/* Copyright (c) 2013, 2025, 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 designed to work 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 either included with
   the program or referenced in the documentation.

   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 "sql/xa.h"

#include <memory>
#include <new>
#include <string>
#include <unordered_map>
#include <utility>

#include "include/mutex_lock.h"  // MUTEX_LOCK
#include "m_string.h"
#include "map_helpers.h"
#include "my_dbug.h"
#include "my_macros.h"
#include "my_psi_config.h"
#include "my_sys.h"
#include "mysql/my_loglevel.h"
#include "mysql/plugin.h"  // MYSQL_XIDDATASIZE
#include "mysql/psi/mysql_mutex.h"
#include "mysql/psi/mysql_transaction.h"
#include "mysql/service_mysql_alloc.h"
#include "mysql/strings/m_ctype.h"
#include "mysql_com.h"
#include "mysqld_error.h"
#include "scope_guard.h"  // Scope_guard
#include "sql/auth/sql_security_ctx.h"
#include "sql/log.h"
#include "sql/mdl.h"
#include "sql/mdl_context_backup.h"  // MDL_context_backup_manager
#include "sql/mysqld.h"              // server_id
#include "sql/protocol.h"
#include "sql/psi_memory_key.h"  // key_memory_xa_transaction_contexts
#include "sql/query_options.h"
#include "sql/sql_class.h"  // THD
#include "sql/sql_const.h"
#include "sql/sql_error.h"
#include "sql/sql_list.h"
#include "sql/system_variables.h"
#include "sql/transaction.h"  // trans_begin, trans_rollback
#include "sql/transaction_info.h"
#include "sql/xa/transaction_cache.h"
#include "sql_string.h"
#include "template_utils.h"
#include "thr_mutex.h"

#include <iostream>

// Used to create keys for the map
static std::string to_string(XID const &xid) {
  return std::string(pointer_cast<const char *>(xid.key()), xid.key_length());
}

struct transaction_free_hash {
  void operator()(Transaction_ctx *transaction) const {
    // Only time it's allocated is during recovery process.
    if (transaction->xid_state()->is_detached()) delete transaction;
  }
};

#ifdef HAVE_PSI_INTERFACE
xa::Transaction_cache::Transaction_cache()
    : m_key_LOCK_transaction_cache{},
      m_transaction_cache{m_key_LOCK_transaction_cache} {
  const char *category = "sql";
  mysql_mutex_register(category, this->m_transaction_cache_mutexes, 1);
  mysql_mutex_init(this->m_key_LOCK_transaction_cache,
                   &this->m_LOCK_transaction_cache, MY_MUTEX_INIT_FAST);
}
#else
xa::Transaction_cache::Transaction_cache()
    : m_transaction_cache{PSI_INSTRUMENT_ME} {
  mysql_mutex_init(PSI_INSTRUMENT_ME, &this->m_LOCK_transaction_cache,
                   MY_MUTEX_INIT_FAST);
}
#endif /* HAVE_PSI_INTERFACE */

bool xa::Transaction_cache::detach(Transaction_ctx *transaction) {
  bool res = false;
  XID_STATE *xs = transaction->xid_state();
  XID xid = *(xs->get_xid());
  bool was_logged = xs->is_binlogged();

  assert(xs->has_state(XID_STATE::XA_PREPARED));

  auto &instance = xa::Transaction_cache::instance();
  MUTEX_LOCK(mutex_guard, &instance.m_LOCK_transaction_cache);

  assert(instance.m_transaction_cache.count(to_string(xid)) != 0);
  instance.m_transaction_cache.erase(to_string(xid));
  res = xa::Transaction_cache::create_and_insert_new_transaction(
      &xid, was_logged, transaction);

  return res;
}

void xa::Transaction_cache::remove(Transaction_ctx *transaction) {
  auto &instance = xa::Transaction_cache::instance();
  MUTEX_LOCK(mutex_guard, &instance.m_LOCK_transaction_cache);
  const auto it = instance.m_transaction_cache.find(
      to_string(*transaction->xid_state()->get_xid()));
  if (it != instance.m_transaction_cache.end() &&
      it->second.get() == transaction)
    instance.m_transaction_cache.erase(it);
}

bool xa::Transaction_cache::insert(XID *xid, Transaction_ctx *transaction) {
  auto &instance = xa::Transaction_cache::instance();
  bool res{false};
  {
    MUTEX_LOCK(mutex_guard, &instance.m_LOCK_transaction_cache);
    std::shared_ptr<Transaction_ctx> ptr{transaction, transaction_free_hash{}};
    res = !instance.m_transaction_cache.emplace(to_string(*xid), std::move(ptr))
               .second;
  }
  if (res) {
    my_error(ER_XAER_DUPID, MYF(0));
  }
  return res;
}

bool xa::Transaction_cache::insert(XID *xid) {
  auto &instance = xa::Transaction_cache::instance();
  MUTEX_LOCK(mutex_guard, &instance.m_LOCK_transaction_cache);
  if (instance.m_transaction_cache.count(to_string(*xid))) return false;

  /*
    It's assumed that XA transaction was binlogged before the server
    shutdown. If --log-bin has changed since that from OFF to ON, XA
    COMMIT or XA ROLLBACK of this transaction may be logged alone into
    the binary log.
  */
  bool res = xa::Transaction_cache::create_and_insert_new_transaction(xid, true,
                                                                      nullptr);

  return res;
}

std::shared_ptr<Transaction_ctx> xa::Transaction_cache::find(
    XID *xid, filter_predicate_t filter) {
  auto &instance = xa::Transaction_cache::instance();
  MUTEX_LOCK(mutex_guard, &instance.m_LOCK_transaction_cache);
  auto found = instance.m_transaction_cache.find(to_string(*xid));
  if (found == instance.m_transaction_cache.end()) return nullptr;
  if (!found->second->xid_state()->get_xid()->eq(xid)) return nullptr;
  if (filter != nullptr && !filter(found->second)) return nullptr;
  return found->second;
}

xa::Transaction_cache::list xa::Transaction_cache::get_cached_transactions() {
  auto &instance = xa::Transaction_cache::instance();
  list to_return;
  MUTEX_LOCK(mutex_guard, &instance.m_LOCK_transaction_cache);
  for (auto [_, trx] : instance.m_transaction_cache) to_return.push_back(trx);
  return to_return;
}

void xa::Transaction_cache::initialize() { xa::Transaction_cache::instance(); }

void xa::Transaction_cache::dispose() {
  auto &instance = xa::Transaction_cache::instance();
  mysql_mutex_destroy(&instance.m_LOCK_transaction_cache);
}

xa::Transaction_cache &xa::Transaction_cache::instance() {
  static xa::Transaction_cache new_instance;
  return new_instance;
}

bool xa::Transaction_cache::create_and_insert_new_transaction(
    XID *xid, bool is_binlogged_arg, const Transaction_ctx *src) {
  Transaction_ctx *transaction = new (std::nothrow) Transaction_ctx();
  XID_STATE *xs;

  if (!transaction) {
    my_error(ER_OUTOFMEMORY, MYF(ME_FATALERROR), sizeof(Transaction_ctx));
    return true;
  }
  if (src) {
    // Copy over the session unsafe rollback flags from the original
    // Transaction_ctx object, so that we can emit warnings also when
    // rolling back with the detached Transaction_ctx object.
    transaction->set_unsafe_rollback_flags(
        Transaction_ctx::SESSION,
        src->get_unsafe_rollback_flags(Transaction_ctx::SESSION));
  }

  xs = transaction->xid_state();
  xs->start_detached_xa(xid, is_binlogged_arg);

  auto &instance = xa::Transaction_cache::instance();
  return !instance.m_transaction_cache
              .emplace(to_string(*xs->get_xid()),
                       std::shared_ptr<Transaction_ctx>{
                           transaction, transaction_free_hash{}})
              .second;
}
