pytorch

6e640a0a - Revise the socket implementation of c10d (#68226)

Revise the socket implementation of c10d (#68226) Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/68226 **Note that this PR is unusually big due to the urgency of the changes. Please reach out to me in case you wish to have a "pair" review.** This PR introduces a major refactoring of the socket implementation of the C10d library. A big portion of the logic is now contained in the `Socket` class and a follow-up PR will further consolidate the remaining parts. As of today the changes in this PR offer: - significantly better error handling and much more verbose logging (see the example output below) - explicit support for IPv6 and dual-stack sockets - correct handling of signal interrupts - better Windows support A follow-up PR will consolidate `send`/`recv` logic into `Socket` and fully migrate to non-blocking sockets. ## Example Output ``` [I logging.h:21] The client socket will attempt to connect to an IPv6 address on (127.0.0.1, 29501). [I logging.h:21] The client socket is attempting to connect to [localhost]:29501. [W logging.h:28] The server socket on [localhost]:29501 is not yet listening (Error: 111 - Connection refused), retrying... [I logging.h:21] The server socket will attempt to listen on an IPv6 address. [I logging.h:21] The server socket is attempting to listen on [::]:29501. [I logging.h:21] The server socket has started to listen on [::]:29501. [I logging.h:21] The client socket will attempt to connect to an IPv6 address on (127.0.0.1, 29501). [I logging.h:21] The client socket is attempting to connect to [localhost]:29501. [I logging.h:21] The client socket has connected to [localhost]:29501 on [localhost]:42650. [I logging.h:21] The server socket on [::]:29501 has accepted a connection from [localhost]:42650. [I logging.h:21] The client socket has connected to [localhost]:29501 on [localhost]:42722. [I logging.h:21] The server socket on [::]:29501 has accepted a connection from [localhost]:42722. [I logging.h:21] The client socket will attempt to connect to an IPv6 address on (127.0.0.1, 29501). [I logging.h:21] The client socket is attempting to connect to [localhost]:29501. [I logging.h:21] The client socket has connected to [localhost]:29501 on [localhost]:42724. [I logging.h:21] The server socket on [::]:29501 has accepted a connection from [localhost]:42724. [I logging.h:21] The client socket will attempt to connect to an IPv6 address on (127.0.0.1, 29501). [I logging.h:21] The client socket is attempting to connect to [localhost]:29501. [I logging.h:21] The client socket has connected to [localhost]:29501 on [localhost]:42726. [I logging.h:21] The server socket on [::]:29501 has accepted a connection from [localhost]:42726. ``` ghstack-source-id: 143501987 Test Plan: Run existing unit and integration tests on devserver, Fedora, Ubuntu, macOS Big Sur, Windows 10. Reviewed By: Babar, wilson100hong, mrshenli Differential Revision: D32372333 fbshipit-source-id: 2204ffa28ed0d3683a9cb3ebe1ea8d92a831325a