Export of internal Abseil changes

--
f0456157cdc6cef6dbb5d2f99f9dc3ca0e213fab by Abseil Team <absl-team@google.com>:

Improve flag_benchmark reproducibility, test multiple threads

This adds multiple threads to the flags benchmark, and also uses some
linker magic to ensure that the defined flags are mapped to a consistent
alignment regardless of other code changes in the benchmark binary.

The benchmark performance in multiple threads is somewhat sensitive to
the alignment of the FlagImpl class, depending on whether the flag value
and the absl::Mutex are on the same cacheline or different ones. Making
all flags be cacheline-aligned would probably waste too much memory,
so this CL instead just makes the memory alignment consistent within the
tests.

PiperOrigin-RevId: 347536882

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a019646d306b9497a1eba7efa5e2c4c651d9979d by Derek Mauro <dmauro@google.com>:

Fix other comments in node_hash_set.h

PiperOrigin-RevId: 347462975

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66a4b39fe84a3e81935ad08ee76291df13d1d5e6 by Abseil Team <absl-team@google.com>:

Internal change

PiperOrigin-RevId: 347436244

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52f4d18c2c4439d26428f64ac4de41e6183919ee by Mark Barolak <mbar@google.com>:

container: fix introduction for node_hash_set.h

Import of https://github.com/abseil/abseil-cpp/pull/861

PiperOrigin-RevId: 347432772
GitOrigin-RevId: f0456157cdc6cef6dbb5d2f99f9dc3ca0e213fab
Change-Id: I629f27e5b9584d92b0a42284c1acf708779bad3f
5 files changed
tree: 82fc5e49db344026ea67cffea1c30f3ac73ed6f6
  1. .github/
  2. absl/
  3. ci/
  4. CMake/
  5. .clang-format
  6. .gitignore
  7. ABSEIL_ISSUE_TEMPLATE.md
  8. AUTHORS
  9. BUILD.bazel
  10. CMakeLists.txt
  11. conanfile.py
  12. CONTRIBUTING.md
  13. FAQ.md
  14. LICENSE
  15. LTS.md
  16. README.md
  17. UPGRADES.md
  18. WORKSPACE
README.md

Abseil - C++ Common Libraries

The repository contains the Abseil C++ library code. Abseil is an open-source collection of C++ code (compliant to C++11) designed to augment the C++ standard library.

Table of Contents

About Abseil

Abseil is an open-source collection of C++ library code designed to augment the C++ standard library. The Abseil library code is collected from Google's own C++ code base, has been extensively tested and used in production, and is the same code we depend on in our daily coding lives.

In some cases, Abseil provides pieces missing from the C++ standard; in others, Abseil provides alternatives to the standard for special needs we've found through usage in the Google code base. We denote those cases clearly within the library code we provide you.

Abseil is not meant to be a competitor to the standard library; we've just found that many of these utilities serve a purpose within our code base, and we now want to provide those resources to the C++ community as a whole.

Quickstart

If you want to just get started, make sure you at least run through the Abseil Quickstart. The Quickstart contains information about setting up your development environment, downloading the Abseil code, running tests, and getting a simple binary working.

Building Abseil

Bazel is the official build system for Abseil, which is supported on most major platforms (Linux, Windows, macOS, for example) and compilers. See the quickstart for more information on building Abseil using the Bazel build system.

If you require CMake support, please check the CMake build instructions.

Codemap

Abseil contains the following C++ library components:

  • base Abseil Fundamentals
    The base library contains initialization code and other code which all other Abseil code depends on. Code within base may not depend on any other code (other than the C++ standard library).
  • algorithm
    The algorithm library contains additions to the C++ <algorithm> library and container-based versions of such algorithms.
  • container
    The container library contains additional STL-style containers, including Abseil's unordered “Swiss table” containers.
  • debugging
    The debugging library contains code useful for enabling leak checks, and stacktrace and symbolization utilities.
  • hash
    The hash library contains the hashing framework and default hash functor implementations for hashable types in Abseil.
  • memory
    The memory library contains C++11-compatible versions of std::make_unique() and related memory management facilities.
  • meta
    The meta library contains C++11-compatible versions of type checks available within C++14 and C++17 versions of the C++ <type_traits> library.
  • numeric
    The numeric library contains C++11-compatible 128-bit integers.
  • strings
    The strings library contains a variety of strings routines and utilities, including a C++11-compatible version of the C++17 std::string_view type.
  • synchronization
    The synchronization library contains concurrency primitives (Abseil's absl::Mutex class, an alternative to std::mutex) and a variety of synchronization abstractions.
  • time
    The time library contains abstractions for computing with absolute points in time, durations of time, and formatting and parsing time within time zones.
  • types
    The types library contains non-container utility types, like a C++11-compatible version of the C++17 std::optional type.
  • utility
    The utility library contains utility and helper code.

License

The Abseil C++ library is licensed under the terms of the Apache license. See LICENSE for more information.

Links

For more information about Abseil: