gRPC-Core Release 1.23.0 gangnam

[kart...@google.com]

This is 1.23.0 gangnam release announcement for gRPC-Core and the wrapped languages C++, C#, Objective-C, Python, PHP and Ruby. Latest release notes are here.

Core

---

-  Backport #19924 to v1.23.x. ([#19935](https://github.com/grpc/grpc/pull/19935))

-  Add missing APP callback context for custom iomgr. ([#19687](https://github.com/grpc/grpc/pull/19687))

-  Increase lower bound on DNS re-resolution period to 30 seconds. ([#19661](https://github.com/grpc/grpc/pull/19661))

-  Make sure there is at least a header in the frame storge of H2. ([#19657](https://github.com/grpc/grpc/pull/19657))

-  Fix segfault when forking while using gevent. ([#19556](https://github.com/grpc/grpc/pull/19556))

-  Mpmcqueue. ([#19358](https://github.com/grpc/grpc/pull/19358))

-  Disable the backup poller when using the background poller. ([#19454](https://github.com/grpc/grpc/pull/19454))

-  Clearly callout the behavior for listening ports. ([#19529](https://github.com/grpc/grpc/pull/19529))

-  Enable CFStream by default on  iOS. ([#19439](https://github.com/grpc/grpc/pull/19439))

-  Fix DNS resolver cooldown. ([#19489](https://github.com/grpc/grpc/pull/19489))

-  Simplify and fix c-ares TCP path on Windows. ([#19397](https://github.com/grpc/grpc/pull/19397))

-   Modify codegen to use grpc_impl namespace and other cleanup. ([#19435](https://github.com/grpc/grpc/pull/19435))

C++

---

-  Channel idleness. ([#19634](https://github.com/grpc/grpc/pull/19634))

-  Threadpool. ([#19544](https://github.com/grpc/grpc/pull/19544))

-  Bump min CMake to 3.5.1 to match Google benchmark. ([#19467](https://github.com/grpc/grpc/pull/19467))

-  Migrate from dep.proto. to dep[ProtoInfo] provider. ([#19420](https://github.com/grpc/grpc/pull/19420))

C#

---

-  Move ChannelExtensions (interceptor support) to Grpc.Core.Api (for v1.23.x branch). ([#19853](https://github.com/grpc/grpc/pull/19853))

-  Refactor ChannelCredentials and move to Grpc.Core.Api. ([#19712](https://github.com/grpc/grpc/pull/19712))

-  C# bump major version to 2.x. ([#19796](https://github.com/grpc/grpc/pull/19796))

-  Add ChannelBase, change ClientBase constructor argument. ([#19599](https://github.com/grpc/grpc/pull/19599))

-  Remove System.Interactive.Async dependency. ([#19059](https://github.com/grpc/grpc/pull/19059))

-  dont use shutdownRef count for sync completion queue. ([#19629](https://github.com/grpc/grpc/pull/19629))

-  C# - remove delegate allocation and boxing from cancellation registrations. ([#19610](https://github.com/grpc/grpc/pull/19610))

-  csharp: Remove a double-box on Timespec. ([#19525](https://github.com/grpc/grpc/pull/19525))

-  C#: add System.Memory dependency and use Span<> internally for all target frameworks . ([#19569](https://github.com/grpc/grpc/pull/19569))

-  csharp remove byte[] allocations during UTF8 encode/decode. ([#19511](https://github.com/grpc/grpc/pull/19511))

-  csharp: remove AuthContext's Lazy<T> usage . ([#19533](https://github.com/grpc/grpc/pull/19533))

-  csharp avoid capture-context in HandleNewServerRpc => HandleCallAsync. ([#19526](https://github.com/grpc/grpc/pull/19526))

-  Make sure Grpc metapackage includes Grpc.Core.targets. ([#19449](https://github.com/grpc/grpc/pull/19449))

Objective-C

---

-  ObjC experimental Bazel build support. ([#19621](https://github.com/grpc/grpc/pull/19621))

-  Implement global interceptor. ([#19322](https://github.com/grpc/grpc/pull/19322))

PHP

---

-  PHP: Fix missing addref in channel::constructor(). ([#19737](https://github.com/grpc/grpc/pull/19737))

Python

---

-  Check call.trailing_metadata() for None before iterating it. ([#19708](https://github.com/grpc/grpc/pull/19708))

-  Add a sanity check for the Python release process. ([#19635](https://github.com/grpc/grpc/pull/19635))

-  Enforce a finite bound on the time gap between signal receipt and signal handler execution. ([#19481](https://github.com/grpc/grpc/pull/19481))

-  Python Compression Example. ([#19421](https://github.com/grpc/grpc/pull/19421))

Ruby

---

-  Don't require_relative for an absolute path. ([#19585](https://github.com/grpc/grpc/pull/19585))

-  Drop support for ruby < 2.3. ([#19304](https://github.com/grpc/grpc/pull/19304))