Debug.h

#ifndef _debug_
#ifdef DEBUG
#define _debug_

#ifdef dprint

#undef dprint
#undef dprint_np
#undef dcall
#undef dprintf
#undef dprintf_np

#endif
/*
  Usage: DEBUG must be defined before this header file is included, typically

  #define DEBUG
  #include "Debug.h"

  This defines macros dprint(), dcall() and dprintf();
  dprint(x) is equivalent to std::cout << x << std::endl;
    example: dprint("Hits in layer=" << ilayer);

  dcall(x) simply calls x
    example: dcall(pre_prop_print(ilay, mkfp));

  dprintf(x) is equivalent to printf(x)
    example: dprintf("Bad label for simtrack %d -- %d\n", itrack, track.label());

  All printouts are also controlled by a bool variable "debug"
  bool debug = true; is declared as a file global in an anonymous
  namespace, and thus can be overridden within any interior scope
  as needed, so one could change the global to false and only set
  a local to true within certain scopes.

  All are protected by a file scope mutex to avoid mixed printouts.
  This mutex can also be acquired within a block via dmutex_guard:

  if (debug) {
    dmutex_guard;
    [do complicated stuff]
  }

  The mutex is not reentrant, so avoid using dprint et al. within a scope
  where the mutex has already been acquired, as doing so will deadlock.
 */
#include <mutex>

#define dmutex_guard std::lock_guard<std::mutex> dlock(debug_mutex)
#define dprint(x) if (debug) { dmutex_guard; std::cout << x << std::endl; }
#define dprint_np(n,x) if(debug && n < N_proc) { dmutex_guard; std::cout << n << ": " << x << std::endl; }
#define dcall(x)  if (debug) { dmutex_guard; x; }
#define dprintf(...) if (debug) { dmutex_guard; printf(__VA_ARGS__); }
#define dprintf_np(n, ...) if (debug && n < N_proc) { dmutex_guard; std::cout << n << ": "; printf(__VA_ARGS__); }

namespace
{
  bool debug = false; // default, can be overridden locally
  std::mutex debug_mutex;

  struct foo_doo_debug_unused { void foo() { debug = true; } };
}

#else

#define dprint(x) (void(0))
#define dprint_np(n,x) (void(0))
#define dcall(x) (void(0))
#define dprintf(...) (void(0))
#define dprintf_np(n,...) (void(0))

#endif

#endif