Add locking for all session data structure

[lttng-tools.git] / ltt-sessiond / session.h

diff --git a/ltt-sessiond/session.h b/ltt-sessiond/session.h
index 4227f92441b736d0bc2f656ca71c93475bf7f919..9eaa1c535e783897f0ed0ce90bf806b89f7e5e30 100644 (file)
--- a/ltt-sessiond/session.h
+++ b/ltt-sessiond/session.h
@@ -22,30 +22,53 @@
 #include <lttng/lttng.h>
 #include <urcu/list.h>
 
 #include <lttng/lttng.h>
 #include <urcu/list.h>
 

-/* Global session list */
+/*
+ * Tracing session list
+ *
+ * Statically declared in session.c and can be accessed by using
+ * get_session_list() function that returns the pointer to the list.
+ */

 struct ltt_session_list {
 struct ltt_session_list {

+       /*
+        * This lock protects any read/write access to the list and count (which is
+        * basically the list size). All public functions in session.c acquire this
+        * lock and release it before returning. If none of those functions are
+        * used, the lock MUST be acquired in order to iterate or/and do any
+        * actions on that list.
+        */
+       pthread_mutex_t lock;
+       /*
+        * Number of element in the list.
+        */
+       unsigned int count;

        struct cds_list_head head;
 };
 
        struct cds_list_head head;
 };
 

-extern struct ltt_session_list ltt_session_list;
-
-/* ltt-session - This data structure contains information needed
- * to identify a tracing session for both LTTng and UST.
+/*
+ * This data structure contains information needed to identify a tracing
+ * session for both LTTng and UST.

  */
 struct ltt_session {
  */
 struct ltt_session {

-       struct cds_list_head list;

        char *name;
        char *path;
        char *name;
        char *path;

-       struct cds_list_head ust_traces;

        struct ltt_kernel_session *kernel_session;
        struct ltt_kernel_session *kernel_session;

+       struct cds_list_head ust_traces;

        unsigned int ust_trace_count;
        unsigned int ust_trace_count;

-       pid_t ust_consumer;
+       /*
+        * Protect any read/write on this session data structure. This lock must be
+        * acquired *before* using any public functions declared below. Use
+        * lock_session() and unlock_session() for that.
+        */
+       pthread_mutex_t lock;
+       struct cds_list_head list;

 };
 
 /* Prototypes */
 int create_session(char *name, char *path);
 int destroy_session(char *name);
 void get_lttng_session(struct lttng_session *sessions);
 };
 
 /* Prototypes */
 int create_session(char *name, char *path);
 int destroy_session(char *name);
 void get_lttng_session(struct lttng_session *sessions);

+void lock_session(struct ltt_session *session);
+void unlock_session(struct ltt_session *session);

 struct ltt_session *find_session_by_name(char *name);
 unsigned int get_session_count(void);
 struct ltt_session_list *get_session_list(void);
 struct ltt_session *find_session_by_name(char *name);
 unsigned int get_session_count(void);
 struct ltt_session_list *get_session_list(void);