Putting a mutex on the steering as there is a potential race condition here

if the http thread steers a parameter at the same time as the main thread
dispatches the queue.

Tom


git-svn-id: http://svn.cactuscode.org/arrangements/CactusConnect/HTTPD/trunk@96 1faa4e14-9dd3-4be0-9f0e-ffe519881164

1 files changed, 24 insertions, 0 deletions

diff --git a/src/Steer.c b/src/Steer.c
index d1da668..2f89e9b 100644
--- a/src/Steer.c
+++ b/src/Steer.c
@@ -17,6 +17,10 @@
 #include <stdlib.h>
 #include <string.h>
 
+#ifdef PTHREADS
+#include <pthread.h>
+#endif
+
 #ifdef CCTK_MPI
 #include "mpi.h"
 #endif
@@ -55,6 +59,10 @@ static int SteerParameters(void);
 static char *queuebuffer    = NULL;
 static int queuebuffer_size = 0;
 
+#ifdef PTHREADS
+static pthread_mutex_t steer_mutex = PTHREAD_MUTEX_INITIALIZER;
+#endif
+
 /********************************************************************
  *********************     External Routines   **********************
  ********************************************************************/
@@ -82,6 +90,10 @@ int HTTP_SteerQueue(const char *thorn, const char *parameter, const char *value)
   
   retval = 0;
 
+#ifdef PTHREADS
+  pthread_mutex_lock(&steer_mutex);
+#endif
+
   buffer_length = queuebuffer ? strlen(queuebuffer) : 0;
 
   /* Added length will be lengthof(thorn::par=val\n) */
@@ -110,6 +122,10 @@ int HTTP_SteerQueue(const char *thorn, const char *parameter, const char *value)
             thorn,parameter, value);
   }
 
+#ifdef PTHREADS
+  pthread_mutex_unlock(&steer_mutex);
+#endif
+
   return retval;
 }
 
@@ -129,10 +145,18 @@ int HTTP_SteerQueue(const char *thorn, const char *parameter, const char *value)
 @@*/
 int HTTP_SteerDispatch(void)
 {
+#ifdef PTHREADS
+  pthread_mutex_lock(&steer_mutex);
+#endif
+
   CommunicateBuffer();
 
   SteerParameters();
 
+#ifdef PTHREADS
+  pthread_mutex_unlock(&steer_mutex);
+#endif
+
   return 0;
 }