From bada05a88369051ee60623b006929dd728f704e8 Mon Sep 17 00:00:00 2001
From: Vladislav Vaintroub <wlad@mariadb.com>
Date: Sun, 12 Jan 2020 13:45:36 +0100
Subject: tpool - implement post-task callback (for Innodb debugging)

---
 storage/innobase/srv/srv0srv.cc | 10 ++++++++++
 tpool/task.cc                   | 16 ++++++++++++++++
 tpool/task_group.cc             |  1 +
 tpool/tpool.h                   | 13 +++++++++++++
 tpool/tpool_generic.cc          |  2 +-
 tpool/tpool_win.cc              |  1 +
 6 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/storage/innobase/srv/srv0srv.cc b/storage/innobase/srv/srv0srv.cc
index d7408222fd6..adc25bb4eeb 100644
--- a/storage/innobase/srv/srv0srv.cc
+++ b/storage/innobase/srv/srv0srv.cc
@@ -714,6 +714,13 @@ static void thread_pool_thread_end()
 }
 
 
+#ifndef DBUG_OFF
+static void dbug_after_task_callback()
+{
+  ut_ad(!sync_check_iterate(sync_check()));
+}
+#endif
+
 void srv_thread_pool_init()
 {
   DBUG_ASSERT(!srv_thread_pool);
@@ -725,6 +732,9 @@ void srv_thread_pool_init()
 #endif
   srv_thread_pool->set_thread_callbacks(thread_pool_thread_init,
                                         thread_pool_thread_end);
+#ifndef DBUG_OFF
+  tpool::set_after_task_callback(dbug_after_task_callback);
+#endif
 }
 
 
diff --git a/tpool/task.cc b/tpool/task.cc
index 6d456aa6f30..c8384321e50 100644
--- a/tpool/task.cc
+++ b/tpool/task.cc
@@ -21,6 +21,21 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02111 - 1301 USA*/
 
 namespace tpool
 {
+
+#ifndef DBUG_OFF
+static callback_func_np after_task_callback;
+void set_after_task_callback(callback_func_np cb)
+{
+  after_task_callback= cb;
+}
+
+void execute_after_task_callback()
+{
+  if (after_task_callback)
+    after_task_callback();
+}
+#endif
+
   task::task(callback_func func, void* arg, task_group* group) :
     m_func(func), m_arg(arg), m_group(group) {}
 
@@ -35,6 +50,7 @@ namespace tpool
     {
       /* Execute directly. */
       m_func(m_arg);
+      dbug_execute_after_task_callback();
       release();
     }
   }
diff --git a/tpool/task_group.cc b/tpool/task_group.cc
index b52fe7c0f67..97fbb0911c8 100644
--- a/tpool/task_group.cc
+++ b/tpool/task_group.cc
@@ -53,6 +53,7 @@ namespace tpool
       if (t)
       {
         t->m_func(t->m_arg);
+        dbug_execute_after_task_callback();
         t->release();
       }
       lk.lock();
diff --git a/tpool/tpool.h b/tpool/tpool.h
index 472e59d5d9e..939ae919ff6 100644
--- a/tpool/tpool.h
+++ b/tpool/tpool.h
@@ -51,6 +51,7 @@ namespace tpool
  Task callback function
  */
 typedef void (*callback_func)(void *);
+typedef void (*callback_func_np)(void);
 class task;
 
 /** A class that can be used e.g. for
@@ -174,6 +175,18 @@ class thread_pool;
 
 extern aio *create_simulated_aio(thread_pool *tp);
 
+#ifndef DBUG_OFF
+/*
+  This function is useful for debugging to make sure all mutexes are released
+  inside a task callback
+*/
+void set_after_task_callback(callback_func_np cb);
+void execute_after_task_callback();
+#define dbug_execute_after_task_callback() execute_after_task_callback()
+#else
+#define dbug_execute_after_task_callback() do{}while(0)
+#endif
+
 class thread_pool
 {
 protected:
diff --git a/tpool/tpool_generic.cc b/tpool/tpool_generic.cc
index fd5cba67e80..ec4f39b930b 100644
--- a/tpool/tpool_generic.cc
+++ b/tpool/tpool_generic.cc
@@ -293,7 +293,7 @@ public:
         return;
 
       m_callback(m_data);
-
+      dbug_execute_after_task_callback();
       m_running = false;
 
       if (m_pool && m_period)
diff --git a/tpool/tpool_win.cc b/tpool/tpool_win.cc
index 878d1af87c8..09fd49d9411 100644
--- a/tpool/tpool_win.cc
+++ b/tpool/tpool_win.cc
@@ -93,6 +93,7 @@ class thread_pool_win : public thread_pool
         return;
       }
       timer->m_func(timer->m_data);
+      dbug_execute_after_task_callback();
       if (timer->m_period)
         timer->set_time(timer->m_period, timer->m_period);
     }
-- 
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