Refactoring: add back constness of public API structures

[lttng-ust.git] / include / ust-context-provider.h

diff --git a/include/ust-context-provider.h b/include/ust-context-provider.h
index 0425a31d6e398f1989c5a90c176034eafc5ab227..85beac90b58d510c92d264315e3f8bcc82dd8a20 100644 (file)
--- a/include/ust-context-provider.h
+++ b/include/ust-context-provider.h
@@ -13,42 +13,63 @@
 
 #include <stddef.h>
 #include <lttng/ust-events.h>
-#include <urcu/hlist.h>
+
+#include "ust-dynamic-type.h"
+
+struct lttng_ust_registered_context_provider;
+
+/*
+ * Context value
+ *
+ * IMPORTANT: this structure is part of the ABI between the probe and
+ * UST. Additional selectors may be added in the future, mapping to new
+ * union fields, which means the overall size of this structure may
+ * increase. This means this structure should never be nested within a
+ * public structure interface, nor embedded in an array.
+ */
+
+struct lttng_ust_ctx_value {
+       enum lttng_ust_dynamic_type sel;        /* Type selector */
+       union {
+               int64_t s64;
+               uint64_t u64;
+               const char *str;
+               double d;
+       } u;
+};
+
+/*
+ * Context provider
+ *
+ * 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_ust_context_provider {
-       char *name;
-       size_t (*get_size)(struct lttng_ctx_field *field, size_t offset);
-       void (*record)(struct lttng_ctx_field *field,
-                      struct lttng_ust_lib_ring_buffer_ctx *ctx,
-                      struct lttng_channel *chan);
-       void (*get_value)(struct lttng_ctx_field *field,
-                        struct lttng_ctx_value *value);
-       struct cds_hlist_node node;
+       uint32_t struct_size;
+
+       const char *name;
+       size_t (*get_size)(void *priv, size_t offset);
+       void (*record)(void *priv, struct lttng_ust_lib_ring_buffer_ctx *ctx,
+                      struct lttng_ust_channel_buffer *chan);
+       void (*get_value)(void *priv, struct lttng_ust_ctx_value *value);
+       void *priv;
+
+       /* End of base ABI. Fields below should be used after checking struct_size. */
 };
 
-int lttng_ust_context_provider_register(struct lttng_ust_context_provider *provider);
-void lttng_ust_context_provider_unregister(struct lttng_ust_context_provider *provider);
-
-int lttng_context_is_app(const char *name);
-
-void lttng_ust_context_set_session_provider(const char *name,
-               size_t (*get_size)(struct lttng_ctx_field *field, size_t offset),
-               void (*record)(struct lttng_ctx_field *field,
-                       struct lttng_ust_lib_ring_buffer_ctx *ctx,
-                       struct lttng_channel *chan),
-               void (*get_value)(struct lttng_ctx_field *field,
-                       struct lttng_ctx_value *value));
-
-int lttng_ust_add_app_context_to_ctx_rcu(const char *name, struct lttng_ctx **ctx);
-int lttng_ust_context_set_provider_rcu(struct lttng_ctx **_ctx,
-               const char *name,
-               size_t (*get_size)(struct lttng_ctx_field *field, size_t offset),
-               void (*record)(struct lttng_ctx_field *field,
-                       struct lttng_ust_lib_ring_buffer_ctx *ctx,
-                       struct lttng_channel *chan),
-               void (*get_value)(struct lttng_ctx_field *field,
-                       struct lttng_ctx_value *value));
-int lttng_context_add_rcu(struct lttng_ctx **ctx_p,
-               const struct lttng_ctx_field *f);
+/*
+ * Returns an opaque pointer on success, which must be passed to
+ * lttng_ust_context_provider_unregister for unregistration. Returns
+ * NULL on error.
+ */
+struct lttng_ust_registered_context_provider *lttng_ust_context_provider_register(struct lttng_ust_context_provider *provider);
+
+void lttng_ust_context_provider_unregister(struct lttng_ust_registered_context_provider *reg_provider);
 
 #endif /* _LTTNG_UST_CONTEXT_PROVIDER_H */