Create 33974-add-public-lockedfile-pkg.md

Author: azr

design/33974-add-public-lockedfile-pkg.md

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+# Proposal: make the internal [lockedfile](https://godoc.org/github.com/golang/go/src/cmd/go/internal/lockedfile/) package public
+
+Author(s): [Adrien Delorme]
+
+Last updated: 2019-10-15
+
+Discussion at https://golang.org/issue/33974.
+
+## Abstract
+
+Move already existing code residing golang/go/src/cmd/go/internal/lockedfile to
+`x/exp`. At `x/exp/lockedfile`.
+
+## Background
+
+A few Golang open source projects are implementing file locking mechanisms
+( https://github.com/gofrs/flock, https://github.com/MichaelS11/go-file-lock,
+https://github.com/juju/fslock ) but they do not seem to be maintained anymore,
+issues are ignored and they seem untrusted.
+As a result some major projects are doing their own version of it; ex:
+[terraform](https://github.com/hashicorp/terraform/blob/1ff9a540202b8c36e33db950374bbb4495737d8f/states/statemgr/filesystem_lock_unix.go),
+[boltdb](https://github.com/boltdb/bolt/search?q=flock&unscoped_q=flock).
+After some researches it seemed to us that the already existing and maintained
+[lockedfile](https://godoc.org/github.com/golang/go/src/cmd/go/internal/lockedfile/)
+package is the best 'open source' version.
+
+File locking seems complicated and low level enough to be more closely
+maintained by the go community ( and/or team ? ).
+We think it would benefit the mass to make such a package public: since it's
+already being part of the go code and therefore being maintained; it should be
+made public.
+
+## Proposal
+
+We propose to copy the golang/go/src/cmd/go/internal/lockedfile to `x/exp`. To
+make it public. Not changing any of the named types for now.
+
+## Rationale
+
+The golang/go/src/cmd/go/internal/lockedfile already exists but has untrusted &
+unmaintained alternatives.
+
+* Making this package public will make it more used. A tiny surge of issues
+  might come in the beginning; at the benefits of everyone. ( Unless it's
+  bug free !! ).
+
+* There exists a https://godoc.org/github.com/rogpeppe/go-internal package that
+  exports a lot of internal packages from the go repo. But if go-internal
+  became wildly popular; in order to have a bug fixed or a feature introduced
+  in; a user would still need to open a PR on the go repo; then the author of
+  go-internal would need to update the package.
+
+## Compatibility
+
+There are no compatibility issues. Since this will be a code addition.
+
+## Implementation
+
+Adrien Delorme plans to do copy the internal/lockedfile package from cmd/go to
+`x/exp`.