Export of internal Abseil changes.
--
ee19e203eca970ff88e8f25ce4e19c32e143b988 by Jon Cohen <cohenjon@google.com>:

Exception safety testing no longer uses absl::optional

PiperOrigin-RevId: 220336204

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460666eb0b316a8b4aeedc589644d53b05251bd1 by Derek Mauro <dmauro@google.com>:

Rework SwissTable SSE2 support
  - Use SSE2 on MSVC when available
    https://github.com/abseil/abseil-cpp/issues/210
  - Emulate _mm_cmpgt_epi8 with other SSE2 instructions when using
    -funsigned-char under GCC
    https://github.com/abseil/abseil-cpp/issues/209

PiperOrigin-RevId: 220312351

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1f4318ecedf8d539b7b698eb803d613ad6b69278 by Abseil Team <absl-team@google.com>:

Change CollectPerfectRatios to use 10 trials to smooth out the outliers in the
sample.

PiperOrigin-RevId: 220286579

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6755abc2673553a7f578bb29c6e9ca8d991bc9c8 by Abseil Team <absl-team@google.com>:

Internal change

PiperOrigin-RevId: 220274307

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8645b6187329ebf0aaf3c2de2888ba44466cd879 by Abseil Team <absl-team@google.com>:

* #endif for a header guard should reference the guard macro in a comment

PiperOrigin-RevId: 220206868

--
3987a7ad11319230910931cd2468b60b3fd1b85c by Gennadiy Civil <misterg@google.com>:

Internal Change

PiperOrigin-RevId: 220136674

--
cc908c1db2ee0d4523dc813e33f600583bb986c5 by Abseil Team <absl-team@google.com>:

absl: fix backoff logic in SpinLockWait

There are 3 bugs in loop variable handling:
1. It starts with 0, but AbslInternalSpinLockDelay ignores loop == 0.
So it does not actually wait when it should.
2. loop is incremented after successful state changes,
but it should not (why would be increase backoff delay after that?).
3. loop is incremented after CAS failures,
but it should not (why would be increase backoff delay after that?).

Use the same handling of loop as used in SpinLock.

PiperOrigin-RevId: 220136079

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a0a1c6ef5910ebd28e07215d7df03cc0da0b3eed by Abseil Team <absl-team@google.com>:

absl: relax unnecessarily strong memory ordering in SpinLock::SlowLock

We don't need to acquire visibility over anything when setting kSpinLockSleeper.
Replace the confusing and unnecessarily strong memory order with relaxed.

PiperOrigin-RevId: 220023380

--
c50858b51af28b9fca1a62616324f85f3e84ea74 by Tom Manshreck <shreck@google.com>:

Update comments in flat_hash_map, node_hash_{set, map} and the containers developer guide

PiperOrigin-RevId: 219938692

--
e87b7d1a5f61e165b1c44d3b16d8d967197cdfce by CJ Johnson <johnsoncj@google.com>:

Rearranges the public methods of InlinedVector and cleans up the comments

PiperOrigin-RevId: 219896257

--
f3234c466f792e0fc4bfd21fc7919dba5e679375 by CJ Johnson <johnsoncj@google.com>:

Adds branch prediction to exceptional early exit cases of inlined vector's API

PiperOrigin-RevId: 219887173

--
4dfccf1a81ca0425912d3da25a8470f78c532ce4 by CJ Johnson <johnsoncj@google.com>:

Fixes the InlinedVector public interface to use the allocator type references instead of assuming the type
Also cleans up some cruft in formatting and comments

PiperOrigin-RevId: 219878876

--
4bb6a2b892abb10bd6a424db7e94ed8640802470 by Tom Manshreck <shreck@google.com>:

Add comments on constructor and assignment operator support to flat_hash_set

PiperOrigin-RevId: 219825338

--
c23f973e2f7f4feea0da36bf8a9c3f8a8954bb74 by Abseil Team <absl-team@google.com>:

Import of CCTZ from GitHub.

PiperOrigin-RevId: 219823847
GitOrigin-RevId: ee19e203eca970ff88e8f25ce4e19c32e143b988
Change-Id: I288c927ca481dc57340420dbb4c278a05cf15e83
21 files changed
tree: b6d2b5e5d1471695a7551db93b68ca43883c6547
  1. absl/
  2. CMake/
  3. .clang-format
  4. .gitignore
  5. ABSEIL_ISSUE_TEMPLATE.md
  6. AUTHORS
  7. CMakeLists.txt
  8. CONTRIBUTING.md
  9. LICENSE
  10. LTS.md
  11. README.md
  12. 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: