Bump github.com/cloudflare/tableflip from 1.0.0 to 1.2.1

[dependabot]

Bumps github.com/cloudflare/tableflip from 1.0.0 to 1.2.1.

Release notes

Sourced from github.com/cloudflare/tableflip's releases.

Fix clearing O_NONBLOCK on upgrade

The Go runtime has annoying behaviour around setting and clearing O_NONBLOCK: exec.Cmd.Start() ends up calling os.File.Fd() for any file in exec.Cmd.ExtraFiles. os.File.Fd() disables both the use of the runtime poller for the file and clears O_NONBLOCK from the underlying open file descriptor.

This can lead to goroutines hanging in a parent process, after at least one failed upgrade. The bug manifests by goroutines which rely on either a deadline or interruption via Close() to be unblocked being stuck in read or accept like syscalls,. As far as I can tell we've not experienced this problem in production, so it's most likely quite rare.

Support net.PacketConn

Add built-in support for passing net.PacketConn around. This was possible using Fds.AddConn, but the new PacketConn support will also do correct unlinking of Unix domain sockets if necessary.

Allow compiling programs using tableflip on Windows

So far, developers working on a code base that uses tableflip on a Windows machine had a poor experience. Editing and building the program didn't work. Thanks to @​kohenkatz the library compiles on Windows without errors, and tableflip.New returns an error on Windows. Developers can use this to shim out the upgrader using the new testing subpackage.

Commits

• cae714b ensure that inherited files are nonblocking
• 57f992b require Go 1.14
• 5f43f42 remove go 1.12 compatibility
• 4b4e680 migrate to github actions
• 77aba94 Refactor some methods to take advantage of the new *WithCallback methods
• 40abd35 Allow opening connection with callbacks
• 4baec98 Add ListenConfig as Option to Upgrader
• ad79e1f Fix spurious Upgrader test failures
• 062b0ef Tidy up TestUpgraderOnOS
• c31a00e Add support for net.PacketConn
• Additional commits viewable in compare view

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