From 049555ae5eb7c778e80f7b090530f2580aa84f3d Mon Sep 17 00:00:00 2001
From: yaworsky <yaworsky>
Date: Fri, 18 Nov 2005 09:37:37 +0000
Subject: Fixed race condition
---
daemon/dest_file.c | 66 +++++++++++++++++++++---------------------------------
1 file changed, 26 insertions(+), 40 deletions(-)
diff --git a/daemon/dest_file.c b/daemon/dest_file.c
index fb63195..7ede68c 100644
--- a/daemon/dest_file.c
+++ b/daemon/dest_file.c
@@ -236,10 +236,18 @@ static void flush_coalescer( struct file_writer* writer )
/******************************************************************************
* destroy_file_writer
+ *
+ * destination's critical section cs_file_writers must be held when calling
+ * this function
*/
static void destroy_file_writer( struct file_writer* writer )
{
TRACE_ENTER( "%p\n", writer );
+ if( writer->destination )
+ {
+ struct dest_extra *extra = writer->destination->extra;
+ extra->file_writers = g_list_remove( extra->file_writers, writer );
+ }
if( writer->fifo_event ) CloseHandle( writer->fifo_event );
if( writer->shutdown_event ) CloseHandle( writer->shutdown_event );
DeleteCriticalSection( &writer->fifo_cs );
@@ -251,6 +259,9 @@ static void destroy_file_writer( struct file_writer* writer )
/******************************************************************************
* create_file_writer
+ *
+ * destination's critical section cs_file_writers must be held when calling
+ * this function
*/
static struct file_writer* create_file_writer( gchar* file_name,
struct destination* destination )
@@ -304,27 +315,6 @@ error:
return NULL;
}
-/******************************************************************************
- * detach_writer_from_destination
- */
-static void detach_writer_from_destination( struct file_writer* writer )
-{
- struct dest_extra *extra;
-
- TRACE_ENTER( "%p\n", writer );
- if( !writer->destination )
- {
- TRACE_LEAVE( "done; already detached\n" );
- return;
- }
- extra = writer->destination->extra;
- EnterCriticalSection( &extra->cs_file_writers );
- extra->file_writers = g_list_remove( extra->file_writers, writer );
- LeaveCriticalSection( &extra->cs_file_writers );
- writer->destination = NULL;
- TRACE_LEAVE( "done\n" );
-}
-
/******************************************************************************
* pop_messages_from_queue
*
@@ -365,8 +355,10 @@ static void pop_messages_from_queue( struct file_writer* writer )
static unsigned __stdcall writer_thread_proc( void* arg )
{
struct file_writer *writer = arg;
+ struct dest_extra *extra = writer->destination->extra;
HANDLE wait_objects[2] = { writer->fifo_event, writer->shutdown_event };
gchar *pathname;
+ gboolean inside_cs = FALSE;
TRACE_ENTER( "writer=%p\n", writer );
@@ -402,35 +394,29 @@ static unsigned __stdcall writer_thread_proc( void* arg )
for(;;)
{
- DWORD w = WaitForMultipleObjects( 2, wait_objects, FALSE, WRITER_KEEPALIVE_TIME );
- if( WAIT_TIMEOUT == w )
+ switch( WaitForMultipleObjects( 2, wait_objects, FALSE, WRITER_KEEPALIVE_TIME ) )
{
- /* prepare to suicide; at this point a new message may be put into queue;
- detach writer from destination and continue to write any pending messages */
- detach_writer_from_destination( writer );
- /* from now no new messages will be put into queue */
- break;
- }
-
- if( WAIT_OBJECT_0 + 1 == w )
- /* shutdown */
- break;
+ case WAIT_TIMEOUT:
+ case WAIT_OBJECT_0 + 1:
+ /* no new messages should be put into the queue until we close the file */
+ EnterCriticalSection( &extra->cs_file_writers );
+ inside_cs = TRUE;
+ goto done;
- if( WAIT_OBJECT_0 == w )
+ case WAIT_OBJECT_0:
pop_messages_from_queue( writer );
+ break;
+ }
}
done:
- /* FIXME: possible race condition
- We detach writer from destination before close file.
- So if a new message has arrived and detached writer is flushing its queue
- then a new instance will can not open file.
- */
- detach_writer_from_destination( writer );
pop_messages_from_queue( writer );
flush_coalescer( writer );
if( writer->fd != INVALID_HANDLE_VALUE ) CloseHandle( writer->fd );
+
destroy_file_writer( writer );
+ if( inside_cs )
+ LeaveCriticalSection( &extra->cs_file_writers );
purge_log_dirs();
--
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