93 lines
2.4 KiB
C++
93 lines
2.4 KiB
C++
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/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <folly/ClockGettimeWrappers.h>
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#include <folly/CPortability.h>
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#include <folly/Likely.h>
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#include <folly/portability/Time.h>
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#include <chrono>
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#include <ctime>
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#ifndef _WIN32
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#define _GNU_SOURCE 1
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#include <dlfcn.h>
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#endif
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namespace folly {
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namespace chrono {
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static int64_t clock_gettime_ns_fallback(clockid_t clock) {
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struct timespec ts;
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int r = clock_gettime(clock, &ts);
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if (UNLIKELY(r != 0)) {
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// Mimic what __clock_gettime_ns does (even though this can be a legit
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// value).
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return -1;
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}
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std::chrono::nanoseconds result =
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std::chrono::seconds(ts.tv_sec) + std::chrono::nanoseconds(ts.tv_nsec);
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return result.count();
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}
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// Initialize with default behavior, which we might override on Linux hosts
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// with VDSO support.
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int (*clock_gettime)(clockid_t, timespec* ts) = &::clock_gettime;
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int64_t (*clock_gettime_ns)(clockid_t) = &clock_gettime_ns_fallback;
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// In MSAN mode use glibc's versions as they are intercepted by the MSAN
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// runtime which properly tracks memory initialization.
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#if defined(FOLLY_HAVE_LINUX_VDSO) && !defined(FOLLY_SANITIZE_MEMORY)
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namespace {
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struct VdsoInitializer {
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VdsoInitializer() {
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m_handle = dlopen("linux-vdso.so.1", RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
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if (!m_handle) {
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return;
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}
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void* p = dlsym(m_handle, "__vdso_clock_gettime");
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if (p) {
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folly::chrono::clock_gettime = (int (*)(clockid_t, timespec*))p;
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}
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p = dlsym(m_handle, "__vdso_clock_gettime_ns");
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if (p) {
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folly::chrono::clock_gettime_ns = (int64_t(*)(clockid_t))p;
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}
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}
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~VdsoInitializer() {
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if (m_handle) {
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clock_gettime = &::clock_gettime;
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clock_gettime_ns = &clock_gettime_ns_fallback;
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dlclose(m_handle);
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}
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}
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private:
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void* m_handle;
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};
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const VdsoInitializer vdso_initializer;
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} // namespace
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#endif
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} // namespace chrono
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} // namespace folly
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