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

 *

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 *

 * 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.

 *

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#ifndef SHARE_VM_RUNTIME_SYNCHRONIZER_HPP

#define SHARE_VM_RUNTIME_SYNCHRONIZER_HPP

#include "oops/markOop.hpp"

#include "runtime/basicLock.hpp"

#include "runtime/handles.hpp"

#include "runtime/perfData.hpp"

class ObjectMonitor;

struct DeflateMonitorCounters {

  int nInuse;          // currently associated with objects

  int nInCirculation;  // extant

  int nScavenged;      // reclaimed

};

class ObjectSynchronizer : AllStatic {

  friend class VMStructs;

 public:

  typedef enum {

    owner_self,

    owner_none,

    owner_other

  } LockOwnership;

  typedef enum {

    inflate_cause_vm_internal = 0,

    inflate_cause_monitor_enter = 1,

    inflate_cause_wait = 2,

    inflate_cause_notify = 3,

    inflate_cause_hash_code = 4,

    inflate_cause_jni_enter = 5,

    inflate_cause_jni_exit = 6,

    inflate_cause_nof = 7 // Number of causes

  } InflateCause;

  // 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 synchronized.

  //

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

  // Handle all interpreter, compiler and jni cases

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

  static void notify(Handle obj, TRAPS);

  static void notifyall(Handle obj, TRAPS);

  static bool quick_notify(oopDesc* obj, Thread* Self, bool All);

  static bool quick_enter(oop obj, Thread* Self, BasicLock* Lock);

  // 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);

  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, const InflateCause cause);

  // This version is only for internal use

  static ObjectMonitor* inflate_helper(oop obj);

  static const char* inflate_cause_name(const InflateCause cause);

  // 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(DeflateMonitorCounters* counters);

  static void deflate_thread_local_monitors(Thread* thread, DeflateMonitorCounters* counters);

  static void prepare_deflate_idle_monitors(DeflateMonitorCounters* counters);

  static void finish_deflate_idle_monitors(DeflateMonitorCounters* counters);

  // For a given monitor list: global or per-thread, deflate idle monitors

  static int deflate_monitor_list(ObjectMonitor** listheadp,

                                  ObjectMonitor** freeHeadp,

                                  ObjectMonitor** freeTailp);

  static bool deflate_monitor(ObjectMonitor* mid, oop obj,

                              ObjectMonitor** freeHeadp,

                              ObjectMonitor** freeTailp);

  static bool is_cleanup_needed();

  static void oops_do(OopClosure* f);

  // Process oops in thread local used monitors

  static void thread_local_used_oops_do(Thread* thread, OopClosure* f);

  // debugging

  static void sanity_checks(const bool verbose,

                            const unsigned int cache_line_size,

                            int *error_cnt_ptr, int *warning_cnt_ptr);

  static int  verify_objmon_isinpool(ObjectMonitor *addr) PRODUCT_RETURN0;

 private:

  enum { _BLOCKSIZE = 128 };

  // global list of blocks of monitors

  // gBlockList is really PaddedEnd<ObjectMonitor> *, but we don't

  // want to expose the PaddedEnd template more than necessary.

  static ObjectMonitor * volatile gBlockList;

  // global monitor free list

  static ObjectMonitor * volatile gFreeList;

  // global monitor in-use list, for moribund threads,

  // monitors they inflated need to be scanned for deflation

  static ObjectMonitor * volatile gOmInUseList;

  // count of entries in gOmInUseList

  static int gOmInUseCount;

  // Process oops in all monitors

  static void global_oops_do(OopClosure* f);

  // Process oops in all global used monitors (i.e. moribund thread's monitors)

  static void global_used_oops_do(OopClosure* f);

  // Process oops in monitors on the given list

  static void list_oops_do(ObjectMonitor* list, OopClosure* f);

};

// 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, THREAD); }

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

};

#endif // SHARE_VM_RUNTIME_SYNCHRONIZER_HPP