Before there was a "graceful function": RunWithShutdownFns, it's mainly
for some modules which doesn't support context.

The old queue system doesn't work well with context, so the old queues
need it.

After the queue refactoring, the new queue works with context well, so,
use Golang context as much as possible, the `RunWithShutdownFns` could
be removed (replaced by RunWithCancel for context cancel mechanism), the
related code could be simplified.

This PR also fixes some legacy queue-init problems, eg:

* typo : archiver: "unable to create codes indexer queue" => "unable to
create repo-archive queue"
* no nil check for failed queues, which causes unfriendly panic

After this PR, many goroutines could have better display name:

![image](https://github.com/go-gitea/gitea/assets/2114189/701b2a9b-8065-4137-aeaa-0bda2b34604a)

![image](https://github.com/go-gitea/gitea/assets/2114189/f1d5f50f-0534-40f0-b0be-f2c9daa5fe92)

# ⚠️ Breaking

Many deprecated queue config options are removed (actually, they should
have been removed in 1.18/1.19).

If you see the fatal message when starting Gitea: "Please update your
app.ini to remove deprecated config options", please follow the error
messages to remove these options from your app.ini.

Example:

```
2023/05/06 19:39:22 [E] Removed queue option: `[indexer].ISSUE_INDEXER_QUEUE_TYPE`. Use new options in `[queue.issue_indexer]`
2023/05/06 19:39:22 [E] Removed queue option: `[indexer].UPDATE_BUFFER_LEN`. Use new options in `[queue.issue_indexer]`
2023/05/06 19:39:22 [F] Please update your app.ini to remove deprecated config options
```

Many options in `[queue]` are are dropped, including:
`WRAP_IF_NECESSARY`, `MAX_ATTEMPTS`, `TIMEOUT`, `WORKERS`,
`BLOCK_TIMEOUT`, `BOOST_TIMEOUT`, `BOOST_WORKERS`, they can be removed
from app.ini.

# The problem

The old queue package has some legacy problems:

* complexity: I doubt few people could tell how it works.
* maintainability: Too many channels and mutex/cond are mixed together,
too many different structs/interfaces depends each other.
* stability: due to the complexity & maintainability, sometimes there
are strange bugs and difficult to debug, and some code doesn't have test
(indeed some code is difficult to test because a lot of things are mixed
together).
* general applicability: although it is called "queue", its behavior is
not a well-known queue.
* scalability: it doesn't seem easy to make it work with a cluster
without breaking its behaviors.

It came from some very old code to "avoid breaking", however, its
technical debt is too heavy now. It's a good time to introduce a better
"queue" package.

# The new queue package

It keeps using old config and concept as much as possible.

* It only contains two major kinds of concepts:
    * The "base queue": channel, levelqueue, redis
* They have the same abstraction, the same interface, and they are
tested by the same testing code.
* The "WokerPoolQueue", it uses the "base queue" to provide "worker
pool" function, calls the "handler" to process the data in the base
queue.
* The new code doesn't do "PushBack"
* Think about a queue with many workers, the "PushBack" can't guarantee
the order for re-queued unhandled items, so in new code it just does
"normal push"
* The new code doesn't do "pause/resume"
* The "pause/resume" was designed to handle some handler's failure: eg:
document indexer (elasticsearch) is down
* If a queue is paused for long time, either the producers blocks or the
new items are dropped.
* The new code doesn't do such "pause/resume" trick, it's not a common
queue's behavior and it doesn't help much.
* If there are unhandled items, the "push" function just blocks for a
few seconds and then re-queue them and retry.
* The new code doesn't do "worker booster"
* Gitea's queue's handlers are light functions, the cost is only the
go-routine, so it doesn't make sense to "boost" them.
* The new code only use "max worker number" to limit the concurrent
workers.
* The new "Push" never blocks forever
* Instead of creating more and more blocking goroutines, return an error
is more friendly to the server and to the end user.

There are more details in code comments: eg: the "Flush" problem, the
strange "code.index" hanging problem, the "immediate" queue problem.

Almost ready for review.

TODO:

* [x] add some necessary comments during review
* [x] add some more tests if necessary
* [x] update documents and config options
* [x] test max worker / active worker
* [x] re-run the CI tasks to see whether any test is flaky
* [x] improve the `handleOldLengthConfiguration` to provide more
friendly messages
* [x] fine tune default config values (eg: length?)

## Code coverage:

![image](https://user-images.githubusercontent.com/2114189/236620635-55576955-f95d-4810-b12f-879026a3afdf.png)

Fix #23000.

Our trace logging is far from perfect and is difficult to follow.

This PR:

* Add trace logging for process manager add and remove.
* Fixes an errant read file for git refs in getMergeCommit
* Brings in the pullrequest `String` and `ColorFormat` methods
introduced in #22568
* Adds a lot more logging in to testPR etc.

Ref #22578

---------

Signed-off-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: delvh <dev.lh@web.de>
Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>

Co-authored-by: KN4CK3R <admin@oldschoolhack.me>
Co-authored-by: Lauris BH <lauris@nix.lv>

Change all license headers to comply with REUSE specification.

Fix #16132

Co-authored-by: flynnnnnnnnnn <flynnnnnnnnnn@github>
Co-authored-by: John Olheiser <john.olheiser@gmail.com>

This PR adds a context parameter to a bunch of methods. Some helper
`xxxCtx()` methods got replaced with the normal name now.

Co-authored-by: delvh <dev.lh@web.de>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

Fix #19513

This PR introduce a new db method `InTransaction(context.Context)`,
and also builtin check on `db.TxContext` and `db.WithTx`.
There is also a new method `db.AutoTx` has been introduced but could be used by other PRs.

`WithTx` will always open a new transaction, if a transaction exist in context, return an error.
`AutoTx` will try to open a new transaction if no transaction exist in context.
That means it will always enter a transaction if there is no error.

Co-authored-by: delvh <dev.lh@web.de>
Co-authored-by: 6543 <6543@obermui.de>

I found myself wondering whether a PR I scheduled for automerge was
actually merged. It was, but I didn't receive a mail notification for it
- that makes sense considering I am the doer and usually don't want to
receive such notifications. But ideally I want to receive a notification
when a PR was merged because I scheduled it for automerge.

This PR implements exactly that.

The implementation works, but I wonder if there's a way to avoid passing
the "This PR was automerged" state down so much. I tried solving this
via the database (checking if there's an automerge scheduled for this PR
when sending the notification) but that did not work reliably, probably
because sending the notification happens async and the entry might have
already been deleted. My implementation might be the most
straightforward but maybe not the most elegant.

Signed-off-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: Lauris BH <lauris@nix.lv>
Co-authored-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

Add nakedret, unconvert, wastedassign, stylecheck and nolintlint linters to improve code readability

- nakedret - https://github.com/alexkohler/nakedret - nakedret is a Go static analysis tool to find naked returns in functions greater than a specified function length.
- unconvert - https://github.com/mdempsky/unconvert - Remove unnecessary type conversions
- wastedassign - https://github.com/sanposhiho/wastedassign -  wastedassign finds wasted assignment statements.
- notlintlint -  Reports ill-formed or insufficient nolint directives
- stylecheck - https://staticcheck.io/docs/checks/#ST - keep style consistent
  - excluded: [ST1003 - Poorly chosen identifier](https://staticcheck.io/docs/checks/#ST1003) and [ST1005 - Incorrectly formatted error string](https://staticcheck.io/docs/checks/#ST1005)

* Move access and repo permission to models/perm/access

* fix test

* fix git test

* Move functions sequence

* Some improvements per @KN4CK3R and @delvh

* Move issues related code to models/issues

* Move some issues related sub package

* Merge

* Fix test

* Fix test

* Fix test

* Fix test

* Rename some files

* Move almost all functions' parameter db.Engine to context.Context
* remove some unnecessary wrap functions

* Move access and repo permission to models/perm/access

* Remove unnecessary code

* delete pullautomerges on repo/user deletion
* delete reviewstates on repo/user deletion
* optimize automerhe code
* add index to reviewstate

* Allow custom default merge message with .gitea/MERGE_MESSAGE_<merge_style>_TEMPLATE.md

* Some improvements

* Follow some advices

* Fix bug

* Fix bug

* Fix lint

* Fix close comment

* Fix test

* Fix and docs

* Improve codes

* Update docs and remove unnecessary variables

* return error for GetDefaultMergeMessage

* Fix test

* improve code

* ignore unknow unit type

* return error for GetDefaultMergeMessage

* Update services/pull/merge.go

* Some improvements

* Follow some advices

* Fix bug

* Fix lint

* Improve codes

* Update docs and remove unnecessary variables

* return error for GetDefaultMergeMessage

* improve code

* Handle deleted HeadRepo in GetDefaultMergeMessage

Signed-off-by: Andrew Thornton <art27@cantab.net>

* Fix test

* Fix test

Co-authored-by: zeripath <art27@cantab.net>

* Fix indention

Signed-off-by: kolaente <k@knt.li>

* Add option to merge a pr right now without waiting for the checks to succeed

Signed-off-by: kolaente <k@knt.li>

* Fix lint

Signed-off-by: kolaente <k@knt.li>

* Add scheduled pr merge to tables used for testing

Signed-off-by: kolaente <k@knt.li>

* Add status param to make GetPullRequestByHeadBranch reusable

Signed-off-by: kolaente <k@knt.li>

* Move "Merge now" to a seperate button to make the ui clearer

Signed-off-by: kolaente <k@knt.li>

* Update models/scheduled_pull_request_merge.go

Co-authored-by: 赵智超 <1012112796@qq.com>

* Update web_src/js/index.js

Co-authored-by: 赵智超 <1012112796@qq.com>

* Update web_src/js/index.js

Co-authored-by: 赵智超 <1012112796@qq.com>

* Re-add migration after merge

* Fix frontend lint

* Fix version compare

* Add vendored dependencies

* Add basic tets

* Make sure the api route is capable of scheduling PRs for merging

* Fix comparing version

* make vendor

* adopt refactor

* apply suggestion: User -> Doer

* init var once

* Fix Test

* Update templates/repo/issue/view_content/comments.tmpl

* adopt

* nits

* next

* code format

* lint

* use same name schema; rm CreateUnScheduledPRToAutoMergeComment

* API: can not create schedule twice

* Add TestGetBranchNamesForSha

* nits

* new go routine for each pull to merge

* Update models/pull.go

Co-authored-by: a101211279 <1012112796@qq.com>

* Update models/scheduled_pull_request_merge.go

Co-authored-by: a101211279 <1012112796@qq.com>

* fix & add renaming sugestions

* Update services/automerge/pull_auto_merge.go

Co-authored-by: a101211279 <1012112796@qq.com>

* fix conflict relicts

* apply latest refactors

* fix: migration after merge

* Update models/error.go

Co-authored-by: delvh <dev.lh@web.de>

* Update options/locale/locale_en-US.ini

Co-authored-by: delvh <dev.lh@web.de>

* Update options/locale/locale_en-US.ini

Co-authored-by: delvh <dev.lh@web.de>

* adapt latest refactors

* fix test

* use more context

* skip potential edgecases

* document func usage

* GetBranchNamesForSha() -> GetRefsBySha()

* start refactoring

* ajust to new changes

* nit

* docu nit

* the great check move

* move checks for branchprotection into own package

* resolve todo now ...

* move & rename

* unexport if posible

* fix

* check if merge is allowed before merge on scheduled pull

* debugg

* wording

* improve SetDefaults & nits

* NotAllowedToMerge -> DisallowedToMerge

* fix test

* merge files

* use package "errors"

* merge files

* add string names

* other implementation for gogit

* adapt refactor

* more context for models/pull.go

* GetUserRepoPermission use context

* more ctx

* use context for loading pull head/base-repo

* more ctx

* more ctx

* models.LoadIssueCtx()

* models.LoadIssueCtx()

* Handle pull_service.Merge in one DB transaction

* add TODOs

* next

* next

* next

* more ctx

* more ctx

* Start refactoring structure of old pull code ...

* move code into new packages

* shorter names ... and finish **restructure**

* Update models/branches.go

Co-authored-by: zeripath <art27@cantab.net>

* finish UpdateProtectBranch

* more and fix

* update datum

* template: use "svg" helper

* rename prQueue 2 prPatchCheckerQueue

* handle automerge in queue

* lock pull on git&db actions ...

* lock pull on git&db actions ...

* add TODO notes

* the regex

* transaction in tests

* GetRepositoryByIDCtx

* shorter table name and lint fix

* close transaction bevore notify

* Update models/pull.go

* next

* CheckPullMergable check all branch protections!

* Update routers/web/repo/pull.go

* CheckPullMergable check all branch protections!

* Revert "PullService lock via pullID (#19520)" (for now...)

This reverts commit 6cde7c9159.

* Update services/pull/check.go

* Use for a repo action one database transaction

* Apply suggestions from code review

* Apply suggestions from code review

Co-authored-by: delvh <dev.lh@web.de>

* Update services/issue/status.go

Co-authored-by: delvh <dev.lh@web.de>

* Update services/issue/status.go

Co-authored-by: delvh <dev.lh@web.de>

* use db.WithTx()

* gofmt

* make pr.GetDefaultMergeMessage() context aware

* make MergePullRequestForm.SetDefaults context aware

* use db.WithTx()

* pull.SetMerged only with context

* fix deadlock in `test-sqlite\#TestAPIBranchProtection`

* dont forget templates

* db.WithTx allow to set the parentCtx

* handle db transaction in service packages but not router

* issue_service.ChangeStatus just had caused another deadlock :/
it has to do something with how notification package is handled

* if we merge a pull in one database transaktion, we get a lock, because merge infoce internal api that cant handle open db sessions to the same repo

* ajust to current master

* Apply suggestions from code review

Co-authored-by: delvh <dev.lh@web.de>

* dont open db transaction in router

* make generate-swagger

* one _success less

* wording nit

* rm

* adapt

* remove not needed test files

* rm less diff & use attr in JS

* ...

* Update services/repository/files/commit.go

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

* ajust db schema for PullAutoMerge

* skip broken pull refs

* more context in error messages

* remove webUI part for another pull

* remove more WebUI only parts

* API: add CancleAutoMergePR

* Apply suggestions from code review

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

* fix lint

* Apply suggestions from code review

* cancle -> cancel

Co-authored-by: delvh <dev.lh@web.de>

* change queue identifyer

* fix swagger

* prevent nil issue

* fix and dont drop error

* as per @zeripath

* Update integrations/git_test.go

Co-authored-by: delvh <dev.lh@web.de>

* Update integrations/git_test.go

Co-authored-by: delvh <dev.lh@web.de>

* more declarative integration tests (dedup code)

* use assert.False/True helper

Co-authored-by: 赵智超 <1012112796@qq.com>
Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: delvh <dev.lh@web.de>
Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>