Bug#33607959 CODE CLEANUP FOR pfs_processlist_enabled

This fix is a code cleanup, no change in behavior.

Before this fix, the variable
  pfs_processlist_enabled
was located inside the performance_schema implementation.

This is incorrect, as pfs_processlist_enabled:
- does not control the instrumentation itself
- only controls the behavior of SHOW PROCESSLIST in the SQL layer.

This fix moves pfs_processlist_enabled to the SQL layer,
and removes dead code.

Change-Id: Icfee49e94e26f30715a13b0508d8bf840bbc1517

Author: marcalff

sql/log_event.cc

@@ -71,6 +71,7 @@
 #include "sql/my_decimal.h"   // my_decimal
 #include "sql/rpl_handler.h"  // RUN_HOOK
 #include "sql/rpl_tblmap.h"
+#include "sql/sql_show_processlist.h"  // pfs_processlist_enabled
 #include "sql/system_variables.h"
 #include "sql/tc_log.h"
 #include "sql_const.h"
@@ -174,8 +175,6 @@ PSI_memory_key key_memory_log_event;
 PSI_memory_key key_memory_Incident_log_event_message;
 PSI_memory_key key_memory_Rows_query_log_event_rows_query;
 
-extern bool pfs_processlist_enabled;
-
 using std::max;
 using std::min;
 

sql/parse_tree_nodes.cc

@@ -93,8 +93,6 @@
 #include "sql_string.h"
 #include "template_utils.h"
 
-extern bool pfs_processlist_enabled;
-
 namespace {
 
 template <typename Context, typename Node>
@@ -2348,8 +2346,11 @@ Sql_cmd *PT_show_processlist::make_cmd(THD *thd) {
   LEX *lex = thd->lex;
   lex->sql_command = m_sql_command;
 
-  m_sql_cmd.set_use_pfs(pfs_processlist_enabled);
-  if (pfs_processlist_enabled) {
+  // Read once, to avoid race conditions.
+  bool use_pfs = pfs_processlist_enabled;
+
+  m_sql_cmd.set_use_pfs(use_pfs);
+  if (use_pfs) {
     if (build_processlist_query(m_pos, thd, m_sql_cmd.verbose()))
       return nullptr;
   }

sql/sql_show.h

@@ -162,8 +162,6 @@ class Sql_cmd_show : public Sql_cmd_select {
   bool execute(THD *thd) override;
 
  protected:
-  // Use for SHOW commands that operate on a single table.
-  bool check_privileges_for_table(THD *thd, bool is_temporary);
   enum_sql_command m_sql_command;
 };
 
@@ -475,7 +473,6 @@ class Sql_cmd_show_processlist : public Sql_cmd_show {
 
  private:
   bool use_pfs() { return m_use_pfs; }
-  bool execute_with_performance_schema(THD *thd);
 
   const bool m_verbose{false};
   bool m_use_pfs{false};

sql/sql_show_processlist.cc

@@ -20,10 +20,10 @@
    along with this program; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */
 
-#include "sql/sql_show_processlist.h"
-
 #include <stddef.h>
 
+#include "sql/sql_show_processlist.h"
+
 #include "lex_string.h"
 #include "m_string.h"  // STRING_WITH_LEN
 #include "sql/auth/auth_acls.h"
@@ -40,7 +40,10 @@
 #include "sql/strfunc.h"
 #include "sql_string.h"
 
-extern bool pfs_processlist_enabled;
+/**
+  Implement SHOW PROCESSLIST by using performance schema.processlist
+*/
+bool pfs_processlist_enabled = false;
 
 static const LEX_CSTRING field_id = {STRING_WITH_LEN("ID")};
 static const LEX_CSTRING alias_id = {STRING_WITH_LEN("Id")};
@@ -143,7 +146,7 @@ bool build_processlist_query(const POS &pos, THD *thd, bool verbose) {
       new (thd->mem_root) PTI_simple_ident_ident(pos, field_info);
   if (ident_info == nullptr) return true;
 
-  /* Info length is either "25" or "100" depending on verbose */
+  /* Info length is either "100" or "1024" depending on verbose */
   Item_int *item_info_len = new (thd->mem_root) Item_int(pos, info_len);
   if (item_info_len == nullptr) return true;
 

sql/sql_show_processlist.h

@@ -27,6 +27,8 @@
 
 class THD;
 
+extern bool pfs_processlist_enabled;
+
 bool build_processlist_query(const POS &pos, THD *thd, bool verbose);
 
 #endif /* SQL_SHOW_PROCESSLIST_H */

sql/sys_vars.cc

@@ -126,9 +126,10 @@
 #include "sql/sp_head.h"          // SP_PSI_STATEMENT_INFO_COUNT
 #include "sql/sql_backup_lock.h"  // is_instance_backup_locked
 #include "sql/sql_lex.h"
-#include "sql/sql_locale.h"     // my_locale_by_number
-#include "sql/sql_parse.h"      // killall_non_super_threads
-#include "sql/sql_tmp_table.h"  // internal_tmp_mem_storage_engine_names
+#include "sql/sql_locale.h"            // my_locale_by_number
+#include "sql/sql_parse.h"             // killall_non_super_threads
+#include "sql/sql_show_processlist.h"  // pfs_processlist_enabled
+#include "sql/sql_tmp_table.h"         // internal_tmp_mem_storage_engine_names
 #include "sql/ssl_acceptor_context_operator.h"
 #include "sql/system_variables.h"
 #include "sql/table_cache.h"  // Table_cache_manager

storage/perfschema/pfs_instr_class.cc

@@ -66,14 +66,6 @@
 */
 bool pfs_enabled = true;
 
-/**
-  Global flag used to enable and disable SHOW PROCESSLIST in the
-  performance schema. This flag only takes effect if the performance schema
-  is configured to support SHOW PROCESSLIST.
-  @sa performance-schema-enable-processlist
-*/
-bool pfs_processlist_enabled = false;
-
 /**
   Global performance schema reference count for plugin and component events.
   Incremented when a shared library is being unloaded, decremented when

storage/perfschema/pfs_instr_class.h

@@ -82,7 +82,6 @@ class PFS_opaque_container_page;
 */
 
 extern bool pfs_enabled;
-extern bool pfs_processlist_enabled;
 
 /** Global ref count for plugin and component events. */
 extern std::atomic<uint32> pfs_unload_plugin_ref_count;

storage/perfschema/pfs_server.h

@@ -296,14 +296,6 @@ struct PFS_global_param {
 */
 extern PFS_global_param pfs_param;
 
-/**
-  Global flag used to enable and disable SHOW PROCESSLIST in the
-  performance schema. This flag only takes effect if the performance schema
-  is configured to support SHOW PROCESSLIST.
-  @sa performance-schema-enable-processlist
-*/
-extern bool pfs_processlist_enabled;
-
 /**
   Null initialization.
   Disable all instrumentation, size all internal buffers to 0.