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)

3 files changed, 6 insertions, 185 deletions

diff --git a/models/migrations/base/testlogger.go b/models/migrations/base/testlogger.go
deleted file mode 100644
index 80e672952a..0000000000
--- a/models/migrations/base/testlogger.go
+++ /dev/null
@@ -1,180 +0,0 @@
-// Copyright 2019 The Gitea Authors. All rights reserved.
-// SPDX-License-Identifier: MIT
-
-package base
-
-import (
-	"context"
-	"fmt"
-	"os"
-	"runtime"
-	"strings"
-	"sync"
-	"testing"
-	"time"
-
-	"code.gitea.io/gitea/modules/json"
-	"code.gitea.io/gitea/modules/log"
-	"code.gitea.io/gitea/modules/queue"
-)
-
-var (
-	prefix    string
-	slowTest  = 10 * time.Second
-	slowFlush = 5 * time.Second
-)
-
-// TestLogger is a logger which will write to the testing log
-type TestLogger struct {
-	log.WriterLogger
-}
-
-var writerCloser = &testLoggerWriterCloser{}
-
-type testLoggerWriterCloser struct {
-	sync.RWMutex
-	t []*testing.TB
-}
-
-func (w *testLoggerWriterCloser) setT(t *testing.TB) {
-	w.Lock()
-	w.t = append(w.t, t)
-	w.Unlock()
-}
-
-func (w *testLoggerWriterCloser) Write(p []byte) (int, error) {
-	w.RLock()
-	var t *testing.TB
-	if len(w.t) > 0 {
-		t = w.t[len(w.t)-1]
-	}
-	w.RUnlock()
-	if t != nil && *t != nil {
-		if len(p) > 0 && p[len(p)-1] == '\n' {
-			p = p[:len(p)-1]
-		}
-
-		defer func() {
-			err := recover()
-			if err == nil {
-				return
-			}
-			var errString string
-			errErr, ok := err.(error)
-			if ok {
-				errString = errErr.Error()
-			} else {
-				errString, ok = err.(string)
-			}
-			if !ok {
-				panic(err)
-			}
-			if !strings.HasPrefix(errString, "Log in goroutine after ") {
-				panic(err)
-			}
-		}()
-
-		(*t).Log(string(p))
-		return len(p), nil
-	}
-	return len(p), nil
-}
-
-func (w *testLoggerWriterCloser) Close() error {
-	w.Lock()
-	if len(w.t) > 0 {
-		w.t = w.t[:len(w.t)-1]
-	}
-	w.Unlock()
-	return nil
-}
-
-// PrintCurrentTest prints the current test to os.Stdout
-func PrintCurrentTest(t testing.TB, skip ...int) func() {
-	start := time.Now()
-	actualSkip := 1
-	if len(skip) > 0 {
-		actualSkip = skip[0]
-	}
-	_, filename, line, _ := runtime.Caller(actualSkip)
-
-	if log.CanColorStdout {
-		fmt.Fprintf(os.Stdout, "=== %s (%s:%d)\n", fmt.Formatter(log.NewColoredValue(t.Name())), strings.TrimPrefix(filename, prefix), line)
-	} else {
-		fmt.Fprintf(os.Stdout, "=== %s (%s:%d)\n", t.Name(), strings.TrimPrefix(filename, prefix), line)
-	}
-	writerCloser.setT(&t)
-	return func() {
-		took := time.Since(start)
-		if took > slowTest {
-			if log.CanColorStdout {
-				fmt.Fprintf(os.Stdout, "+++ %s is a slow test (took %v)\n", fmt.Formatter(log.NewColoredValue(t.Name(), log.Bold, log.FgYellow)), fmt.Formatter(log.NewColoredValue(took, log.Bold, log.FgYellow)))
-			} else {
-				fmt.Fprintf(os.Stdout, "+++ %s is a slow test (took %v)\n", t.Name(), took)
-			}
-		}
-		timer := time.AfterFunc(slowFlush, func() {
-			if log.CanColorStdout {
-				fmt.Fprintf(os.Stdout, "+++ %s ... still flushing after %v ...\n", fmt.Formatter(log.NewColoredValue(t.Name(), log.Bold, log.FgRed)), slowFlush)
-			} else {
-				fmt.Fprintf(os.Stdout, "+++ %s ... still flushing after %v ...\n", t.Name(), slowFlush)
-			}
-		})
-		if err := queue.GetManager().FlushAll(context.Background(), -1); err != nil {
-			t.Errorf("Flushing queues failed with error %v", err)
-		}
-		timer.Stop()
-		flushTook := time.Since(start) - took
-		if flushTook > slowFlush {
-			if log.CanColorStdout {
-				fmt.Fprintf(os.Stdout, "+++ %s had a slow clean-up flush (took %v)\n", fmt.Formatter(log.NewColoredValue(t.Name(), log.Bold, log.FgRed)), fmt.Formatter(log.NewColoredValue(flushTook, log.Bold, log.FgRed)))
-			} else {
-				fmt.Fprintf(os.Stdout, "+++ %s had a slow clean-up flush (took %v)\n", t.Name(), flushTook)
-			}
-		}
-		_ = writerCloser.Close()
-	}
-}
-
-// Printf takes a format and args and prints the string to os.Stdout
-func Printf(format string, args ...interface{}) {
-	if log.CanColorStdout {
-		for i := 0; i < len(args); i++ {
-			args[i] = log.NewColoredValue(args[i])
-		}
-	}
-	fmt.Fprintf(os.Stdout, "\t"+format, args...)
-}
-
-// NewTestLogger creates a TestLogger as a log.LoggerProvider
-func NewTestLogger() log.LoggerProvider {
-	logger := &TestLogger{}
-	logger.Colorize = log.CanColorStdout
-	logger.Level = log.TRACE
-	return logger
-}
-
-// Init inits connection writer with json config.
-// json config only need key "level".
-func (log *TestLogger) Init(config string) error {
-	err := json.Unmarshal([]byte(config), log)
-	if err != nil {
-		return err
-	}
-	log.NewWriterLogger(writerCloser)
-	return nil
-}
-
-// Flush when log should be flushed
-func (log *TestLogger) Flush() {
-}
-
-// ReleaseReopen does nothing
-func (log *TestLogger) ReleaseReopen() error {
-	return nil
-}
-
-// GetName returns the default name for this implementation
-func (log *TestLogger) GetName() string {
-	return "test"
-}
diff --git a/models/migrations/base/tests.go b/models/migrations/base/tests.go
index 124111f51f..08eded7fdc 100644
--- a/models/migrations/base/tests.go
+++ b/models/migrations/base/tests.go
@@ -11,7 +11,6 @@ import (
 	"path"
 	"path/filepath"
 	"runtime"
-	"strings"
 	"testing"
 
 	"code.gitea.io/gitea/models/unittest"
@@ -19,6 +18,7 @@ import (
 	"code.gitea.io/gitea/modules/git"
 	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/setting"
+	"code.gitea.io/gitea/modules/testlogger"
 
 	"github.com/stretchr/testify/assert"
 	"xorm.io/xorm"
@@ -32,7 +32,7 @@ func PrepareTestEnv(t *testing.T, skip int, syncModels ...interface{}) (*xorm.En
 	t.Helper()
 	ourSkip := 2
 	ourSkip += skip
-	deferFn := PrintCurrentTest(t, ourSkip)
+	deferFn := testlogger.PrintCurrentTest(t, ourSkip)
 	assert.NoError(t, os.RemoveAll(setting.RepoRootPath))
 	assert.NoError(t, unittest.CopyDir(path.Join(filepath.Dir(setting.AppPath), "tests/gitea-repositories-meta"), setting.RepoRootPath))
 	ownerDirs, err := os.ReadDir(setting.RepoRootPath)
@@ -110,9 +110,7 @@ func PrepareTestEnv(t *testing.T, skip int, syncModels ...interface{}) (*xorm.En
 }
 
 func MainTest(m *testing.M) {
-	log.Register("test", NewTestLogger)
-	_, filename, _, _ := runtime.Caller(0)
-	prefix = strings.TrimSuffix(filename, "tests/testlogger.go")
+	log.Register("test", testlogger.NewTestLogger)
 
 	giteaRoot := base.SetupGiteaRoot()
 	if giteaRoot == "" {
diff --git a/models/unittest/testdb.go b/models/unittest/testdb.go
index a5b126350d..10a70ad9f8 100644
--- a/models/unittest/testdb.go
+++ b/models/unittest/testdb.go
@@ -202,6 +202,9 @@ type FixturesOptions struct {
 func CreateTestEngine(opts FixturesOptions) error {
 	x, err := xorm.NewEngine("sqlite3", "file::memory:?cache=shared&_txlock=immediate")
 	if err != nil {
+		if strings.Contains(err.Error(), "unknown driver") {
+			return fmt.Errorf(`sqlite3 requires: import _ "github.com/mattn/go-sqlite3" or -tags sqlite,sqlite_unlock_notify%s%w`, "\n", err)
+		}
 		return err
 	}
 	x.SetMapper(names.GonicMapper{})