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Diffstat (limited to 'utils/memory.cpp')
| -rw-r--r-- | utils/memory.cpp | 158 |
1 files changed, 158 insertions, 0 deletions
diff --git a/utils/memory.cpp b/utils/memory.cpp new file mode 100644 index 000000000000..ca121f6f4dec --- /dev/null +++ b/utils/memory.cpp @@ -0,0 +1,158 @@ +// 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); +} |