polardbxengine/storage/perfschema/table_global_variables.cc

/* Copyright (c) 2015, 2019, 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.

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  as designated in a particular file or component or in included license
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  This program is distributed in the hope that it will be useful,
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  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 */

/**
  @file storage/perfschema/table_global_variables.cc
  Table GLOBAL_VARIABLES (implementation).
*/

#include "storage/perfschema/table_global_variables.h"

#include <stddef.h>
#include <new>

#include "my_dbug.h"
#include "my_thread.h"
#include "sql/current_thd.h"
#include "sql/field.h"
#include "sql/mysqld.h"
#include "sql/plugin_table.h"
#include "sql/sql_audit.h"  // audit_global_variable_get
#include "sql/sql_class.h"
#include "sql/table.h"
#include "storage/perfschema/pfs_column_types.h"
#include "storage/perfschema/pfs_column_values.h"
#include "storage/perfschema/pfs_global.h"
#include "storage/perfschema/pfs_instr_class.h"

bool PFS_index_global_variables::match(const System_variable *pfs) {
  if (m_fields >= 1) {
    if (!m_key.match(pfs)) {
      return false;
    }
  }

  return true;
}

THR_LOCK table_global_variables::m_table_lock;

Plugin_table table_global_variables::m_table_def(
    /* Schema name */
    "performance_schema",
    /* Name */
    "global_variables",
    /* Definition */
    "  VARIABLE_NAME VARCHAR(64) not null,\n"
    "  VARIABLE_VALUE VARCHAR(1024),\n"
    "  PRIMARY KEY (VARIABLE_NAME) USING HASH\n",
    /* Options */
    " ENGINE=PERFORMANCE_SCHEMA",
    /* Tablespace */
    nullptr);

PFS_engine_table_share table_global_variables::m_share = {
    &pfs_readonly_world_acl,
    table_global_variables::create,
    NULL, /* write_row */
    NULL, /* delete_all_rows */
    table_global_variables::get_row_count,
    sizeof(pos_t),
    &m_table_lock,
    &m_table_def,
    true, /* perpetual */
    PFS_engine_table_proxy(),
    {0},
    false /* m_in_purgatory */
};

PFS_engine_table *table_global_variables::create(PFS_engine_table_share *) {
  return new table_global_variables();
}

ha_rows table_global_variables::get_row_count(void) {
  mysql_mutex_lock(&LOCK_plugin_delete);
  mysql_rwlock_rdlock(&LOCK_system_variables_hash);
  ha_rows system_var_count = get_system_variable_hash_records();
  mysql_rwlock_unlock(&LOCK_system_variables_hash);
  mysql_mutex_unlock(&LOCK_plugin_delete);
  return system_var_count;
}

table_global_variables::table_global_variables()
    : PFS_engine_table(&m_share, &m_pos),
      m_sysvar_cache(false),
      m_pos(0),
      m_next_pos(0),
      m_context(NULL) {}

void table_global_variables::reset_position(void) {
  m_pos.m_index = 0;
  m_next_pos.m_index = 0;
}

int table_global_variables::rnd_init(bool scan) {
  /*
    Build a list of system variables from the global system variable hash.
    Filter by scope.
  */
  m_sysvar_cache.materialize_global();

  /* Record the version of the system variable hash, store in TLS. */
  ulonglong hash_version = m_sysvar_cache.get_sysvar_hash_version();
  m_context = (table_global_variables_context *)current_thd->alloc(
      sizeof(table_global_variables_context));
  new (m_context) table_global_variables_context(hash_version, !scan);
  return 0;
}

int table_global_variables::rnd_next(void) {
  if (m_context && !m_context->versions_match()) {
    system_variable_warning();
    return HA_ERR_END_OF_FILE;
  }

  for (m_pos.set_at(&m_next_pos); m_pos.m_index < m_sysvar_cache.size();
       m_pos.next()) {
    const System_variable *system_var = m_sysvar_cache.get(m_pos.m_index);
    if (system_var != NULL) {
      m_next_pos.set_after(&m_pos);
      return make_row(system_var);
    }
  }
  return HA_ERR_END_OF_FILE;
}

int table_global_variables::rnd_pos(const void *pos) {
  if (m_context && !m_context->versions_match()) {
    system_variable_warning();
    return HA_ERR_END_OF_FILE;
  }

  set_position(pos);
  DBUG_ASSERT(m_pos.m_index < m_sysvar_cache.size());

  const System_variable *system_var = m_sysvar_cache.get(m_pos.m_index);
  if (system_var != NULL) {
    return make_row(system_var);
  }
  return HA_ERR_RECORD_DELETED;
}

int table_global_variables::index_init(uint idx MY_ATTRIBUTE((unused)), bool) {
  /*
    Build a list of system variables from the global system variable hash.
    Filter by scope.
  */
  m_sysvar_cache.materialize_global();

  /* Record the version of the system variable hash, store in TLS. */
  ulonglong hash_version = m_sysvar_cache.get_sysvar_hash_version();
  m_context = (table_global_variables_context *)current_thd->alloc(
      sizeof(table_global_variables_context));
  new (m_context) table_global_variables_context(hash_version, false);

  PFS_index_global_variables *result = NULL;
  DBUG_ASSERT(idx == 0);
  result = PFS_NEW(PFS_index_global_variables);
  m_opened_index = result;
  m_index = result;

  return 0;
}

int table_global_variables::index_next(void) {
  if (m_context && !m_context->versions_match()) {
    system_variable_warning();
    return HA_ERR_END_OF_FILE;
  }

  for (m_pos.set_at(&m_next_pos); m_pos.m_index < m_sysvar_cache.size();
       m_pos.next()) {
    const System_variable *system_var = m_sysvar_cache.get(m_pos.m_index);
    if (system_var != NULL) {
      if (m_opened_index->match(system_var)) {
        if (!make_row(system_var)) {
          m_next_pos.set_after(&m_pos);
          return 0;
        }
      }
    }
  }
  return HA_ERR_END_OF_FILE;
}

int table_global_variables::make_row(const System_variable *system_var) {
  if (system_var->is_null()) {
    return HA_ERR_RECORD_DELETED;
  }

  m_row.m_variable_name.make_row(system_var->m_name, system_var->m_name_length);
  m_row.m_variable_value.make_row(system_var);

  /*
    We are about to return a row to the SQL layer.
    Notify the audit plugins that a global variable is read.
  */
  mysql_audit_notify(current_thd, AUDIT_EVENT(MYSQL_AUDIT_GLOBAL_VARIABLE_GET),
                     m_row.m_variable_name.m_str,
                     m_row.m_variable_value.get_str(),
                     m_row.m_variable_value.get_length());

  return 0;
}

int table_global_variables::read_row_values(TABLE *table, unsigned char *buf,
                                            Field **fields, bool read_all) {
  Field *f;

  /* Set the null bits */
  DBUG_ASSERT(table->s->null_bytes == 1);
  buf[0] = 0;

  for (; (f = *fields); fields++) {
    if (read_all || bitmap_is_set(table->read_set, f->field_index)) {
      switch (f->field_index) {
        case 0: /* VARIABLE_NAME */
          set_field_varchar_utf8(f, m_row.m_variable_name.m_str,
                                 m_row.m_variable_name.m_length);
          break;
        case 1: /* VARIABLE_VALUE */
          m_row.m_variable_value.set_field(f);
          break;
        default:
          DBUG_ASSERT(false);
      }
    }
  }

  return 0;
}