Export of internal Abseil changes

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007ce045d5d38a727ededdb5bf06e64785fd73bd by Martijn Vels <mvels@google.com>:

Add `cord_enable_btree` feature flag (default false).

PiperOrigin-RevId: 383729939

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98e7dc6a0407b0fd7b8713d883cdb3a766e0583d by Benjamin Barenblat <bbaren@google.com>:

Eliminate some byte swapping from randen_slow

Stop swapping bytes when serializing randen_slow’s Vector128 into and
out of memory. Instead, simply index different bytes in the AES round
function. This requires byte swapping the te{0..3} lookup tables, but it
produces an 8% speedup on my Xeon W-2135.

PiperOrigin-RevId: 383689402

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180b6bf45049188840d439b16a28e6b968669340 by Evan Brown <ezb@google.com>:

Minor simplification in drop_deletes_without_resize() - save probe_offset outside the lambda.

Also, add some consts, avoid an auto, and use lambda capture by value instead of reference.

I realized that the compiler can already optimize this - https://godbolt.org/z/Wxd9c4TfK, but I think this way makes the code a bit clearer.

PiperOrigin-RevId: 383646658

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781706a974c4dc1c0abbb6b801fca0550229e883 by Martijn Vels <mvels@google.com>:

Change storage to contain 3 bytes.

As per the comments in the code, this allows us to utilize all available space in CordRep that may otherwise be 'lost' in padding in derived clases. For the upcoming CordrepBtree class, we want a strong guarantee on having a 64 bytes aligned implementation.

PiperOrigin-RevId: 383633963

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8fe22ecf92492fa6649938a2215934ebfe01c714 by Derek Mauro <dmauro@google.com>:

Remove reference to str_format_arg.h, which no longer exists

PiperOrigin-RevId: 383517865

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79397f3b18f18c1e2d7aea993b687329d626ce64 by Benjamin Barenblat <bbaren@google.com>:

Use absl::uint128 for AES random number generator

Replace randen’s internal 128-bit integer struct, u64x2, with
absl::uint128. This eliminates some code and improves support for
big-endian platforms.
PiperOrigin-RevId: 383475671
GitOrigin-RevId: 007ce045d5d38a727ededdb5bf06e64785fd73bd
Change-Id: Ia9d9c40de557221f1744fb0d6d4d6ca7ac569070
9 files changed
tree: 8d53095e0ee1b45e7c2920a296aeb337f909bc95
  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. create_lts.py
  14. FAQ.md
  15. LICENSE
  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 and CMake are the official build systems for Abseil.

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 and CMake Quickstart.

Support

Abseil is officially supported on many platforms. See the Abseil platform support guide for details on supported operating systems, compilers, CPUs, etc.

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.
  • cleanup
    The cleanup library contains the control-flow-construct-like type absl::Cleanup which is used for executing a callback on scope exit.
  • 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.
  • status
    The status contains abstractions for error handling, specifically absl::Status and absl::StatusOr<T>.
  • 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.

Releases

Abseil recommends users “live-at-head” (update to the latest commit from the master branch as often as possible). However, we realize this philosophy doesn't work for every project, so we also provide Long Term Support Releases to which we backport fixes for severe bugs. See our release management document for more details.

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: