/*

 * 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 "memory/allocation.inline.hpp"

#include "runtime/atomic.hpp"

#include "runtime/orderAccess.hpp"

#include "utilities/globalDefinitions.hpp"

#include "utilities/lockFreeStack.hpp"

#include "threadHelper.inline.hpp"

#include "unittest.hpp"

#include <new>

class LockFreeStackTestElement {

  typedef LockFreeStackTestElement Element;

  Element* volatile _entry;

  Element* volatile _entry1;

  size_t _id;

  static Element* volatile* entry_ptr(Element& e) { return &e._entry; }

  static Element* volatile* entry1_ptr(Element& e) { return &e._entry1; }

public:

  LockFreeStackTestElement(size_t id = 0) : _entry(), _entry1(), _id(id) {}

  size_t id() const { return _id; }

  void set_id(size_t value) { _id = value; }

  typedef LockFreeStack<Element, &entry_ptr> Stack;

  typedef LockFreeStack<Element, &entry1_ptr> Stack1;

};

typedef LockFreeStackTestElement Element;

typedef Element::Stack Stack;

typedef Element::Stack1 Stack1;

static void initialize_ids(Element* elements, size_t size) {

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

    elements[i].set_id(i);

  }

}

class LockFreeStackTestBasics : public ::testing::Test {

public:

  LockFreeStackTestBasics();

  static const size_t nelements = 10;

  Element elements[nelements];

  Stack stack;

private:

  void initialize();

};

const size_t LockFreeStackTestBasics::nelements;

LockFreeStackTestBasics::LockFreeStackTestBasics() : stack() {

  initialize_ids(elements, nelements);

  initialize();

}

void LockFreeStackTestBasics::initialize() {

  ASSERT_TRUE(stack.empty());

  ASSERT_EQ(0u, stack.length());

  ASSERT_TRUE(stack.pop() == NULL);

  ASSERT_TRUE(stack.top() == NULL);

  for (size_t id = 0; id < nelements; ++id) {

    ASSERT_EQ(id, stack.length());

    Element* e = &elements[id];

    ASSERT_EQ(id, e->id());

    stack.push(*e);

    ASSERT_FALSE(stack.empty());

    ASSERT_EQ(e, stack.top());

  }

}

TEST_F(LockFreeStackTestBasics, push_pop) {

  for (size_t i = nelements; i > 0; ) {

    ASSERT_FALSE(stack.empty());

    ASSERT_EQ(i, stack.length());

    --i;

    Element* e = stack.pop();

    ASSERT_TRUE(e != NULL);

    ASSERT_EQ(&elements[i], e);

    ASSERT_EQ(i, e->id());

  }

  ASSERT_TRUE(stack.empty());

  ASSERT_EQ(0u, stack.length());

  ASSERT_TRUE(stack.pop() == NULL);

}

TEST_F(LockFreeStackTestBasics, prepend_one) {

  Stack other_stack;

  ASSERT_TRUE(other_stack.empty());

  ASSERT_TRUE(other_stack.pop() == NULL);

  ASSERT_EQ(0u, other_stack.length());

  ASSERT_TRUE(other_stack.top() == NULL);

  ASSERT_TRUE(other_stack.pop() == NULL);

  other_stack.prepend(*stack.pop_all());

  ASSERT_EQ(nelements, other_stack.length());

  ASSERT_TRUE(stack.empty());

  ASSERT_EQ(0u, stack.length());

  ASSERT_TRUE(stack.pop() == NULL);

  ASSERT_TRUE(stack.top() == NULL);

  for (size_t i = nelements; i > 0; ) {

    ASSERT_EQ(i, other_stack.length());

    --i;

    Element* e = other_stack.pop();

    ASSERT_TRUE(e != NULL);

    ASSERT_EQ(&elements[i], e);

    ASSERT_EQ(i, e->id());

  }

  ASSERT_EQ(0u, other_stack.length());

  ASSERT_TRUE(other_stack.pop() == NULL);

}

TEST_F(LockFreeStackTestBasics, prepend_two) {

  Stack other_stack;

  ASSERT_TRUE(other_stack.empty());

  ASSERT_EQ(0u, other_stack.length());

  ASSERT_TRUE(other_stack.top() == NULL);

  ASSERT_TRUE(other_stack.pop() == NULL);

  Element* top = stack.pop_all();

  ASSERT_EQ(top, &elements[nelements - 1]);

  other_stack.prepend(*top, elements[0]);

  for (size_t i = nelements; i > 0; ) {

    ASSERT_EQ(i, other_stack.length());

    --i;

    Element* e = other_stack.pop();

    ASSERT_TRUE(e != NULL);

    ASSERT_EQ(&elements[i], e);

    ASSERT_EQ(i, e->id());

  }

  ASSERT_EQ(0u, other_stack.length());

  ASSERT_TRUE(other_stack.pop() == NULL);

}

TEST_F(LockFreeStackTestBasics, two_stacks) {

  Stack1 stack1;

  ASSERT_TRUE(stack1.pop() == NULL);

  for (size_t id = 0; id < nelements; ++id) {

    stack1.push(elements[id]);

  }

  ASSERT_EQ(nelements, stack1.length());

  Element* e0 = stack.top();

  Element* e1 = stack1.top();

  while (true) {

    ASSERT_EQ(e0, e1);

    if (e0 == NULL) break;

    e0 = stack.next(*e0);

    e1 = stack1.next(*e1);

  }

  for (size_t i = nelements; i > 0; ) {

    ASSERT_EQ(i, stack.length());

    ASSERT_EQ(i, stack1.length());

    --i;

    Element* e = stack.pop();

    ASSERT_TRUE(e != NULL);

    ASSERT_EQ(&elements[i], e);

    ASSERT_EQ(i, e->id());

    Element* e1 = stack1.pop();

    ASSERT_TRUE(e1 != NULL);

    ASSERT_EQ(&elements[i], e1);

    ASSERT_EQ(i, e1->id());

    ASSERT_EQ(e, e1);

  }

  ASSERT_EQ(0u, stack.length());

  ASSERT_EQ(0u, stack1.length());

  ASSERT_TRUE(stack.pop() == NULL);

  ASSERT_TRUE(stack1.pop() == NULL);

}

class LockFreeStackTestThread : public JavaTestThread {

  uint _id;

  Stack* _from;

  Stack* _to;

  volatile size_t* _processed;

  size_t _process_limit;

  size_t _local_processed;

  volatile bool _ready;

public:

  LockFreeStackTestThread(Semaphore* post,

                          uint id,

                          Stack* from,

                          Stack* to,

                          volatile size_t* processed,

                          size_t process_limit) :

    JavaTestThread(post),

    _id(id),

    _from(from),

    _to(to),

    _processed(processed),

    _process_limit(process_limit),

    _local_processed(0),

    _ready(false)

  {}

  virtual void main_run() {

    OrderAccess::release_store_fence(&_ready, true);

    while (true) {

      Element* e = _from->pop();

      if (e != NULL) {

        _to->push(*e);

        Atomic::inc(_processed);

        ++_local_processed;

      } else if (OrderAccess::load_acquire(_processed) == _process_limit) {

        tty->print_cr("thread %u processed " SIZE_FORMAT, _id, _local_processed);

        return;

      }

    }

  }

  bool ready() const { return OrderAccess::load_acquire(&_ready); }

};

TEST_VM(LockFreeStackTest, stress) {

  Semaphore post;

  Stack initial_stack;

  Stack start_stack;

  Stack middle_stack;

  Stack final_stack;

  volatile size_t stage1_processed = 0;

  volatile size_t stage2_processed = 0;

  const size_t nelements = 10000;

  Element* elements = NEW_C_HEAP_ARRAY(Element, nelements, mtOther);

  for (size_t id = 0; id < nelements; ++id) {

    ::new (&elements[id]) Element(id);

    initial_stack.push(elements[id]);

  }

  ASSERT_EQ(nelements, initial_stack.length());

  // - stage1 threads pop from start_stack and push to middle_stack.

  // - stage2 threads pop from middle_stack and push to final_stack.

  // - all threads in a stage count the number of elements processed in

  //   their corresponding stageN_processed counter.

  const uint stage1_threads = 2;

  const uint stage2_threads = 2;

  const uint nthreads = stage1_threads + stage2_threads;

  LockFreeStackTestThread* threads[nthreads] = {};

  for (uint i = 0; i < ARRAY_SIZE(threads); ++i) {

    Stack* from = &start_stack;

    Stack* to = &middle_stack;

    volatile size_t* processed = &stage1_processed;

    if (i >= stage1_threads) {

      from = &middle_stack;

      to = &final_stack;

      processed = &stage2_processed;

    }

    threads[i] =

      new LockFreeStackTestThread(&post, i, from, to, processed, nelements);

    threads[i]->doit();

    while (!threads[i]->ready()) {} // Wait until ready to start test.

  }

  // Transfer elements to start_stack to start test.

  start_stack.prepend(*initial_stack.pop_all());

  // Wait for all threads to complete.

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

    post.wait();

  }

  // Verify expected state.

  ASSERT_EQ(nelements, stage1_processed);

  ASSERT_EQ(nelements, stage2_processed);

  ASSERT_EQ(0u, initial_stack.length());

  ASSERT_EQ(0u, start_stack.length());

  ASSERT_EQ(0u, middle_stack.length());

  ASSERT_EQ(nelements, final_stack.length());

  while (final_stack.pop() != NULL) {}

  FREE_C_HEAP_ARRAY(Element, elements);

}