[tor-commits] [tor/master] trace: Better structure lib/trace and configure options
nickm at torproject.org
nickm at torproject.org
Fri Jul 10 17:05:59 UTC 2020
commit 6fc6cbd9b347ee1f82a024a04c0276bbc6e82c99
Author: David Goulet <dgoulet at torproject.org>
Date: Thu Jan 9 12:17:49 2020 -0500
trace: Better structure lib/trace and configure options
In the next commits, we'll add more tracing options for instrumentation and
specific tracer.
This rename follows a more meaningful naming standard. It also adds a catch
all "HAVE_TRACING" define that indicate in the code that we have tracing
enabled.
Part of #32910
Signed-off-by: David Goulet <dgoulet at torproject.org>
---
configure.ac | 29 +++++++++++++++++++--------
src/lib/trace/debug.h | 30 ++++++++++++++++++----------
src/lib/trace/events.h | 52 +++++++++++++++++++-----------------------------
src/lib/trace/include.am | 10 ++++++----
4 files changed, 66 insertions(+), 55 deletions(-)
diff --git a/configure.ac b/configure.ac
index a6df7149a..680111b10 100644
--- a/configure.ac
+++ b/configure.ac
@@ -256,15 +256,22 @@ AC_ARG_ENABLE(seccomp,
AC_ARG_ENABLE(libscrypt,
AS_HELP_STRING(--disable-libscrypt, [do not attempt to use libscrypt]))
-dnl Enable event tracing which are transformed to debug log statement.
-AC_ARG_ENABLE(event-tracing-debug,
- AS_HELP_STRING(--enable-event-tracing-debug, [build with event tracing to debug log]))
-AM_CONDITIONAL([USE_EVENT_TRACING_DEBUG], [test "x$enable_event_tracing_debug" = "xyes"])
+dnl --- Tracing Options. ---
-if test x$enable_event_tracing_debug = xyes; then
- AC_DEFINE([USE_EVENT_TRACING_DEBUG], [1], [Tracing framework to log debug])
- AC_DEFINE([TOR_EVENT_TRACING_ENABLED], [1], [Compile the event tracing instrumentation])
-fi
+dnl Tracepoints event to debug logs.
+AC_ARG_ENABLE(tracing-instrumentation-log-debug,
+ AS_HELP_STRING([--enable-tracing-instrumentation-log-debug],
+ [build with tracing event to debug log]),
+ AC_DEFINE([USE_TRACING_INSTRUMENTATION_LOG_DEBUG], [1],
+ [Tracepoints to log debug]), [])
+AM_CONDITIONAL([USE_TRACING_INSTRUMENTATION_LOG_DEBUG],
+ [test "x$enable_tracing_instrumentation_log_debug" = "xyes"])
+
+dnl Define that tracing is supported.
+AM_COND_IF([USE_TRACING_INSTRUMENTATION_LOG_DEBUG],
+ AC_DEFINE([HAVE_TRACING], [1], [Compiled with tracing support]))
+
+dnl -- End Tracing Options. --
dnl Enable Android only features.
AC_ARG_ENABLE(android,
@@ -2718,6 +2725,12 @@ PPRINT_PROP_BOOL([libFuzzer support (--enable-libfuzzer)], $value)
test "x$enable_oss_fuzz" = "xyes" && value=1 || value=0
PPRINT_PROP_BOOL([OSS-Fuzz support (--enable-oss-fuzz)], $value)
+AS_ECHO
+PPRINT_SUBTITLE([Tracing])
+
+test "x$enable_tracing_instrumentation_log_debug" = "xyes" && value=1 || value=0
+PPRINT_PROP_BOOL([Tracepoints to log_debug() (--enable-tracing-instrumentation-log-debug)], $value)
+
AS_ECHO
PPRINT_SUBTITLE([Install Directories])
diff --git a/src/lib/trace/debug.h b/src/lib/trace/debug.h
index 87b3074e0..84a2867a6 100644
--- a/src/lib/trace/debug.h
+++ b/src/lib/trace/debug.h
@@ -6,8 +6,10 @@
* \brief Macros for debugging our event-trace support.
**/
-#ifndef TOR_TRACE_LOG_DEBUG_H
-#define TOR_TRACE_LOG_DEBUG_H
+#ifndef TOR_TRACE_DEBUG_H
+#define TOR_TRACE_DEBUG_H
+
+#ifdef USE_TRACING_INSTRUMENTATION_LOG_DEBUG
#include "lib/log/log.h"
@@ -17,14 +19,20 @@
/* Send every event to a debug log level. This is useful to debug new trace
* events without implementing them for a specific event tracing framework.
- * Note that the arguments are ignored since at this step we do not know the
- * types and amount there is. */
+ *
+ * NOTE: arguments can't be used becaue there is no easy generic ways to learn
+ * their type and amount. It is probably doable with massive C pre-processor
+ * trickery but this is meant to be simple. */
+
+#define TOR_TRACE_LOG_DEBUG(subsystem, event_name, ...) \
+ log_debug(LD_GENERAL, "Tracepoint \"" XSTR(event_name) "\" from " \
+ "subsystem \"" XSTR(subsystem) "\" hit.")
+
+#else /* defined(USE_TRACING_INSTRUMENTATION_LOG_DEBUG) */
+
+/* NOP the debug event. */
+#define TOR_TRACE_LOG_DEBUG(subsystem, name, ...)
-/* Example on how to map a tracepoint to log_debug(). */
-#undef tor_trace
-#define tor_trace(subsystem, name, args...) \
- log_debug(LD_GENERAL, "Trace event \"" XSTR(name) "\" from " \
- "\"" XSTR(subsystem) "\" hit. " \
- "(line "XSTR(__LINE__) ")")
+#endif /* defined(USE_TRACING_INSTRUMENTATION_LOG_DEBUG) */
-#endif /* !defined(TOR_TRACE_LOG_DEBUG_H) */
+#endif /* !defined(TOR_TRACE_DEBUG_H) */
diff --git a/src/lib/trace/events.h b/src/lib/trace/events.h
index 368f85dd0..b1b31fdc9 100644
--- a/src/lib/trace/events.h
+++ b/src/lib/trace/events.h
@@ -6,40 +6,28 @@
* \brief Header file for Tor event tracing.
**/
-#ifndef TOR_TRACE_EVENTS_H
-#define TOR_TRACE_EVENTS_H
-
-/*
- * The following defines a generic event tracing function name that has to be
- * used to trace events in the code base.
- *
- * That generic function is then defined by a event tracing framework. For
- * instance, the "log debug" framework sends all trace events to log_debug()
- * which is defined in src/trace/debug.h which can only be enabled at compile
- * time (--enable-event-tracing-debug).
- *
- * By default, every trace events in the code base are replaced by a NOP. See
- * doc/HACKING/Tracing.md for more information on how to use event tracing or
- * add events.
- */
-
-#ifdef TOR_EVENT_TRACING_ENABLED
-/* Map every trace event to a per subsystem macro. */
-#define tor_trace(subsystem, name, ...) \
- tor_trace_##subsystem(name, __VA_ARGS__)
-
-/* Enable event tracing for the debug framework where all trace events are
- * mapped to a log_debug(). */
-#ifdef USE_EVENT_TRACING_DEBUG
+#ifndef TOR_LIB_TRACE_EVENTS_H
+#define TOR_LIB_TRACE_EVENTS_H
+
+/* XXX: DOCDOC once framework is stable. */
+
+#ifdef HAVE_TRACING
+
+#define tor_trace(subsystem, event_name, ...) \
+ do { \
+ TOR_TRACE_LOG_DEBUG(tor_ ## subsystem, event_name); \
+ } while (0)
+
+/* This corresponds to the --enable-tracing-instrumentation-log-debug
+ * configure option which maps all tracepoints to a log_debug() statement. */
#include "lib/trace/debug.h"
-#endif
-#else /* !defined(TOR_EVENT_TRACING_ENABLED) */
+#else /* !defined(HAVE_TRACING) */
-/* Reaching this point, we NOP every event declaration because event tracing
- * is not been enabled at compile time. */
-#define tor_trace(subsystem, name, args...)
+/* Reaching this point, tracing is disabled thus we NOP every tracepoints
+ * declaration so we have no execution cost at runtime. */
+#define tor_trace(subsystem, name, ...)
-#endif /* defined(TOR_EVENT_TRACING_ENABLED) */
+#endif /* defined(HAVE_TRACING) */
-#endif /* !defined(TOR_TRACE_EVENTS_H) */
+#endif /* !defined(TOR_LIB_TRACE_EVENTS_H) */
diff --git a/src/lib/trace/include.am b/src/lib/trace/include.am
index 98098c87f..1669943dc 100644
--- a/src/lib/trace/include.am
+++ b/src/lib/trace/include.am
@@ -2,18 +2,20 @@
noinst_LIBRARIES += \
src/lib/libtor-trace.a
+# ADD_C_FILE: INSERT SOURCES HERE.
+LIBTOR_TRACE_A_SOURCES = \
+ src/lib/trace/trace.c
+
# ADD_C_FILE: INSERT HEADERS HERE.
TRACEHEADERS = \
src/lib/trace/trace.h \
src/lib/trace/events.h
-if USE_EVENT_TRACING_DEBUG
+if USE_TRACING_INSTRUMENTATION_LOG_DEBUG
TRACEHEADERS += \
src/lib/trace/debug.h
endif
-# ADD_C_FILE: INSERT SOURCES HERE.
-src_lib_libtor_trace_a_SOURCES = \
- src/lib/trace/trace.c
+src_lib_libtor_trace_a_SOURCES = $(LIBTOR_TRACE_A_SOURCES)
noinst_HEADERS+= $(TRACEHEADERS)
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