innobase/include/mtr0mtr.h

/*****************************************************************************

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/** @file include/mtr0mtr.h
 Mini-transaction buffer

 Created 11/26/1995 Heikki Tuuri
 *******************************************************/

#ifndef mtr0mtr_h
#define mtr0mtr_h

#include <stddef.h>

#include "univ.i"

#include "buf0types.h"
#include "dyn0buf.h"
#include "fil0fil.h"
#include "log0types.h"
#include "mtr0types.h"
#include "srv0srv.h"
#include "trx0types.h"

/** Start a mini-transaction. */
#define mtr_start(m) (m)->start()

/** Start a synchronous mini-transaction */
#define mtr_start_sync(m) (m)->start(true)

/** Start an asynchronous read-only mini-transaction */
#define mtr_start_ro(m) (m)->start(true, true)

/** Commit a mini-transaction. */
#define mtr_commit(m) (m)->commit()

/** Set and return a savepoint in mtr.
@return	savepoint */
#define mtr_set_savepoint(m) (m)->get_savepoint()

/** Release the (index tree) s-latch stored in an mtr memo after a
savepoint. */
#define mtr_release_s_latch_at_savepoint(m, s, l) \
  (m)->release_s_latch_at_savepoint((s), (l))

/** Get the logging mode of a mini-transaction.
@return	logging mode: MTR_LOG_NONE, ... */
#define mtr_get_log_mode(m) (m)->get_log_mode()

/** Change the logging mode of a mini-transaction.
@return	old mode */
#define mtr_set_log_mode(m, d) (m)->set_log_mode((d))

/** Get the flush observer of a mini-transaction.
@return flush observer object */
#define mtr_get_flush_observer(m) (m)->get_flush_observer()

/** Set the flush observer of a mini-transaction. */
#define mtr_set_flush_observer(m, d) (m)->set_flush_observer((d))

/** Read 1 - 4 bytes from a file page buffered in the buffer pool.
@return	value read */
#define mtr_read_ulint(p, t, m) (m)->read_ulint((p), (t))

/** Release an object in the memo stack.
@return true if released */
#define mtr_memo_release(m, o, t) (m)->memo_release((o), (t))

#ifdef UNIV_DEBUG

/** Check if memo contains the given item ignore if table is intrinsic
@return true if contains or table is intrinsic. */
#define mtr_is_block_fix(m, o, t, table) \
  (mtr_memo_contains(m, o, t) || table->is_intrinsic())

/** Check if memo contains the given page ignore if table is intrinsic
@return true if contains or table is intrinsic. */
#define mtr_is_page_fix(m, p, t, table) \
  (mtr_memo_contains_page(m, p, t) || table->is_intrinsic())

/** Check if memo contains the given item.
@return	true if contains */
#define mtr_memo_contains(m, o, t) (m)->memo_contains((m)->get_memo(), (o), (t))

/** Check if memo contains the given page.
@return	true if contains */
#define mtr_memo_contains_page(m, p, t) \
  (m)->memo_contains_page_flagged((p), (t))
#endif /* UNIV_DEBUG */

/** Print info of an mtr handle. */
#define mtr_print(m) (m)->print()

/** Return the log object of a mini-transaction buffer.
@return	log */
#define mtr_get_log(m) (m)->get_log()

/** Push an object to an mtr memo stack. */
#define mtr_memo_push(m, o, t) (m)->memo_push(o, t)

/** Lock an rw-lock in s-mode. */
#define mtr_s_lock(l, m) (m)->s_lock((l), __FILE__, __LINE__)

/** Lock an rw-lock in x-mode. */
#define mtr_x_lock(l, m) (m)->x_lock((l), __FILE__, __LINE__)

/** Lock a tablespace in x-mode. */
#define mtr_x_lock_space(s, m) (m)->x_lock_space((s), __FILE__, __LINE__)

/** Lock an rw-lock in sx-mode. */
#define mtr_sx_lock(l, m) (m)->sx_lock((l), __FILE__, __LINE__)

#define mtr_memo_contains_flagged(m, p, l) (m)->memo_contains_flagged((p), (l))

#define mtr_memo_contains_page_flagged(m, p, l) \
  (m)->memo_contains_page_flagged((p), (l))

#define mtr_release_block_at_savepoint(m, s, b) \
  (m)->release_block_at_savepoint((s), (b))

#define mtr_block_sx_latch_at_savepoint(m, s, b) \
  (m)->sx_latch_at_savepoint((s), (b))

#define mtr_block_x_latch_at_savepoint(m, s, b) \
  (m)->x_latch_at_savepoint((s), (b))

/** Check if a mini-transaction is dirtying a clean page.
@param b	block being x-fixed
@return true if the mtr is dirtying a clean page. */
#define mtr_block_dirtied(b) mtr_t::is_block_dirtied((b))

/** Forward declaration of a tablespace object */
struct fil_space_t;

/** Mini-transaction memo stack slot. */
struct mtr_memo_slot_t {
  /** pointer to the object */
  void *object;

  /** type of the stored object (MTR_MEMO_S_LOCK, ...) */
  ulint type;
};

/** Mini-transaction handle and buffer */
struct mtr_t {
  /** State variables of the mtr */
  struct Impl {
    /** memo stack for locks etc. */
    mtr_buf_t m_memo;

    /** mini-transaction log */
    mtr_buf_t m_log;

    /** true if mtr has made at least one buffer pool page dirty */
    bool m_made_dirty;

    /** true if inside ibuf changes */
    bool m_inside_ibuf;

    /** true if the mini-transaction modified buffer pool pages */
    bool m_modifications;

    /** true if mtr is forced to NO_LOG mode because redo logging is
    disabled globally. In this case, mtr increments the global counter
    at ::start and must decrement it back at ::commit. */
    bool m_marked_nolog;

    /** Shard index used for incrementing global counter at ::start. We need
    to use the same shard while decrementing counter at ::commit. */
    size_t m_shard_index;

    /** Count of how many page initial log records have been
    written to the mtr log */
    ib_uint32_t m_n_log_recs;

    /** specifies which operations should be logged; default
    value MTR_LOG_ALL */
    mtr_log_t m_log_mode;

    /** State of the transaction */
    mtr_state_t m_state;

    /** Flush Observer */
    FlushObserver *m_flush_observer;

#ifdef UNIV_DEBUG
    /** For checking corruption. */
    ulint m_magic_n;

#endif /* UNIV_DEBUG */

    /** Owning mini-transaction */
    mtr_t *m_mtr;
  };

#ifndef UNIV_HOTBACKUP
  /** mtr global logging */
  class Logging {
   public:
    /** mtr global redo logging state.
    Enable Logging  :
    [ENABLED] -> [ENABLED_RESTRICT] -> [DISABLED]

    Disable Logging :
    [DISABLED] -> [ENABLED_RESTRICT] -> [ENABLED_DBLWR] -> [ENABLED] */

    enum State : uint32_t {
      /* Redo Logging is enabled. Server is crash safe. */
      ENABLED,
      /* Redo logging is enabled. All non-logging mtr are finished with the
      pages flushed to disk. Double write is enabled. Some pages could be
      still getting written to disk without double-write. Not safe to crash. */
      ENABLED_DBLWR,
      /* Redo logging is enabled but there could be some mtrs still running
      in no logging mode. Redo archiving and clone are not allowed to start.
      No double-write */
      ENABLED_RESTRICT,
      /* Redo logging is disabled and all new mtrs would not generate any redo.
      Redo archiving and clone are not allowed. */
      DISABLED
    };

    /** Initialize logging state at server start up. */
    void init() {
      m_state.store(ENABLED);
      /* We use sharded counter and force sequentially consistent counting
      which is the general default for c++ atomic operation. If we try to
      optimize it further specific to current operations, we could use
      Release-Acquire ordering i.e. std::memory_order_release during counting
      and std::memory_order_acquire while checking for the count. However,
      sharding looks to be good enough for now and we should go for non default
      memory ordering only with some visible proof for improvement. */
      m_count_nologging_mtr.set_order(std::memory_order_seq_cst);
      Counter::clear(m_count_nologging_mtr);
    }

    /** Disable mtr redo logging. Server is crash unsafe without logging.
    @param[in]	thd	server connection THD
    @return mysql error code. */
    int disable(THD *thd);

    /** Enable mtr redo logging. Ensure that the server is crash safe
    before returning.
    @param[in]	thd	server connection THD
    @return mysql error code. */
    int enable(THD *thd);

    /** Mark a no-logging mtr to indicate that it would not generate redo log
    and system is crash unsafe.
    @return true iff logging is disabled and mtr is marked. */
    bool mark_mtr(size_t index) {
      /* Have initial check to avoid incrementing global counter for regular
      case when redo logging is enabled. */
      if (is_disabled()) {
        /* Increment counter to restrict state change DISABLED to ENABLED. */
        Counter::inc(m_count_nologging_mtr, index);

        /* Check if the no-logging is still disabled. At this point, if we
        find the state disabled, it is no longer possible for the state move
        back to enabled till the mtr finishes and we unmark the mtr. */
        if (is_disabled()) {
          return (true);
        }
        Counter::dec(m_count_nologging_mtr, index);
      }
      return (false);
    }

    /** unmark a no logging mtr. */
    void unmark_mtr(size_t index) {
      ut_ad(!is_enabled());
      ut_ad(Counter::total(m_count_nologging_mtr) > 0);
      Counter::dec(m_count_nologging_mtr, index);
    }

    /* @return flush loop count for faster response when logging is disabled. */
    uint32_t get_nolog_flush_loop() const { return (NOLOG_MAX_FLUSH_LOOP); }

    /** @return true iff redo logging is enabled and server is crash safe. */
    bool is_enabled() const { return (m_state.load() == ENABLED); }

    /** @return true iff redo logging is disabled and new mtrs are not going
    to generate redo log. */
    bool is_disabled() const { return (m_state.load() == DISABLED); }

    /** @return true iff we can skip data page double write. */
    bool dblwr_disabled() const {
      auto state = m_state.load();
      return (state == DISABLED || state == ENABLED_RESTRICT);
    }

    /* Force faster flush loop for quicker adaptive flush response when logging
    is disabled. When redo logging is disabled the system operates faster with
    dirty pages generated at much faster rate. */
    static constexpr uint32_t NOLOG_MAX_FLUSH_LOOP = 5;

   private:
    /** Wait till all no-logging mtrs are finished.
    @return mysql error code. */
    int wait_no_log_mtr(THD *thd);

   private:
    /** Global redo logging state. */
    std::atomic<State> m_state;

    using Shards = Counter::Shards<128>;

    /** Number of no logging mtrs currently running. */
    Shards m_count_nologging_mtr;
  };

  /** Check if redo logging is disabled globally and mark
  the global counter till mtr ends. */
  void check_nolog_and_mark();

  /** Check if the mtr has marked the global no log counter and
  unmark it. */
  void check_nolog_and_unmark();
#endif /* !UNIV_HOTBACKUP */

  mtr_t() {
    m_impl.m_state = MTR_STATE_INIT;
    m_impl.m_marked_nolog = false;
    m_impl.m_shard_index = 0;
  }

  ~mtr_t() {
#ifdef UNIV_DEBUG
    switch (m_impl.m_state) {
      case MTR_STATE_ACTIVE:
        ut_ad(m_impl.m_memo.size() == 0);
        break;
      case MTR_STATE_INIT:
      case MTR_STATE_COMMITTED:
        break;
      case MTR_STATE_COMMITTING:
        ut_error;
    }
#endif /* UNIV_DEBUG */
#ifndef UNIV_HOTBACKUP
    /* Safety check in case mtr is not committed. */
    if (m_impl.m_state != MTR_STATE_INIT) {
      check_nolog_and_unmark();
    }
#endif /* !UNIV_HOTBACKUP */
  }

  /** Start a mini-transaction.
  @param sync		true if it is a synchronous mini-transaction
  @param read_only	true if read only mini-transaction */
  void start(bool sync = true, bool read_only = false);

  /** @return whether this is an asynchronous mini-transaction. */
  bool is_async() const { return (!m_sync); }

  /** Request a future commit to be synchronous. */
  void set_sync() { m_sync = true; }

  /** Commit the mini-transaction. */
  void commit();

  /** Return current size of the buffer.
  @return	savepoint */
  ulint get_savepoint() const MY_ATTRIBUTE((warn_unused_result)) {
    ut_ad(is_active());
    ut_ad(m_impl.m_magic_n == MTR_MAGIC_N);

    return (m_impl.m_memo.size());
  }

  /** Release the (index tree) s-latch stored in an mtr memo after a
  savepoint.
  @param savepoint	value returned by @see set_savepoint.
  @param lock		latch to release */
  inline void release_s_latch_at_savepoint(ulint savepoint, rw_lock_t *lock);

  /** Release the block in an mtr memo after a savepoint. */
  inline void release_block_at_savepoint(ulint savepoint, buf_block_t *block);

  /** SX-latch a not yet latched block after a savepoint. */
  inline void sx_latch_at_savepoint(ulint savepoint, buf_block_t *block);

  /** X-latch a not yet latched block after a savepoint. */
  inline void x_latch_at_savepoint(ulint savepoint, buf_block_t *block);

  /** Get the logging mode.
  @return	logging mode */
  inline mtr_log_t get_log_mode() const MY_ATTRIBUTE((warn_unused_result));

  /** Change the logging mode.
  @param mode	 logging mode
  @return	old mode */
  mtr_log_t set_log_mode(mtr_log_t mode);

  /** Read 1 - 4 bytes from a file page buffered in the buffer pool.
  @param ptr	pointer from where to read
  @param type	MLOG_1BYTE, MLOG_2BYTES, MLOG_4BYTES
  @return	value read */
  inline uint32_t read_ulint(const byte *ptr, mlog_id_t type) const
      MY_ATTRIBUTE((warn_unused_result));

  /** Locks a rw-latch in S mode.
  NOTE: use mtr_s_lock().
  @param lock	rw-lock
  @param file	file name from where called
  @param line	line number in file */
  inline void s_lock(rw_lock_t *lock, const char *file, ulint line);

  /** Locks a rw-latch in X mode.
  NOTE: use mtr_x_lock().
  @param lock	rw-lock
  @param file	file name from where called
  @param line	line number in file */
  inline void x_lock(rw_lock_t *lock, const char *file, ulint line);

  /** Locks a rw-latch in X mode.
  NOTE: use mtr_sx_lock().
  @param lock	rw-lock
  @param file	file name from where called
  @param line	line number in file */
  inline void sx_lock(rw_lock_t *lock, const char *file, ulint line);

  /** Acquire a tablespace X-latch.
  NOTE: use mtr_x_lock_space().
  @param[in]	space		tablespace instance
  @param[in]	file		file name from where called
  @param[in]	line		line number in file */
  void x_lock_space(fil_space_t *space, const char *file, ulint line);

  /** Release an object in the memo stack.
  @param object	object
  @param type	object type: MTR_MEMO_S_LOCK, ... */
  void memo_release(const void *object, ulint type);

  /** Release a page latch.
  @param[in]	ptr	pointer to within a page frame
  @param[in]	type	object type: MTR_MEMO_PAGE_X_FIX, ... */
  void release_page(const void *ptr, mtr_memo_type_t type);

  /** Note that the mini-transaction has modified data. */
  void set_modified() { m_impl.m_modifications = true; }

  /** Set the state to not-modified. This will not log the
  changes.  This is only used during redo log apply, to avoid
  logging the changes. */
  void discard_modifications() { m_impl.m_modifications = false; }

  /** Get the LSN of commit().
  @return the commit LSN
  @retval 0 if the transaction only modified temporary tablespaces or logging
  is disabled globally. */
  lsn_t commit_lsn() const MY_ATTRIBUTE((warn_unused_result)) {
    ut_ad(has_committed());
    ut_ad(m_impl.m_log_mode == MTR_LOG_ALL);
    return (m_commit_lsn);
  }

  /** Note that we are inside the change buffer code. */
  void enter_ibuf() { m_impl.m_inside_ibuf = true; }

  /** Note that we have exited from the change buffer code. */
  void exit_ibuf() { m_impl.m_inside_ibuf = false; }

  /** @return true if we are inside the change buffer code */
  bool is_inside_ibuf() const MY_ATTRIBUTE((warn_unused_result)) {
    return (m_impl.m_inside_ibuf);
  }

  /*
  @return true if the mini-transaction is active */
  bool is_active() const MY_ATTRIBUTE((warn_unused_result)) {
    return (m_impl.m_state == MTR_STATE_ACTIVE);
  }

  /** Get flush observer
  @return flush observer */
  FlushObserver *get_flush_observer() const MY_ATTRIBUTE((warn_unused_result)) {
    return (m_impl.m_flush_observer);
  }

  /** Set flush observer
  @param[in]	observer	flush observer */
  void set_flush_observer(FlushObserver *observer) {
    ut_ad(observer == nullptr || m_impl.m_log_mode == MTR_LOG_NO_REDO);

    m_impl.m_flush_observer = observer;
  }

#ifdef UNIV_DEBUG
  /** Check if memo contains the given item.
  @param memo	memo stack
  @param object	object to search
  @param type	type of object
  @return	true if contains */
  static bool memo_contains(mtr_buf_t *memo, const void *object, ulint type)
      MY_ATTRIBUTE((warn_unused_result));

  /** Check if memo contains the given item.
  @param ptr		object to search
  @param flags		specify types of object (can be ORred) of
                          MTR_MEMO_PAGE_S_FIX ... values
  @return true if contains */
  bool memo_contains_flagged(const void *ptr, ulint flags) const
      MY_ATTRIBUTE((warn_unused_result));

  /** Check if memo contains the given page.
  @param[in]	ptr	pointer to within buffer frame
  @param[in]	flags	specify types of object with OR of
                          MTR_MEMO_PAGE_S_FIX... values
  @return	the block
  @retval	NULL	if not found */
  buf_block_t *memo_contains_page_flagged(const byte *ptr, ulint flags) const
      MY_ATTRIBUTE((warn_unused_result));

  /** Mark the given latched page as modified.
  @param[in]	ptr	pointer to within buffer frame */
  void memo_modify_page(const byte *ptr);

  /** Print info of an mtr handle. */
  void print() const;

  /** @return true if the mini-transaction has committed */
  bool has_committed() const MY_ATTRIBUTE((warn_unused_result)) {
    return (m_impl.m_state == MTR_STATE_COMMITTED);
  }

  /** @return true if the mini-transaction is committing */
  bool is_committing() const {
    return (m_impl.m_state == MTR_STATE_COMMITTING);
  }

  /** @return true if mini-transaction contains modifications. */
  bool has_modifications() const MY_ATTRIBUTE((warn_unused_result)) {
    return (m_impl.m_modifications);
  }

  /** @return the memo stack */
  const mtr_buf_t *get_memo() const MY_ATTRIBUTE((warn_unused_result)) {
    return (&m_impl.m_memo);
  }

  /** @return the memo stack */
  mtr_buf_t *get_memo() MY_ATTRIBUTE((warn_unused_result)) {
    return (&m_impl.m_memo);
  }

  /** Computes the number of bytes that would be written to the redo
  log if mtr was committed right now (excluding headers of log blocks).
  @return  number of bytes of the colllected log records increased
           by 1 if MLOG_MULTI_REC_END would already be required */
  size_t get_expected_log_size() const {
    return (m_impl.m_log.size() + (m_impl.m_n_log_recs > 1 ? 1 : 0));
  }

  void wait_for_flush();
#endif /* UNIV_DEBUG */

  /** @return true if a record was added to the mini-transaction */
  bool is_dirty() const MY_ATTRIBUTE((warn_unused_result)) {
    return (m_impl.m_made_dirty);
  }

  /** Note that a record has been added to the log */
  void added_rec() { ++m_impl.m_n_log_recs; }

  /** Get the buffered redo log of this mini-transaction.
  @return	redo log */
  const mtr_buf_t *get_log() const MY_ATTRIBUTE((warn_unused_result)) {
    ut_ad(m_impl.m_magic_n == MTR_MAGIC_N);

    return (&m_impl.m_log);
  }

  /** Get the buffered redo log of this mini-transaction.
  @return	redo log */
  mtr_buf_t *get_log() MY_ATTRIBUTE((warn_unused_result)) {
    ut_ad(m_impl.m_magic_n == MTR_MAGIC_N);

    return (&m_impl.m_log);
  }

  /** Push an object to an mtr memo stack.
  @param object	object
  @param type	object type: MTR_MEMO_S_LOCK, ... */
  inline void memo_push(void *object, mtr_memo_type_t type);

  /** Check if this mini-transaction is dirtying a clean page.
  @param block	block being x-fixed
  @return true if the mtr is dirtying a clean page. */
  static bool is_block_dirtied(const buf_block_t *block)
      MY_ATTRIBUTE((warn_unused_result));

  /** Matrix to check if a mode update request should be ignored. */
  static bool s_mode_update[MTR_LOG_MODE_MAX][MTR_LOG_MODE_MAX];

#ifdef UNIV_DEBUG
  /** For checking invalid mode update requests. */
  static bool s_mode_update_valid[MTR_LOG_MODE_MAX][MTR_LOG_MODE_MAX];
#endif /* UNIV_DEBUG */

#ifndef UNIV_HOTBACKUP
  /** Instance level logging information for all mtrs. */
  static Logging s_logging;
#endif /* !UNIV_HOTBACKUP */

 private:
  Impl m_impl;

  /** LSN at commit time */
  lsn_t m_commit_lsn;

  /** true if it is synchronous mini-transaction */
  bool m_sync;

  class Command;

  friend class Command;
};

#ifndef UNIV_HOTBACKUP
#ifdef UNIV_DEBUG

/** Reserves space in the log buffer and writes a single MLOG_TEST.
@param[in,out]  log      redo log
@param[in]      payload  number of extra bytes within the record,
                         not greater than 1024
@return end_lsn pointing to the first byte after the written record */
lsn_t mtr_commit_mlog_test(log_t &log, size_t payload = 0);

/** Reserves space in the log buffer and writes a single MLOG_TEST.
Adjusts size of the payload in the record, in order to fill the current
block up to its boundary. If nothing else is happening in parallel,
we could expect to see afterwards:
(cur_lsn + space_left) % OS_FILE_LOG_BLOCK_SIZE == LOG_BLOCK_HDR_SIZE,
where cur_lsn = log_get_lsn(log).
@param[in,out]  log         redo log
@param[in]      space_left  extra bytes left to the boundary of block,
                            must be not greater than 496 */
void mtr_commit_mlog_test_filling_block(log_t &log, size_t space_left = 0);

#endif /* UNIV_DEBUG */
#endif /* !UNIV_HOTBACKUP */

#include "mtr0mtr.ic"

#endif /* mtr0mtr_h */