[syslog-ng] [PATCH] afmongodb, afsql: Fix a race condition in the queue handling.

[Gergely Nagy]

On occassions where we received a message, woke up the worker thread,
then received two two others before the worker finished, we had a high
chance of triggering an assertion, because we ended up calling the
insert before the parallel_push stuff managed to wake up the thread
and clear the callbacks.

Now we explicitly clear parallel_push before popping the queue head,
for the simple reason that we do not need it at that point anymore.

Many thanks to Balazs Scheidler <bazsi at balabit.hu> for pointing out
what happens.

Signed-off-by: Gergely Nagy <algernon at balabit.hu>
---
 modules/afmongodb/afmongodb.c |    1 +
 modules/afsql/afsql.c         |    1 +
 2 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/modules/afmongodb/afmongodb.c b/modules/afmongodb/afmongodb.c
index 0f01f05..b2bd615 100644
--- a/modules/afmongodb/afmongodb.c
+++ b/modules/afmongodb/afmongodb.c
@@ -263,6 +263,7 @@ afmongodb_worker_insert (MongoDBDestDriver *self)
   afmongodb_dd_connect(self, TRUE);
 
   g_mutex_lock(self->queue_mutex);
+  log_queue_reset_parallel_push(self->queue);
   success = log_queue_pop_head(self->queue, &msg, &path_options, FALSE, FALSE);
   g_mutex_unlock(self->queue_mutex);
   if (!success)
diff --git a/modules/afsql/afsql.c b/modules/afsql/afsql.c
index 20db131..6fbd656 100644
--- a/modules/afsql/afsql.c
+++ b/modules/afsql/afsql.c
@@ -682,6 +682,7 @@ afsql_dd_insert_db(AFSqlDestDriver *self)
   else
     {
       g_mutex_lock(self->db_thread_mutex);
+      log_queue_reset_parallel_push(self->queue);
       success = log_queue_pop_head(self->queue, &msg, &path_options, (self->flags & AFSQL_DDF_EXPLICIT_COMMITS), FALSE);
       g_mutex_unlock(self->db_thread_mutex);
       if (!success)
-- 
1.7.6.3