external/bsd/kyua-cli/dist/utils/memory.cpp

   1 // Copyright 2012 Google Inc.
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  15 //   without specific prior written permission.
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  28
  29 #include "utils/memory.hpp"
  30
  31 #if defined(HAVE_CONFIG_H)
  32 #   include "config.h"
  33 #endif
  34
  35 extern "C" {
  36 #if defined(HAVE_SYS_TYPES_H)
  37 #   include <sys/types.h>
  38 #endif
  39 #if defined(HAVE_SYS_PARAM_H)
  40 #   include <sys/param.h>
  41 #endif
  42 #if defined(HAVE_SYS_SYSCTL_H)
  43 #   include <sys/sysctl.h>
  44 #endif
  45 }
  46
  47 #include <cerrno>
  48 #include <cstddef>
  49 #include <cstring>
  50 #include <stdexcept>
  51
  52 #include "utils/defs.hpp"
  53 #include "utils/format/macros.hpp"
  54 #include "utils/logging/macros.hpp"
  55 #include "utils/units.hpp"
  56 #include "utils/sanity.hpp"
  57
  58 namespace units = utils::units;
  59
  60
  61 namespace {
  62
  63
  64 /// Name of the method to query the available memory as detected by configure.
  65 static const char* query_type = MEMORY_QUERY_TYPE;
  66
  67
  68 /// Value of query_type when we do not know how to query the memory.
  69 static const char* query_type_unknown = "unknown";
  70
  71
  72 /// Value of query_type when we have to use sysctlbyname(3).
  73 static const char* query_type_sysctlbyname = "sysctlbyname";
  74
  75
  76 /// Name of the sysctl MIB with the physical memory as detected by configure.
  77 ///
  78 /// This should only be used if memory_query_type is 'sysctl'.
  79 static const char* query_sysctl_mib = MEMORY_QUERY_SYSCTL_MIB;
  80
  81
  82 #if !defined(HAVE_SYSCTLBYNAME)
  83 /// Stub for sysctlbyname(3) for systems that don't have it.
  84 ///
  85 /// The whole purpose of this fake function is to allow the caller code to be
  86 /// compiled on any machine regardless of the presence of sysctlbyname(3).  This
  87 /// will prevent the code from breaking when it is compiled on a machine without
  88 /// this function.  It also prevents "unused variable" warnings in the caller
  89 /// code.
  90 ///
  91 /// \param unused_name Unused.
  92 /// \param unused_oldp Unused.
  93 /// \param unused_oldlenp Unused.
  94 /// \param unused_newp Unused.
  95 /// \param unused_newlen Unused.
  96 ///
  97 /// \return Nothing; this always crashes.
  98 static int
  99 sysctlbyname(const char* UTILS_UNUSED_PARAM(name),
 100              void* UTILS_UNUSED_PARAM(oldp),
 101              std::size_t* UTILS_UNUSED_PARAM(oldlenp),
 102              const void* UTILS_UNUSED_PARAM(newp),
 103              std::size_t UTILS_UNUSED_PARAM(newlen))
 104 {
 105     UNREACHABLE;
 106 }
 107 #endif
 108
 109
 110 }  // anonymous namespace
 111
 112
 113 /// Gets the value of an integral sysctl MIB.
 114 ///
 115 /// \pre The system supports the sysctlbyname(3) function.
 116 ///
 117 /// \param mib The name of the sysctl MIB to query.
 118 ///
 119 /// \return The value of the MIB, if found.
 120 ///
 121 /// \throw std::runtime_error If the sysctlbyname(3) call fails.  This might be
 122 ///     a bit drastic.  If it turns out that this causes problems, we could just
 123 ///     change the code to log the error instead of raising an exception.
 124 static int64_t
 125 query_sysctl(const char* mib)
 126 {
 127     // This must be explicitly initialized to 0.  If the sysctl query returned a
 128     // value smaller in size than value_length, we would get garbage otherwise.
 129     int64_t value = 0;
 130     std::size_t value_length = sizeof(value);
 131     if (::sysctlbyname(mib, &value, &value_length, NULL, 0) == -1) {
 132         const int original_errno = errno;
 133         throw std::runtime_error(F("Failed to get sysctl(%s) value: %s") %
 134                                  mib % std::strerror(original_errno));
 135     }
 136     return value;
 137 }
 138
 139
 140 /// Queries the total amount of physical memory.
 141 ///
 142 /// The real query is run only once and the result is cached.  Further calls to
 143 /// this function will always return the same value.
 144 ///
 145 /// \return The amount of physical memory, in bytes.  If the code does not know
 146 /// how to query the memory, this logs a warning and returns 0.
 147 units::bytes
 148 utils::physical_memory(void)
 149 {
 150     static int64_t amount = -1;
 151     if (amount == -1) {
 152         if (std::strcmp(query_type, query_type_unknown) == 0) {
 153             LW("Don't know how to query the physical memory");
 154             amount = 0;
 155         } else if (std::strcmp(query_type, query_type_sysctlbyname) == 0) {
 156             amount = query_sysctl(query_sysctl_mib);
 157         } else
 158             UNREACHABLE_MSG("Unimplemented memory query type");
 159         LI(F("Physical memory as returned by query type '%s': %s") %
 160            query_type % amount);
 161     }
 162     POST(amount > -1);
 163     return units::bytes(amount);
 164 }