From b16aeb6756bdab08cdf12d40baab5b51f7d15b16 Mon Sep 17 00:00:00 2001 From: Abseil Team Date: Mon, 7 Jan 2019 09:01:16 -0800 Subject: Export of internal Abseil changes. -- 5f1cf6547231f1b1daad6d1b785df6b0b999b3c9 by Samuel Benzaquen : Fix uninitialized member in the `iterator` class by using a union of the two possible states of the iterator. This silences a Wuninitialized warning in gcc>=7. PiperOrigin-RevId: 228175148 -- 98b4e3204c0ec3cfd4cb037e24d443ea4b63fc84 by CJ Johnson : Factors out the implementation of InlinedVector::swap(...) into a private member function PiperOrigin-RevId: 228173383 -- f1432ad3a8b05285c6d55bc4754cfae765485b7f by Abseil Team : Import of CCTZ from GitHub. PiperOrigin-RevId: 227891984 -- 03fc00c7a4efc6000e6d9125cb2e252bffda76fe by Andy Getzendanner : Add a missing linebreak to a comment and markdownify two unordered lists. PiperOrigin-RevId: 227861389 -- 0d66c9afba4fc9aa52e61d9fb410e165018a7b48 by Abseil Team : Add an API to register a new source for the cycle clock. PiperOrigin-RevId: 227779218 -- 14d3f9b70c8818b8541e5fb2f6ca4c59d479de31 by Andy Getzendanner : Correct a typo in a stripping marker. PiperOrigin-RevId: 227750014 -- 59df88740f4e315beb57a8772f8bcf7879440c74 by Matt Kulukundis : Switch thread local handling to be more cross platform PiperOrigin-RevId: 227695133 -- 75deed5bfcb5c42534e933f104aa7d94e11e348d by Abseil Team : Rollback workaround toolchain bug for incorrect handling of thread_local in inline functions PiperOrigin-RevId: 227689133 -- 54994bf0afec026e6e0e7a199df0bbb4b7d9a4aa by Derek Mauro : Add -pthread to linkopts where it actually belongs, on the library that uses it. Fixes https://github.com/abseil/abseil-cpp/issues/240. PiperOrigin-RevId: 227612492 -- 893875f3536b7e0a1bad993aa6b2e083abb3b25a by Derek Mauro : Internal change PiperOrigin-RevId: 227582833 -- 506c9b8e9002ca3389c7040473b68d4cbf94bdcc by Matt Kulukundis : Workaround toolchain bug for incorrect handling of thread_local in inline functions PiperOrigin-RevId: 227561449 -- 29ee90d96dfe3114cf93f9bb92ea0cc9e768a407 by Derek Mauro : Internal change PiperOrigin-RevId: 227054634 GitOrigin-RevId: 5f1cf6547231f1b1daad6d1b785df6b0b999b3c9 Change-Id: Ibc90566d92ee6e0ad7e150f513ec7f5d22ec0a94 --- absl/base/internal/cycleclock.cc | 12 +++++++++++- absl/base/internal/cycleclock.h | 14 ++++++++++++++ absl/base/internal/per_thread_tls.h | 12 ++++++++---- 3 files changed, 33 insertions(+), 5 deletions(-) (limited to 'absl/base/internal') diff --git a/absl/base/internal/cycleclock.cc b/absl/base/internal/cycleclock.cc index a742df01..9eb13b8c 100644 --- a/absl/base/internal/cycleclock.cc +++ b/absl/base/internal/cycleclock.cc @@ -22,6 +22,7 @@ #include "absl/base/internal/cycleclock.h" +#include #include // NOLINT(build/c++11) #include "absl/base/internal/unscaledcycleclock.h" @@ -52,17 +53,26 @@ static constexpr int32_t kShift = 2; #endif static constexpr double kFrequencyScale = 1.0 / (1 << kShift); +static std::atomic cycle_clock_source; } // namespace int64_t CycleClock::Now() { - return base_internal::UnscaledCycleClock::Now() >> kShift; + auto fn = cycle_clock_source.load(std::memory_order_relaxed); + if (fn == nullptr) { + return base_internal::UnscaledCycleClock::Now() >> kShift; + } + return fn() >> kShift; } double CycleClock::Frequency() { return kFrequencyScale * base_internal::UnscaledCycleClock::Frequency(); } +void CycleClockSource::Register(CycleClockSourceFunc source) { + cycle_clock_source.store(source, std::memory_order_relaxed); +} + #else int64_t CycleClock::Now() { diff --git a/absl/base/internal/cycleclock.h b/absl/base/internal/cycleclock.h index 60e97158..9853a66c 100644 --- a/absl/base/internal/cycleclock.h +++ b/absl/base/internal/cycleclock.h @@ -71,6 +71,20 @@ class CycleClock { CycleClock& operator=(const CycleClock&) = delete; }; +using CycleClockSourceFunc = int64_t (*)(); + +class CycleClockSource { + private: + // CycleClockSource::Register() + // + // Register a function that provides an alternate source for the unscaled CPU + // cycle count value. The source function must be async signal safe, must not + // call CycleClock::Now(), and must have a frequency that matches that of the + // unscaled clock used by CycleClock. A nullptr value resets CycleClock to use + // the default source. + static void Register(CycleClockSourceFunc source); +}; + } // namespace base_internal } // namespace absl diff --git a/absl/base/internal/per_thread_tls.h b/absl/base/internal/per_thread_tls.h index 2428bdc1..56359853 100644 --- a/absl/base/internal/per_thread_tls.h +++ b/absl/base/internal/per_thread_tls.h @@ -16,13 +16,17 @@ #define ABSL_BASE_INTERNAL_PER_THREAD_TLS_H_ // This header defines two macros: +// // If the platform supports thread-local storage: -// ABSL_PER_THREAD_TLS_KEYWORD is the C keyword needed to declare a -// thread-local variable ABSL_PER_THREAD_TLS is 1 +// +// * ABSL_PER_THREAD_TLS_KEYWORD is the C keyword needed to declare a +// thread-local variable +// * ABSL_PER_THREAD_TLS is 1 // // Otherwise: -// ABSL_PER_THREAD_TLS_KEYWORD is empty -// ABSL_PER_THREAD_TLS is 0 +// +// * ABSL_PER_THREAD_TLS_KEYWORD is empty +// * ABSL_PER_THREAD_TLS is 0 // // Microsoft C supports thread-local storage. // GCC supports it if the appropriate version of glibc is available, -- cgit v1.2.3