Optimize undo spaces lock

mysql-test/r/all_persisted_variables.result

@@ -46,17 +46,17 @@ include/assert.inc [Expect 500+ variables in the table. Due to open Bugs, we are
 
 # Test SET PERSIST
 
-include/assert.inc [Expect 445 persisted variables in the table.]
+include/assert.inc [Expect 446 persisted variables in the table.]
 
 ************************************************************
 * 3. Restart server, it must preserve the persisted variable
 *    settings. Verify persisted configuration.
 ************************************************************
 # restart
 
-include/assert.inc [Expect 445 persisted variables in persisted_variables table.]
-include/assert.inc [Expect 445 persisted variables shown as PERSISTED in variables_info table.]
-include/assert.inc [Expect 445 persisted variables with matching peristed and global values.]
+include/assert.inc [Expect 446 persisted variables in persisted_variables table.]
+include/assert.inc [Expect 446 persisted variables shown as PERSISTED in variables_info table.]
+include/assert.inc [Expect 446 persisted variables with matching peristed and global values.]
 
 ************************************************************
 * 4. Test RESET PERSIST IF EXISTS. Verify persisted variable

mysql-test/suite/innodb/r/monitor.result

@@ -178,6 +178,9 @@ undo_truncate_count	disabled
 undo_truncate_start_logging_count	disabled
 undo_truncate_done_logging_count	disabled
 undo_truncate_usec	disabled
+undo_truncate_snapshot_ticket_grant_count	disabled
+undo_truncate_snapshot_ticket_try_count	disabled
+undo_truncate_snapshot_ticket_wait_count	disabled
 log_lsn_last_flush	disabled
 log_lsn_last_checkpoint	disabled
 log_lsn_current	disabled

mysql-test/suite/innodb_undo/r/undo_tablespace_snapshot.result

@@ -0,0 +1,47 @@
+#
+# undo tablespace counter
+#
+SHOW VARIABLES LIKE 'innodb_rollback_segments';
+Variable_name	Value
+innodb_rollback_segments	1
+SELECT NAME, SPACE_TYPE, STATE FROM INFORMATION_SCHEMA.INNODB_TABLESPACES
+WHERE SPACE_TYPE = 'Undo' ORDER BY NAME;
+NAME	SPACE_TYPE	STATE
+innodb_undo_001	Undo	active
+innodb_undo_002	Undo	active
+SET GLOBAL innodb_purge_stop_now=ON;
+create table t1(
+keyc int,
+c1 char(255),
+c2 char(255),
+c3 char(255),
+c4 char(255),
+c5 char(255),
+c6 char(255),
+primary key(keyc)) engine = innodb;
+CREATE PROCEDURE populate_t1()
+BEGIN
+DECLARE i INT DEFAULT 1;
+while (i <= 20000) DO
+insert into t1 values (i, 'a', 'b', 'c', 'd', 'e', 'f' );
+SET i = i + 1;
+END WHILE;
+END |
+call populate_t1();
+delete from t1 where keyc < 10000;
+update t1 set c1 = 'mysql' where  keyc > 10000;
+update t1 set c2 = 'mysql' where  keyc > 10000;
+update t1 set c3= 'mysql' where keyc > 10000;
+update t1 set c4= 'mysql' where keyc > 10000;
+update t1 set c5= 'mysql' where keyc > 10000;
+update t1 set c6= 'mysql' where keyc > 10000;
+SELECT @@innodb_undo_spaces_snapshot_tickets;
+@@innodb_undo_spaces_snapshot_tickets
+100
+SET GLOBAL debug="+d,until_undo_spaces_snapshot_change,abort_if_use_undospace_latch";
+SET GLOBAL innodb_purge_run_now=ON;
+SET GLOBAL debug="-d,until_undo_spaces_snapshot_change";
+update t1 set c6= 'modified' where keyc = 10000;
+SET GLOBAL debug="-d,abort_if_use_undospace_latch";
+drop PROCEDURE populate_t1;
+drop table t1;

mysql-test/suite/innodb_undo/t/undo_tablespace_snapshot-master.opt

@@ -0,0 +1,6 @@
+--innodb_rollback_segments=1
+--innodb_undo_log_truncate=1
+--innodb_max_undo_log_size=11M
+--innodb_purge_rseg_truncate_frequency=1
+--log-error-verbosity=3
+--innodb_undo_spaces_snapshot_tickets=100

mysql-test/suite/innodb_undo/t/undo_tablespace_snapshot.test

@@ -0,0 +1,71 @@
+--echo #
+--echo # undo tablespace counter
+--echo #
+
+# This test uses debug settings like innodb_purge_stop_now.
+--source include/have_debug.inc
+
+# Valgrind would complain about memory leaks when we crash on purpose.
+--source include/not_valgrind.inc
+
+--source include/big_test.inc
+--source include/have_innodb_default_undo_tablespaces.inc
+
+SHOW VARIABLES LIKE 'innodb_rollback_segments';
+SELECT NAME, SPACE_TYPE, STATE FROM INFORMATION_SCHEMA.INNODB_TABLESPACES
+       WHERE SPACE_TYPE = 'Undo' ORDER BY NAME;
+
+SET GLOBAL innodb_purge_stop_now=ON;
+
+--connect(conn1,localhost,root,,test)
+--connection conn1
+
+create table t1(
+  keyc int,
+  c1 char(255),
+  c2 char(255),
+  c3 char(255),
+  c4 char(255),
+  c5 char(255),
+  c6 char(255),
+  primary key(keyc)) engine = innodb;
+
+delimiter |;
+CREATE PROCEDURE populate_t1()
+BEGIN
+        DECLARE i INT DEFAULT 1;
+        while (i <= 20000) DO
+                insert into t1 values (i, 'a', 'b', 'c', 'd', 'e', 'f' );
+                SET i = i + 1;
+        END WHILE;
+END |
+delimiter ;|
+
+call populate_t1();
+delete from t1 where keyc < 10000;
+update t1 set c1 = 'mysql' where  keyc > 10000;
+update t1 set c2 = 'mysql' where  keyc > 10000;
+update t1 set c3= 'mysql' where keyc > 10000;
+update t1 set c4= 'mysql' where keyc > 10000;
+update t1 set c5= 'mysql' where keyc > 10000;
+update t1 set c6= 'mysql' where keyc > 10000;
+
+SELECT @@innodb_undo_spaces_snapshot_tickets;
+SET GLOBAL debug="+d,until_undo_spaces_snapshot_change,abort_if_use_undospace_latch";
+SET GLOBAL innodb_purge_run_now=ON;
+
+# Wait until until_undo_spaces_snapshot_change to be reached.
+--sleep 10
+
+connection default;
+SET GLOBAL debug="-d,until_undo_spaces_snapshot_change";
+# The command can succeed iff until_undo_spaces_snapshot_change loop has ended. Otherwise abort_if_use_undospace_latch will be triggered.
+update t1 set c6= 'modified' where keyc = 10000;
+
+# Cleanup
+SET GLOBAL debug="-d,abort_if_use_undospace_latch";
+drop PROCEDURE populate_t1;
+drop table t1;
+--disconnect conn1
+
+--sleep 5

mysql-test/suite/sys_vars/r/all_vars.result

@@ -48,6 +48,8 @@ innodb_log_spin_cpu_pct_hwm
 innodb_log_spin_cpu_pct_hwm
 innodb_log_wait_for_flush_spin_hwm
 innodb_log_wait_for_flush_spin_hwm
+innodb_undo_spaces_snapshot_tickets
+innodb_undo_spaces_snapshot_tickets
 keyring_operations
 keyring_operations
 log_replica_updates

mysql-test/suite/sys_vars/r/innodb_monitor_disable_basic.result

@@ -178,6 +178,9 @@ undo_truncate_count	disabled
 undo_truncate_start_logging_count	disabled
 undo_truncate_done_logging_count	disabled
 undo_truncate_usec	disabled
+undo_truncate_snapshot_ticket_grant_count	disabled
+undo_truncate_snapshot_ticket_try_count	disabled
+undo_truncate_snapshot_ticket_wait_count	disabled
 log_lsn_last_flush	disabled
 log_lsn_last_checkpoint	disabled
 log_lsn_current	disabled

mysql-test/suite/sys_vars/r/innodb_monitor_enable_basic.result

@@ -178,6 +178,9 @@ undo_truncate_count	disabled
 undo_truncate_start_logging_count	disabled
 undo_truncate_done_logging_count	disabled
 undo_truncate_usec	disabled
+undo_truncate_snapshot_ticket_grant_count	disabled
+undo_truncate_snapshot_ticket_try_count	disabled
+undo_truncate_snapshot_ticket_wait_count	disabled
 log_lsn_last_flush	disabled
 log_lsn_last_checkpoint	disabled
 log_lsn_current	disabled

mysql-test/suite/sys_vars/r/innodb_monitor_reset_all_basic.result

@@ -178,6 +178,9 @@ undo_truncate_count	disabled
 undo_truncate_start_logging_count	disabled
 undo_truncate_done_logging_count	disabled
 undo_truncate_usec	disabled
+undo_truncate_snapshot_ticket_grant_count	disabled
+undo_truncate_snapshot_ticket_try_count	disabled
+undo_truncate_snapshot_ticket_wait_count	disabled
 log_lsn_last_flush	disabled
 log_lsn_last_checkpoint	disabled
 log_lsn_current	disabled

mysql-test/suite/sys_vars/r/innodb_monitor_reset_basic.result

@@ -178,6 +178,9 @@ undo_truncate_count	disabled
 undo_truncate_start_logging_count	disabled
 undo_truncate_done_logging_count	disabled
 undo_truncate_usec	disabled
+undo_truncate_snapshot_ticket_grant_count	disabled
+undo_truncate_snapshot_ticket_try_count	disabled
+undo_truncate_snapshot_ticket_wait_count	disabled
 log_lsn_last_flush	disabled
 log_lsn_last_checkpoint	disabled
 log_lsn_current	disabled

mysql-test/t/all_persisted_variables.test

@@ -56,7 +56,7 @@ let $total_global_vars=`SELECT COUNT(*)
    AND variable_name NOT LIKE 'debug_%'
    AND variable_name NOT LIKE '%telemetry%'`;
 
-let $total_persistent_vars=445;
+let $total_persistent_vars=446;
 
 --echo ***************************************************************
 --echo * 0. Verify that variables present in performance_schema.global

storage/innobase/CMakeLists.txt

@@ -254,6 +254,7 @@ SET(INNOBASE_SOURCES
   trx/trx0sys.cc
   trx/trx0trx.cc
   trx/trx0undo.cc
+  trx/undo_spaces_snapshot.cc
   usr/usr0sess.cc
   ut/ut0dbg.cc
   ut/ut0list.cc

storage/innobase/handler/ha_innodb.cc

@@ -611,6 +611,8 @@ static ulonglong innobase_fts_flags() {
   return (FTS_ORDERED_RESULT | FTS_DOCID_IN_RESULT);
 }
 
+static constexpr uint innodb_undo_spaces_snapshot_tickets_max = 1048576;
+
 /** Find and Retrieve the FTS doc_id for the current result row
 @param[in,out]  fts_hdl FTS handler
 @return the document ID */
@@ -22315,6 +22317,13 @@ static MYSQL_SYSVAR_ULONG(sync_array_size, srv_sync_array_size,
                           1,          /* Minimum value */
                           1024, 0);   /* Maximum value */
 
+static MYSQL_SYSVAR_UINT(undo_spaces_snapshot_tickets, innodb_undo_spaces_snapshot_tickets,
+                          PLUGIN_VAR_OPCMDARG,
+                          "Ticket number of undo spaces snapshot.", nullptr,
+                          nullptr, 0, /* Default setting */
+                          0,          /* Minimum value */
+                          innodb_undo_spaces_snapshot_tickets_max, 0);   /* Maximum value */
+
 static MYSQL_SYSVAR_ULONG(
     fast_shutdown, srv_fast_shutdown, PLUGIN_VAR_OPCMDARG,
     "Speeds up the shutdown process of the InnoDB storage engine. Possible"
@@ -23605,6 +23614,7 @@ static SYS_VAR *innobase_system_variables[] = {
     MYSQL_SYSVAR(undo_directory),
     MYSQL_SYSVAR(temp_tablespaces_dir),
     MYSQL_SYSVAR(sync_array_size),
+    MYSQL_SYSVAR(undo_spaces_snapshot_tickets),
     MYSQL_SYSVAR(compression_failure_threshold_pct),
     MYSQL_SYSVAR(compression_pad_pct_max),
     MYSQL_SYSVAR(default_row_format),

storage/innobase/include/srv0mon.h

@@ -340,6 +340,9 @@ enum monitor_id_t {
   MONITOR_UNDO_TRUNCATE_START_LOGGING_COUNT,
   MONITOR_UNDO_TRUNCATE_DONE_LOGGING_COUNT,
   MONITOR_UNDO_TRUNCATE_MICROSECOND,
+  MONITOR_UNDO_TRUNCATE_SNAPSHOT_TICKET_GRANT_COUNT,
+  MONITOR_UNDO_TRUNCATE_SNAPSHOT_TICKET_TRY_COUNT,
+  MONITOR_UNDO_TRUNCATE_SNAPSHOT_TICKET_WAIT_COUNT,
 
   /* Recovery related counters */
   MONITOR_MODULE_REDO_LOG,

storage/innobase/include/trx0purge.h

@@ -34,6 +34,7 @@ this program; if not, write to the Free Software Foundation, Inc.,
 #ifndef trx0purge_h
 #define trx0purge_h
 
+#include <atomic>
 #include "fil0fil.h"
 #include "mtr0mtr.h"
 #include "page0page.h"
@@ -50,6 +51,8 @@ this program; if not, write to the Free Software Foundation, Inc.,
 /** The global data structure coordinating a purge */
 extern trx_purge_t *purge_sys;
 
+extern unsigned int innodb_undo_spaces_snapshot_tickets;
+
 /** Calculates the file address of an undo log header when we have the file
  address of its history list node.
  @return file address of the log */
@@ -140,6 +143,9 @@ struct purge_iter_t {
 to truncate an undo tablespace. */
 namespace undo {
 
+// Forward declaration
+class Undo_spaces_snapshot;
+
 /** Magic Number to indicate truncate action is complete. */
 const uint32_t s_magic = 76845412;
 
@@ -814,6 +820,8 @@ class Inject_failure_once {
 
 #endif /* UNIV_DEBUG */
 
+extern Undo_spaces_snapshot *undo_spaces_snapshot;
+
 /** Create the truncate log file. Needed to track the state of truncate during
 a crash. An auxiliary redo log file undo_<space_id>_trunc.log will be created
 while the truncate of the UNDO is in progress. This file is required during

storage/innobase/include/undo_spaces_snapshot.h

@@ -0,0 +1,67 @@
+#ifndef UNDO_SPACES_SNAPSHOT_H
+#define UNDO_SPACES_SNAPSHOT_H
+
+#include <atomic>
+#include <vector>
+#include "trx0purge.h"
+
+#ifdef GMOCK_FOUND
+#include "gtest/gtest_prod.h"
+#endif
+
+namespace undo {
+
+class Undo_spaces_snapshot {
+ public:
+  Undo_spaces_snapshot();
+  Undo_spaces_snapshot(const Undo_spaces_snapshot &) = delete;
+  Undo_spaces_snapshot &operator=(const Undo_spaces_snapshot &) = delete;
+  Undo_spaces_snapshot(Undo_spaces_snapshot &&) = delete;
+  Undo_spaces_snapshot &operator=(Undo_spaces_snapshot &&) = delete;
+  ~Undo_spaces_snapshot();
+  /* Reset the snapshot and tickets. The method should never be called when
+   * block_until_tickets_returned is being executed. */
+  void reset(const unsigned int max_tickets,
+             const std::vector<Tablespace *> &tablespaces);
+  /* Return the undo tablespaces size in the snapshot. */
+  std::size_t get_target_undo_tablespaces_size() const;
+  /* Return the unused tickets number. */
+  unsigned int get_unused_tickets_number() const;
+  /* Request a ticket. It will repeatedly call try_request_ticket until either
+  it succeeds or unused_tickets_number equals 0. 
+  Return true if it succeeds.
+  Return false if there is no unused ticket. */
+  bool request_ticket();
+  /* Return a ticket requested earlier. */
+  void return_ticket();
+  /* Block the caller until all used tickets have been returned. */
+  void block_until_tickets_returned();
+  /* Return the max tickets number. */
+  unsigned int get_max_tickets_number() const;
+  /* Wrapper */
+  bool is_active_no_latch_for_undo_space(size_t pos) const;
+  /* Wrapper */
+  ulint get_rsegs_size_for_undo_space(size_t pos) const;
+  /* Wrapper */
+  trx_rseg_t *get_active_for_undo_space(size_t pos, ulint rseg_slot) const;
+
+ private:
+  /* Return the tablespace pointer at pos, or nullptr if pos is out of bound. */
+  Tablespace *at(size_t pos) const;
+
+ private:
+  unsigned int m_max_tickets;
+  std::atomic<unsigned int> m_unused_tickets;
+  std::atomic<unsigned int> m_used_tickets;
+  std::vector<Tablespace *> m_tablespaces;
+  std::atomic<bool> m_is_depriving;
+
+#ifdef FRIEND_TEST
+  FRIEND_TEST(UndoSpacesSnapshotTest, DefaultConstructor);
+  FRIEND_TEST(UndoSpacesSnapshotTest, UseAllTickets);
+  FRIEND_TEST(UndoSpacesSnapshotTest, UseSomeTickets);
+#endif
+}; /* class Undo_spaces_snapshot */
+} /* namespace undo */
+
+#endif  // UNDO_SPACES_SNAPSHOT_H

storage/innobase/srv/srv0mon.cc

@@ -864,6 +864,21 @@ static monitor_info_t innodb_counter_info[] = {
      "Time (in microseconds) spent to process undo truncation", MONITOR_NONE,
      MONITOR_DEFAULT_START, MONITOR_UNDO_TRUNCATE_MICROSECOND},
 
+    {"undo_truncate_snapshot_ticket_grant_count", "undo",
+     "Number of times during undo truncation a snapshot ticket was granted",
+     MONITOR_NONE, MONITOR_DEFAULT_START,
+     MONITOR_UNDO_TRUNCATE_SNAPSHOT_TICKET_GRANT_COUNT},
+
+    {"undo_truncate_snapshot_ticket_try_count", "undo",
+     "Number of times during undo truncation a snapshot ticket was tried",
+     MONITOR_NONE, MONITOR_DEFAULT_START,
+     MONITOR_UNDO_TRUNCATE_SNAPSHOT_TICKET_TRY_COUNT},
+
+    {"undo_truncate_snapshot_ticket_wait_count", "undo",
+     "Number of times during undo truncation the purge coordinator has waited until all tickets were returned",
+     MONITOR_NONE, MONITOR_DEFAULT_START,
+     MONITOR_UNDO_TRUNCATE_SNAPSHOT_TICKET_WAIT_COUNT},
+
     /* ========== Counters for Redo log Module ========== */
     {"module_log", "log", "Redo log Module", MONITOR_MODULE,
      MONITOR_DEFAULT_START, MONITOR_MODULE_REDO_LOG},