/*
   Copyright (c) 2013, 2018, Oracle 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 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,
   51 Franklin Street, Suite 500, Boston, MA 02110-1335 USA */

#ifndef XA_H_INCLUDED
#define XA_H_INCLUDED

#include "my_global.h"        // ulonglong
#include "mysql/plugin.h"     // MYSQL_XIDDATASIZE
#include "mysqld.h"           // server_id
#include "sql_cmd.h"
#include "sql_plugin_ref.h"   // plugin_ref
#include <string.h>
#include "xa_aux.h"

class Protocol;
class THD;
struct xid_t;

enum xa_option_words {XA_NONE, XA_JOIN, XA_RESUME, XA_ONE_PHASE,
                      XA_SUSPEND, XA_FOR_MIGRATE};

static const int TC_HEURISTIC_NOT_USED= 0;
static const int TC_HEURISTIC_RECOVER_COMMIT= 1;
static const int TC_HEURISTIC_RECOVER_ROLLBACK= 2;

/**
  This class represents SQL statement which starts an XA transaction
  with the given xid value.
*/

class Sql_cmd_xa_start : public Sql_cmd
{
public:
  Sql_cmd_xa_start(xid_t *xid_arg, enum xa_option_words xa_option)
  : m_xid(xid_arg), m_xa_opt(xa_option)
  {}

  virtual enum_sql_command sql_command_code() const
  {
    return SQLCOM_XA_START;
  }

  virtual bool execute(THD *thd);

private:
  bool trans_xa_start(THD *thd);
  xid_t *m_xid;
  enum xa_option_words m_xa_opt;
};


/**
  This class represents SQL statement which puts in the IDLE state
  an XA transaction with the given xid value.
*/

class Sql_cmd_xa_end : public Sql_cmd
{
public:
  Sql_cmd_xa_end(xid_t *xid_arg, enum xa_option_words xa_option)
  : m_xid(xid_arg), m_xa_opt(xa_option)
  {}

  virtual enum_sql_command sql_command_code() const
  {
    return SQLCOM_XA_END;
  }

  virtual bool execute(THD *thd);

private:
  bool trans_xa_end(THD *thd);

  xid_t *m_xid;
  enum xa_option_words m_xa_opt;
};


/**
  This class represents SQL statement which puts in the PREPARED state
  an XA transaction with the given xid value.
*/

class Sql_cmd_xa_prepare : public Sql_cmd
{
public:
  explicit Sql_cmd_xa_prepare(xid_t *xid_arg)
  : m_xid(xid_arg)
  {}

  virtual enum_sql_command sql_command_code() const
  {
    return SQLCOM_XA_PREPARE;
  }

  virtual bool execute(THD *thd);

private:
  bool trans_xa_prepare(THD *thd);

  xid_t *m_xid;
};


/**
  This class represents SQL statement which returns to a client
  a list of XID's prepared to a XA commit/rollback.
*/

class Sql_cmd_xa_recover : public Sql_cmd
{
public:
  explicit Sql_cmd_xa_recover(bool print_xid_as_hex)
  : m_print_xid_as_hex(print_xid_as_hex)
  {}

  virtual enum_sql_command sql_command_code() const
  {
    return SQLCOM_XA_RECOVER;
  }

  virtual bool execute(THD *thd);

private:
  bool trans_xa_recover(THD *thd);

  bool m_print_xid_as_hex;
};


/**
  This class represents SQL statement which commits
  and terminates an XA transaction with the given xid value.
*/

class Sql_cmd_xa_commit : public Sql_cmd
{
public:
  Sql_cmd_xa_commit(xid_t *xid_arg, enum xa_option_words xa_option)
  : m_xid(xid_arg), m_xa_opt(xa_option)
  {}

  virtual enum_sql_command sql_command_code() const
  {
    return SQLCOM_XA_COMMIT;
  }

  virtual bool execute(THD *thd);

  enum xa_option_words get_xa_opt() const
  {
    return m_xa_opt;
  }
private:
  bool trans_xa_commit(THD *thd);

  xid_t *m_xid;
  enum xa_option_words m_xa_opt;
};


/**
  This class represents SQL statement which rollbacks and
  terminates an XA transaction with the given xid value.
*/

class Sql_cmd_xa_rollback : public Sql_cmd
{
public:
  explicit Sql_cmd_xa_rollback(xid_t *xid_arg)
  : m_xid(xid_arg)
  {}

  virtual enum_sql_command sql_command_code() const
  {
    return SQLCOM_XA_ROLLBACK;
  }

  virtual bool execute(THD *thd);

private:
  bool trans_xa_rollback(THD *thd);

  xid_t *m_xid;
};


typedef ulonglong my_xid; // this line is the same as in log_event.h
#define MYSQL_XID_PREFIX "MySQLXid"
#define XIDDATASIZE MYSQL_XIDDATASIZE
class XID_STATE;

/**
  struct xid_t is binary compatible with the XID structure as
  in the X/Open CAE Specification, Distributed Transaction Processing:
  The XA Specification, X/Open Company Ltd., 1991.
  http://www.opengroup.org/bookstore/catalog/c193.htm

  @see MYSQL_XID in mysql/plugin.h
*/
typedef struct xid_t
{
private:
  static const uint MYSQL_XID_PREFIX_LEN= 8; // must be a multiple of 8
  static const uint MYSQL_XID_OFFSET= MYSQL_XID_PREFIX_LEN + sizeof(server_id);
  static const uint MYSQL_XID_GTRID_LEN= MYSQL_XID_OFFSET + sizeof(my_xid);

  /**
    -1 means that the XID is null
  */
  long formatID;

  /**
    value from 1 through 64
  */
  long gtrid_length;

  /**
    value from 1 through 64
  */
  long bqual_length;

  /**
    distributed trx identifier. not \0-terminated.
  */
  char data[XIDDATASIZE];

public:
  xid_t()
  : formatID(-1),
    gtrid_length(0),
    bqual_length(0)
  {
    memset(data, 0, XIDDATASIZE);
  }

  long get_format_id() const
  {
    return formatID;
  }

  void set_format_id(long v)
  {
    formatID= v;
  }

  long get_gtrid_length() const
  {
    return gtrid_length;
  }

  void set_gtrid_length(long v)
  {
    gtrid_length= v;
  }

  long get_bqual_length() const
  {
    return bqual_length;
  }

  void set_bqual_length(long v)
  {
    bqual_length= v;
  }

  const char* get_data() const
  {
    return data;
  }

  void set_data(const void* v, long l)
  {
    DBUG_ASSERT(l <= XIDDATASIZE);
    memcpy(data, v, l);
  }

  void reset()
  {
    formatID= -1;
    gtrid_length= 0;
    bqual_length= 0;
    memset(data, 0, XIDDATASIZE);
  }

  void set(long f, const char *g, long gl, const char *b, long bl)
  {
    formatID= f;
    memcpy(data, g, gtrid_length= gl);
    memcpy(data + gl, b, bqual_length= bl);
  }

  my_xid get_my_xid() const
  {
    if (gtrid_length == static_cast<long>(MYSQL_XID_GTRID_LEN) &&
        bqual_length == 0 &&
        !memcmp(data, MYSQL_XID_PREFIX, MYSQL_XID_PREFIX_LEN))
    {
      my_xid tmp;
      memcpy(&tmp, data + MYSQL_XID_OFFSET, sizeof(tmp));
      return tmp;
    }
    return 0;
  }

  uchar *key()
  {
    return reinterpret_cast<uchar *>(&gtrid_length);
  }

  const uchar *key() const
  {
    return reinterpret_cast<const uchar*>(&gtrid_length);
  }

  uint key_length() const
  {
    return sizeof(gtrid_length) + sizeof(bqual_length) +
      gtrid_length + bqual_length;
  }

  /*
    The size of the string containing serialized Xid representation
    is computed as a sum of
      eight as the number of formatting symbols (X'',X'',)
      plus 2 x XIDDATASIZE (2 due to hex format),
      plus space for decimal digits of XID::formatID,
      plus one for 0x0.
   */
  static const uint ser_buf_size=
    8 + 2 * XIDDATASIZE + 4 * sizeof(long) + 1;

  /**
     The method fills XID in a buffer in format of GTRID,BQUAL,FORMATID
     where GTRID, BQUAL are represented as hex strings.

     @param  buf  a pointer to buffer
     @return the value of the first argument
  */

  char *serialize(char *buf) const
  {
    return serialize_xid(buf, formatID, gtrid_length, bqual_length, data);
  }

#ifndef DBUG_OFF
  /**
     Get printable XID value.

     @param buf  pointer to the buffer where printable XID value has to be stored

     @return  pointer to the buffer passed in the first argument
  */
  char* xid_to_str(char *buf) const;
#endif

  bool eq(const xid_t *xid) const
  {
    return xid->formatID == formatID &&
      xid->gtrid_length == gtrid_length &&
      xid->bqual_length == bqual_length &&
      !memcmp(xid->data, data, gtrid_length + bqual_length);
  }

  bool is_null() const
  {
    return formatID == -1;
  }

private:
  void set(const xid_t *xid)
  {
    memcpy(this, xid, sizeof(xid->formatID) + xid->key_length());
  }

  void set(my_xid xid)
  {
    formatID= 1;
    memcpy(data, MYSQL_XID_PREFIX, MYSQL_XID_PREFIX_LEN);
    memcpy(data + MYSQL_XID_PREFIX_LEN, &server_id, sizeof(server_id));
    memcpy(data + MYSQL_XID_OFFSET, &xid, sizeof(xid));
    gtrid_length= MYSQL_XID_GTRID_LEN;
    bqual_length= 0;
  }

  void null()
  {
    formatID= -1;
  }

  friend class XID_STATE;
} XID;


class XID_STATE
{
public:
  enum xa_states {XA_NOTR=0, XA_ACTIVE, XA_IDLE, XA_PREPARED, XA_ROLLBACK_ONLY};

  /**
     Transaction identifier.
     For now, this is only used to catch duplicated external xids.
  */
private:
  static const char *xa_state_names[];

  XID m_xid;
  /// Used by external XA only
  xa_states xa_state;
  bool in_recovery;
  /// Error reported by the Resource Manager (RM) to the Transaction Manager.
  uint rm_error;
  /*
    XA-prepare binary logging status. The flag serves as a facility
    to conduct XA transaction two round binary logging.
    It is set to @c false at XA-start.
    It is set to @c true by binlogging routine of XA-prepare handler as well
    as recovered to @c true at the server recovery upon restart.
    Checked and reset at XA-commit/rollback.
  */
  bool m_is_binlogged;

public:
  XID_STATE()
  : xa_state(XA_NOTR),
    in_recovery(false),
    rm_error(0),
    m_is_binlogged(false)
  { m_xid.null(); }

  void set_state(xa_states state)
  { xa_state= state; }

  enum xa_states get_state()
  { return xa_state; }

  bool has_state(xa_states state) const
  { return xa_state == state; }

  const char* state_name() const
  { return xa_state_names[xa_state]; }

  const XID *get_xid() const
  { return &m_xid; }

  XID *get_xid()
  { return &m_xid; }

  bool has_same_xid(const XID *xid) const
  { return m_xid.eq(xid); }

  void set_query_id(query_id_t query_id)
  {
    if (m_xid.is_null())
      m_xid.set(query_id);
  }

  void set_error(THD *thd);

  void reset_error()
  { rm_error= 0; }

  void cleanup()
  {
    /*
      If rm_error is raised, it means that this piece of a distributed
      transaction has failed and must be rolled back. But the user must
      rollback it explicitly, so don't start a new distributed XA until
      then.
    */
    if (!rm_error)
      m_xid.null();
  }

  void reset()
  {
    xa_state= XA_NOTR;
    m_xid.null();
    in_recovery= false;
    m_is_binlogged= false;
  }

  void start_normal_xa(const XID *xid)
  {
    DBUG_ASSERT(m_xid.is_null());
    xa_state= XA_ACTIVE;
    m_xid.set(xid);
    in_recovery= false;
    rm_error= 0;
  }

  void start_recovery_xa(const XID *xid, bool binlogged_arg= false)
  {
    xa_state= XA_PREPARED;
    m_xid.set(xid);
    in_recovery= true;
    rm_error= 0;
    m_is_binlogged= binlogged_arg;
  }

  bool is_in_recovery() const
  { return in_recovery; }

  bool is_binlogged() const
  { return m_is_binlogged; }

  void set_binlogged()
  { m_is_binlogged= true; }

  void unset_binlogged()
  { m_is_binlogged= false; }

  void store_xid_info(Protocol *protocol, bool print_xid_as_hex) const;

  /**
     Mark a XA transaction as rollback-only if the RM unilaterally
     rolled back the transaction branch.

     @note If a rollback was requested by the RM, this function sets
           the appropriate rollback error code and transits the state
           to XA_ROLLBACK_ONLY.

     @return true if transaction was rolled back or if the transaction
             state is XA_ROLLBACK_ONLY. false otherwise.
  */

  bool xa_trans_rolled_back();


  /**
    Check that XA transaction is in state IDLE or PREPARED.

    @param  report_error  true if state IDLE or PREPARED has to be interpreted
                          as an error, else false

    @return  result of check
      @retval  false  XA transaction is NOT in state IDLE or PREPARED
      @retval  true   XA transaction is in state IDLE or PREPARED
  */

  bool check_xa_idle_or_prepared(bool report_error) const;


  /**
    Check that XA transaction has an uncommitted work. Report an error
    to a mysql user in case when there is an uncommitted work for XA transaction.

    @return  result of check
      @retval  false  XA transaction is NOT in state IDLE, PREPARED
                      or ROLLBACK_ONLY.
      @retval  true   XA transaction is in state IDLE or PREPARED
                      or ROLLBACK_ONLY.
  */

  bool check_has_uncommitted_xa() const;


  /**
    Check if an XA transaction has been started.

    @param  report_error  true if report an error in case when
                          XA transaction has been stared, else false.

    @return  result of check
      @retval  false  XA transaction hasn't been started (XA_NOTR)
      @retval  true   XA transaction has been started (!XA_NOTR)
  */

  bool check_in_xa(bool report_error) const;
};


class Transaction_ctx;

/**
  Initialize a cache to store Transaction_ctx and a mutex to protect access
  to the cache

  @return        result of initialization
    @retval false  success
    @retval true   failure
*/

bool transaction_cache_init();


/**
  Search information about XA transaction by a XID value.

  @param xid    Pointer to a XID structure that identifies a XA transaction.

  @return  pointer to a Transaction_ctx that describes the whole transaction
           including XA-specific information (XID_STATE).
    @retval  NULL     failure
    @retval  != NULL  success
*/

Transaction_ctx *transaction_cache_search(XID *xid);


/**
  Insert information about XA transaction into a cache indexed by XID.

  @param xid     Pointer to a XID structure that identifies a XA transaction.
  @param transaction
                 Pointer to Transaction object that is inserted.

  @return  operation result
    @retval  false   success or a cache already contains XID_STATE
                     for this XID value
    @retval  true    failure
*/

bool transaction_cache_insert(XID *xid, Transaction_ctx *transaction);

/**
  Transaction is marked in the cache as if it's recovered.
  The method allows to sustain prepared transaction disconnection.

  @param transaction
                 Pointer to Transaction object that is replaced.

  @return  operation result
    @retval  false   success or a cache already contains XID_STATE
                     for this XID value
    @retval  true    failure
*/

bool transaction_cache_detach(Transaction_ctx *transaction);


/**
  Insert information about XA transaction being recovered into a cache
  indexed by XID.

  @param xid     Pointer to a XID structure that identifies a XA transaction.

  @return  operation result
    @retval  false   success or a cache already contains Transaction_ctx
                     for this XID value
    @retval  true    failure
*/

bool transaction_cache_insert_recovery(XID *xid);


/**
  Remove information about transaction from a cache.

  @param transaction     Pointer to a Transaction_ctx that has to be removed
                         from a cache.
*/

void transaction_cache_delete(Transaction_ctx *transaction);


/**
  Release resources occupied by transaction cache.
*/

void transaction_cache_free();


/**
  This is a specific to "slave" applier collection of standard cleanup
  actions to reset XA transaction state at the end of XA prepare rather than
  to do it at the transaction commit, see @c ha_commit_one_phase.
  THD of the slave applier is dissociated from a transaction object in engine
  that continues to exist there.

  @param  THD current thread
  @return the value of is_error()
*/

bool applier_reset_xa_trans(THD *thd);


/* interface to randomly access plugin data */
struct st_plugin_int *plugin_find_by_type(const LEX_CSTRING &plugin, int type);

/**
  The function detaches existing storage engines transaction
  context from thd. Backup area to save it is provided to low level
  storage engine function.

  is invoked by plugin_foreach() after
  trans_xa_start() for each storage engine.

  @param[in,out]     thd     Thread context
  @param             plugin  Reference to handlerton

  @return    FALSE   on success, TRUE otherwise.
*/

my_bool detach_native_trx(THD *thd, plugin_ref plugin,
                                      void *unused);
/**
  The function reattaches existing storage engines transaction
  context to thd. Backup area to save it is provided to low level
  storage engine function.

  is invoked by plugin_foreach() after
  trans_xa_prepare() for each storage engine.

  @param[in,out]     thd     Thread context
  @param             plugin  Reference to handlerton

  @return    FALSE   on success,
             TRUE    otherwise.
*/

my_bool reattach_native_trx(THD *thd, plugin_ref plugin, void *);

/**
  Reset some transaction state information and delete corresponding
  Transaction_ctx object from cache.

  @param thd    Current thread
*/

void cleanup_trans_state(THD *thd);


/**
  Rollback the active XA transaction.

  @note Resets rm_error before calling ha_rollback(), so
        the thd->transaction.xid structure gets reset
        by ha_rollback() / THD::transaction::cleanup().

  @return true if the rollback failed, false otherwise.
*/

bool xa_trans_force_rollback(THD *thd);
#endif
