MINOR: trace: change the TRACE() calling convention to put the args and cb last

Previously the callback was almost mandatory so it made sense to have it
before the message. Now that it can default to the one declared in the
trace source, most TRACE() calls contain series of empty args and callbacks,
which make them suitable for being at the end and being totally omitted.

This patch thus reverses the TRACE arguments so that the message appears
first, then the mask, then arg1..arg4, then the callback. In practice
we'll mostly see 1 arg, or 2 args and nothing else, and it will not be
needed anymore to pass long series of commas in the middle of the
arguments. However if a source is enforced, the empty commas will still
be needed for all omitted arguments.

diff --git a/include/proto/trace.h b/include/proto/trace.h
index 7207233de1578cf949d681912422dfd0d34de647..5df7107c46fa137429164591e9de17ee5f668328 100644 (file)
--- a/include/proto/trace.h
+++ b/include/proto/trace.h
@@ -36,29 +36,36 @@
 #define _TRC_LOC(f,l) __TRC_LOC(f, ":", l)
 #define __TRC_LOC(f,c,l) f c #l
 
+/* truncate a macro arg list to exactly 5 args and replace missing ones with NULL */
+#define TRC_5ARGS(a1,a2,a3,a4,a5,...) DEFNULL(a1),DEFNULL(a2),DEFNULL(a3),DEFNULL(a4),DEFNULL(a5)
+
 /* For convenience, TRACE() alone uses the file's default TRACE_LEVEL, most
- * likely TRACE_LEVEL_DEVELOPER. The 4 arguments are the 4 source-specific
- * arguments that are passed to the cb() callback dedicated to decoding, and
- * which may be used for special tracking. These 4 arguments as well as the
- * cb() function pointer may all be NULL, or simply omitted (in which case
- * they will be replaced by a NULL). This ordering allows many TRACE() calls
- * to be placed using copy-paste and just change the message at the end.
+ * likely TRACE_LEVEL_DEVELOPER, though the other explicit variants specify
+ * the desired level and will work when TRACE_LEVEL is not set. The 5 optional
+ * arguments are the 4 source-specific arguments that are passed to the cb()
+ * callback dedicated to decoding, and which may be used for special tracking.
+ * These 4 arguments as well as the cb() function pointer may all be NULL, or
+ * simply omitted (in which case they will be replaced by a NULL). This
+ * ordering allows many TRACE() calls to be placed using copy-paste and just
+ * change the message at the beginning.
  */
+#define TRACE(msg, mask, ...)    \
+       trace(TRACE_LEVEL,           (mask), TRACE_SOURCE, ist(TRC_LOC), TRC_5ARGS(__VA_ARGS__,,,,,), ist(msg))
+
+#define TRACE_USER(msg, mask, ...)                     \
+       trace(TRACE_LEVEL_USER,      (mask), TRACE_SOURCE, ist(TRC_LOC), TRC_5ARGS(__VA_ARGS__,,,,,), ist(msg))
+
+#define TRACE_PAYLOAD(msg, mask, ...)  \
+       trace(TRACE_LEVEL_PAYLOAD,   (mask), TRACE_SOURCE, ist(TRC_LOC), TRC_5ARGS(__VA_ARGS__,,,,,), ist(msg))
+
+#define TRACE_PROTO(msg, mask, ...)    \
+       trace(TRACE_LEVEL_PROTO,     (mask), TRACE_SOURCE, ist(TRC_LOC), TRC_5ARGS(__VA_ARGS__,,,,,), ist(msg))
+
+#define TRACE_STATE(msg, mask, ...)    \
+       trace(TRACE_LEVEL_STATE,     (mask), TRACE_SOURCE, ist(TRC_LOC), TRC_5ARGS(__VA_ARGS__,,,,,), ist(msg))
 
-#define TRACE(mask, a1, a2, a3, a4, cb, msg)    \
-       trace(TRACE_LEVEL, (mask), TRACE_SOURCE, ist(TRC_LOC), DEFNULL(a1), DEFNULL(a2), DEFNULL(a3), DEFNULL(a4), DEFNULL(cb), ist(msg))
-
-/* and explicit trace levels (recommended) */
-#define TRACE_USER(mask, a1, a2, a3, a4, cb, msg)     \
-       trace(TRACE_LEVEL_USER,      (mask), TRACE_SOURCE, ist(TRC_LOC), DEFNULL(a1), DEFNULL(a2), DEFNULL(a3), DEFNULL(a4), DEFNULL(cb), ist(msg))
-#define TRACE_PAYLOAD(mask, a1, a2, a3, a4, cb, msg)  \
-       trace(TRACE_LEVEL_PAYLOAD,   (mask), TRACE_SOURCE, ist(TRC_LOC), DEFNULL(a1), DEFNULL(a2), DEFNULL(a3), DEFNULL(a4), DEFNULL(cb), ist(msg))
-#define TRACE_PROTO(mask, a1, a2, a3, a4, cb, msg)    \
-       trace(TRACE_LEVEL_PROTO,     (mask), TRACE_SOURCE, ist(TRC_LOC), DEFNULL(a1), DEFNULL(a2), DEFNULL(a3), DEFNULL(a4), DEFNULL(cb), ist(msg))
-#define TRACE_STATE(mask, a1, a2, a3, a4, cb, msg)    \
-       trace(TRACE_LEVEL_STATE,     (mask), TRACE_SOURCE, ist(TRC_LOC), DEFNULL(a1), DEFNULL(a2), DEFNULL(a3), DEFNULL(a4), DEFNULL(cb), ist(msg))
-#define TRACE_DEVEL(mask, a1, a2, a3, a4, cb, msg)    \
-       trace(TRACE_LEVEL_DEVELOPER, (mask), TRACE_SOURCE, ist(TRC_LOC), DEFNULL(a1), DEFNULL(a2), DEFNULL(a3), DEFNULL(a4), DEFNULL(cb), ist(msg))
+#define TRACE_DEVEL(msg, mask, ...)    \
+       trace(TRACE_LEVEL_DEVELOPER, (mask), TRACE_SOURCE, ist(TRC_LOC), TRC_5ARGS(__VA_ARGS__,,,,,), ist(msg))
 
 extern struct list trace_sources;
 extern THREAD_LOCAL struct buffer trace_buf;