You may use a subset of the utilities provided by the Abseil library when writing WebRTC C++ code. Below, we list the explicitly allowed and the explicitly disallowed subsets of Abseil; if you find yourself in need of something that isn’t in either subset, please add it to the allowed subset in this doc in the same CL that adds the first use.
For build targets of type rtc_library
, rtc_source_set
and
rtc_static_library
, dependencies on Abseil need to be listed in absl_deps
instead of deps
.
This is needed in order to support the Abseil component build in Chromium. In that build mode, WebRTC will depend on a monolithic Abseil build target that will generate a shared library.
absl::AnyInvocable
absl::bind_front
absl::Cleanup
absl::InlinedVector
absl::WrapUnique
absl::optional
and related stuff fromabsl/types/optional.h
.absl::string_view
- The functions in
absl/strings/ascii.h
,absl/strings/match.h
, andabsl/strings/str_replace.h
. - The functions in
absl/strings/escaping.h
. absl::is_trivially_copy_constructible
,absl::is_trivially_copy_assignable
, andabsl::is_trivially_destructible
fromabsl/meta/type_traits.h
.absl::variant
and related stuff fromabsl/types/variant.h
.- The functions in
absl/algorithm/algorithm.h
andabsl/algorithm/container.h
. absl/base/const_init.h
for mutex initialization.- The macros in
absl/base/attributes.h
,absl/base/config.h
andabsl/base/macros.h
. absl/numeric/bits.h
Use std::make_unique
instead.
Use webrtc::Mutex
instead.
Chromium has a ban on new static initializers, and absl::Mutex
uses
one. To make absl::Mutex
available, we would need to nicely ask the
Abseil team to remove that initializer (like they already did for a
spinlock initializer). Additionally, absl::Mutex
handles time in a
way that may not be compatible with the rest of WebRTC.
Use rtc::ArrayView
instead.
absl::Span
differs from rtc::ArrayView
on several points, and both
of them differ from the std::span
that was voted into
C++20—and std::span
is likely to undergo further changes
before C++20 is finalized. We should just keep using rtc::ArrayView
and avoid absl::Span
until C++20 is finalized and the Abseil team
has decided if they will change absl::Span
to match.
Bug.
Use rtc::SimpleStringBuilder
to build strings.
These are optimized for speed, not binary size. Even StrCat
calls
with a modest number of arguments can easily add several hundred bytes
to the binary.