polardbxengine/storage/perfschema/table_variables_by_thread.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_variables_by_thread.cc
  Table VARIABLES_BY_THREAD (implementation).
*/

#include "storage/perfschema/table_variables_by_thread.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_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_variables_by_thread::match(PFS_thread *pfs) {
  if (m_fields >= 1) {
    if (!m_key_1.match(pfs)) {
      return false;
    }
  }

  return true;
}

bool PFS_index_variables_by_thread::match(const System_variable *pfs) {
  if (m_fields >= 2) {
    if (!m_key_2.match(pfs)) {
      return false;
    }
  }

  return true;
}

THR_LOCK table_variables_by_thread::m_table_lock;

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

PFS_engine_table_share table_variables_by_thread::m_share = {
    &pfs_readonly_acl,
    table_variables_by_thread::create,
    NULL, /* write_row */
    NULL, /* delete_all_rows */
    table_variables_by_thread::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_variables_by_thread::create(PFS_engine_table_share *) {
  return new table_variables_by_thread();
}

ha_rows table_variables_by_thread::get_row_count(void) {
  mysql_mutex_lock(&LOCK_plugin_delete);
  mysql_rwlock_rdlock(&LOCK_system_variables_hash);
  ulong system_var_count = get_system_variable_hash_records();
  mysql_rwlock_unlock(&LOCK_system_variables_hash);
  mysql_mutex_unlock(&LOCK_plugin_delete);
  return (global_thread_container.get_row_count() * system_var_count);
}

table_variables_by_thread::table_variables_by_thread()
    : PFS_engine_table(&m_share, &m_pos),
      m_sysvar_cache(true),
      m_pos(),
      m_next_pos(),
      m_context(NULL) {}

void table_variables_by_thread::reset_position(void) {
  m_pos.reset();
  m_next_pos.reset();
}

int table_variables_by_thread::rnd_init(bool scan) {
  /* Build array of SHOW_VARs from system variable hash. */
  m_sysvar_cache.initialize_session();

  /* Record the version of the system variable hash, store in TLS. */
  ulonglong hash_version = m_sysvar_cache.get_sysvar_hash_version();

  m_context = (table_variables_by_thread_context *)current_thd->alloc(
      sizeof(table_variables_by_thread_context));
  new (m_context) table_variables_by_thread_context(hash_version, !scan);
  return 0;
}

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

  bool has_more_thread = true;

  for (m_pos.set_at(&m_next_pos); has_more_thread; m_pos.next_thread()) {
    PFS_thread *pfs_thread =
        global_thread_container.get(m_pos.m_index_1, &has_more_thread);

    /* Materialize all variables for the current thread. Assign a dedicated
     * mem_root. */
    if (m_sysvar_cache.materialize_session(pfs_thread, true) == 0) {
      const System_variable *system_var = m_sysvar_cache.get(m_pos.m_index_2);
      if (system_var != NULL) {
        /* If make_row() fails, get the next thread. */
        if (!make_row(pfs_thread, system_var)) {
          m_next_pos.set_after(&m_pos);
          return 0;
        }
      }
    }
  }
  return HA_ERR_END_OF_FILE;
}

int table_variables_by_thread::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_1 < global_thread_container.get_row_count());

  PFS_thread *pfs_thread = global_thread_container.get(m_pos.m_index_1);

  /* Materialize the requested variable. */
  if (m_sysvar_cache.materialize_session(pfs_thread, m_pos.m_index_2) == 0) {
    /* Get the first (and only) element from the cache. */
    const System_variable *system_var = m_sysvar_cache.get();
    if (system_var != NULL) {
      return make_row(pfs_thread, system_var);
    }
  }
  return HA_ERR_RECORD_DELETED;
}

int table_variables_by_thread::index_init(uint idx MY_ATTRIBUTE((unused)),
                                          bool) {
  /* Build array of SHOW_VARs from the system variable hash. */
  m_sysvar_cache.initialize_session();

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

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

  return 0;
}

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

  bool has_more_thread = true;

  for (m_pos.set_at(&m_next_pos); has_more_thread; m_pos.next_thread()) {
    PFS_thread *pfs_thread =
        global_thread_container.get(m_pos.m_index_1, &has_more_thread);

    if (pfs_thread != NULL) {
      if (m_opened_index->match(pfs_thread)) {
        if (m_sysvar_cache.materialize_session(pfs_thread, true) == 0) {
          const System_variable *system_var;
          do {
            system_var = m_sysvar_cache.get(m_pos.m_index_2);
            if (system_var != NULL) {
              if (m_opened_index->match(system_var)) {
                if (!make_row(pfs_thread, system_var)) {
                  m_next_pos.set_after(&m_pos);
                  return 0;
                }
              }
              m_pos.m_index_2++;
            }
          } while (system_var != NULL);
        }
      }
    }
  }
  return HA_ERR_END_OF_FILE;
}

int table_variables_by_thread::make_row(PFS_thread *thread,
                                        const System_variable *system_var) {
  pfs_optimistic_state lock;

  if (system_var->is_null()) {
    return HA_ERR_RECORD_DELETED;
  }

  /* Protect this reader against a thread termination */
  thread->m_lock.begin_optimistic_lock(&lock);

  m_row.m_thread_internal_id = thread->m_thread_internal_id;

  if (m_row.m_variable_name.make_row(system_var->m_name,
                                     system_var->m_name_length) != 0) {
    return HA_ERR_RECORD_DELETED;
  }

  if (m_row.m_variable_value.make_row(system_var) != 0) {
    return HA_ERR_RECORD_DELETED;
  }

  if (!thread->m_lock.end_optimistic_lock(&lock)) {
    return HA_ERR_RECORD_DELETED;
  }

  return 0;
}

int table_variables_by_thread::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: /* THREAD_ID */
          set_field_ulonglong(f, m_row.m_thread_internal_id);
          break;
        case 1: /* VARIABLE_NAME */
          set_field_varchar_utf8(f, m_row.m_variable_name.m_str,
                                 m_row.m_variable_name.m_length);
          break;
        case 2: /* VARIABLE_VALUE */
          m_row.m_variable_value.set_field(f);
          break;
        default:
          DBUG_ASSERT(false);
      }
    }
  }

  return 0;
}