0028532118
This change moves the unique package away from using a concurrent map and instead toward a bespoke concurrent canonicalization map. The map holds all its keys weakly, though keys may be looked up by value. The result is the strong pointer for the canonical value. Entries in the map are automatically cleaned up once the canonical reference no longer exists. Why do this? There's a problem with the current implementation when it comes to chains of unique.Handle: because the unique map will have a unique.Handle stored in its keys, each nested handle must be cleaned up 1 GC at a time. It takes N GC cycles, at minimum, to clean up a nested chain of N handles. This implementation, where the *only* value in the set is weakly-held, does not have this problem. The entire chain is dropped at once. The canon map implementation is a stripped-down version of HashTrieMap. The weak set implementation also has lower memory overheads by virtue of the fact that keys are all stored weakly. Whereas the previous map had both a T and a weak.Pointer[T], this *only* has a weak.Pointer[T]. The canonicalization map is a better abstraction overall and dramatically simplifies the unique.Make code. While we're here, delete the background goroutine and switch to runtime.AddCleanup. This is a step toward fixing #71772. We still need some kind of back-pressure mechanism, which will be implemented in a follow-up CL. For #71772. Fixes #71846. Change-Id: I5b2ee04ebfc7f6dd24c2c4a959dd0f6a8af24ca4 Reviewed-on: https://go-review.googlesource.com/c/go/+/650256 LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: David Chase <drchase@google.com> Auto-Submit: Michael Knyszek <mknyszek@google.com> |
||
|---|---|---|
| .github | ||
| api | ||
| doc | ||
| lib | ||
| misc | ||
| src | ||
| test | ||
| .gitattributes | ||
| .gitignore | ||
| CONTRIBUTING.md | ||
| LICENSE | ||
| PATENTS | ||
| README.md | ||
| SECURITY.md | ||
| codereview.cfg | ||
| go.env | ||
README.md
The Go Programming Language
Go is an open source programming language that makes it easy to build simple, reliable, and efficient software.
Gopher image by Renee French, licensed under Creative Commons 4.0 Attribution license.
Our canonical Git repository is located at https://go.googlesource.com/go. There is a mirror of the repository at https://github.com/golang/go.
Unless otherwise noted, the Go source files are distributed under the BSD-style license found in the LICENSE file.
Download and Install
Binary Distributions
Official binary distributions are available at https://go.dev/dl/.
After downloading a binary release, visit https://go.dev/doc/install for installation instructions.
Install From Source
If a binary distribution is not available for your combination of operating system and architecture, visit https://go.dev/doc/install/source for source installation instructions.
Contributing
Go is the work of thousands of contributors. We appreciate your help!
To contribute, please read the contribution guidelines at https://go.dev/doc/contribute.
Note that the Go project uses the issue tracker for bug reports and proposals only. See https://go.dev/wiki/Questions for a list of places to ask questions about the Go language.