merge

1 files changed, 31 insertions, 0 deletions

diff --git a/mysys/my_winthread.c b/mysys/my_winthread.c
index 9fb1dd14b6c..aecb2f7cc78 100644
--- a/mysys/my_winthread.c
+++ b/mysys/my_winthread.c
@@ -147,4 +147,35 @@ int pthread_cancel(pthread_t thread)
   errno= EINVAL;
   return -1;
 }
+
+/*
+ One time initialization. For simplicity, we assume initializer thread
+ does not exit within init_routine().
+*/
+int my_pthread_once(my_pthread_once_t *once_control, 
+    void (*init_routine)(void))
+{
+  LONG state= InterlockedCompareExchange(once_control, MY_PTHREAD_ONCE_INPROGRESS,
+                                          MY_PTHREAD_ONCE_INIT);
+  switch(state)
+  {
+  case MY_PTHREAD_ONCE_INIT:
+    /* This is initializer thread */
+    (*init_routine)();
+    *once_control= MY_PTHREAD_ONCE_DONE;
+    break;
+
+  case MY_PTHREAD_ONCE_INPROGRESS:
+    /* init_routine in progress. Wait for its completion */
+    while(*once_control == MY_PTHREAD_ONCE_INPROGRESS)
+    {
+      Sleep(1);
+    }
+    break;
+  case MY_PTHREAD_ONCE_DONE:
+    /* Nothing to do */
+    break;
+  }
+  return 0;
+}
 #endif