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+// Copyright 2012 The Kyua Authors.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+// * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+// * Redistributions in binary form must reproduce the above copyright
+// notice, this list of conditions and the following disclaimer in the
+// documentation and/or other materials provided with the distribution.
+// * Neither the name of Google Inc. nor the names of its contributors
+// may be used to endorse or promote products derived from this software
+// without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "utils/memory.hpp"
+
+#if defined(HAVE_CONFIG_H)
+# include "config.h"
+#endif
+
+extern "C" {
+#if defined(HAVE_SYS_TYPES_H)
+# include <sys/types.h>
+#endif
+#if defined(HAVE_SYS_PARAM_H)
+# include <sys/param.h>
+#endif
+#if defined(HAVE_SYS_SYSCTL_H)
+# include <sys/sysctl.h>
+#endif
+}
+
+#include <cerrno>
+#include <cstddef>
+#include <cstring>
+#include <stdexcept>
+
+#include "utils/defs.hpp"
+#include "utils/format/macros.hpp"
+#include "utils/logging/macros.hpp"
+#include "utils/units.hpp"
+#include "utils/sanity.hpp"
+
+namespace units = utils::units;
+
+
+namespace {
+
+
+/// Name of the method to query the available memory as detected by configure.
+static const char* query_type = MEMORY_QUERY_TYPE;
+
+
+/// Value of query_type when we do not know how to query the memory.
+static const char* query_type_unknown = "unknown";
+
+
+/// Value of query_type when we have to use sysctlbyname(3).
+static const char* query_type_sysctlbyname = "sysctlbyname";
+
+
+/// Name of the sysctl MIB with the physical memory as detected by configure.
+///
+/// This should only be used if memory_query_type is 'sysctl'.
+static const char* query_sysctl_mib = MEMORY_QUERY_SYSCTL_MIB;
+
+
+#if !defined(HAVE_SYSCTLBYNAME)
+/// Stub for sysctlbyname(3) for systems that don't have it.
+///
+/// The whole purpose of this fake function is to allow the caller code to be
+/// compiled on any machine regardless of the presence of sysctlbyname(3). This
+/// will prevent the code from breaking when it is compiled on a machine without
+/// this function. It also prevents "unused variable" warnings in the caller
+/// code.
+///
+/// \return Nothing; this always crashes.
+static int
+sysctlbyname(const char* /* name */,
+ void* /* oldp */,
+ std::size_t* /* oldlenp */,
+ const void* /* newp */,
+ std::size_t /* newlen */)
+{
+ UNREACHABLE;
+}
+#endif
+
+
+} // anonymous namespace
+
+
+/// Gets the value of an integral sysctl MIB.
+///
+/// \pre The system supports the sysctlbyname(3) function.
+///
+/// \param mib The name of the sysctl MIB to query.
+///
+/// \return The value of the MIB, if found.
+///
+/// \throw std::runtime_error If the sysctlbyname(3) call fails. This might be
+/// a bit drastic. If it turns out that this causes problems, we could just
+/// change the code to log the error instead of raising an exception.
+static int64_t
+query_sysctl(const char* mib)
+{
+ // This must be explicitly initialized to 0. If the sysctl query returned a
+ // value smaller in size than value_length, we would get garbage otherwise.
+ int64_t value = 0;
+ std::size_t value_length = sizeof(value);
+ if (::sysctlbyname(mib, &value, &value_length, NULL, 0) == -1) {
+ const int original_errno = errno;
+ throw std::runtime_error(F("Failed to get sysctl(%s) value: %s") %
+ mib % std::strerror(original_errno));
+ }
+ return value;
+}
+
+
+/// Queries the total amount of physical memory.
+///
+/// The real query is run only once and the result is cached. Further calls to
+/// this function will always return the same value.
+///
+/// \return The amount of physical memory, in bytes. If the code does not know
+/// how to query the memory, this logs a warning and returns 0.
+units::bytes
+utils::physical_memory(void)
+{
+ static int64_t amount = -1;
+ if (amount == -1) {
+ if (std::strcmp(query_type, query_type_unknown) == 0) {
+ LW("Don't know how to query the physical memory");
+ amount = 0;
+ } else if (std::strcmp(query_type, query_type_sysctlbyname) == 0) {
+ amount = query_sysctl(query_sysctl_mib);
+ } else
+ UNREACHABLE_MSG("Unimplemented memory query type");
+ LI(F("Physical memory as returned by query type '%s': %s") %
+ query_type % amount);
+ }
+ POST(amount > -1);
+ return units::bytes(amount);
+}