binlog.h

#ifndef BINLOG_H_INCLUDED
/* Copyright (c) 2010, 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 St, Fifth Floor, Boston, MA 02110-1301  USA */

#define BINLOG_H_INCLUDED

#include <string.h>
#include <sys/types.h>
#include <time.h>
#include <atomic>
#include <utility>

#include "libbinlogevents/include/binlog_event.h"  // enum_binlog_checksum_alg
#include "m_string.h"                              // llstr
#include "my_dbug.h"
#include "my_inttypes.h"
#include "my_io.h"
#include "my_sharedlib.h"
#include "my_sys.h"
#include "mysql/components/services/bits/mysql_cond_bits.h"
#include "mysql/components/services/bits/mysql_mutex_bits.h"
#include "mysql/components/services/bits/psi_cond_bits.h"
#include "mysql/components/services/bits/psi_file_bits.h"
#include "mysql/components/services/bits/psi_mutex_bits.h"
#include "mysql/psi/mysql_cond.h"
#include "mysql/psi/mysql_mutex.h"
#include "mysql/udf_registration_types.h"
#include "mysql_com.h"          // Item_result
#include "sql/binlog_reader.h"  // Binlog_file_reader
#include "sql/rpl_commit_stage_manager.h"
#include "sql/rpl_trx_tracking.h"
#include "sql/tc_log.h"            // TC_LOG
#include "sql/transaction_info.h"  // Transaction_ctx
#include "thr_mutex.h"

class Format_description_log_event;
class Gtid_monitoring_info;
class Gtid_set;
class Ha_trx_info;
class Incident_log_event;
class Log_event;
class Master_info;
class Relay_log_info;
class Rows_log_event;
class Sid_map;
class THD;
class Transaction_boundary_parser;
class binlog_cache_data;
class user_var_entry;
class Binlog_cache_storage;

struct Gtid;

typedef int64 query_id_t;

/*
  Maximum unique log filename extension.
  Note: setting to 0x7FFFFFFF due to atol windows
        overflow/truncate.
 */
#define MAX_LOG_UNIQUE_FN_EXT 0x7FFFFFFF

/*
  Maximum allowed unique log filename extension for
  RESET MASTER TO command - 2 Billion
 */
#define MAX_ALLOWED_FN_EXT_RESET_MASTER 2000000000

struct Binlog_user_var_event {
  user_var_entry *user_var_event;
  char *value;
  ulong length;
  Item_result type;
  uint charset_number;
  bool unsigned_flag;
};

/* log info errors */
#define LOG_INFO_EOF -1
#define LOG_INFO_IO -2
#define LOG_INFO_INVALID -3
#define LOG_INFO_SEEK -4
#define LOG_INFO_MEM -6
#define LOG_INFO_FATAL -7
#define LOG_INFO_IN_USE -8
#define LOG_INFO_EMFILE -9
#define LOG_INFO_BACKUP_LOCK -10
#define LOG_INFO_NOT_IN_USE -11

/* bitmap to MYSQL_BIN_LOG::close() */
#define LOG_CLOSE_INDEX 1
#define LOG_CLOSE_TO_BE_OPENED 2
#define LOG_CLOSE_STOP_EVENT 4

struct LOG_INFO {
  char log_file_name[FN_REFLEN] = {0};
  my_off_t index_file_offset, index_file_start_offset;
  my_off_t pos;
  bool fatal;       // if the purge happens to give us a negative offset
  int entry_index;  // used in purge_logs(), calculatd in find_log_pos().
  int encrypted_header_size;
  my_thread_id thread_id;
  LOG_INFO()
      : index_file_offset(0),
        index_file_start_offset(0),
        pos(0),
        fatal(false),
        entry_index(0),
        encrypted_header_size(0),
        thread_id(0) {
    memset(log_file_name, 0, FN_REFLEN);
  }
};

/*
  TODO use mmap instead of IO_CACHE for binlog
  (mmap+fsync is two times faster than write+fsync)
*/
class MYSQL_BIN_LOG : public TC_LOG {
 public:
  class Binlog_ofile;

 private:
  enum enum_log_state { LOG_OPENED, LOG_CLOSED, LOG_TO_BE_OPENED };

  /* LOCK_log is inited by init_pthread_objects() */
  mysql_mutex_t LOCK_log;
  char *name;
  char log_file_name[FN_REFLEN];
  char db[NAME_LEN + 1];
  bool write_error, inited;
  Binlog_ofile *m_binlog_file;

  /** Instrumentation key to use for file io in @c log_file */
  PSI_file_key m_log_file_key;
  /** The instrumentation key to use for @ LOCK_log. */
  PSI_mutex_key m_key_LOCK_log;
  /** The instrumentation key to use for @ LOCK_index. */
  PSI_mutex_key m_key_LOCK_index;
  /** The instrumentation key to use for @ LOCK_binlog_end_pos. */
  PSI_mutex_key m_key_LOCK_binlog_end_pos;
  /** The PFS instrumentation key for @ LOCK_commit_queue. */
  PSI_mutex_key m_key_LOCK_commit_queue;
  /** The PFS instrumentation key for @ LOCK_after_commit_queue. */
  PSI_mutex_key m_key_LOCK_after_commit_queue;
  /** The PFS instrumentation key for @ LOCK_done. */
  PSI_mutex_key m_key_LOCK_done;
  /** The PFS instrumentation key for @ LOCK_flush_queue. */
  PSI_mutex_key m_key_LOCK_flush_queue;
  /** The PFS instrumentation key for @ LOCK_sync_queue. */
  PSI_mutex_key m_key_LOCK_sync_queue;
  /** The PFS instrumentation key for @ LOCK_wait_for_group_turn. */
  PSI_mutex_key m_key_LOCK_wait_for_group_turn;
  /** The PFS instrumentation key for @ COND_done. */
  PSI_mutex_key m_key_COND_done;
  /** The PFS instrumentation key for @ COND_flush_queue. */
  PSI_mutex_key m_key_COND_flush_queue;
  /** The instrumentation key to use for @ LOCK_commit. */
  PSI_mutex_key m_key_LOCK_commit;
  /** The instrumentation key to use for @ LOCK_after_commit. */
  PSI_mutex_key m_key_LOCK_after_commit;
  /** The instrumentation key to use for @ LOCK_sync. */
  PSI_mutex_key m_key_LOCK_sync;
  /** The instrumentation key to use for @ LOCK_xids. */
  PSI_mutex_key m_key_LOCK_xids;
  /** The instrumentation key to use for @ m_key_LOCK_log_info. */
  PSI_mutex_key m_key_LOCK_log_info;
  /** The instrumentation key to use for @ update_cond. */
  PSI_cond_key m_key_update_cond;
  /** The instrumentation key to use for @ prep_xids_cond. */
  PSI_cond_key m_key_prep_xids_cond;
  /** The PFS instrumentation key for @ COND_wait_for_group_turn. */
  PSI_cond_key m_key_COND_wait_for_group_turn;
  /** The instrumentation key to use for opening the log file. */
  PSI_file_key m_key_file_log;
  /** The instrumentation key to use for opening the log index file. */
  PSI_file_key m_key_file_log_index;
  /** The instrumentation key to use for opening a log cache file. */
  PSI_file_key m_key_file_log_cache;
  /** The instrumentation key to use for opening a log index cache file. */
  PSI_file_key m_key_file_log_index_cache;

  /* POSIX thread objects are inited by init_pthread_objects() */
  mysql_mutex_t LOCK_index;
  mysql_mutex_t LOCK_commit;
  mysql_mutex_t LOCK_after_commit;
  mysql_mutex_t LOCK_sync;
  mysql_mutex_t LOCK_binlog_end_pos;
  mysql_mutex_t LOCK_xids;
  mysql_cond_t update_cond;

  std::atomic<my_off_t> atomic_binlog_end_pos;
  ulonglong bytes_written;
  IO_CACHE index_file;
  char index_file_name[FN_REFLEN];
  /*
    crash_safe_index_file is temp file used for guaranteeing
    index file crash safe when master server restarts.
  */
  IO_CACHE crash_safe_index_file;
  char crash_safe_index_file_name[FN_REFLEN];
  /*
    purge_file is a temp file used in purge_logs so that the index file
    can be updated before deleting files from disk, yielding better crash
    recovery. It is created on demand the first time purge_logs is called
    and then reused for subsequent calls. It is cleaned up in cleanup().
  */
  IO_CACHE purge_index_file;
  char purge_index_file_name[FN_REFLEN];
  /*
     The max size before rotation (usable only if log_type == LOG_BIN: binary
     logs and relay logs).
     For a binlog, max_size should be max_binlog_size.
     For a relay log, it should be max_relay_log_size if this is non-zero,
     max_binlog_size otherwise.
     max_size is set in init(), and dynamically changed (when one does SET
     GLOBAL MAX_BINLOG_SIZE|MAX_RELAY_LOG_SIZE) by fix_max_binlog_size and
     fix_max_relay_log_size).
  */
  ulong max_size;

  // current file sequence number for load data infile binary logging
  uint file_id;

  /* pointer to the sync period variable, for binlog this will be
     sync_binlog_period, for relay log this will be
     sync_relay_log_period
  */
  uint *sync_period_ptr;
  uint sync_counter;

  mysql_cond_t m_prep_xids_cond;
  std::atomic<int32> m_atomic_prep_xids{0};

  /**
    Increment the prepared XID counter.
   */
  void inc_prep_xids(THD *thd);

  /**
    Decrement the prepared XID counter.

    Signal m_prep_xids_cond if the counter reaches zero.
   */
  void dec_prep_xids(THD *thd);

  int32 get_prep_xids() { return m_atomic_prep_xids; }

  inline uint get_sync_period() { return *sync_period_ptr; }

 public:
  /*
    This is used to start writing to a new log file. The difference from
    new_file() is locking. new_file_without_locking() does not acquire
    LOCK_log.
  */
  int new_file_without_locking(
      Format_description_log_event *extra_description_event);

  /**
    Checks whether binlog caches are disabled (binlog does not cache data) or
    empty in case binloggging is enabled in the current call to this function.
    This function may be safely called in case binlogging is disabled.
    @retval true binlog local caches are empty or disabled and binlogging is
    enabled
    @retval false binlog local caches are enabled and contain data or binlogging
    is disabled
  */
  bool is_current_stmt_binlog_enabled_and_caches_empty(const THD *thd) const;

 private:
  int new_file_impl(bool need_lock,
                    Format_description_log_event *extra_description_event);

  bool open(PSI_file_key log_file_key, const char *log_name,
            const char *new_name, uint32 new_index_number);
  bool init_and_set_log_file_name(const char *log_name, const char *new_name,
                                  uint32 new_index_number);
  int generate_new_name(char *new_name, const char *log_name,
                        uint32 new_index_number = 0);
  /**
   * Read binary log stream header and Format_desc event from
   * binlog_file_reader. Check for LOG_EVENT_BINLOG_IN_USE_F flag.
   * @param[in] binlog_file_reader
   * @return true - LOG_EVENT_BINLOG_IN_USE_F is set
   *         false - LOG_EVENT_BINLOG_IN_USE_F is not set or an error occurred
   *                 while reading log events
   */
  bool read_binlog_in_use_flag(Binlog_file_reader &binlog_file_reader);

 protected:
  /**
  @brief Notifies waiting threads that binary log has been updated
  */
  void signal_update();

 public:
  const char *generate_name(const char *log_name, const char *suffix,
                            char *buff);
  bool is_open() const { return atomic_log_state != LOG_CLOSED; }

  /* This is relay log */
  bool is_relay_log;

  uint8 checksum_alg_reset;  // to contain a new value when binlog is rotated
  /*
    Holds the last seen in Relay-Log FD's checksum alg value.
    The initial value comes from the slave's local FD that heads
    the very first Relay-Log file. In the following the value may change
    with each received master's FD_m.
    Besides to be used in verification events that IO thread receives
    (except the 1st fake Rotate, see @c Master_info:: checksum_alg_before_fd),
    the value specifies if/how to compute checksum for slave's local events
    and the first fake Rotate (R_f^1) coming from the master.
    R_f^1 needs logging checksum-compatibly with the RL's heading FD_s.

    Legends for the checksum related comments:

    FD     - Format-Description event,
    R      - Rotate event
    R_f    - The fake Rotate event
    E      - An arbitrary event

    The underscore indexes for any event
    `_s'   - Indicates the event is generated by the Replica
    `_m'   - By the Source

    Two special underscore indexes of FD:
    FD_q   - Format Description event for queuing   (relay-logging)
    FD_e   - Format Description event for executing (relay-logging)

    Upper indexes:
    E^n    - n:th event is a sequence

    RL     - Relay Log
    (A)    - checksum algorithm descriptor value
    FD.(A) - the value of (A) in FD
  */
  binary_log::enum_binlog_checksum_alg relay_log_checksum_alg;

  MYSQL_BIN_LOG(uint *sync_period, bool relay_log = false);
  ~MYSQL_BIN_LOG() override;

  void set_psi_keys(
      PSI_mutex_key key_LOCK_index, PSI_mutex_key key_LOCK_commit,
      PSI_mutex_key key_LOCK_commit_queue, PSI_mutex_key key_LOCK_after_commit,
      PSI_mutex_key key_LOCK_after_commit_queue, PSI_mutex_key key_LOCK_done,
      PSI_mutex_key key_LOCK_flush_queue, PSI_mutex_key key_LOCK_log,
      PSI_mutex_key key_LOCK_binlog_end_pos, PSI_mutex_key key_LOCK_sync,
      PSI_mutex_key key_LOCK_sync_queue, PSI_mutex_key key_LOCK_xids,
      PSI_mutex_key key_LOCK_log_info,
      PSI_mutex_key key_LOCK_wait_for_group_turn, PSI_cond_key key_COND_done,
      PSI_cond_key key_COND_flush_queue, PSI_cond_key key_update_cond,
      PSI_cond_key key_prep_xids_cond,
      PSI_cond_key key_COND_wait_for_group_turn, PSI_file_key key_file_log,
      PSI_file_key key_file_log_index, PSI_file_key key_file_log_cache,
      PSI_file_key key_file_log_index_cache) {
    m_key_COND_done = key_COND_done;
    m_key_COND_flush_queue = key_COND_flush_queue;

    m_key_LOCK_commit_queue = key_LOCK_commit_queue;
    m_key_LOCK_after_commit_queue = key_LOCK_after_commit_queue;
    m_key_LOCK_done = key_LOCK_done;
    m_key_LOCK_flush_queue = key_LOCK_flush_queue;
    m_key_LOCK_sync_queue = key_LOCK_sync_queue;

    m_key_LOCK_index = key_LOCK_index;
    m_key_LOCK_log = key_LOCK_log;
    m_key_LOCK_binlog_end_pos = key_LOCK_binlog_end_pos;
    m_key_LOCK_commit = key_LOCK_commit;
    m_key_LOCK_after_commit = key_LOCK_after_commit;
    m_key_LOCK_sync = key_LOCK_sync;
    m_key_LOCK_xids = key_LOCK_xids;
    m_key_LOCK_log_info = key_LOCK_log_info;
    m_key_update_cond = key_update_cond;
    m_key_prep_xids_cond = key_prep_xids_cond;
    m_key_file_log = key_file_log;
    m_key_file_log_index = key_file_log_index;
    m_key_file_log_cache = key_file_log_cache;
    m_key_file_log_index_cache = key_file_log_index_cache;

    m_key_LOCK_wait_for_group_turn = key_LOCK_wait_for_group_turn;
    m_key_COND_wait_for_group_turn = key_COND_wait_for_group_turn;
  }

 public:
  /** Manage the MTS dependency tracking */
  Transaction_dependency_tracker m_dependency_tracker;

  /**
    Find the oldest binary log referenced by the index file

    @param[out] binlog_file_name the file name of oldest log found
    @param[out] errmsg the error message outputted, which is left untouched
                if the function returns false
    @return false on success, true on error.
  */
  bool find_first_log(std::string &binlog_file_name, std::string &errmsg);

  /**
    Find the oldest binary log that contains any GTID that
    is not in the given gtid set.

    @param[out] binlog_file_name the file name of oldest binary log found
    @param[in]  gtid_set the given gtid set
    @param[out] first_gtid the first GTID information from the binary log
                file returned at binlog_file_name
    @param[out] errmsg the error message outputted, which is left untouched
                if the function returns false
    @return false on success, true on error.
  */
  bool find_first_log_not_in_gtid_set(char *binlog_file_name,
                                      const Gtid_set *gtid_set,
                                      Gtid *first_gtid, std::string &errmsg);

  /**
    Reads the set of all GTIDs in the binary/relay log, and the set
    of all lost GTIDs in the binary log, and stores each set in
    respective argument.

    @param gtid_set Will be filled with all GTIDs in this binary/relay
    log.
    @param lost_groups Will be filled with all GTIDs in the
    Previous_gtids_log_event of the first binary log that has a
    Previous_gtids_log_event. This is requested to binary logs but not
    to relay logs.
    @param verify_checksum If true, checksums will be checked.
    @param need_lock If true, LOCK_log, LOCK_index, and
    global_sid_lock->wrlock are acquired; otherwise they are asserted
    to be taken already.
    @param [out] trx_parser  This will be used to return the actual
    relaylog transaction parser state because of the possibility
    of partial transactions.
    @param [out] partial_trx If a transaction was left incomplete
    on the relaylog, its GTID information should be returned to be
    used in the case of the rest of the transaction be added to the
    relaylog.
    @param is_server_starting True if the server is starting.
    @return false on success, true on error.
  */
  bool init_gtid_sets(Gtid_set *gtid_set, Gtid_set *lost_groups,
                      bool verify_checksum, bool need_lock,
                      Transaction_boundary_parser *trx_parser,
                      Gtid_monitoring_info *partial_trx,
                      bool is_server_starting = false);

  void set_previous_gtid_set_relaylog(Gtid_set *previous_gtid_set_param) {
    assert(is_relay_log);
    previous_gtid_set_relaylog = previous_gtid_set_param;
  }
  /**
    If the thread owns a GTID, this function generates an empty
    transaction and releases ownership of the GTID.

    - If the binary log is disabled for this thread, the GTID is
      inserted directly into the mysql.gtid_executed table and the
      GTID is included in @@global.gtid_executed.  (This only happens
      for DDL, since DML will save the GTID into table and release
      ownership inside ha_commit_trans.)

    - If the binary log is enabled for this thread, an empty
      transaction consisting of GTID, BEGIN, COMMIT is written to the
      binary log, the GTID is included in @@global.gtid_executed, and
      the GTID is added to the mysql.gtid_executed table on the next
      binlog rotation.

    This function must be called by any committing statement (COMMIT,
    implicitly committing statements, or Xid_log_event), after the
    statement has completed execution, regardless of whether the
    statement updated the database.

    This logic ensures that an empty transaction is generated for the
    following cases:

    - Explicit empty transaction:
      SET GTID_NEXT = 'UUID:NUMBER'; BEGIN; COMMIT;

    - Transaction or DDL that gets completely filtered out in the
      slave thread.

    @param thd The committing thread

    @retval 0 Success
    @retval nonzero Error
  */
  int gtid_end_transaction(THD *thd);
  /**
    Re-encrypt previous existent binary/relay logs as below.
      Starting from the next to last entry on the index file, iterating
      down to the first one:
        - If the file is encrypted, re-encrypt it. Otherwise, skip it.
        - If failed to open the file, report an error.

    @retval False Success
    @retval True  Error
  */
  bool reencrypt_logs();

 private:
  std::atomic<enum_log_state> atomic_log_state{LOG_CLOSED};

  /* The previous gtid set in relay log. */
  Gtid_set *previous_gtid_set_relaylog;

  int open(const char *opt_name) override { return open_binlog(opt_name); }

  /**
    Enter a stage of the ordered commit procedure.

    Entering is stage is done by:

    - Atomically entering a queue of THD objects (which is just one for
      the first phase).

    - If the queue was empty, the thread is the leader for that stage
      and it should process the entire queue for that stage.

    - If the queue was not empty, the thread is a follower and can go
      waiting for the commit to finish.

    The function will lock the stage mutex if the calling thread was designated
    leader for the phase.

    @param[in] thd    Session structure
    @param[in] stage  The stage to enter
    @param[in] queue  Thread queue for the stage
    @param[in] leave_mutex  Mutex that will be released when changing stage
    @param[in] enter_mutex  Mutex that will be taken when changing stage

    @retval true  In case this thread did not become leader, the function
                  returns true *after* the leader has completed the commit
                  on its behalf, so the thread should continue doing the
                  thread-local processing after the commit
                  (i.e. call finish_commit).

    @retval false The thread is the leader for the stage and should do
                  the processing.
  */
  bool change_stage(THD *thd, Commit_stage_manager::StageID stage, THD *queue,
                    mysql_mutex_t *leave_mutex, mysql_mutex_t *enter_mutex);
  std::pair<int, my_off_t> flush_thread_caches(THD *thd);
  int flush_cache_to_file(my_off_t *flush_end_pos);
  int finish_commit(THD *thd);
  std::pair<bool, bool> sync_binlog_file(bool force);
  void process_commit_stage_queue(THD *thd, THD *queue);
  void process_after_commit_stage_queue(THD *thd, THD *first);

  /**
    Set thread variables used while flushing a transaction.

    @param[in] thd  thread whose variables need to be set
    @param[in] all   This is @c true if this is a real transaction commit, and
                 @c false otherwise.
    @param[in] skip_commit
                 This is @c true if the call to @c ha_commit_low should
                 be skipped (it is handled by the caller somehow) and @c
                 false otherwise (the normal case).
  */
  void init_thd_variables(THD *thd, bool all, bool skip_commit);

  /**
    Fetch and empty BINLOG_FLUSH_STAGE and COMMIT_ORDER_FLUSH_STAGE flush queues
    and flush transactions to the disk, and unblock threads executing slave
    preserve commit order.

    @param[in] check_and_skip_flush_logs
                 if false then flush prepared records of transactions to the log
                 of storage engine.
                 if true then flush prepared records of transactions to the log
                 of storage engine only if COMMIT_ORDER_FLUSH_STAGE queue is
                 non-empty.

    @return Pointer to the first session of the BINLOG_FLUSH_STAGE stage queue.
  */
  THD *fetch_and_process_flush_stage_queue(
      const bool check_and_skip_flush_logs = false);

  /**
    Execute the flush stage.

    @param[out] total_bytes_var Pointer to variable that will be set to total
                                number of bytes flushed, or NULL.

    @param[out] rotate_var Pointer to variable that will be set to true if
                           binlog rotation should be performed after releasing
                           locks. If rotate is not necessary, the variable will
                           not be touched.

    @param[out] out_queue_var  Pointer to the sessions queue in flush stage.

    @return Error code on error, zero on success
  */
  int process_flush_stage_queue(my_off_t *total_bytes_var, bool *rotate_var,
                                THD **out_queue_var);

  /**
    Flush and commit the transaction.

    This will execute an ordered flush and commit of all outstanding
    transactions and is the main function for the binary log group
    commit logic. The function performs the ordered commit in four stages.

    Pre-condition: transactions should have called ha_prepare_low, using
                   HA_IGNORE_DURABILITY, before entering here.

    Stage#0 implements replica-preserve-commit-order for applier threads that
    write the binary log. i.e. it forces threads to enter the queue in the
    correct commit order.

    The stage#1 flushes the caches to the binary log and under
    LOCK_log and marks all threads that were flushed as not pending.

    The stage#2 syncs the binary log for all transactions in the group.

    The stage#3 executes under LOCK_commit and commits all transactions in
    order.

    There are three queues of THD objects: one for each stage.
    The Commit_order_manager maintains it own queue and its own order for the
    commit. So Stage#0 doesn't maintain separate StageID.

    When a transaction enters a stage, it adds itself to a queue. If the queue
    was empty so that this becomes the first transaction in the queue, the
    thread is the *leader* of the queue. Otherwise it is a *follower*. The
    leader will do all work for all threads in the queue, and the followers
    will wait until the last stage is finished.

    Stage 0 (SLAVE COMMIT ORDER):
    1. If replica-preserve-commit-order and is slave applier worker thread, then
       waits until its turn to commit i.e. till it is on the top of the queue.
    2. When it reaches top of the queue, it signals next worker in the commit
       order queue to awake.

    Stage 1 (FLUSH):
    1. Sync the engines (ha_flush_logs), since they prepared using non-durable
       settings (HA_IGNORE_DURABILITY).
    2. Generate GTIDs for all transactions in the queue.
    3. Write the session caches for all transactions in the queue to the binary
       log.
    4. Increment the counter of prepared XIDs.

    Stage 2 (SYNC):
    1. If it is time to sync, based on the sync_binlog option, sync the binlog.
    2. If sync_binlog==1, signal dump threads that they can read up to the
       position after the last transaction in the queue

    Stage 3 (COMMIT):
    This is performed by each thread separately, if binlog_order_commits=0.
    Otherwise by the leader does it for all threads.
    1. Call the after_sync hook.
    2. update the max_committed counter in the dependency_tracker
    3. call ha_commit_low
    4. Call the after_commit hook
    5. Update gtids
    6. Decrement the counter of prepared transactions

    If the binary log needs to be rotated, it is done after this. During
    rotation, it takes a lock that prevents new commit groups from executing the
    flush stage, and waits until the counter of prepared transactions becomes 0,
    before it creates the new file.

    @param[in] thd Session to commit transaction for
    @param[in] all This is @c true if this is a real transaction commit, and
                   @c false otherwise.
    @param[in] skip_commit
                   This is @c true if the call to @c ha_commit_low should
                   be skipped and @c false otherwise (the normal case).
  */
  int ordered_commit(THD *thd, bool all, bool skip_commit = false);
  void handle_binlog_flush_or_sync_error(THD *thd, bool need_lock_log,
                                         const char *message);
  bool do_write_cache(Binlog_cache_storage *cache,
                      class Binlog_event_writer *writer);
  void report_binlog_write_error();

 public:
  int open_binlog(const char *opt_name);
  void close() override;
  enum_result commit(THD *thd, bool all) override;
  int rollback(THD *thd, bool all) override;
  bool truncate_relaylog_file(Master_info *mi, my_off_t valid_pos);
  int prepare(THD *thd, bool all) override;
#if defined(MYSQL_SERVER)

  void update_thd_next_event_pos(THD *thd);
  int flush_and_set_pending_rows_event(THD *thd, Rows_log_event *event,
                                       bool is_transactional);

#endif /* defined(MYSQL_SERVER) */
  void add_bytes_written(ulonglong inc) { bytes_written += inc; }
  void reset_bytes_written() { bytes_written = 0; }
  void harvest_bytes_written(Relay_log_info *rli, bool need_log_space_lock);
  void set_max_size(ulong max_size_arg);

  void update_binlog_end_pos(bool need_lock = true);
  void update_binlog_end_pos(const char *file, my_off_t pos);

  /**
    Wait until we get a signal that the binary log has been updated.

    NOTES
    @param[in] timeout    a pointer to a timespec;
                          NULL means to wait w/o timeout.
    @retval    0          if got signalled on update
    @retval    non-0      if wait timeout elapsed
    @note
      LOCK_binlog_end_pos must be owned before calling this function, may be
      temporarily released while the thread is waiting and is reacquired before
      returning from the function
  */
  int wait_for_update(const std::chrono::nanoseconds &timeout);

  /**
    Wait until we get a signal that the binary log has been updated.
    @retval    0          success
    @note
      LOCK_binlog_end_pos must be owned before calling this function, may be
      temporarily released while the thread is waiting and is reacquired before
      returning from the function
  */
  int wait_for_update();

 public:
  void init_pthread_objects();
  void cleanup();
  /**
    Create a new binary log.
    @param log_name Name of binlog
    @param new_name Name of binlog, too. todo: what's the difference
    between new_name and log_name?
    @param max_size_arg The size at which this binlog will be rotated.
    @param null_created_arg If false, and a Format_description_log_event
    is written, then the Format_description_log_event will have the
    timestamp 0. Otherwise, it the timestamp will be the time when the
    event was written to the log.
    @param need_lock_index If true, LOCK_index is acquired; otherwise
    LOCK_index must be taken by the caller.
    @param need_sid_lock If true, the read lock on global_sid_lock
    will be acquired.  Otherwise, the caller must hold the read lock
    on global_sid_lock.
    @param extra_description_event The master's FDE to be written by the I/O
    thread while creating a new relay log file. This should be NULL for
    binary log files.
    @param new_index_number The binary log file index number to start from
    after the RESET MASTER TO command is called.
  */
  bool open_binlog(const char *log_name, const char *new_name,
                   ulong max_size_arg, bool null_created_arg,
                   bool need_lock_index, bool need_sid_lock,
                   Format_description_log_event *extra_description_event,
                   uint32 new_index_number = 0);
  bool open_index_file(const char *index_file_name_arg, const char *log_name,
                       bool need_lock_index);
  /* Use this to start writing a new log file */
  int new_file(Format_description_log_event *extra_description_event);

  bool write_event(Log_event *event_info);
  bool write_cache(THD *thd, class binlog_cache_data *cache_data,
                   class Binlog_event_writer *writer);
  /**
    Assign automatic generated GTIDs for all commit group threads in the flush
    stage having gtid_next.type == AUTOMATIC_GTID.

    @param first_seen The first thread seen entering the flush stage.
    @return Returns false if succeeds, otherwise true is returned.
  */
  bool assign_automatic_gtids_to_flush_group(THD *first_seen);
  bool write_transaction(THD *thd, binlog_cache_data *cache_data,
                         Binlog_event_writer *writer);

  /**
     Write a dml into statement cache and then flush it into binlog. It writes
     Gtid_log_event and BEGIN, COMMIT automatically.

     It is aimed to handle cases of "background" logging where a statement is
     logged indirectly, like "TRUNCATE TABLE a_memory_table". So don't use it on
     any normal statement.

     @param[in] thd  the THD object of current thread.
     @param[in] stmt the DML statement.
     @param[in] stmt_len the length of the DML statement.
     @param[in] sql_command the type of SQL command.

     @return Returns false if succeeds, otherwise true is returned.
  */
  bool write_stmt_directly(THD *thd, const char *stmt, size_t stmt_len,
                           enum enum_sql_command sql_command);

  void report_cache_write_error(THD *thd, bool is_transactional);
  bool check_write_error(const THD *thd);
  bool write_incident(THD *thd, bool need_lock_log, const char *err_msg,
                      bool do_flush_and_sync = true);
  bool write_incident(Incident_log_event *ev, THD *thd, bool need_lock_log,
                      const char *err_msg, bool do_flush_and_sync = true);
  bool write_event_to_binlog(Log_event *ev);
  bool write_event_to_binlog_and_flush(Log_event *ev);
  bool write_event_to_binlog_and_sync(Log_event *ev);
  void start_union_events(THD *thd, query_id_t query_id_param);
  void stop_union_events(THD *thd);
  bool is_query_in_union(THD *thd, query_id_t query_id_param);

  bool write_buffer(const char *buf, uint len, Master_info *mi);
  bool write_event(Log_event *ev, Master_info *mi);

  /**
     Logging XA commit/rollback of a prepared transaction.

     It fills in the appropriate event in the statement cache whenever xid
     state is marked with is_binlogged() flag that indicates the prepared
     part of the transaction must've been logged.

     About early returns from the function:
     - ONE_PHASE option to XA-COMMIT is handled to skip writing XA-commit
       event now.
     - check is for the read-only XA that is not to be logged.

     @param thd          THD handle
     @return error code, 0 success
  */
  int write_xa_to_cache(THD *thd);

 private:
  bool after_write_to_relay_log(Master_info *mi);
  /**
   * Truncte log file and clear LOG_EVENT_BINLOG_IN_USE_F when update is set.
   * @param[in] log_name name of the log file to be trunacted
   * @param[in] valid_pos position at which to truncate the log file
   * @param[in] binlog_size length of the log file before truncated
   * @param[in] update should the LOG_EVENT_BINLOG_IN_USE_F flag be cleared
   *                   true - set LOG_EVENT_BINLOG_IN_USE_F to 0
   *                   false - do not modify LOG_EVENT_BINLOG_IN_USE_F flag
   * @return true - sucess, false - failed
   */
  bool truncate_update_log_file(const char *log_name, my_off_t valid_pos,
                                my_off_t binlog_size, bool update);

 public:
  void make_log_name(char *buf, const char *log_ident);
  bool is_active(const char *log_file_name) const;
  int remove_logs_from_index(LOG_INFO *linfo, bool need_update_threads);
  int rotate(bool force_rotate, bool *check_purge);

  /**
    @brief This function runs automatic purge if the conditions to meet
    automatic purge are met. Such conditions are: log is open, instance is not
    locked for backup and automatic purge is enabled.

    If all conditions are met, purge is done according to the configuration
    of the purge window.
   */
  void auto_purge();

  /**
    @brief This member function is to be called at server startup. It checks if
    purge can be done and does if it can.
   */
  void auto_purge_at_server_startup();
  int rotate_and_purge(THD *thd, bool force_rotate);

  bool flush();
  /**
     Flush binlog cache and synchronize to disk.

     This function flushes events in binlog cache to binary log file,
     it will do synchronizing according to the setting of system
     variable 'sync_binlog'. If file is synchronized, @c synced will
     be set to 1, otherwise 0.

     @param[in] force if true, ignores the 'sync_binlog' and synchronizes the
     file.

     @retval 0 Success
     @retval other Failure
  */
  bool flush_and_sync(const bool force = false);
  int purge_logs(const char *to_log, bool included, bool need_lock_index,
                 bool need_update_threads, ulonglong *decrease_log_space,
                 bool auto_purge);
  int purge_logs_before_date(time_t purge_time, bool auto_purge);
  int set_crash_safe_index_file_name(const char *base_file_name);
  int open_crash_safe_index_file();
  int close_crash_safe_index_file();
  int add_log_to_index(uchar *log_file_name, size_t name_len,
                       bool need_lock_index);
  int move_crash_safe_index_file_to_index_file(bool need_lock_index);
  int set_purge_index_file_name(const char *base_file_name);
  int open_purge_index_file(bool destroy);
  bool is_inited_purge_index_file();
  int close_purge_index_file();
  int sync_purge_index_file();
  int register_purge_index_entry(const char *entry);
  int register_create_index_entry(const char *entry);
  int purge_index_entry(THD *thd, ulonglong *decrease_log_space,
                        bool need_lock_index);
  bool reset_logs(THD *thd, bool delete_only = false);
  void close(uint exiting, bool need_lock_log, bool need_lock_index);

  // iterating through the log index file
  int find_log_pos(LOG_INFO *linfo, const char *log_name, bool need_lock_index);
  int find_next_log(LOG_INFO *linfo, bool need_lock_index);
  int find_next_relay_log(char log_name[FN_REFLEN + 1]);
  int get_current_log(LOG_INFO *linfo, bool need_lock_log = true);
  int raw_get_current_log(LOG_INFO *linfo);
  uint next_file_id();
  /**
    Retrieves the contents of the index file associated with this log object
    into an `std::list<std::string>` object. The order held by the index file is
    kept.

    @param need_lock_index whether or not the lock over the index file should be
                           acquired inside the function.

    @return a pair: a function status code; a list of `std::string` objects with
            the content of the log index file.
  */
  std::pair<int, std::list<std::string>> get_log_index(
      bool need_lock_index = true);
  inline char *get_index_fname() { return index_file_name; }
  inline char *get_log_fname() { return log_file_name; }
  const char *get_name() const { return name; }
  inline mysql_mutex_t *get_log_lock() { return &LOCK_log; }
  inline mysql_mutex_t *get_commit_lock() { return &LOCK_commit; }
  inline mysql_mutex_t *get_after_commit_lock() { return &LOCK_after_commit; }
  inline mysql_cond_t *get_log_cond() { return &update_cond; }
  inline Binlog_ofile *get_binlog_file() { return m_binlog_file; }

  inline void lock_index() { mysql_mutex_lock(&LOCK_index); }
  inline void unlock_index() { mysql_mutex_unlock(&LOCK_index); }
  inline IO_CACHE *get_index_file() { return &index_file; }

  /**
    Function to report the missing GTIDs.

    This function logs the missing transactions on master to its error log
    as a warning. If the missing GTIDs are too long to print in a message,
    it suggests the steps to extract the missing transactions.

    This function also informs slave about the GTID set sent by the slave,
    transactions missing on the master and few suggestions to recover from
    the error. This message shall be wrapped by
    ER_SOURCE_FATAL_ERROR_READING_BINLOG on slave and will be logged as an
    error.

    This function will be called from mysql_binlog_send() function.

    @param slave_executed_gtid_set     GTID set executed by slave
    @param errmsg                      Pointer to the error message
  */
  void report_missing_purged_gtids(const Gtid_set *slave_executed_gtid_set,
                                   std::string &errmsg);

  /**
    Function to report the missing GTIDs.

    This function logs the missing transactions on master to its error log
    as a warning. If the missing GTIDs are too long to print in a message,
    it suggests the steps to extract the missing transactions.

    This function also informs slave about the GTID set sent by the slave,
    transactions missing on the master and few suggestions to recover from
    the error. This message shall be wrapped by
    ER_SOURCE_FATAL_ERROR_READING_BINLOG on slave and will be logged as an
    error.

    This function will be called from find_first_log_not_in_gtid_set()
    function.

    @param previous_gtid_set           Previous GTID set found
    @param slave_executed_gtid_set     GTID set executed by slave
    @param errmsg                      Pointer to the error message
  */
  void report_missing_gtids(const Gtid_set *previous_gtid_set,
                            const Gtid_set *slave_executed_gtid_set,
                            std::string &errmsg);
  static const int MAX_RETRIES_FOR_DELETE_RENAME_FAILURE = 5;
  /*
    It is called by the threads (e.g. dump thread, applier thread) which want
    to read hot log without LOCK_log protection.
  */
  my_off_t get_binlog_end_pos() const {
    mysql_mutex_assert_not_owner(&LOCK_log);
    return atomic_binlog_end_pos;
  }
  mysql_mutex_t *get_binlog_end_pos_lock() { return &LOCK_binlog_end_pos; }
  void lock_binlog_end_pos() { mysql_mutex_lock(&LOCK_binlog_end_pos); }
  void unlock_binlog_end_pos() { mysql_mutex_unlock(&LOCK_binlog_end_pos); }

  /**
    Deep copy global_sid_map and gtid_executed.
    Both operations are done under LOCK_commit and global_sid_lock
    protection.

    @param[out] sid_map  The Sid_map to which global_sid_map will
                         be copied.
    @param[out] gtid_set The Gtid_set to which gtid_executed will
                         be copied.

    @return the operation status
      @retval 0      OK
      @retval !=0    Error
  */
  int get_gtid_executed(Sid_map *sid_map, Gtid_set *gtid_set);

  /*
    True while rotating binlog, which is caused by logging Incident_log_event.
  */
  bool is_rotating_caused_by_incident;

 public:
  /**
    Register LOG_INFO so that log_in_use and adjust_linfo_offsets can
    operate on all logs. Note that register_log_info, unregister_log_info,
    log_in_use, adjust_linfo_offsets are is used on global mysql_bin_log object.
    @param log_info pointer to LOG_INFO which is registred
  */
  void register_log_info(LOG_INFO *log_info);
  /**
    Unregister LOG_INFO when it is no longer needed.
    @param log_info pointer to LOG_INFO which is registred
  */
  void unregister_log_info(LOG_INFO *log_info);
  /**
    Check if any threads use log name.
    @note This method expects the LOCK_index to be taken so there are no
    concurrent edits against linfo objects being iterated
    @param log_name name of a log which is checked for usage

  */
  int log_in_use(const char *log_name);
  /**
    Adjust the position pointer in the binary log file for all running replicas.
    SYNOPSIS
      adjust_linfo_offsets()
      purge_offset Number of bytes removed from start of log index file
    NOTES
      - This is called when doing a PURGE when we delete lines from the
        index log file. This method expects the LOCK_index to be taken so there
    are no concurrent edits against linfo objects being iterated. REQUIREMENTS
      - Before calling this function, we have to ensure that no threads are
        using any binary log file before purge_offset.
    TODO
      - Inform the replica threads that they should sync the position
        in the binary log file with flush_relay_log_info.
        Now they sync is done for next read.
  */
  void adjust_linfo_offsets(my_off_t purge_offset);

 private:
  mysql_mutex_t LOCK_log_info;
  // Set of log info objects that are in usage and might prevent some other
  // operations from executing.
  std::set<LOG_INFO *> log_info_set;
};

struct LOAD_FILE_INFO {
  THD *thd;
  my_off_t last_pos_in_file;
  bool logged_data_file, log_delayed;
};

extern MYSQL_PLUGIN_IMPORT MYSQL_BIN_LOG mysql_bin_log;

/**
  Check if the the transaction is empty.

  @param thd The client thread that executed the current statement.

  @retval true No changes found in any storage engine
  @retval false Otherwise.

**/
bool is_transaction_empty(THD *thd);
/**
  Check if the transaction has no rw flag set for any of the storage engines.

  @param thd The client thread that executed the current statement.
  @param trx_scope The transaction scope to look into.

  @retval the number of engines which have actual changes.
 */
int check_trx_rw_engines(THD *thd, Transaction_ctx::enum_trx_scope trx_scope);

/**
  Check if at least one of transacaction and statement binlog caches contains
  an empty transaction, other one is empty or contains an empty transaction,
  which has two binlog events "BEGIN" and "COMMIT".

  @param thd The client thread that executed the current statement.

  @retval true  At least one of transacaction and statement binlog caches
                contains an empty transaction, other one is empty or
                contains an empty transaction.
  @retval false Otherwise.
*/
bool is_empty_transaction_in_binlog_cache(const THD *thd);
bool trans_has_updated_trans_table(const THD *thd);
bool stmt_has_updated_trans_table(Ha_trx_info_list const &ha_list);
bool ending_trans(THD *thd, const bool all);
bool ending_single_stmt_trans(THD *thd, const bool all);
bool trans_cannot_safely_rollback(const THD *thd);
bool stmt_cannot_safely_rollback(const THD *thd);

int log_loaded_block(IO_CACHE *file);

/**
   @brief Purges the binary log files up to the file name passed as
          a paramenter. Purge will not delete the file passed as
          an argument.

   @param thd The session context.
   @param to_log Up to which log file to purge.
   @return true if there was an error.
   @return false if there was no error.
 */
bool purge_source_logs_to_file(THD *thd, const char *to_log);

bool purge_source_logs_before_date(THD *thd, time_t purge_time);
bool show_binlog_events(THD *thd, MYSQL_BIN_LOG *binary_log);
bool mysql_show_binlog_events(THD *thd);
void check_binlog_cache_size(THD *thd);
void check_binlog_stmt_cache_size(THD *thd);
bool binlog_enabled();
void register_binlog_handler(THD *thd, bool trx);
int query_error_code(const THD *thd, bool not_killed);

extern const char *log_bin_index;
extern const char *log_bin_basename;
extern bool opt_binlog_order_commits;
extern ulong rpl_read_size;
/**
  Turns a relative log binary log path into a full path, based on the
  opt_bin_logname or opt_relay_logname. Also trims the cr-lf at the
  end of the full_path before return to avoid any server startup
  problem on windows.

  @param from         The log name we want to make into an absolute path.
  @param to           The buffer where to put the results of the
                      normalization.
  @param is_relay_log Switch that makes is used inside to choose which
                      option (opt_bin_logname or opt_relay_logname) to
                      use when calculating the base path.

  @returns true if a problem occurs, false otherwise.
 */

bool normalize_binlog_name(char *to, const char *from, bool is_relay_log);

#endif /* BINLOG_H_INCLUDED */