lttng abi documentation: clarify getter usage requirements

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/lttng-abi.h b/lttng-abi.h
index 822b8839a4fa815868ae051b1f4cf7a4b0f76ba1..b414549cbacb48de2e31d524281d9ccce8805fcb 100644 (file)
--- a/lttng-abi.h
+++ b/lttng-abi.h
@@ -225,24 +225,30 @@ struct lttng_kernel_filter_bytecode {
 /* Event FD ioctl */
 #define LTTNG_KERNEL_FILTER                    _IO(0xF6, 0x90)
 
-/* LTTng-specific ioctls for the lib ringbuffer */
+/*
+ * LTTng-specific ioctls for the lib ringbuffer.
+ *
+ * Operations applying to the current sub-buffer need to occur between
+ * a get/put or get_next/put_next ioctl pair.
+ */
+
 /* returns the timestamp begin of the current sub-buffer */
 #define LTTNG_RING_BUFFER_GET_TIMESTAMP_BEGIN  _IOR(0xF6, 0x20, uint64_t)
 /* returns the timestamp end of the current sub-buffer */
 #define LTTNG_RING_BUFFER_GET_TIMESTAMP_END    _IOR(0xF6, 0x21, uint64_t)
-/* returns the number of events discarded */
+/* returns the number of events discarded of the current sub-buffer */
 #define LTTNG_RING_BUFFER_GET_EVENTS_DISCARDED _IOR(0xF6, 0x22, uint64_t)
-/* returns the packet payload size */
+/* returns the packet payload size of the current sub-buffer */
 #define LTTNG_RING_BUFFER_GET_CONTENT_SIZE     _IOR(0xF6, 0x23, uint64_t)
-/* returns the actual packet size */
+/* returns the packet size of the current sub-buffer*/
 #define LTTNG_RING_BUFFER_GET_PACKET_SIZE      _IOR(0xF6, 0x24, uint64_t)
-/* returns the stream id */
+/* returns the stream id (invariant for the stream) */
 #define LTTNG_RING_BUFFER_GET_STREAM_ID                _IOR(0xF6, 0x25, uint64_t)
-/* returns the current timestamp */
+/* returns the current timestamp as perceived from the tracer */
 #define LTTNG_RING_BUFFER_GET_CURRENT_TIMESTAMP        _IOR(0xF6, 0x26, uint64_t)
-/* returns the packet sequence number */
+/* returns the packet sequence number of the current sub-buffer */
 #define LTTNG_RING_BUFFER_GET_SEQ_NUM          _IOR(0xF6, 0x27, uint64_t)
-/* returns the stream instance id */
+/* returns the stream instance id (invariant for the stream) */
 #define LTTNG_RING_BUFFER_INSTANCE_ID          _IOR(0xF6, 0x28, uint64_t)
 
 #ifdef CONFIG_COMPAT
@@ -252,25 +258,25 @@ struct lttng_kernel_filter_bytecode {
 /* returns the timestamp end of the current sub-buffer */
 #define LTTNG_RING_BUFFER_COMPAT_GET_TIMESTAMP_END \
        LTTNG_RING_BUFFER_GET_TIMESTAMP_END
-/* returns the number of events discarded */
+/* returns the number of events discarded of the current sub-buffer */
 #define LTTNG_RING_BUFFER_COMPAT_GET_EVENTS_DISCARDED \
        LTTNG_RING_BUFFER_GET_EVENTS_DISCARDED
-/* returns the packet payload size */
+/* returns the packet payload size of the current sub-buffer */
 #define LTTNG_RING_BUFFER_COMPAT_GET_CONTENT_SIZE \
        LTTNG_RING_BUFFER_GET_CONTENT_SIZE
-/* returns the actual packet size */
+/* returns the packet size of the current sub-buffer */
 #define LTTNG_RING_BUFFER_COMPAT_GET_PACKET_SIZE \
        LTTNG_RING_BUFFER_GET_PACKET_SIZE
-/* returns the stream id */
+/* returns the stream id (invariant for the stream) */
 #define LTTNG_RING_BUFFER_COMPAT_GET_STREAM_ID \
        LTTNG_RING_BUFFER_GET_STREAM_ID
-/* returns the current timestamp */
+/* returns the current timestamp as perceived from the tracer */
 #define LTTNG_RING_BUFFER_COMPAT_GET_CURRENT_TIMESTAMP \
        LTTNG_RING_BUFFER_GET_CURRENT_TIMESTAMP
-/* returns the packet sequence number */
+/* returns the packet sequence number of the current sub-buffer */
 #define LTTNG_RING_BUFFER_COMPAT_GET_SEQ_NUM   \
        LTTNG_RING_BUFFER_GET_SEQ_NUM
-/* returns the stream instance id */
+/* returns the stream instance id (invariant for the stream) */
 #define LTTNG_RING_BUFFER_COMPAT_INSTANCE_ID   \
        LTTNG_RING_BUFFER_INSTANCE_ID
 #endif /* CONFIG_COMPAT */