src/trace/events.h

   1 /* Copyright (c) 2017, The Tor Project, Inc. */
   2 /* See LICENSE for licensing information */
   3
   4 /**
   5  * \file events.h
   6  * \brief Header file for Tor event tracing.
   7  **/
   8
   9 #ifndef TOR_TRACE_EVENTS_H
  10 #define TOR_TRACE_EVENTS_H
  11
  12 /*
  13  * The following defines a generic event tracing function name that has to be
  14  * used to trace events in the code base.
  15  *
  16  * That generic function is then defined by a event tracing framework. For
  17  * instance, the "log debug" framework sends all trace events to log_debug()
  18  * which is defined in src/trace/debug.h which can only be enabled at compile
  19  * time (--enable-event-tracing-debug).
  20  *
  21  * By default, every trace events in the code base are replaced by a NOP. See
  22  * doc/HACKING/Tracing.md for more information on how to use event tracing or
  23  * add events.
  24  */
  25
  26 #ifdef TOR_EVENT_TRACING_ENABLED
  27 /* Map every trace event to a per subsystem macro. */
  28 #define tor_trace(subsystem, name, ...) \
  29   tor_trace_##subsystem(name, __VA_ARGS__)
  30
  31 /* Enable event tracing for the debug framework where all trace events are
  32  * mapped to a log_debug(). */
  33 #ifdef USE_EVENT_TRACING_DEBUG
  34 #include "trace/debug.h"
  35 #endif
  36
  37 #else /* TOR_EVENT_TRACING_ENABLED */
  38
  39 /* Reaching this point, we NOP every event declaration because event tracing
  40  * is not been enabled at compile time. */
  41 #define tor_trace(subsystem, name, args...)
  42
  43 #endif /* TOR_EVENT_TRACING_ENABLED */
  44
  45 #endif /* TOR_TRACE_EVENTS_H */