Introduces rtc_base/synchronization/mutex.h.
This change introduces a new non-reentrant mutex to WebRTC. It
enables eventual migration to Abseil's mutex.
The mutex types supportable by webrtc::Mutex are
- absl::Mutex
- CriticalSection (Windows only)
- pthread_mutex (POSIX only)
In addition to introducing the mutexes, the CL also changes
PacketBuffer to use the new mutex instead of rtc::CriticalSection.
The method of yielding from critical_section.cc was given a
mini-cleanup and YieldCurrentThread() was added to
rtc_base/synchronization/yield.h/cc.
Additionally, google_benchmark benchmarks for the mutexes were added
(test courtesy of danilchap@), and some results from a pthread/Abseil
shootout were added showing Abseil has the advantage in higher
contention.
Bug: webrtc:11567, webrtc:11634
Change-Id: Iaec324ccb32ec3851bf6db3fd290f5ea5dee4c81
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/176230
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Reviewed-by: Tommi <tommi@webrtc.org>
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#31443}
diff --git a/abseil-in-webrtc.md b/abseil-in-webrtc.md
index 0541d3c..8615a33 100644
--- a/abseil-in-webrtc.md
+++ b/abseil-in-webrtc.md
@@ -23,9 +23,11 @@
* `absl::variant` and related stuff from `absl/types/variant.h`.
* The functions in `absl/algorithm/algorithm.h` and
`absl/algorithm/container.h`.
+* `absl/base/const_init.h` for mutex initialization.
* The macros in `absl/base/attributes.h`, `absl/base/config.h` and
`absl/base/macros.h`.
+
## **Disallowed**
### `absl::make_unique`
@@ -34,7 +36,7 @@
### `absl::Mutex`
-*Use `rtc::CriticalSection` 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
