bc0977f1c9
Follow #31908. The main refactor is that it has removed the returned context of `Lock`. The returned context of `Lock` in old code is to provide a way to let callers know that they have lost the lock. But in most cases, callers shouldn't cancel what they are doing even it has lost the lock. And the design would confuse developers and make them use it incorrectly. See the discussion history: https://github.com/go-gitea/gitea/pull/31813#discussion_r1732041513 and https://github.com/go-gitea/gitea/pull/31813#discussion_r1734078998 It's a breaking change, but since the new module hasn't been used yet, I think it's OK to not add the `pr/breaking` label. ## Design principles It's almost copied from #31908, but with some changes. ### Use spinlock even in memory implementation (unchanged) In actual use cases, users may cancel requests. `sync.Mutex` will block the goroutine until the lock is acquired even if the request is canceled. And the spinlock is more suitable for this scenario since it's possible to give up the lock acquisition. Although the spinlock consumes more CPU resources, I think it's acceptable in most cases. ### Do not expose the mutex to callers (unchanged) If we expose the mutex to callers, it's possible for callers to reuse the mutex, which causes more complexity. For example: ```go lock := GetLocker(key) lock.Lock() // ... // even if the lock is unlocked, we cannot GC the lock, // since the caller may still use it again. lock.Unlock() lock.Lock() // ... lock.Unlock() // callers have to GC the lock manually. RemoveLocker(key) ``` That's why https://github.com/go-gitea/gitea/pull/31813#discussion_r1721200549 In this PR, we only expose `ReleaseFunc` to callers. So callers just need to call `ReleaseFunc` to release the lock, and do not need to care about the lock's lifecycle. ```go release, err := locker.Lock(ctx, key) if err != nil { return err } // ... release() // if callers want to lock again, they have to re-acquire the lock. release, err := locker.Lock(ctx, key) // ... ``` In this way, it's also much easier for redis implementation to extend the mutex automatically, so that callers do not need to care about the lock's lifecycle. See also https://github.com/go-gitea/gitea/pull/31813#discussion_r1722659743 ### Use "release" instead of "unlock" (unchanged) For "unlock", it has the meaning of "unlock an acquired lock". So it's not acceptable to call "unlock" when failed to acquire the lock, or call "unlock" multiple times. It causes more complexity for callers to decide whether to call "unlock" or not. So we use "release" instead of "unlock" to make it clear. Whether the lock is acquired or not, callers can always call "release", and it's also safe to call "release" multiple times. But the code DO NOT expect callers to not call "release" after acquiring the lock. If callers forget to call "release", it will cause resource leak. That's why it's always safe to call "release" without extra checks: to avoid callers to forget to call it. ### Acquired locks could be lost, but the callers shouldn't stop Unlike `sync.Mutex` which will be locked forever once acquired until calling `Unlock`, for distributed lock, the acquired lock could be lost. For example, the caller has acquired the lock, and it holds the lock for a long time since auto-extending is working for redis. However, it lost the connection to the redis server, and it's impossible to extend the lock anymore. In #31908, it will cancel the context to make the operation stop, but it's not safe. Many operations are not revert-able. If they have been interrupted, then the instance goes corrupted. So `Lock` won't return `ctx` anymore in this PR. ### Multiple ways to use the lock 1. Regular way ```go release, err := Lock(ctx, key) if err != nil { return err } defer release() // ... ``` 2. Early release ```go release, err := Lock(ctx, key) if err != nil { return err } defer release() // ... // release the lock earlier release() // continue to do something else // ... ``` 3. Functional way ```go if err := LockAndDo(ctx, key, func(ctx context.Context) error { // ... return nil }); err != nil { return err } ```
Gitea
Purpose
The goal of this project is to make the easiest, fastest, and most painless way of setting up a self-hosted Git service.
As Gitea is written in Go, it works across all the platforms and architectures that are supported by Go, including Linux, macOS, and Windows on x86, amd64, ARM and PowerPC architectures. This project has been forked from Gogs since November of 2016, but a lot has changed.
For online demonstrations, you can visit demo.gitea.com.
For accessing free Gitea service (with a limited number of repositories), you can visit gitea.com.
To quickly deploy your own dedicated Gitea instance on Gitea Cloud, you can start a free trial at cloud.gitea.com.
Building
From the root of the source tree, run:
TAGS="bindata" make build
or if SQLite support is required:
TAGS="bindata sqlite sqlite_unlock_notify" make build
The build target is split into two sub-targets:
make backendwhich requires Go Stable, the required version is defined in go.mod.make frontendwhich requires Node.js LTS or greater.
Internet connectivity is required to download the go and npm modules. When building from the official source tarballs which include pre-built frontend files, the frontend target will not be triggered, making it possible to build without Node.js.
More info: https://docs.gitea.com/installation/install-from-source
Using
./gitea web
Note
If you're interested in using our APIs, we have experimental support with documentation.
Contributing
Expected workflow is: Fork -> Patch -> Push -> Pull Request
Note
- YOU MUST READ THE CONTRIBUTORS GUIDE BEFORE STARTING TO WORK ON A PULL REQUEST.
- If you have found a vulnerability in the project, please write privately to security@gitea.io. Thanks!
Translating
Translations are done through Crowdin. If you want to translate to a new language ask one of the managers in the Crowdin project to add a new language there.
You can also just create an issue for adding a language or ask on discord on the #translation channel. If you need context or find some translation issues, you can leave a comment on the string or ask on Discord. For general translation questions there is a section in the docs. Currently a bit empty but we hope to fill it as questions pop up.
https://docs.gitea.com/contributing/localization
Further information
For more information and instructions about how to install Gitea, please look at our documentation. If you have questions that are not covered by the documentation, you can get in contact with us on our Discord server or create a post in the discourse forum.
We maintain a list of Gitea-related projects at gitea/awesome-gitea.
The official Gitea CLI is developed at gitea/tea.
Authors
Backers
Thank you to all our backers! 🙏 [Become a backer]
Sponsors
Support this project by becoming a sponsor. Your logo will show up here with a link to your website. [Become a sponsor]
FAQ
How do you pronounce Gitea?
Gitea is pronounced /ɡɪ’ti:/ as in "gi-tea" with a hard g.
Why is this not hosted on a Gitea instance?
We're working on it.
License
This project is licensed under the MIT License. See the LICENSE file for the full license text.
Screenshots
Looking for an overview of the interface? Check it out!
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