P_S 5.7.28

storage/perfschema/table_uvar_by_thread.cc

@@ -0,0 +1,329 @@
+/* Copyright (c) 2013, 2015, 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.
+
+  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 */
+
+/**
+  @file storage/perfschema/table_uvar_by_thread.cc
+  Table USER_VARIABLES_BY_THREAD (implementation).
+*/
+
+#include "my_global.h"
+#include "my_thread.h"
+#include "pfs_instr_class.h"
+#include "pfs_column_types.h"
+#include "pfs_column_values.h"
+#include "table_uvar_by_thread.h"
+#include "pfs_global.h"
+#include "pfs_visitor.h"
+#include "pfs_buffer_container.h"
+
+/* Iteration on THD from the sql layer. */
+#include "sql_class.h"
+//#include "mysqld_thd_manager.h"
+
+class Find_thd_user_var //: public Find_THD_Impl
+{
+public:
+  Find_thd_user_var(THD *unsafe_thd)
+    : m_unsafe_thd(unsafe_thd)
+  {}
+
+  virtual bool operator()(THD *thd)
+  {
+    if (thd != m_unsafe_thd)
+      return false;
+
+    if (thd->user_vars.records == 0)
+      return false;
+
+    mysql_mutex_lock(&thd->LOCK_thd_data);
+    return true;
+  }
+
+private:
+  THD *m_unsafe_thd;
+};
+
+void User_variables::materialize(PFS_thread *pfs, THD *thd)
+{
+  reset();
+
+  m_pfs= pfs;
+  m_thread_internal_id= pfs->m_thread_internal_id;
+  m_array.reserve(thd->user_vars.records);
+
+  user_var_entry *sql_uvar;
+
+  uint index= 0;
+  User_variable empty;
+
+  /* Protects thd->user_vars. */
+  mysql_mutex_assert_owner(&thd->LOCK_thd_data);
+
+  for (;;)
+  {
+    sql_uvar= reinterpret_cast<user_var_entry*> (my_hash_element(& thd->user_vars, index));
+    if (sql_uvar == NULL)
+      break;
+
+    /*
+      m_array is a container of objects (not pointers)
+
+      Naive code can:
+      - build locally a new entry
+      - add it to the container
+      but this causes useless object construction, destruction, and deep copies.
+
+      What we do here:
+      - add a dummy (empty) entry
+      - the container does a deep copy on something empty,
+        so that there is nothing to copy.
+      - get a reference to the entry added in the container
+      - complete -- in place -- the entry initialization
+    */
+    m_array.push(empty);
+    User_variable & pfs_uvar= *m_array.back();
+
+    /* Copy VARIABLE_NAME */
+    const char *name= sql_uvar->name.str;
+    size_t name_length= sql_uvar->name.length;
+    DBUG_ASSERT(name_length <= sizeof(pfs_uvar.m_name));
+    pfs_uvar.m_name.make_row(name, name_length);
+
+    /* Copy VARIABLE_VALUE */
+    bool null_value;
+    String *str_value;
+    String str_buffer;
+    uint decimals= 0;
+    str_value= sql_uvar->val_str(& null_value, & str_buffer, decimals);
+    if (str_value != NULL)
+    {
+      pfs_uvar.m_value.make_row(str_value->ptr(), str_value->length());
+    }
+    else
+    {
+      pfs_uvar.m_value.make_row(NULL, 0);
+    }
+
+    index++;
+  }
+}
+
+THR_LOCK table_uvar_by_thread::m_table_lock;
+
+PFS_engine_table_share
+table_uvar_by_thread::m_share=
+{
+  { C_STRING_WITH_LEN("user_variables_by_thread") },
+  &pfs_readonly_acl,
+  table_uvar_by_thread::create,
+  NULL, /* write_row */
+  NULL, /* delete_all_rows */
+  table_uvar_by_thread::get_row_count,
+  sizeof(pos_t),
+  &m_table_lock,
+  { C_STRING_WITH_LEN("CREATE TABLE user_variables_by_thread("
+  "THREAD_ID BIGINT unsigned not null,"
+  "VARIABLE_NAME VARCHAR(64) not null,"
+  "VARIABLE_VALUE LONGBLOB)") },
+  false  /* perpetual */
+};
+
+PFS_engine_table*
+table_uvar_by_thread::create(void)
+{
+  return new table_uvar_by_thread();
+}
+
+ha_rows
+table_uvar_by_thread::get_row_count(void)
+{
+  /*
+    This is an estimate only, not a hard limit.
+    The row count is given as a multiple of thread_max,
+    so that a join between:
+    - table performance_schema.threads
+    - table performance_schema.user_variables_by_thread
+    will still evaluate relative table sizes correctly
+    when deciding a join order.
+  */
+  return global_thread_container.get_row_count() * 10;
+}
+
+table_uvar_by_thread::table_uvar_by_thread()
+  : PFS_engine_table(&m_share, &m_pos),
+    m_row_exists(false), m_pos(), m_next_pos()
+{}
+
+void table_uvar_by_thread::reset_position(void)
+{
+  m_pos.reset();
+  m_next_pos.reset();
+}
+
+int table_uvar_by_thread::rnd_next(void)
+{
+  PFS_thread *thread;
+  bool has_more_thread= true;
+
+  for (m_pos.set_at(&m_next_pos);
+       has_more_thread;
+       m_pos.next_thread())
+  {
+    thread= global_thread_container.get(m_pos.m_index_1, & has_more_thread);
+    if (thread != NULL)
+    {
+      if (materialize(thread) == 0)
+      {
+        const User_variable *uvar= m_THD_cache.get(m_pos.m_index_2);
+        if (uvar != NULL)
+        {
+          make_row(thread, uvar);
+          m_next_pos.set_after(&m_pos);
+          return 0;
+        }
+      }
+    }
+  }
+
+  return HA_ERR_END_OF_FILE;
+}
+
+int
+table_uvar_by_thread::rnd_pos(const void *pos)
+{
+  PFS_thread *thread;
+
+  set_position(pos);
+
+  thread= global_thread_container.get(m_pos.m_index_1);
+  if (thread != NULL)
+  {
+    if (materialize(thread) == 0)
+    {
+      const User_variable *uvar= m_THD_cache.get(m_pos.m_index_2);
+      if (uvar != NULL)
+      {
+        make_row(thread, uvar);
+        return 0;
+      }
+    }
+  }
+
+  return HA_ERR_RECORD_DELETED;
+}
+
+int table_uvar_by_thread::materialize(PFS_thread *thread)
+{
+  if (m_THD_cache.is_materialized(thread))
+    return 0;
+
+  if (! thread->m_lock.is_populated())
+    return 1;
+
+  THD *unsafe_thd= thread->m_thd;
+  if (unsafe_thd == NULL)
+    return 1;
+
+  Find_thd_user_var finder(unsafe_thd);
+  THD *safe_thd= NULL;//Global_THD_manager::get_instance()->find_thd(&finder);
+  if (safe_thd == NULL)
+    return 1;
+
+  m_THD_cache.materialize(thread, safe_thd);
+  mysql_mutex_unlock(&safe_thd->LOCK_thd_data);
+  return 0;
+}
+
+void table_uvar_by_thread
+::make_row(PFS_thread *thread, const User_variable *uvar)
+{
+  pfs_optimistic_state lock;
+  m_row_exists= false;
+
+  /* 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;
+
+  /* uvar is materialized, pointing to it directly. */
+  m_row.m_variable_name= & uvar->m_name;
+  m_row.m_variable_value= & uvar->m_value;
+
+  if (! thread->m_lock.end_optimistic_lock(&lock))
+    return;
+
+  m_row_exists= true;
+}
+
+int table_uvar_by_thread
+::read_row_values(TABLE *table,
+                  unsigned char *buf,
+                  Field **fields,
+                  bool read_all)
+{
+  Field *f;
+
+  if (unlikely(! m_row_exists))
+    return HA_ERR_RECORD_DELETED;
+
+  /* Set the null bits */
+  DBUG_ASSERT(table->s->null_bytes == 1);
+  buf[0]= 0;
+
+  DBUG_ASSERT(m_row.m_variable_name != NULL);
+  DBUG_ASSERT(m_row.m_variable_value != NULL);
+
+  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 */
+        if (m_row.m_variable_value->get_value_length() > 0)
+        {
+          set_field_blob(f,
+                         m_row.m_variable_value->get_value(),
+                         m_row.m_variable_value->get_value_length());
+        }
+        else
+        {
+          f->set_null();
+        }
+        break;
+      default:
+        DBUG_ASSERT(false);
+      }
+    }
+  }
+
+  return 0;
+}
+