/*

 * Copyright (c) 2018, 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

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 */

#ifndef SHARE_UTILITIES_CONCURRENT_HASH_TABLE_TASKS_INLINE_HPP

#define SHARE_UTILITIES_CONCURRENT_HASH_TABLE_TASKS_INLINE_HPP

#include "utilities/concurrentHashTable.inline.hpp"

// This inline file contains BulkDeleteTask and GrowTasks which are both bucket

// operations, which they are serialized with each other.

// Base class for pause and/or parallel bulk operations.

template <typename VALUE, typename CONFIG, MEMFLAGS F>

class ConcurrentHashTable<VALUE, CONFIG, F>::BucketsOperation {

 protected:

  ConcurrentHashTable<VALUE, CONFIG, F>* _cht;

  // Default size of _task_size_log2

  static const size_t DEFAULT_TASK_SIZE_LOG2 = 12;

  // The table is split into ranges, every increment is one range.

  volatile size_t _next_to_claim;

  size_t _task_size_log2; // Number of buckets.

  size_t _stop_task;      // Last task

  size_t _size_log2;      // Table size.

  BucketsOperation(ConcurrentHashTable<VALUE, CONFIG, F>* cht)

    : _cht(cht), _next_to_claim(0), _task_size_log2(DEFAULT_TASK_SIZE_LOG2),

    _stop_task(0), _size_log2(0) {}

  // Returns true if you succeeded to claim the range start -> (stop-1).

  bool claim(size_t* start, size_t* stop) {

    size_t claimed = Atomic::add((size_t)1, &_next_to_claim) - 1;

    if (claimed >= _stop_task) {

      return false;

    }

    *start = claimed * (((size_t)1) << _task_size_log2);

    *stop  = ((*start) + (((size_t)1) << _task_size_log2));

    return true;

  }

  // Calculate starting values.

  void setup() {

    _size_log2 = _cht->_table->_log2_size;

    size_t tmp = _size_log2 > _task_size_log2 ?

                 _size_log2 - _task_size_log2 : 0;

    _stop_task = (((size_t)1) << tmp);

  }

  // Returns false if all ranges are claimed.

  bool have_more_work() {

    return OrderAccess::load_acquire(&_next_to_claim) >= _stop_task;

  }

  // If we have changed size.

  bool is_same_table() {

    // Not entirely true.

    return _size_log2 != _cht->_table->_log2_size;

  }

  void thread_owns_resize_lock(Thread* thread) {

    assert(BucketsOperation::_cht->_resize_lock_owner == thread,

           "Should be locked by me");

    assert(BucketsOperation::_cht->_resize_lock->owned_by_self(),

           "Operations lock not held");

  }

  void thread_owns_only_state_lock(Thread* thread) {

    assert(BucketsOperation::_cht->_resize_lock_owner == thread,

           "Should be locked by me");

    assert(!BucketsOperation::_cht->_resize_lock->owned_by_self(),

           "Operations lock held");

  }

  void thread_do_not_own_resize_lock(Thread* thread) {

    assert(!BucketsOperation::_cht->_resize_lock->owned_by_self(),

           "Operations lock held");

    assert(BucketsOperation::_cht->_resize_lock_owner != thread,

           "Should not be locked by me");

  }

};

// For doing pausable/parallel bulk delete.

template <typename VALUE, typename CONFIG, MEMFLAGS F>

class ConcurrentHashTable<VALUE, CONFIG, F>::BulkDeleteTask :

  public BucketsOperation

{

 public:

  BulkDeleteTask(ConcurrentHashTable<VALUE, CONFIG, F>* cht)

    : BucketsOperation(cht) {

  }

  // Before start prepare must be called.

  bool prepare(Thread* thread) {

    bool lock = BucketsOperation::_cht->try_resize_lock(thread);

    if (!lock) {

      return false;

    }

    this->setup();

    this->thread_owns_resize_lock(thread);

    return true;

  }

  // Does one range destroying all matching EVALUATE_FUNC and

  // DELETE_FUNC is called be destruction. Returns true if there is more work.

  template <typename EVALUATE_FUNC, typename DELETE_FUNC>

  bool doTask(Thread* thread, EVALUATE_FUNC& eval_f, DELETE_FUNC& del_f) {

    size_t start, stop;

    assert(BucketsOperation::_cht->_resize_lock_owner != NULL,

           "Should be locked");

    if (!this->claim(&start, &stop)) {

      return false;

    }

    BucketsOperation::_cht->do_bulk_delete_locked_for(thread, start, stop,

                                                      eval_f, del_f);

    return true;

  }

  // Pauses this operations for a safepoint.

  void pause(Thread* thread) {

    this->thread_owns_resize_lock(thread);

    // This leaves internal state locked.

    BucketsOperation::_cht->unlock_resize_lock(thread);

    this->thread_do_not_own_resize_lock(thread);

  }

  // Continues this operations after a safepoint.

  bool cont(Thread* thread) {

    this->thread_do_not_own_resize_lock(thread);

    if (!BucketsOperation::_cht->try_resize_lock(thread)) {

      this->thread_do_not_own_resize_lock(thread);

      return false;

    }

    if (BucketsOperation::is_same_table()) {

      BucketsOperation::_cht->unlock_resize_lock(thread);

      this->thread_do_not_own_resize_lock(thread);

      return false;

    }

    this->thread_owns_resize_lock(thread);

    return true;

  }

  // Must be called after ranges are done.

  void done(Thread* thread) {

    this->thread_owns_resize_lock(thread);

    BucketsOperation::_cht->unlock_resize_lock(thread);

    this->thread_do_not_own_resize_lock(thread);

  }

};

template <typename VALUE, typename CONFIG, MEMFLAGS F>

class ConcurrentHashTable<VALUE, CONFIG, F>::GrowTask :

  public BucketsOperation

{

 public:

  GrowTask(ConcurrentHashTable<VALUE, CONFIG, F>* cht) : BucketsOperation(cht) {

  }

  // Before start prepare must be called.

  bool prepare(Thread* thread) {

    if (!BucketsOperation::_cht->internal_grow_prolog(

          thread, BucketsOperation::_cht->_log2_size_limit)) {

      return false;

    }

    this->thread_owns_resize_lock(thread);

    BucketsOperation::setup();

    return true;

  }

  // Re-sizes a portion of the table. Returns true if there is more work.

  bool doTask(Thread* thread) {

    size_t start, stop;

    assert(BucketsOperation::_cht->_resize_lock_owner != NULL,

           "Should be locked");

    if (!this->claim(&start, &stop)) {

      return false;

    }

    BucketsOperation::_cht->internal_grow_range(thread, start, stop);

    assert(BucketsOperation::_cht->_resize_lock_owner != NULL,

           "Should be locked");

    return true;

  }

  // Pauses growing for safepoint

  void pause(Thread* thread) {

    // This leaves internal state locked.

    this->thread_owns_resize_lock(thread);

    BucketsOperation::_cht->_resize_lock->unlock();

    this->thread_owns_only_state_lock(thread);

  }

  // Continues growing after safepoint.

  void cont(Thread* thread) {

    this->thread_owns_only_state_lock(thread);

    // If someone slips in here directly after safepoint.

    while (!BucketsOperation::_cht->_resize_lock->try_lock())

      { /* for ever */ };

    this->thread_owns_resize_lock(thread);

  }

  // Must be called after doTask returns false.

  void done(Thread* thread) {

    this->thread_owns_resize_lock(thread);

    BucketsOperation::_cht->internal_grow_epilog(thread);

    this->thread_do_not_own_resize_lock(thread);

  }

};

#endif // include guard