/* Copyright (c) 2018, 2021, Alibaba and/or its affiliates. All rights reserved.
   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/PolarDB-X Engine 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/PolarDB-X Engine.
   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 St, Fifth Floor, Boston, MA 02110-1301  USA */

#include "consensus_fifo_cache_manager.h"
#include "mysqld.h"
#include "log.h"
#include "mysql/thread_pool_priv.h"
#include "consensus_log_manager.h"

int ConsensusFifoCacheManager::init(uint64 max_log_cache_size_arg)
{
  max_log_cache_size = max_log_cache_size_arg;
  fifo_cache_size = 0;
  lock_blob_index = 0;
  current_log_count = 0;
  key_memory_cache_mem_root = key_memory_ConsensusLogManager;
  key_LOCK_consensuslog_cache = key_rwlock_ConsensusLog_log_cache_lock;
  mysql_rwlock_init(key_LOCK_consensuslog_cache, &LOCK_consensuslog_cache);
  log_cache_list = new ConsensusLogEntry[reserve_list_size];
  rleft = rright = 0;

  mysql_mutex_init(key_fifo_cache_cleaner, &cleaner_mutex, MY_MUTEX_INIT_FAST);
  mysql_cond_init(0, &cleaner_cond);
  is_running = TRUE;
  if (mysql_thread_create(key_thread_cleaner, &cleaner_handle, NULL,
      fifo_cleaner_wrapper, (void *)this))
  {
    sql_print_error("Fail to create thread fifo_cleaner.");
    abort();
  }
  inited = TRUE;
  return 0;
}


int ConsensusFifoCacheManager::cleanup()
{
  if (inited)
  {
    is_running = FALSE;
    mysql_cond_signal(&cleaner_cond);
    my_thread_join(&cleaner_handle, NULL);
    mysql_rwlock_destroy(&LOCK_consensuslog_cache);
    for (size_t i = rleft; i < rright; i = (i+1) % reserve_list_size)
    {
      if (log_cache_list[i].buf_size > 0)
        my_free(log_cache_list[i].buffer);
    }
    delete [] log_cache_list;

    mysql_mutex_destroy(&cleaner_mutex);
    mysql_cond_destroy(&cleaner_cond);

  }
  return 0;
}

int ConsensusFifoCacheManager::get_log_from_cache(uint64 index, uint64 *term, std::string& log_content, bool *outer, uint *flag, uint64 *checksum)
{
  DBUG_EXECUTE_IF("skip_consensus_fifo_cache", {return ALREADY_SWAP_OUT;});
  mysql_rwlock_rdlock(&LOCK_consensuslog_cache);
  if (max_log_cache_size == 0 || current_log_count == 0 || index < log_cache_list[rleft].index)
  {
    mysql_rwlock_unlock(&LOCK_consensuslog_cache);
    return ALREADY_SWAP_OUT;
  }

  size_t lasti = (rright + reserve_list_size - 1) % reserve_list_size;
  if (index > log_cache_list[lasti].index /* out of range */)
  {
    sql_print_error("Consensus fifo log cache out of range , the max index in cache is  %llu, the required index is %llu",
      log_cache_list[lasti].index , index);
    mysql_rwlock_unlock(&LOCK_consensuslog_cache);
    return OUT_OF_RANGE;
  }
  ConsensusLogEntry log_entry = log_cache_list[(rleft + index - log_cache_list[rleft].index) % reserve_list_size];
  *term = log_entry.term;
  *outer = log_entry.outer;
  *flag = log_entry.flag;
  log_content.assign((char*)(log_entry.buffer), log_entry.buf_size);
  *checksum = log_entry.checksum;
  mysql_rwlock_unlock(&LOCK_consensuslog_cache);
  return 0;
}


int ConsensusFifoCacheManager::add_log_to_cache(uint64 term, uint64 index, size_t buf_size, uchar *buffer, bool outer, uint flag, uint64 checksum,  bool reuse_buffer)
{
  if (opt_consensus_disable_fifo_cache)
    return 1;

  uchar *new_buffer = 0;
  /* spin loop to make sure enough space left */
  while (current_log_count >= reserve_list_size - 1)
    mysql_cond_signal(&cleaner_cond);
  if (reuse_buffer)
    new_buffer = buffer;
  else
    new_buffer = (uchar*)my_memdup(key_memory_cache_mem_root, (char*)buffer, buf_size, MYF(MY_WME));
  log_cache_list[rright] = (ConsensusLogEntry){term, index, buf_size, new_buffer, outer, flag, checksum};
  rright = (rright + 1) % reserve_list_size;
  fifo_cache_size += buf_size;
  current_log_count++;
  mysql_cond_signal(&cleaner_cond);
  consensus_log_manager.set_cache_index(index);
  return 0;
}

int ConsensusFifoCacheManager::trunc_log_from_cache(uint64 index)
{
  consensus_log_manager.set_cache_index(index - 1);
  mysql_rwlock_wrlock(&LOCK_consensuslog_cache);
  sql_print_information("FIFO before truncate , first index of cache is %llu, cache size is %u", log_cache_list[rleft].index, (rright + reserve_list_size - rleft) % reserve_list_size);
  if (max_log_cache_size == 0 || current_log_count == 0)
  {
    mysql_rwlock_unlock(&LOCK_consensuslog_cache);
    return 0;
  }
  size_t start_point = 0;
  if (index <= log_cache_list[rleft].index)
  {
    start_point = rleft;
  }
  else
  {
    start_point = (rleft + index - log_cache_list[rleft].index) % reserve_list_size;
  }
  size_t cur_pos = start_point;
  // truncate [start_point, rright)
  while (cur_pos != rright)
  {
    if (log_cache_list[cur_pos].buf_size > 0)
      my_free(log_cache_list[cur_pos].buffer);
    fifo_cache_size -= log_cache_list[cur_pos].buf_size;
    current_log_count--;
    cur_pos = (cur_pos + 1) % reserve_list_size;
  }
  rright = start_point;
  sql_print_information("FIFO after truncate , first index of cache is %llu, cache size is %u", log_cache_list[rleft].index, (rright + reserve_list_size - rleft) % reserve_list_size);
  mysql_rwlock_unlock(&LOCK_consensuslog_cache);
  return 0;
}


uint64 ConsensusFifoCacheManager::get_log_size_from_cache(uint64 begin_index, uint64 end_index, uint64 max_packet_size)
{
  uint64 total_size = 0;
  mysql_rwlock_rdlock(&LOCK_consensuslog_cache);

  size_t lasti = (rright + reserve_list_size - 1) % reserve_list_size;
  size_t lefti = log_cache_list[rleft].index;
  for (uint64 i = begin_index; i <= end_index; i++)
  {
    if (i < lefti || i > log_cache_list[lasti].index)
      break;
    else
      total_size += log_cache_list[(rleft + i - lefti) % reserve_list_size].buf_size;
    if (total_size > max_packet_size)
      break;
  }
  mysql_rwlock_unlock(&LOCK_consensuslog_cache);
  return total_size;
}

uint64 ConsensusFifoCacheManager::get_first_index_of_fifo_cache()
{
  uint64 ret = 0;
  mysql_rwlock_rdlock(&LOCK_consensuslog_cache);
  ret = log_cache_list[rleft].index;
  mysql_rwlock_unlock(&LOCK_consensuslog_cache);
  return ret;
}

void ConsensusFifoCacheManager::set_lock_blob_index(uint64 lock_blob_index_arg)
{
  sql_print_information("ConsensusFifoCacheManager set lock_blob_index to %llu", lock_blob_index_arg);
  lock_blob_index = lock_blob_index_arg;
}

void ConsensusFifoCacheManager::clean_consensus_fifo_cache()
{
  mysql_mutex_lock(&cleaner_mutex);
  while (is_running.load())
  {
    mysql_cond_wait(&cleaner_cond, &cleaner_mutex);
    mysql_rwlock_wrlock(&LOCK_consensuslog_cache);
    while ((fifo_cache_size > max_log_cache_size || (current_log_count + 1) >= reserve_list_size)
        && (current_log_count > 1))
    {
      if (log_cache_list[rleft].index == lock_blob_index
          && (current_log_count + 1) < reserve_list_size)
        break;
      ConsensusLogEntry old_log = log_cache_list[rleft];
      if (old_log.buf_size > 0)
        my_free(old_log.buffer);
      fifo_cache_size -= old_log.buf_size;
      current_log_count--;
      rleft = (rleft + 1) % reserve_list_size;
    }
    mysql_rwlock_unlock(&LOCK_consensuslog_cache);
  }
  mysql_mutex_unlock(&cleaner_mutex);
}

void *fifo_cleaner_wrapper(void *arg)
{
  ConsensusFifoCacheManager *fifo = (ConsensusFifoCacheManager *)arg;
  fifo->clean_consensus_fifo_cache();
  return NULL;
}