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.

1 files changed, 49 insertions, 11 deletions

diff --git a/sql-common/mysql_async.c b/sql-common/mysql_async.c
index c130eab5061..8f3a91e26fa 100644
--- a/sql-common/mysql_async.c
+++ b/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;
-  b->timeout_value= 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;
 }
 
 
@@ -239,9 +260,26 @@ 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;
 }