/* Copyright (c) 2015, 2023, Oracle and/or its affiliates.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.

   This program is also distributed with certain software (including
   but not limited to OpenSSL) that is licensed under separate terms,
   as designated in a particular file or component or in included license
   documentation.  The authors of MySQL hereby grant you an additional
   permission to link the program and your derivative works with the
   separately licensed software that they have included with MySQL.

   This program 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 2.0, for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA */

/* Simple unit tests for thread id partitioned rwlocks. */

// First include (the generated) my_config.h, to get correct platform defines.
#include "my_config.h"

#include "auth/partitioned_rwlock.h"

#include <gtest/gtest.h>
#include "thread_utils.h"


namespace partitioned_rwlock_unittest {

using thread::Thread;

TEST(PartitionedRwlock, InitDestroy)
{
  Partitioned_rwlock rwlock;

  bool r= rwlock.init(32
#ifdef HAVE_PSI_INTERFACE
                      , PSI_NOT_INSTRUMENTED
#endif
                      );
  EXPECT_FALSE(r);
  rwlock.destroy();

  r= rwlock.init(8
#ifdef HAVE_PSI_INTERFACE
                 , PSI_NOT_INSTRUMENTED
#endif
                 );
  EXPECT_FALSE(r);
  rwlock.destroy();
}


class Reader_thread : public Thread
{
public:
  void init(uint thread_id, Partitioned_rwlock *rwlock, volatile uint *shared_counter)
  {
    m_thread_id= thread_id;
    m_rwlock= rwlock;
    m_shared_counter= shared_counter;
  }
  virtual void run()
  {
    for (uint i=0; i < 1000; ++i)
    {
      Partitioned_rwlock_read_guard lock(m_rwlock, m_thread_id);
      /*
        With correct rwlock implementation readers should not
        observe counter values not divisible by 100.
      */
      EXPECT_EQ(0U, (*m_shared_counter % 100));
    }
  }
private:
  uint m_thread_id;
  Partitioned_rwlock *m_rwlock;
  volatile uint *m_shared_counter;
};

class Writer_thread : public Thread
{
public:
  Writer_thread(Partitioned_rwlock *rwlock, volatile uint *shared_counter)
    : m_rwlock(rwlock), m_shared_counter(shared_counter)
  {
  }
  virtual void run()
  {
    for (uint i=0; i < 1000; ++i)
    {
      Partitioned_rwlock_write_guard lock(m_rwlock);
      /*
        Add 100 to counter value using 100 single increments. We rely
        on counter being "volatile" to prevent compiler optimizations.
      */
      for (uint j=0; j < 100; ++j)
      {
        ++*m_shared_counter;
      }
    }
  }
private:
  Partitioned_rwlock *m_rwlock;
  volatile uint *m_shared_counter;
};

/**
  Concurrent test which easily breaks if rwlock implementation is wrong
  (e.g. if wrlock() operation doesn't lock all partitions).
*/

TEST(PartitionedRwlock, Concurrent)
{
  const uint PARTS_NUM= 32;

  Partitioned_rwlock rwlock;
  volatile uint shared_counter= 0;
  rwlock.init(PARTS_NUM
#ifdef HAVE_PSI_INTERFACE
              , PSI_NOT_INSTRUMENTED
#endif
              );

  Reader_thread readers[PARTS_NUM];
  Writer_thread writer(&rwlock, &shared_counter);
  for (uint i=0; i < PARTS_NUM; ++i)
    readers[i].init(i, &rwlock, &shared_counter);

  writer.start();
  for (uint i=0; i < PARTS_NUM; ++i)
    readers[i].start();

  for (uint i=0; i < PARTS_NUM; ++i)
    readers[i].join();
  writer.join();

  rwlock.destroy();
}

}