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