread* THREAD); // Implements Unsafe.tryMonitorEnter

  static void jni_exit    (oop obj,    Thread* THREAD);

  // Handle all interpreter, compiler and jni cases

  static void wait               (Handle obj, jlong millis, TRAPS);

  static void notify             (Handle obj,               TRAPS);

  static void notifyall          (Handle obj,               TRAPS);

  // Special internal-use-only method for use by JVM infrastructure

  // that needs to wait() on a java-level object but that can't risk

  // throwing unexpected InterruptedExecutionExceptions.

  static void waitUninterruptibly (Handle obj, jlong Millis, Thread * THREAD) ;

  // used by classloading to free classloader object lock,

  // wait on an internal lock, and reclaim original lock

  // with original recursion count

  static intptr_t complete_exit  (Handle obj,                TRAPS);

  static void reenter            (Handle obj, intptr_t recursion, TRAPS);

  // thread-specific and global objectMonitor free list accessors

//  static void verifyInUse (Thread * Self) ; too slow for general assert/debug

  static ObjectMonitor * omAlloc (Thread * Self) ;

  static void omRelease (Thread * Self, ObjectMonitor * m, bool FromPerThreadAlloc) ;

  static void omFlush   (Thread * Self) ;

  // Inflate light weight monitor to heavy weight monitor

  static ObjectMonitor* inflate(Thread * Self, oop obj);

  // This version is only for internal use

  static ObjectMonitor* inflate_helper(oop obj);

  // Returns the identity hash value for an oop

  // NOTE: It may cause monitor inflation

  static intptr_t identity_hash_value_for(Handle obj);

  static intptr_t FastHashCode (Thread * Self, oop obj) ;

  // java.lang.Thread support

  static bool current_thread_holds_lock(JavaThread* thread, Handle h_obj);

  static LockOwnership query_lock_ownership(JavaThread * self, Handle h_obj);

  static JavaThread* get_lock_owner(Handle h_obj, bool doLock);

  // JNI detach support

  static void release_monitors_owned_by_thread(TRAPS);

  static void monitors_iterate(MonitorClosure* m);

  // GC: we current use aggressive monitor deflation policy

  // Basically we deflate all monitors that are not busy.

  // An adaptive profile-based deflation policy could be used if needed

  static void deflate_idle_monitors();

  static int walk_monitor_list(ObjectMonitor** listheadp,

                               ObjectMonitor** FreeHeadp,

                               ObjectMonitor** FreeTailp);

  static bool deflate_monitor(ObjectMonitor* mid, oop obj, ObjectMonitor** FreeHeadp,

                              ObjectMonitor** FreeTailp);

  static void oops_do(OopClosure* f);

  // debugging

  static void trace_locking(Handle obj, bool is_compiled, bool is_method, bool is_locking) PRODUCT_RETURN;

  static void verify() PRODUCT_RETURN;

  static int  verify_objmon_isinpool(ObjectMonitor *addr) PRODUCT_RETURN0;

 private:

  enum { _BLOCKSIZE = 128 };

  static ObjectMonitor* gBlockList;

  static ObjectMonitor * volatile gFreeList;

  static ObjectMonitor * volatile gOmInUseList; // for moribund thread, so monitors they inflated still get scanned

  static int gOmInUseCount;

};

// ObjectLocker enforced balanced locking and can never thrown an

// IllegalMonitorStateException. However, a pending exception may

// have to pass through, and we must also be able to deal with

// asynchronous exceptions. The caller is responsible for checking

// the threads pending exception if needed.

// doLock was added to support classloading with UnsyncloadClass which

// requires flag based choice of locking the classloader lock.

class ObjectLocker : public StackObj {

 private:

  Thread*   _thread;

  Handle    _obj;

  BasicLock _lock;

  bool      _dolock;   // default true

 public:

  ObjectLocker(Handle obj, Thread* thread, bool doLock = true);

  ~ObjectLocker();

  // Monitor behavior

  void wait      (TRAPS)      { ObjectSynchronizer::wait     (_obj, 0, CHECK); } // wait forever

  void notify_all(TRAPS)      { ObjectSynchronizer::notifyall(_obj,    CHECK); }

  void waitUninterruptibly (TRAPS) { ObjectSynchronizer::waitUninterruptibly (_obj, 0, CHECK);}

  // complete_exit gives up lock completely, returning recursion count

  // reenter reclaims lock with original recursion count

  intptr_t complete_exit(TRAPS) { return  ObjectSynchronizer::complete_exit(_obj, CHECK_0); }

  void reenter(intptr_t recursion, TRAPS) { ObjectSynchronizer::reenter(_obj, recursion, CHECK); }

};