/*

 * Copyright (c) 2019, 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.

 *

 */

#include "precompiled.hpp"

#include "gc/g1/g1FreeIdSet.hpp"

#include "memory/allocation.hpp"

#include "runtime/atomic.hpp"

#include "runtime/interfaceSupport.inline.hpp"

#include "runtime/semaphore.inline.hpp"

#include "runtime/thread.hpp"

#include "utilities/debug.hpp"

#include "utilities/globalDefinitions.hpp"

#include "utilities/ostream.hpp"

#include "threadHelper.inline.hpp"

#include "unittest.hpp"

struct G1FreeIdSet::TestSupport : AllStatic {

  static uint next(const G1FreeIdSet& set, uint index) {

    assert(index < set._size, "precondition");

    return set._next[index];

  }

  static uint start(const G1FreeIdSet& set) { return set._start; }

  static uint size(const G1FreeIdSet& set) { return set._size; }

  static uintx mask(const G1FreeIdSet& set) { return set._head_index_mask; }

  static uintx head(const G1FreeIdSet& set) { return Atomic::load(&set._head); }

  static uint head_index(const G1FreeIdSet& set, uintx head) {

    return set.head_index(head);

  }

};

typedef G1FreeIdSet::TestSupport TestSupport;

TEST_VM(G1FreeIdSetTest, initial_state) {

  const uint start = 5;

  const uint size = 4;

  G1FreeIdSet set(start, size);

  ASSERT_EQ(start, TestSupport::start(set));

  ASSERT_EQ(size, TestSupport::size(set));

  ASSERT_EQ(7u, TestSupport::mask(set));

  ASSERT_EQ(0u, TestSupport::head(set));

  for (uint i = 0; i < size; ++i) {

    ASSERT_EQ(i + 1, TestSupport::next(set, i));

  }

}

TEST_VM(G1FreeIdSetTest, non_blocking_ops) {

  const uint start = 5;

  const uint size = 3;

  G1FreeIdSet set(start, size);

  ASSERT_EQ(5u, set.claim_par_id());

  ASSERT_EQ(1u, TestSupport::head_index(set, TestSupport::head(set)));

  ASSERT_EQ(6u, set.claim_par_id());

  ASSERT_EQ(2u, TestSupport::head_index(set, TestSupport::head(set)));

  ASSERT_EQ(7u, set.claim_par_id());

  ASSERT_EQ(3u, TestSupport::head_index(set, TestSupport::head(set)));

  set.release_par_id(5u);

  set.release_par_id(6u);

  ASSERT_EQ(6u, set.claim_par_id());

  ASSERT_EQ(5u, set.claim_par_id());

}

class TestG1FreeIdSetThread : public JavaTestThread {

  G1FreeIdSet* _set;

  volatile size_t* _total_allocations;

  volatile bool* _continue_running;

  size_t _allocations;

  uint _thread_number;

public:

  TestG1FreeIdSetThread(uint thread_number,

                        Semaphore* post,

                        G1FreeIdSet* set,

                        volatile size_t* total_allocations,

                        volatile bool* continue_running) :

    JavaTestThread(post),

    _set(set),

    _total_allocations(total_allocations),

    _continue_running(continue_running),

    _allocations(0),

    _thread_number(thread_number)

  {}

  virtual void main_run() {

      uint id = _set->claim_par_id();

      _set->release_par_id(id);

      ++_allocations;

      ThreadBlockInVM tbiv(this); // Safepoint check.

    }

    tty->print_cr("%u allocations: " SIZE_FORMAT, _thread_number, _allocations);

    Atomic::add(_allocations, _total_allocations);

  }

};

TEST_VM(G1FreeIdSetTest, stress) {

  const uint start = 5;

  const uint size = 3;

  const uint nthreads = size + 1;

  const uint milliseconds_to_run = 1000;

  Semaphore post;

  volatile size_t total_allocations = 0;

  volatile bool continue_running = true;

  G1FreeIdSet set(start, size);

  TestG1FreeIdSetThread* threads[nthreads] = {};

  for (uint i = 0; i < nthreads; ++i) {

    threads[i] = new TestG1FreeIdSetThread(i,

                                           &post,

                                           &set,

                                           &total_allocations,

                                           &continue_running);

    threads[i]->doit();

  }

  JavaThread* this_thread = JavaThread::current();

  tty->print_cr("Stressing G1FreeIdSet for %u ms", milliseconds_to_run);

  {

    ThreadInVMfromNative invm(this_thread);

    this_thread->sleep(milliseconds_to_run);

  }

  for (uint i = 0; i < nthreads; ++i) {

    ThreadInVMfromNative invm(this_thread);

    post.wait_with_safepoint_check(this_thread);

  }

  tty->print_cr("total allocations: " SIZE_FORMAT, total_allocations);

  tty->print_cr("final free list: ");

  uint ids[size] = {};

  for (uint i = 0; i < size; ++i) {

    uint id = set.claim_par_id();

    uint index = id - TestSupport::start(set);

    ASSERT_LT(index, TestSupport::size(set));

    tty->print_cr("  %u: %u", i, index);

  }

  ASSERT_EQ(size, TestSupport::head_index(set, TestSupport::head(set)));

}