libvirt/src/util/virprobe.h

/*
 * virprobe.h: dynamic operation tracing
 *
 * Copyright (C) 2006-2014 Red Hat, Inc.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library.  If not, see
 * <http://www.gnu.org/licenses/>.
 *
 */

#ifndef __VIR_PROBE_H__
# define __VIR_PROBE_H__

# include "internal.h"
# include "virlog.h"

# if WITH_DTRACE_PROBES
#  ifndef LIBVIRT_PROBES_H
#   define LIBVIRT_PROBES_H
#   include "libvirt_probes.h"
#  endif /* LIBVIRT_PROBES_H */

/* Systemtap 1.2 headers have a bug where they cannot handle a
 * variable declared with array type.  Work around this by casting all
 * arguments.  This is some gross use of the preprocessor because
 * PROBE is a var-arg macro, but it is better than the alternative of
 * making all callers to PROBE have to be aware of the issues.  And
 * hopefully, if we ever add a call to PROBE with other than 9
 * end arguments, you can figure out the pattern to extend this hack.
 */
#  define VIR_COUNT_ARGS(...) VIR_ARG11(__VA_ARGS__, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1)
#  define VIR_ARG11(_1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, ...) _11
#  define VIR_ADD_CAST_EXPAND(a, b, ...) VIR_ADD_CAST_PASTE(a, b, __VA_ARGS__)
#  define VIR_ADD_CAST_PASTE(a, b, ...) a##b(__VA_ARGS__)

/* The double cast is necessary to silence gcc warnings; any pointer
 * can safely go to intptr_t and back to void *, which collapses
 * arrays into pointers; while any integer can be widened to intptr_t
 * then cast to void *.  */
#  define VIR_ADD_CAST(a) ((void *)(intptr_t)(a))
#  define VIR_ADD_CAST1(a)                                  \
    VIR_ADD_CAST(a)
#  define VIR_ADD_CAST2(a, b)                               \
    VIR_ADD_CAST(a), VIR_ADD_CAST(b)
#  define VIR_ADD_CAST3(a, b, c)                            \
    VIR_ADD_CAST(a), VIR_ADD_CAST(b), VIR_ADD_CAST(c)
#  define VIR_ADD_CAST4(a, b, c, d)                         \
    VIR_ADD_CAST(a), VIR_ADD_CAST(b), VIR_ADD_CAST(c),      \
    VIR_ADD_CAST(d)
#  define VIR_ADD_CAST5(a, b, c, d, e)                      \
    VIR_ADD_CAST(a), VIR_ADD_CAST(b), VIR_ADD_CAST(c),      \
    VIR_ADD_CAST(d), VIR_ADD_CAST(e)
#  define VIR_ADD_CAST6(a, b, c, d, e, f)                   \
    VIR_ADD_CAST(a), VIR_ADD_CAST(b), VIR_ADD_CAST(c),      \
    VIR_ADD_CAST(d), VIR_ADD_CAST(e), VIR_ADD_CAST(f)
#  define VIR_ADD_CAST7(a, b, c, d, e, f, g)                \
    VIR_ADD_CAST(a), VIR_ADD_CAST(b), VIR_ADD_CAST(c),      \
    VIR_ADD_CAST(d), VIR_ADD_CAST(e), VIR_ADD_CAST(f),      \
    VIR_ADD_CAST(g)
#  define VIR_ADD_CAST8(a, b, c, d, e, f, g, h)             \
    VIR_ADD_CAST(a), VIR_ADD_CAST(b), VIR_ADD_CAST(c),      \
    VIR_ADD_CAST(d), VIR_ADD_CAST(e), VIR_ADD_CAST(f),      \
    VIR_ADD_CAST(g), VIR_ADD_CAST(h)
#  define VIR_ADD_CAST9(a, b, c, d, e, f, g, h, i)          \
    VIR_ADD_CAST(a), VIR_ADD_CAST(b), VIR_ADD_CAST(c),      \
    VIR_ADD_CAST(d), VIR_ADD_CAST(e), VIR_ADD_CAST(f),      \
    VIR_ADD_CAST(g), VIR_ADD_CAST(h), VIR_ADD_CAST(i)

#  define VIR_ADD_CASTS(...)                                            \
    VIR_ADD_CAST_EXPAND(VIR_ADD_CAST, VIR_COUNT_ARGS(__VA_ARGS__),      \
                        __VA_ARGS__)

#  define PROBE_EXPAND(NAME, ARGS) NAME(ARGS)
#  define PROBE(NAME, FMT, ...)                              \
    VIR_INFO_INT(&virLogSelf,                                \
                  __FILE__, __LINE__, __func__,              \
                  #NAME ": " FMT, __VA_ARGS__);              \
    if (LIBVIRT_ ## NAME ## _ENABLED()) {                    \
        PROBE_EXPAND(LIBVIRT_ ## NAME,                       \
                     VIR_ADD_CASTS(__VA_ARGS__));            \
    }
# else
#  define PROBE(NAME, FMT, ...)                              \
    VIR_INFO_INT(&virLogSelf,                                \
                 __FILE__, __LINE__, __func__,               \
                 #NAME ": " FMT, __VA_ARGS__);
# endif

#endif /* __VIR_PROBE_H__ */