X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=blobdiff_plain;f=include%2Flttng%2Fsession.h;h=7e328b625f29ffcef9faf6fbcdc1172a83f45805;hp=6c54d7e4f5e55fc5fe4dde03ff8a4812e5411a97;hb=e9af56b3027eebc314384a797c01e6a7e35c8fd2;hpb=b178f53e90c376dd44b020535c32649edef8f80e

diff --git a/include/lttng/session.h b/include/lttng/session.h
index 6c54d7e4f..7e328b625 100644
--- a/include/lttng/session.h
+++ b/include/lttng/session.h
@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2014 - David Goulet <dgoulet@efficios.com>
+ * Copyright (C) 2019 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
  *
  * This library is free software; you can redistribute it and/or modify it
  * under the terms of the GNU Lesser General Public License, version 2.1 only,
@@ -23,6 +24,7 @@ extern "C" {
 #endif
 
 struct lttng_session_descriptor;
+struct lttng_destruction_handle;
 
 /*
  * Basic session information.
@@ -32,7 +34,7 @@ struct lttng_session_descriptor;
  *
  * The structures should be initialized to zero before use.
  */
-#define LTTNG_SESSION_PADDING1             12
+#define LTTNG_SESSION_PADDING1             8
 struct lttng_session {
 	char name[LTTNG_NAME_MAX];
 	/*
@@ -49,7 +51,29 @@ struct lttng_session {
 	uint32_t snapshot_mode;
 	unsigned int live_timer_interval;	/* usec */
 
+	/*
+	 * End of public attributes.
+	 * The remaining fields are used to deal with ABI management concerns.
+	 */
+
+	/*
+	 * 32-bit architectures are already naturally aligned on 4 bytes after
+	 * 'live_timer_interval'. However, the offset does not result in a
+	 * natural alignment on 64-bit architectures. Adding 4 bytes of
+	 * padding here results in an aligned offset after 'alignement_padding'
+	 * for both bitnesses.
+	 *
+	 * This was added since not all compilers appear to align unions in the
+	 * same way. Some (e.g. MSVC) do not seem to impose an alignement
+	 * constraint while others (e.g. gcc, clang, icc) seem to align it to
+	 * ensure 'ptr' is naturally aligned.
+	 */
+	char alignment_padding[4];
 	union {
+		/*
+		 * Ensure the 'extended' union has the same size for both
+		 * 32-bit and 64-bit builds.
+		 */
 		char padding[LTTNG_SESSION_PADDING1];
 		void *ptr;
 	} extended;
@@ -132,6 +156,21 @@ extern int lttng_create_session_live(const char *name, const char *url,
  */
 extern int lttng_destroy_session(const char *name);
 
+/*
+ * Destroy a tracing session.
+ *
+ * Performs the same function as lttng_destroy_session(), but provides
+ * an lttng_destruction_handle which can be used to wait for the completion
+ * of the session's destruction. The lttng_destroy_handle can also be used
+ * obtain the status and archive location of any implicit session
+ * rotation that may have occured during the session's destruction.
+ *
+ * Returns LTTNG_OK on success. The returned handle is owned by the caller
+ * and must be free'd using lttng_destruction_handle_destroy().
+ */
+extern enum lttng_error_code lttng_destroy_session_ext(const char *session_name,
+		struct lttng_destruction_handle **handle);
+
 /*
  * Behaves exactly like lttng_destroy_session but does not wait for data
  * availability.