/*

 * Copyright (c) 2017, 2018, Red Hat, Inc. All rights reserved.

 *

 * 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.

 *

 */

#ifndef SHARE_VM_GC_SHENANDOAH_SHENANDOAHCODEROOTS_HPP

#define SHARE_VM_GC_SHENANDOAH_SHENANDOAHCODEROOTS_HPP

#include "code/codeCache.hpp"

#include "gc/shenandoah/shenandoahSharedVariables.hpp"

#include "memory/allocation.hpp"

#include "memory/iterator.hpp"

class ShenandoahHeap;

class ShenandoahHeapRegion;

class ShenandoahCodeRootsLock;

class ShenandoahParallelCodeHeapIterator {

  friend class CodeCache;

private:

  CodeHeap*     _heap;

  DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE, sizeof(volatile int));

  volatile int  _claimed_idx;

  volatile bool _finished;

  DEFINE_PAD_MINUS_SIZE(1, DEFAULT_CACHE_LINE_SIZE, 0);

public:

  ShenandoahParallelCodeHeapIterator(CodeHeap* heap);

  void parallel_blobs_do(CodeBlobClosure* f);

};

class ShenandoahParallelCodeCacheIterator {

  friend class CodeCache;

private:

  ShenandoahParallelCodeHeapIterator* _iters;

  int                       _length;

public:

  ShenandoahParallelCodeCacheIterator(const GrowableArray<CodeHeap*>* heaps);

  ~ShenandoahParallelCodeCacheIterator();

  void parallel_blobs_do(CodeBlobClosure* f);

};

// ShenandoahNMethod tuple records the internal locations of oop slots within the nmethod.

// This allows us to quickly scan the oops without doing the nmethod-internal scans, that

// sometimes involves parsing the machine code. Note it does not record the oops themselves,

// because it would then require handling these tuples as the new class of roots.

class ShenandoahNMethod : public CHeapObj<mtGC> {

private:

  nmethod* _nm;

  oop**    _oops;

  int      _oops_count;

public:

  ShenandoahNMethod(nmethod *nm, GrowableArray<oop*>* oops);

  ~ShenandoahNMethod();

  nmethod* nm() {

    return _nm;

  }

  bool has_cset_oops(ShenandoahHeap* heap);

  void assert_alive_and_correct() PRODUCT_RETURN;

  void assert_same_oops(GrowableArray<oop*>* oops) PRODUCT_RETURN;

  static bool find_with_nmethod(void* nm, ShenandoahNMethod* other) {

    return other->_nm == nm;

  }

};

class ShenandoahCodeRootsIterator {

  friend class ShenandoahCodeRoots;

protected:

  ShenandoahHeap* _heap;

  ShenandoahParallelCodeCacheIterator _par_iterator;

  ShenandoahSharedFlag _seq_claimed;

  DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE, sizeof(volatile size_t));

  volatile size_t _claimed;

  DEFINE_PAD_MINUS_SIZE(1, DEFAULT_CACHE_LINE_SIZE, 0);

protected:

  ShenandoahCodeRootsIterator();

  ~ShenandoahCodeRootsIterator();

  template<bool CSET_FILTER>

  void dispatch_parallel_blobs_do(CodeBlobClosure *f);

  template<bool CSET_FILTER>

  void fast_parallel_blobs_do(CodeBlobClosure *f);

};

class ShenandoahAllCodeRootsIterator : public ShenandoahCodeRootsIterator {

public:

  ShenandoahAllCodeRootsIterator() : ShenandoahCodeRootsIterator() {};

  void possibly_parallel_blobs_do(CodeBlobClosure *f);

};

class ShenandoahCsetCodeRootsIterator : public ShenandoahCodeRootsIterator {

public:

  ShenandoahCsetCodeRootsIterator() : ShenandoahCodeRootsIterator() {};

  void possibly_parallel_blobs_do(CodeBlobClosure* f);

};

class ShenandoahCodeRoots : public CHeapObj<mtGC> {

  friend class ShenandoahHeap;

  friend class ShenandoahCodeRootsLock;

  friend class ShenandoahCodeRootsIterator;

public:

  static void initialize();

  static void add_nmethod(nmethod* nm);

  static void remove_nmethod(nmethod* nm);

  /**

   * Provides the iterator over all nmethods in the code cache that have oops.

   * @return

   */

  static ShenandoahAllCodeRootsIterator iterator();

  /**

   * Provides the iterator over nmethods that have at least one oop in collection set.

   * @return

   */

  static ShenandoahCsetCodeRootsIterator cset_iterator();

private:

  struct PaddedLock {

    DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE, sizeof(volatile int));

    volatile int _lock;

    DEFINE_PAD_MINUS_SIZE(1, DEFAULT_CACHE_LINE_SIZE, 0);

  };

  static PaddedLock _recorded_nms_lock;

  static GrowableArray<ShenandoahNMethod*>* _recorded_nms;

  static void acquire_lock(bool write) {

    volatile int* loc = &_recorded_nms_lock._lock;

    if (write) {

      while ((OrderAccess::load_acquire(loc) != 0) ||

             Atomic::cmpxchg(-1, loc, 0) != 0) {

        SpinPause();

      }

      assert (*loc == -1, "acquired for write");

    } else {

      while (true) {

        int cur = OrderAccess::load_acquire(loc);

        if (cur >= 0) {

          if (Atomic::cmpxchg(cur + 1, loc, cur) == cur) {

            // Success!

            assert (*loc > 0, "acquired for read");

            return;

          }

        }

        SpinPause();

      }

    }

  }

  static void release_lock(bool write) {

    volatile int* loc = &ShenandoahCodeRoots::_recorded_nms_lock._lock;

    if (write) {

      OrderAccess::release_store_fence(loc, 0);

    } else {

      Atomic::dec(loc);

    }

  }

};

// Very simple unranked read-write lock

class ShenandoahCodeRootsLock : public StackObj {

  friend class ShenandoahCodeRoots;

private:

  const bool _write;

public:

  ShenandoahCodeRootsLock(bool write) : _write(write) {

    ShenandoahCodeRoots::acquire_lock(write);

  }

  ~ShenandoahCodeRootsLock() {

    ShenandoahCodeRoots::release_lock(_write);

  }

};

#endif //SHARE_VM_GC_SHENANDOAH_SHENANDOAHCODEROOTS_HPP