MDEV-3802: Millisecond timeout support in non-blocking client library + fix incorrect blocking.

After the merge of VIO stuff from MySQL 5.6, there were some bugs left
in the non-blocking client library:

 - vio_io_wait() was introduced without any support for non-blocking operation,
   so async queries could turn into sync.

 - Timeouts were changed to milliseconds, but this was not reflected in the
   non-blocking API, also semantics was changed so signed -1 was used for
   "no timeout" rather than unsigned 0.

Fix by implementing and using my_io_wait_async() in the non-blocking case. And
by introducing a new mysql_get_timeout_value_ms() API function that provides
the timeout with millisecond granularity. The old mysql_get_timeout_value()
is kept and fixed to work correctly, converting the timeout to whole seconds.

include/my_context.h

@@ -182,8 +182,8 @@ struct mysql_async_context {
     my_bool r_my_bool;
   } ret_result;
   /*
-    The timeout value, for suspended calls that need to wake up on a timeout
-    (eg. mysql_real_connect_start().
+    The timeout value (in millisecods), for suspended calls that need to wake
+    up on a timeout (eg. mysql_real_connect_start().
   */
   unsigned int timeout_value;
   /*

include/mysql.h

@@ -852,6 +852,7 @@ int STDCALL mysql_close_start(MYSQL *sock);
 int STDCALL mysql_close_cont(MYSQL *sock, int status);
 my_socket STDCALL mysql_get_socket(const MYSQL *mysql);
 unsigned int STDCALL mysql_get_timeout_value(const MYSQL *mysql);
+unsigned int STDCALL mysql_get_timeout_value_ms(const MYSQL *mysql);
 
 /* status return codes */
 #define MYSQL_NO_DATA        100

include/mysql.h.pp

@@ -733,3 +733,4 @@ int mysql_close_start(MYSQL *sock);
 int mysql_close_cont(MYSQL *sock, int status);
 my_socket mysql_get_socket(const MYSQL *mysql);
 unsigned int mysql_get_timeout_value(const MYSQL *mysql);
+unsigned int mysql_get_timeout_value_ms(const MYSQL *mysql);

include/mysql_async.h

@@ -20,14 +20,14 @@
 
 extern int my_connect_async(struct mysql_async_context *b, my_socket fd,
                             const struct sockaddr *name, uint namelen,
-                            uint timeout);
+                            int vio_timeout);
 extern ssize_t my_recv_async(struct mysql_async_context *b, int fd,
-                             unsigned char *buf, size_t size, uint timeout);
+                             unsigned char *buf, size_t size, int timeout);
 extern ssize_t my_send_async(struct mysql_async_context *b, int fd,
                              const unsigned char *buf, size_t size,
-                             uint timeout);
-extern my_bool my_poll_read_async(struct mysql_async_context *b,
-                                  uint timeout);
+                             int timeout);
+extern my_bool my_io_wait_async(struct mysql_async_context *b,
+                                enum enum_vio_io_event event, int timeout);
 #ifdef HAVE_OPENSSL
 extern int my_ssl_read_async(struct mysql_async_context *b, SSL *ssl,
                              void *buf, int size);

sql-common/client.c

@@ -2995,9 +2995,10 @@ connect_sync_or_async(MYSQL *mysql, NET *net, my_socket fd,
       mysql->options.extension->async_context->active)
   {
     my_bool old_mode;
+    int vio_timeout= get_vio_connect_timeout(mysql);
     vio_blocking(net->vio, FALSE, &old_mode);
     return my_connect_async(mysql->options.extension->async_context, fd,
-                            name, namelen, mysql->options.connect_timeout);
+                            name, namelen, vio_timeout);
   }
 
   return my_connect(fd, name, namelen, mysql->options.connect_timeout);

sql-common/mysql_async.c

@@ -56,7 +56,7 @@ my_context_install_suspend_resume_hook(struct mysql_async_context *b,
 /* Asynchronous connect(); socket must already be set non-blocking. */
 int
 my_connect_async(struct mysql_async_context *b, my_socket fd,
-                 const struct sockaddr *name, uint namelen, uint timeout)
+                 const struct sockaddr *name, uint namelen, int vio_timeout)
 {
   int res;
   size_socket s_err_size;
@@ -90,9 +90,13 @@ my_connect_async(struct mysql_async_context *b, my_socket fd,
       return res;
 #endif
     b->events_to_wait_for|= MYSQL_WAIT_WRITE;
-    b->timeout_value= timeout;
-    if (timeout)
+    if (vio_timeout >= 0)
+    {
+      b->timeout_value= vio_timeout;
       b->events_to_wait_for|= MYSQL_WAIT_TIMEOUT;
+    }
+    else
+      b->timeout_value= 0;
     if (b->suspend_resume_hook)
       (*b->suspend_resume_hook)(TRUE, b->suspend_resume_hook_user_data);
     my_context_yield(&b->async_context);
@@ -119,7 +123,7 @@ my_connect_async(struct mysql_async_context *b, my_socket fd,
 
 ssize_t
 my_recv_async(struct mysql_async_context *b, int fd,
-              unsigned char *buf, size_t size, uint timeout)
+              unsigned char *buf, size_t size, int timeout)
 {
   ssize_t res;
 
@@ -129,7 +133,7 @@ my_recv_async(struct mysql_async_context *b, int fd,
     if (res >= 0 || IS_BLOCKING_ERROR())
       return res;
     b->events_to_wait_for= MYSQL_WAIT_READ;
-    if (timeout)
+    if (timeout >= 0)
     {
       b->events_to_wait_for|= MYSQL_WAIT_TIMEOUT;
       b->timeout_value= timeout;
@@ -147,7 +151,7 @@ my_recv_async(struct mysql_async_context *b, int fd,
 
 ssize_t
 my_send_async(struct mysql_async_context *b, int fd,
-              const unsigned char *buf, size_t size, uint timeout)
+              const unsigned char *buf, size_t size, int timeout)
 {
   ssize_t res;
 
@@ -157,7 +161,7 @@ my_send_async(struct mysql_async_context *b, int fd,
     if (res >= 0 || IS_BLOCKING_ERROR())
       return res;
     b->events_to_wait_for= MYSQL_WAIT_WRITE;
-    if (timeout)
+    if (timeout >= 0)
     {
       b->events_to_wait_for|= MYSQL_WAIT_TIMEOUT;
       b->timeout_value= timeout;
@@ -174,16 +178,33 @@ my_send_async(struct mysql_async_context *b, int fd,
 
 
 my_bool
-my_poll_read_async(struct mysql_async_context *b, uint timeout)
+my_io_wait_async(struct mysql_async_context *b, enum enum_vio_io_event event,
+                 int timeout)
 {
-  b->events_to_wait_for= MYSQL_WAIT_READ | MYSQL_WAIT_TIMEOUT;
+  switch (event)
+  {
+  case VIO_IO_EVENT_READ:
+    b->events_to_wait_for = MYSQL_WAIT_READ;
+    break;
+  case VIO_IO_EVENT_WRITE:
+    b->events_to_wait_for = MYSQL_WAIT_WRITE;
+    break;
+  case VIO_IO_EVENT_CONNECT:
+    b->events_to_wait_for = MYSQL_WAIT_WRITE | IF_WIN(0, MYSQL_WAIT_EXCEPT);
+    break;
+  }
+
+  if (timeout >= 0)
+  {
+    b->events_to_wait_for |= MYSQL_WAIT_TIMEOUT;
     b->timeout_value= timeout;
+  }
   if (b->suspend_resume_hook)
     (*b->suspend_resume_hook)(TRUE, b->suspend_resume_hook_user_data);
   my_context_yield(&b->async_context);
   if (b->suspend_resume_hook)
     (*b->suspend_resume_hook)(FALSE, b->suspend_resume_hook_user_data);
-  return (b->events_occured & MYSQL_WAIT_READ) ? 0 : 1;
+  return (b->events_occured & MYSQL_WAIT_TIMEOUT) ? 0 : 1;
 }
 
 
@@ -239,8 +260,25 @@ my_ssl_write_async(struct mysql_async_context *b, SSL *ssl,
 }
 #endif  /* HAVE_OPENSSL */
 
+/*
+  Legacy support of the MariaDB 5.5 version, where timeouts where only in
+  seconds resolution. Applications that use this will be asked to set a timeout
+  at the nearest higher whole-seconds value.
+*/
 unsigned int STDCALL
 mysql_get_timeout_value(const MYSQL *mysql)
+{
+  unsigned int timeout= mysql->options.extension->async_context->timeout_value;
+  /* Avoid overflow. */
+  if (timeout > UINT_MAX - 999)
+    return (timeout - 1)/1000 + 1;
+  else
+    return (timeout+999)/1000;
+}
+
+
+unsigned int STDCALL
+mysql_get_timeout_value_ms(const MYSQL *mysql)
 {
   return mysql->options.extension->async_context->timeout_value;
 }

vio/viosocket.c

@@ -897,6 +897,21 @@ int vio_io_wait(Vio *vio, enum enum_vio_io_event event, int timeout)
   MYSQL_SOCKET_WAIT_VARIABLES(locker, state) /* no ';' */
   DBUG_ENTER("vio_io_wait");
 
+  /*
+    Note that if zero timeout, then we will not block, so we do not need to
+    yield to calling application in the async case.
+  */
+  if (timeout != 0 && vio->async_context && vio->async_context->active)
+  {
+    MYSQL_START_SOCKET_WAIT(locker, &state, vio->mysql_socket,
+                            PSI_SOCKET_SELECT, 0);
+    ret= my_io_wait_async(vio->async_context, event, timeout);
+    if (ret == 0)
+      errno= SOCKET_ETIMEDOUT;
+    MYSQL_END_SOCKET_WAIT(locker, 0);
+    DBUG_RETURN(ret);
+  }
+
   memset(&pfd, 0, sizeof(pfd));
 
   pfd.fd= sd;
@@ -957,6 +972,21 @@ int vio_io_wait(Vio *vio, enum enum_vio_io_event event, int timeout)
   MYSQL_SOCKET_WAIT_VARIABLES(locker, state) /* no ';' */
   DBUG_ENTER("vio_io_wait");
 
+  /*
+    Note that if zero timeout, then we will not block, so we do not need to
+    yield to calling application in the async case.
+  */
+  if (timeout != 0 && vio->async_context && vio->async_context->active)
+  {
+    MYSQL_START_SOCKET_WAIT(locker, &state, vio->mysql_socket,
+                            PSI_SOCKET_SELECT, 0);
+    ret= my_io_wait_async(vio->async_context, event, timeout);
+    if (ret == 0)
+      WSASetLastError(SOCKET_ETIMEDOUT);
+    MYSQL_END_SOCKET_WAIT(locker, 0);
+    DBUG_RETURN(ret);
+  }
+
   /* Convert the timeout, in milliseconds, to seconds and microseconds. */
   if (timeout >= 0)
   {