/*

 * 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.

 *

 */

#include "memory/allocation.hpp"

#include "oops/oop.hpp"

#include "runtime/handles.hpp"

#include "runtime/perfData.hpp"

#include "runtime/safepoint.hpp"

class nmethod;

class DepChange;

//

// nmethodBucket is used to record dependent nmethods for

// deoptimization.  nmethod dependencies are actually <klass, method>

// pairs but we really only care about the klass part for purposes of

// finding nmethods which might need to be deoptimized.  Instead of

// recording the method, a count of how many times a particular nmethod

// was recorded is kept.  This ensures that any recording errors are

// noticed since an nmethod should be removed as many times are it's

// added.

//

class nmethodBucket: public CHeapObj<mtClass> {

  friend class VMStructs;

 private:

  nmethod*       _nmethod;

  volatile int   _count;

  nmethodBucket* volatile _next;

  nmethodBucket* volatile _purge_list_next;

 public:

  nmethodBucket(nmethod* nmethod, nmethodBucket* next) :

    _nmethod(nmethod), _count(1), _next(next), _purge_list_next(NULL) {}

  int count()                                { return _count; }

  int increment()                            { _count += 1; return _count; }

  int decrement();

  nmethodBucket* next();

  nmethodBucket* next_not_unloading();

  void set_next(nmethodBucket* b);

  nmethodBucket* purge_list_next();

  void set_purge_list_next(nmethodBucket* b);

  nmethod* get_nmethod()                     { return _nmethod; }

};

//

// Utility class to manipulate nmethod dependency context.

// Dependency context can be attached either to an InstanceKlass (_dep_context field)

// or CallSiteContext oop for call_site_target dependencies (see javaClasses.hpp).

// DependencyContext class operates on some location which holds a nmethodBucket* value

// and uint64_t integer recording the safepoint counter at the last cleanup.

//

class DependencyContext : public StackObj {

  friend class VMStructs;

  friend class TestDependencyContext;

 private:

  nmethodBucket* volatile* _dependency_context_addr;

  volatile uint64_t*       _last_cleanup_addr;

  bool claim_cleanup();

  void set_dependencies(nmethodBucket* b);

  nmethodBucket* dependencies();

  nmethodBucket* dependencies_not_unloading();

  static PerfCounter*            _perf_total_buckets_allocated_count;

  static PerfCounter*            _perf_total_buckets_deallocated_count;

  static PerfCounter*            _perf_total_buckets_stale_count;

  static PerfCounter*            _perf_total_buckets_stale_acc_count;

  static nmethodBucket* volatile _purge_list;

  static uint64_t                _cleaning_epoch_monotonic;

  static volatile uint64_t       _cleaning_epoch;

 public:

#ifdef ASSERT

  // Safepoints are forbidden during DC lifetime. GC can invalidate

  // _dependency_context_addr if it relocates the holder

  // (e.g. CallSiteContext Java object).

  uint64_t _safepoint_counter;

  DependencyContext(nmethodBucket* volatile* bucket_addr, volatile uint64_t* last_cleanup_addr)

    : _dependency_context_addr(bucket_addr),

      _last_cleanup_addr(last_cleanup_addr),

      _safepoint_counter(SafepointSynchronize::safepoint_counter()) {}

  ~DependencyContext() {

    assert(_safepoint_counter == SafepointSynchronize::safepoint_counter(), "safepoint happened");

  }

#else

  DependencyContext(nmethodBucket* volatile* bucket_addr, volatile uint64_t* last_cleanup_addr)

    : _dependency_context_addr(bucket_addr),

      _last_cleanup_addr(last_cleanup_addr) {}

#endif // ASSERT

  static void init();

  int  mark_dependent_nmethods(DepChange& changes);

  void add_dependent_nmethod(nmethod* nm);

  void remove_dependent_nmethod(nmethod* nm);

  int  remove_all_dependents();

  void clean_unloading_dependents();

  static void purge_dependency_contexts();

  static void release(nmethodBucket* b);

  static void cleaning_start();

  static void cleaning_end();

#ifndef PRODUCT

  void print_dependent_nmethods(bool verbose);

  bool is_dependent_nmethod(nmethod* nm);

#endif //PRODUCT

};