gitea/modules/setting
wxiaoguang 6f9c278559
Rewrite queue (#24505)
# ⚠️ 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)
2023-05-08 19:49:59 +08:00
..
actions.go Refactor the setting to make unit test easier (#22405) 2023-02-20 00:12:01 +08:00
admin.go Refactor the setting to make unit test easier (#22405) 2023-02-20 00:12:01 +08:00
api.go Refactor the setting to make unit test easier (#22405) 2023-02-20 00:12:01 +08:00
asset_dynamic.go Use a general approach to access custom/static/builtin assets (#24022) 2023-04-12 18:16:45 +08:00
asset_static.go Use a general approach to access custom/static/builtin assets (#24022) 2023-04-12 18:16:45 +08:00
attachment.go Add .patch to attachment.ALLOWED_TYPES (#23580) 2023-03-19 15:58:43 -04:00
cache.go Refactor the setting to make unit test easier (#22405) 2023-02-20 00:12:01 +08:00
camo.go Refactor the setting to make unit test easier (#22405) 2023-02-20 00:12:01 +08:00
config_provider.go Rewrite queue (#24505) 2023-05-08 19:49:59 +08:00
cors.go Fix incorrect CORS default values (#24206) 2023-04-19 15:30:10 -04:00
cron_test.go Rewrite queue (#24505) 2023-05-08 19:49:59 +08:00
cron.go Refactor the setting to make unit test easier (#22405) 2023-02-20 00:12:01 +08:00
database_sqlite.go Implement FSFE REUSE for golang files (#21840) 2022-11-27 18:20:29 +00:00
database_test.go Implement FSFE REUSE for golang files (#21840) 2022-11-27 18:20:29 +00:00
database.go Move pidfile creation from setting to web cmd package (#23285) 2023-03-16 15:22:54 +08:00
federation.go Refactor the setting to make unit test easier (#22405) 2023-02-20 00:12:01 +08:00
git.go Support reflogs (#22451) 2023-03-13 15:51:07 +08:00
highlight.go Refactor the setting to make unit test easier (#22405) 2023-02-20 00:12:01 +08:00
i18n.go Refactor the setting to make unit test easier (#22405) 2023-02-20 00:12:01 +08:00
incoming_email.go Refactor the setting to make unit test easier (#22405) 2023-02-20 00:12:01 +08:00
indexer_test.go Implement FSFE REUSE for golang files (#21840) 2022-11-27 18:20:29 +00:00
indexer.go Rewrite queue (#24505) 2023-05-08 19:49:59 +08:00
lfs.go Refactor config provider (#24245) 2023-04-25 23:06:39 +08:00
log.go Refactor config provider (#24245) 2023-04-25 23:06:39 +08:00
mailer_test.go Refactor config provider (#24245) 2023-04-25 23:06:39 +08:00
mailer.go handle deprecated settings (#22992) 2023-02-20 16:18:26 -06:00
markup.go Add .livemd as a markdown extension (#22730) 2023-04-26 11:22:54 -04:00
metrics.go Refactor the setting to make unit test easier (#22405) 2023-02-20 00:12:01 +08:00
migrations.go Refactor the setting to make unit test easier (#22405) 2023-02-20 00:12:01 +08:00
mime_type_map.go Refactor the setting to make unit test easier (#22405) 2023-02-20 00:12:01 +08:00
mirror.go handle deprecated settings (#22992) 2023-02-20 16:18:26 -06:00
oauth2.go Refactor config provider (#24245) 2023-04-25 23:06:39 +08:00
other.go Refactor setting.Other and remove unused SHOW_FOOTER_BRANDING (#24270) 2023-04-22 19:38:25 -04:00
packages_test.go Implement FSFE REUSE for golang files (#21840) 2022-11-27 18:20:29 +00:00
packages.go Add RPM registry (#23380) 2023-05-05 20:33:37 +00:00
picture.go Refactor the setting to make unit test easier (#22405) 2023-02-20 00:12:01 +08:00
project.go Refactor the setting to make unit test easier (#22405) 2023-02-20 00:12:01 +08:00
proxy.go Refactor the setting to make unit test easier (#22405) 2023-02-20 00:12:01 +08:00
queue.go Rewrite queue (#24505) 2023-05-08 19:49:59 +08:00
repository.go Fix the permission of team's Actions unit issue (#24536) 2023-05-05 20:02:30 +08:00
security.go Refactor config provider (#24245) 2023-04-25 23:06:39 +08:00
server.go handle deprecated settings (#22992) 2023-02-20 16:18:26 -06:00
service.go Refactor the setting to make unit test easier (#22405) 2023-02-20 00:12:01 +08:00
session.go Refactor cookie (#24107) 2023-04-13 15:45:33 -04:00
setting_test.go Implement FSFE REUSE for golang files (#21840) 2022-11-27 18:20:29 +00:00
setting.go Merge setting.InitXXX into one function with options (#24389) 2023-05-04 11:55:35 +08:00
ssh.go Prefer native parser for SSH public key parsing (#23798) 2023-04-11 14:34:28 +08:00
storage_test.go Rewrite queue (#24505) 2023-05-08 19:49:59 +08:00
storage.go Refactor config provider (#24245) 2023-04-25 23:06:39 +08:00
task.go handle deprecated settings (#22992) 2023-02-20 16:18:26 -06:00
time.go Remove unused setting time.FORMAT (#24430) 2023-04-29 22:51:43 +02:00
ui.go Don't set meta theme-color by default (#24340) 2023-04-26 00:56:42 -04:00
webhook.go Refactor the setting to make unit test easier (#22405) 2023-02-20 00:12:01 +08:00