1 // Copyright 2012 Google Inc.
2 // All rights reserved.
3 //
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5 // modification, are permitted provided that the following conditions are
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7 //
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9 // notice, this list of conditions and the following disclaimer.
10 // * Redistributions in binary form must reproduce the above copyright
11 // notice, this list of conditions and the following disclaimer in the
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14 // may be used to endorse or promote products derived from this software
15 // without specific prior written permission.
16 //
17 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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27 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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
sysctlbyname(const char * UTILS_UNUSED_PARAM (name),void * UTILS_UNUSED_PARAM (oldp),std::size_t * UTILS_UNUSED_PARAM (oldlenp),const void * UTILS_UNUSED_PARAM (newp),std::size_t UTILS_UNUSED_PARAM (newlen))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
query_sysctl(const char * mib)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
physical_memory(void)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 }
165