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/** @file include/dict0stats.ic
 Code used for calculating and manipulating table statistics.

 Created Jan 23, 2012 Vasil Dimov
 *******************************************************/

#include "dict0dict.h"
#include "dict0types.h"
#include "srv0srv.h"

/** Set the persistent statistics flag for a given table. This is set only
 in the in-memory table object and is not saved on disk. It will be read
 from the .frm file upon first open from MySQL after a server restart. */
UNIV_INLINE
void dict_stats_set_persistent(
    dict_table_t *table, /*!< in/out: table */
    ibool ps_on,         /*!< in: persistent stats explicitly enabled */
    ibool ps_off)        /*!< in: persistent stats explicitly disabled */
{
  /* Not allowed to have both flags set, but a CREATE or ALTER
  statement that contains "STATS_PERSISTENT=0 STATS_PERSISTENT=1" would
  end up having both set. In this case we clear the OFF flag. */
  if (ps_on && ps_off) {
    ps_off = FALSE;
  }

  ib_uint32_t stat_persistent = 0;

  if (ps_on) {
    stat_persistent |= DICT_STATS_PERSISTENT_ON;
  }

  if (ps_off) {
    stat_persistent |= DICT_STATS_PERSISTENT_OFF;
  }

  /* we rely on this assignment to be atomic */
  table->stat_persistent = stat_persistent;
}

/** Check whether persistent statistics is enabled for a given table.
 @return true if enabled, false otherwise */
UNIV_INLINE
ibool dict_stats_is_persistent_enabled(
    const dict_table_t *table) /*!< in: table */
{
  /* Because of the nature of this check (non-locking) it is possible
  that a table becomes:
  * PS-disabled immediately after this function has returned TRUE or
  * PS-enabled immediately after this function has returned FALSE.
  This means that it is possible that we do:
  + dict_stats_update(DICT_STATS_RECALC_PERSISTENT) on a table that has
    just been PS-disabled or
  + dict_stats_update(DICT_STATS_RECALC_TRANSIENT) on a table that has
    just been PS-enabled.
  This is acceptable. Avoiding this would mean that we would have to
  protect the ::stat_persistent with dict_table_stats_lock() like the
  other ::stat_ members which would be too big performance penalty,
  especially when this function is called from
  row_update_statistics_if_needed(). */

  /* we rely on this read to be atomic */
  ib_uint32_t stat_persistent = table->stat_persistent;

  if (stat_persistent & DICT_STATS_PERSISTENT_ON) {
    ut_ad(!(stat_persistent & DICT_STATS_PERSISTENT_OFF));
    return (TRUE);
  } else if (stat_persistent & DICT_STATS_PERSISTENT_OFF) {
    return (FALSE);
  } else {
    return (srv_stats_persistent);
  }
}

/** Set the auto recalc flag for a given table (only honored for a persistent
 stats enabled table). The flag is set only in the in-memory table object
 and is not saved in InnoDB files. It will be read from the .frm file upon
 first open from MySQL after a server restart. */
UNIV_INLINE
void dict_stats_auto_recalc_set(
    dict_table_t *table,   /*!< in/out: table */
    ibool auto_recalc_on,  /*!< in: explicitly enabled */
    ibool auto_recalc_off) /*!< in: explicitly disabled */
{
  ut_ad(!auto_recalc_on || !auto_recalc_off);

  ib_uint32_t stats_auto_recalc = 0;

  if (auto_recalc_on) {
    stats_auto_recalc |= DICT_STATS_AUTO_RECALC_ON;
  }

  if (auto_recalc_off) {
    stats_auto_recalc |= DICT_STATS_AUTO_RECALC_OFF;
  }

  /* we rely on this assignment to be atomic */
  table->stats_auto_recalc = stats_auto_recalc;
}

/** Check whether auto recalc is enabled for a given table.
 @return true if enabled, false otherwise */
UNIV_INLINE
ibool dict_stats_auto_recalc_is_enabled(
    const dict_table_t *table) /*!< in: table */
{
  /* we rely on this read to be atomic */
  ib_uint32_t stats_auto_recalc = table->stats_auto_recalc;

  if (stats_auto_recalc & DICT_STATS_AUTO_RECALC_ON) {
    ut_ad(!(stats_auto_recalc & DICT_STATS_AUTO_RECALC_OFF));
    return (TRUE);
  } else if (stats_auto_recalc & DICT_STATS_AUTO_RECALC_OFF) {
    return (FALSE);
  } else {
    return (srv_stats_auto_recalc);
  }
}

/** Initialize table's stats for the first time when opening a table. */
UNIV_INLINE
void dict_stats_init(dict_table_t *table) /*!< in/out: table */
{
  ut_ad(!mutex_own(&dict_sys->mutex));

  if (table->stat_initialized) {
    return;
  }

  dict_stats_upd_option_t opt;

  if (dict_stats_is_persistent_enabled(table)) {
    opt = DICT_STATS_FETCH_ONLY_IF_NOT_IN_MEMORY;
  } else {
    opt = DICT_STATS_RECALC_TRANSIENT;
  }

  dict_stats_update(table, opt);
}

/** Deinitialize table's stats after the last close of the table. This is
 used to detect "FLUSH TABLE" and refresh the stats upon next open. */
UNIV_INLINE
void dict_stats_deinit(dict_table_t *table) /*!< in/out: table */
{
  /* Don't assert the table->n_ref_count is 0 here, since there could
  be some background threads opening the table concurrently. This is
  not prevented. The cases prevented are in opening table code pathes,
  to acquire an existing table, table->mutex is required */

  dict_table_stats_lock(table, RW_X_LATCH);

  if (!table->stat_initialized) {
    dict_table_stats_unlock(table, RW_X_LATCH);
    return;
  }

  table->stat_initialized = FALSE;

#ifdef UNIV_DEBUG_VALGRIND
  UNIV_MEM_INVALID(&table->stat_n_rows, sizeof(table->stat_n_rows));
  UNIV_MEM_INVALID(&table->stat_clustered_index_size,
                   sizeof(table->stat_clustered_index_size));
  UNIV_MEM_INVALID(&table->stat_sum_of_other_index_sizes,
                   sizeof(table->stat_sum_of_other_index_sizes));
  UNIV_MEM_INVALID(&table->stat_modified_counter,
                   sizeof(table->stat_modified_counter));

  dict_index_t *index;

  for (index = table->first_index(); index != NULL; index = index->next()) {
    ulint n_uniq = dict_index_get_n_unique(index);

    UNIV_MEM_INVALID(index->stat_n_diff_key_vals,
                     n_uniq * sizeof(index->stat_n_diff_key_vals[0]));
    UNIV_MEM_INVALID(index->stat_n_sample_sizes,
                     n_uniq * sizeof(index->stat_n_sample_sizes[0]));
    UNIV_MEM_INVALID(index->stat_n_non_null_key_vals,
                     n_uniq * sizeof(index->stat_n_non_null_key_vals[0]));
    UNIV_MEM_INVALID(&index->stat_index_size, sizeof(index->stat_index_size));
    UNIV_MEM_INVALID(&index->stat_n_leaf_pages,
                     sizeof(index->stat_n_leaf_pages));
  }
#endif /* UNIV_DEBUG_VALGRIND */

  dict_table_stats_unlock(table, RW_X_LATCH);
}