# name       : innodb_thread_concurrency_timer_based.patch
# introduced : 11 or before
# maintainer : Yasufumi
#
#!!! notice !!!
# Any small change to this file in the main branch
# should be done or reviewed by the maintainer!
--- a/storage/innobase/handler/ha_innodb.cc
+++ b/storage/innobase/handler/ha_innodb.cc
@@ -148,6 +148,7 @@
 static ulong innobase_write_io_threads;
 static long innobase_buffer_pool_instances = 1;
 
+static my_bool innobase_thread_concurrency_timer_based;
 static long long innobase_buffer_pool_size, innobase_log_file_size;
 
 /** Percentage of the buffer pool to reserve for 'old' blocks.
@@ -2577,6 +2578,9 @@
 	srv_n_log_files = (ulint) innobase_log_files_in_group;
 	srv_log_file_size = (ulint) innobase_log_file_size;
 
+	srv_thread_concurrency_timer_based =
+		(ibool) innobase_thread_concurrency_timer_based;
+
 #ifdef UNIV_LOG_ARCHIVE
 	srv_log_archive_on = (ulint) innobase_log_archive;
 #endif /* UNIV_LOG_ARCHIVE */
@@ -11601,6 +11605,12 @@
   "Maximum delay between polling for a spin lock (6 by default)",
   NULL, NULL, 6L, 0L, ~0L, 0);
 
+static MYSQL_SYSVAR_BOOL(thread_concurrency_timer_based,
+  innobase_thread_concurrency_timer_based,
+  PLUGIN_VAR_NOCMDARG | PLUGIN_VAR_READONLY,
+  "Use InnoDB timer based concurrency throttling. ",
+  NULL, NULL, FALSE);
+
 static MYSQL_SYSVAR_ULONG(thread_concurrency, srv_thread_concurrency,
   PLUGIN_VAR_RQCMDARG,
   "Helps in performance tuning in heavily concurrent environments. Sets the maximum number of threads allowed inside InnoDB. Value 0 will disable the thread throttling.",
@@ -11859,6 +11869,7 @@
   MYSQL_SYSVAR(spin_wait_delay),
   MYSQL_SYSVAR(table_locks),
   MYSQL_SYSVAR(thread_concurrency),
+  MYSQL_SYSVAR(thread_concurrency_timer_based),
   MYSQL_SYSVAR(thread_sleep_delay),
   MYSQL_SYSVAR(autoinc_lock_mode),
   MYSQL_SYSVAR(show_verbose_locks),
--- a/storage/innobase/include/srv0srv.h
+++ b/storage/innobase/include/srv0srv.h
@@ -165,6 +165,8 @@
 extern ulint	srv_mem_pool_size;
 extern ulint	srv_lock_table_size;
 
+extern ibool	srv_thread_concurrency_timer_based;
+
 extern ulint	srv_n_file_io_threads;
 extern my_bool	srv_random_read_ahead;
 extern ulong	srv_read_ahead_threshold;
--- a/storage/innobase/srv/srv0srv.c
+++ b/storage/innobase/srv/srv0srv.c
@@ -349,6 +349,7 @@
 computer. Bigger computers need bigger values. Value 0 will disable the
 concurrency check. */
 
+UNIV_INTERN ibool	srv_thread_concurrency_timer_based = FALSE;
 UNIV_INTERN ulong	srv_thread_concurrency	= 0;
 
 /* this mutex protects srv_conc data structures */
@@ -1148,6 +1149,75 @@
 /*********************************************************************//**
 Puts an OS thread to wait if there are too many concurrent threads
 (>= srv_thread_concurrency) inside InnoDB. The threads wait in a FIFO queue. */
+
+#ifdef HAVE_ATOMIC_BUILTINS
+static void
+enter_innodb_with_tickets(trx_t* trx)
+{
+	trx->declared_to_be_inside_innodb = TRUE;
+	trx->n_tickets_to_enter_innodb = SRV_FREE_TICKETS_TO_ENTER;
+	return;
+}
+
+static void
+srv_conc_enter_innodb_timer_based(trx_t* trx)
+{
+	lint	conc_n_threads;
+	ibool	has_yielded = FALSE;
+	ulint	has_slept = 0;
+
+	if (trx->declared_to_be_inside_innodb) {
+		ut_print_timestamp(stderr);
+		fputs(
+"  InnoDB: Error: trying to declare trx to enter InnoDB, but\n"
+"InnoDB: it already is declared.\n", stderr);
+		trx_print(stderr, trx, 0);
+		putc('\n', stderr);
+	}
+retry:
+	if (srv_conc_n_threads < (lint) srv_thread_concurrency) {
+		conc_n_threads = os_atomic_increment_lint(&srv_conc_n_threads, 1);
+		if (conc_n_threads <= (lint) srv_thread_concurrency) {
+			enter_innodb_with_tickets(trx);
+			return;
+		}
+		(void) os_atomic_increment_lint(&srv_conc_n_threads, -1);
+	}
+	if (!has_yielded)
+	{
+		has_yielded = TRUE;
+		os_thread_yield();
+		goto retry;
+	}
+	if (trx->has_search_latch
+	    || NULL != UT_LIST_GET_FIRST(trx->trx_locks)) {
+
+		conc_n_threads = os_atomic_increment_lint(&srv_conc_n_threads, 1);
+		enter_innodb_with_tickets(trx);
+		return;
+	}
+	if (has_slept < 2)
+	{
+		trx->op_info = "sleeping before entering InnoDB";
+		os_thread_sleep(10000);
+		trx->op_info = "";
+		has_slept++;
+	}
+	conc_n_threads = os_atomic_increment_lint(&srv_conc_n_threads, 1);
+	enter_innodb_with_tickets(trx);
+	return;
+}
+
+static void
+srv_conc_exit_innodb_timer_based(trx_t* trx)
+{
+	(void) os_atomic_increment_lint(&srv_conc_n_threads, -1);
+	trx->declared_to_be_inside_innodb = FALSE;
+	trx->n_tickets_to_enter_innodb = 0;
+	return;
+}
+#endif
+
 UNIV_INTERN
 void
 srv_conc_enter_innodb(
@@ -1182,6 +1252,13 @@
 		return;
 	}
 
+#ifdef HAVE_ATOMIC_BUILTINS
+	if (srv_thread_concurrency_timer_based) {
+		srv_conc_enter_innodb_timer_based(trx);
+		return;
+	}
+#endif
+
 	os_fast_mutex_lock(&srv_conc_mutex);
 retry:
 	if (trx->declared_to_be_inside_innodb) {
@@ -1335,6 +1412,14 @@
 	}
 
 	ut_ad(srv_conc_n_threads >= 0);
+#ifdef HAVE_ATOMIC_BUILTINS
+	if (srv_thread_concurrency_timer_based) {
+		(void) os_atomic_increment_lint(&srv_conc_n_threads, 1);
+		trx->declared_to_be_inside_innodb = TRUE;
+		trx->n_tickets_to_enter_innodb = 1;
+		return;
+	}
+#endif
 
 	os_fast_mutex_lock(&srv_conc_mutex);
 
@@ -1368,6 +1453,13 @@
 		return;
 	}
 
+#ifdef HAVE_ATOMIC_BUILTINS
+	if (srv_thread_concurrency_timer_based) {
+		srv_conc_exit_innodb_timer_based(trx);
+		return;
+	}
+#endif
+
 	os_fast_mutex_lock(&srv_conc_mutex);
 
 	ut_ad(srv_conc_n_threads > 0);