Refactoring: struct lttng_channel_ops

[lttng-ust.git] / include / lttng / ust-events.h

diff --git a/include/lttng/ust-events.h b/include/lttng/ust-events.h
index 164c82c4c8288617702a56edc5eec30ba341b6aa..d070a3cc1128d7909b9eec222498a8e551608a6c 100644 (file)
--- a/include/lttng/ust-events.h
+++ b/include/lttng/ust-events.h
@@ -498,8 +498,14 @@ struct lttng_ust_shm_handle;
  * IMPORTANT: this structure is part of the ABI between the probe and
  * UST. Fields need to be only added at the end, never reordered, never
  * removed.
+ *
+ * The field @struct_size should be used to determine the size of the
+ * structure. It should be queried before using additional fields added
+ * at the end of the structure.
  */
-struct lttng_channel_ops {
+struct lttng_ust_channel_ops {
+       uint32_t struct_size;
+
        struct lttng_channel *(*channel_create)(const char *name,
                        void *buf_addr,
                        size_t subbuf_size, size_t num_subbuf,
@@ -527,6 +533,8 @@ struct lttng_channel_ops {
        int (*flush_buffer)(struct channel *chan, struct lttng_ust_shm_handle *handle);
        void (*event_strcpy)(struct lttng_ust_lib_ring_buffer_ctx *ctx,
                        const char *src, size_t len);
+
+       /* End of base ABI. Fields below should be used after checking struct_size. */
 };
 
 /*
@@ -548,7 +556,7 @@ struct lttng_channel {
        struct lttng_session *session;
        int objd;                       /* Object associated to channel */
        struct cds_list_head node;      /* Channel list in session */
-       const struct lttng_channel_ops *ops;
+       const struct lttng_ust_channel_ops *ops;
        int header_type;                /* 0: unset, 1: compact, 2: large */
        struct lttng_ust_shm_handle *handle;    /* shared-memory handle */