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)

10 files changed, 29 insertions, 255 deletions

diff --git a/tests/e2e/e2e_test.go b/tests/e2e/e2e_test.go
index 224b38e728..e75b3db38f 100644
--- a/tests/e2e/e2e_test.go
+++ b/tests/e2e/e2e_test.go
@@ -21,6 +21,7 @@ import (
 	"code.gitea.io/gitea/modules/graceful"
 	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/setting"
+	"code.gitea.io/gitea/modules/testlogger"
 	"code.gitea.io/gitea/modules/util"
 	"code.gitea.io/gitea/modules/web"
 	"code.gitea.io/gitea/routers"
@@ -58,7 +59,7 @@ func TestMain(m *testing.M) {
 
 	exitVal := m.Run()
 
-	tests.WriterCloser.Reset()
+	testlogger.WriterCloser.Reset()
 
 	if err = util.RemoveAll(setting.Indexer.IssuePath); err != nil {
 		fmt.Printf("util.RemoveAll: %v\n", err)
diff --git a/tests/integration/api_branch_test.go b/tests/integration/api_branch_test.go
index 0d4a750a29..6616399a8a 100644
--- a/tests/integration/api_branch_test.go
+++ b/tests/integration/api_branch_test.go
@@ -143,7 +143,6 @@ func testAPICreateBranches(t *testing.T, giteaURL *url.URL) {
 		},
 	}
 	for _, test := range testCases {
-		defer tests.ResetFixtures(t)
 		session := ctx.Session
 		testAPICreateBranch(t, session, "user2", "my-noo-repo", test.OldBranch, test.NewBranch, test.ExpectedHTTPStatus)
 	}
diff --git a/tests/integration/integration_test.go b/tests/integration/integration_test.go
index fbe90ecf78..01f26d567f 100644
--- a/tests/integration/integration_test.go
+++ b/tests/integration/integration_test.go
@@ -29,6 +29,7 @@ import (
 	"code.gitea.io/gitea/modules/json"
 	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/setting"
+	"code.gitea.io/gitea/modules/testlogger"
 	"code.gitea.io/gitea/modules/util"
 	"code.gitea.io/gitea/modules/web"
 	"code.gitea.io/gitea/routers"
@@ -91,21 +92,21 @@ func TestMain(m *testing.M) {
 	// integration test settings...
 	if setting.CfgProvider != nil {
 		testingCfg := setting.CfgProvider.Section("integration-tests")
-		tests.SlowTest = testingCfg.Key("SLOW_TEST").MustDuration(tests.SlowTest)
-		tests.SlowFlush = testingCfg.Key("SLOW_FLUSH").MustDuration(tests.SlowFlush)
+		testlogger.SlowTest = testingCfg.Key("SLOW_TEST").MustDuration(testlogger.SlowTest)
+		testlogger.SlowFlush = testingCfg.Key("SLOW_FLUSH").MustDuration(testlogger.SlowFlush)
 	}
 
 	if os.Getenv("GITEA_SLOW_TEST_TIME") != "" {
 		duration, err := time.ParseDuration(os.Getenv("GITEA_SLOW_TEST_TIME"))
 		if err == nil {
-			tests.SlowTest = duration
+			testlogger.SlowTest = duration
 		}
 	}
 
 	if os.Getenv("GITEA_SLOW_FLUSH_TIME") != "" {
 		duration, err := time.ParseDuration(os.Getenv("GITEA_SLOW_FLUSH_TIME"))
 		if err == nil {
-			tests.SlowFlush = duration
+			testlogger.SlowFlush = duration
 		}
 	}
 
@@ -130,7 +131,7 @@ func TestMain(m *testing.M) {
 	// Instead, "No tests were found",  last nonsense log is "According to the configuration, subsequent logs will not be printed to the console"
 	exitCode := m.Run()
 
-	tests.WriterCloser.Reset()
+	testlogger.WriterCloser.Reset()
 
 	if err = util.RemoveAll(setting.Indexer.IssuePath); err != nil {
 		fmt.Printf("util.RemoveAll: %v\n", err)
diff --git a/tests/mssql.ini.tmpl b/tests/mssql.ini.tmpl
index 9cec6169f9..09e75acb01 100644
--- a/tests/mssql.ini.tmpl
+++ b/tests/mssql.ini.tmpl
@@ -14,7 +14,7 @@ REPO_INDEXER_ENABLED = true
 REPO_INDEXER_PATH = tests/{{TEST_TYPE}}/gitea-{{TEST_TYPE}}-mssql/indexers/repos.bleve
 
 [queue.issue_indexer]
-PATH = tests/{{TEST_TYPE}}/gitea-{{TEST_TYPE}}-mssql/indexers/issues.bleve
+TYPE = level
 DATADIR = tests/{{TEST_TYPE}}/gitea-{{TEST_TYPE}}-mssql/indexers/issues.queue
 
 [queue]
diff --git a/tests/mysql.ini.tmpl b/tests/mysql.ini.tmpl
index b286f37bf8..6fcb2792c3 100644
--- a/tests/mysql.ini.tmpl
+++ b/tests/mysql.ini.tmpl
@@ -12,10 +12,11 @@ SSL_MODE = disable
 [indexer]
 REPO_INDEXER_ENABLED = true
 REPO_INDEXER_PATH = tests/{{TEST_TYPE}}/gitea-{{TEST_TYPE}}-mysql/indexers/repos.bleve
+ISSUE_INDEXER_TYPE = elasticsearch
+ISSUE_INDEXER_CONN_STR = http://elastic:changeme@elasticsearch:9200
 
 [queue.issue_indexer]
-TYPE = elasticsearch
-CONN_STR = http://elastic:changeme@elasticsearch:9200
+TYPE = level
 DATADIR = tests/{{TEST_TYPE}}/gitea-{{TEST_TYPE}}-mysql/indexers/issues.queue
 
 [queue]
diff --git a/tests/mysql8.ini.tmpl b/tests/mysql8.ini.tmpl
index f290efe1dc..e37052da8c 100644
--- a/tests/mysql8.ini.tmpl
+++ b/tests/mysql8.ini.tmpl
@@ -14,7 +14,7 @@ REPO_INDEXER_ENABLED = true
 REPO_INDEXER_PATH = tests/{{TEST_TYPE}}/gitea-{{TEST_TYPE}}-mysql8/indexers/repos.bleve
 
 [queue.issue_indexer]
-PATH = tests/{{TEST_TYPE}}/gitea-{{TEST_TYPE}}-mysql8/indexers/issues.bleve
+TYPE = level
 DATADIR = tests/{{TEST_TYPE}}/gitea-{{TEST_TYPE}}-mysql8/indexers/issues.queue
 
 [queue]
diff --git a/tests/pgsql.ini.tmpl b/tests/pgsql.ini.tmpl
index 15349aa4c2..0f538797c2 100644
--- a/tests/pgsql.ini.tmpl
+++ b/tests/pgsql.ini.tmpl
@@ -15,7 +15,7 @@ REPO_INDEXER_ENABLED = true
 REPO_INDEXER_PATH = tests/{{TEST_TYPE}}/gitea-{{TEST_TYPE}}-pgsql/indexers/repos.bleve
 
 [queue.issue_indexer]
-PATH = tests/{{TEST_TYPE}}/gitea-{{TEST_TYPE}}-pgsql/indexers/issues.bleve
+TYPE = level
 DATADIR = tests/{{TEST_TYPE}}/gitea-{{TEST_TYPE}}-pgsql/indexers/issues.queue
 
 [queue]
diff --git a/tests/sqlite.ini.tmpl b/tests/sqlite.ini.tmpl
index d2e4a2d5ae..24aff9af43 100644
--- a/tests/sqlite.ini.tmpl
+++ b/tests/sqlite.ini.tmpl
@@ -10,7 +10,7 @@ REPO_INDEXER_ENABLED = true
 REPO_INDEXER_PATH    = tests/{{TEST_TYPE}}/gitea-{{TEST_TYPE}}-sqlite/indexers/repos.bleve
 
 [queue.issue_indexer]
-PATH   = tests/{{TEST_TYPE}}/gitea-{{TEST_TYPE}}-sqlite/indexers/issues.bleve
+TYPE = level
 DATADIR = tests/{{TEST_TYPE}}/gitea-{{TEST_TYPE}}-sqlite/indexers/issues.queue
 
 [queue]
diff --git a/tests/test_utils.go b/tests/test_utils.go
index c22b2c356c..de022fde0a 100644
--- a/tests/test_utils.go
+++ b/tests/test_utils.go
@@ -20,10 +20,10 @@ import (
 	"code.gitea.io/gitea/modules/git"
 	"code.gitea.io/gitea/modules/graceful"
 	"code.gitea.io/gitea/modules/log"
-	"code.gitea.io/gitea/modules/queue"
 	repo_module "code.gitea.io/gitea/modules/repository"
 	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/modules/storage"
+	"code.gitea.io/gitea/modules/testlogger"
 	"code.gitea.io/gitea/modules/util"
 	"code.gitea.io/gitea/routers"
 
@@ -61,7 +61,7 @@ func InitTest(requireGitea bool) {
 		_ = os.Setenv("GITEA_CONF", giteaConf)
 		fmt.Printf("Environment variable $GITEA_CONF not set, use default: %s\n", giteaConf)
 		if !setting.EnableSQLite3 {
-			exitf(`Need to enable SQLite3 for sqlite.ini testing, please set: -tags "sqlite,sqlite_unlock_notify"`)
+			exitf(`sqlite3 requires: import _ "github.com/mattn/go-sqlite3" or -tags sqlite,sqlite_unlock_notify`)
 		}
 	}
 
@@ -235,45 +235,18 @@ func PrepareTestEnv(t testing.TB, skip ...int) func() {
 	return deferFn
 }
 
-// ResetFixtures flushes queues, reloads fixtures and resets test repositories within a single test.
-// Most tests should call defer tests.PrepareTestEnv(t)() (or have onGiteaRun do that for them) but sometimes
-// within a single test this is required
-func ResetFixtures(t *testing.T) {
-	assert.NoError(t, queue.GetManager().FlushAll(context.Background(), -1))
-
-	// load database fixtures
-	assert.NoError(t, unittest.LoadFixtures())
-
-	// load git repo fixtures
-	assert.NoError(t, util.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)
-	if err != nil {
-		assert.NoError(t, err, "unable to read the new repo root: %v\n", err)
-	}
-	for _, ownerDir := range ownerDirs {
-		if !ownerDir.Type().IsDir() {
-			continue
-		}
-		repoDirs, err := os.ReadDir(filepath.Join(setting.RepoRootPath, ownerDir.Name()))
-		if err != nil {
-			assert.NoError(t, err, "unable to read the new repo root: %v\n", err)
-		}
-		for _, repoDir := range repoDirs {
-			_ = os.MkdirAll(filepath.Join(setting.RepoRootPath, ownerDir.Name(), repoDir.Name(), "objects", "pack"), 0o755)
-			_ = os.MkdirAll(filepath.Join(setting.RepoRootPath, ownerDir.Name(), repoDir.Name(), "objects", "info"), 0o755)
-			_ = os.MkdirAll(filepath.Join(setting.RepoRootPath, ownerDir.Name(), repoDir.Name(), "refs", "heads"), 0o755)
-			_ = os.MkdirAll(filepath.Join(setting.RepoRootPath, ownerDir.Name(), repoDir.Name(), "refs", "tag"), 0o755)
-		}
+func PrintCurrentTest(t testing.TB, skip ...int) func() {
+	if len(skip) == 1 {
+		skip = []int{skip[0] + 1}
 	}
+	return testlogger.PrintCurrentTest(t, skip...)
+}
 
-	// load LFS object fixtures
-	// (LFS storage can be on any of several backends, including remote servers, so we init it with the storage API)
-	lfsFixtures, err := storage.NewStorage("", storage.LocalStorageConfig{Path: path.Join(filepath.Dir(setting.AppPath), "tests/gitea-lfs-meta")})
-	assert.NoError(t, err)
-	assert.NoError(t, storage.Clean(storage.LFS))
-	assert.NoError(t, lfsFixtures.IterateObjects("", func(path string, _ storage.Object) error {
-		_, err := storage.Copy(storage.LFS, path, lfsFixtures, path)
-		return err
-	}))
+// Printf takes a format and args and prints the string to os.Stdout
+func Printf(format string, args ...interface{}) {
+	testlogger.Printf(format, args...)
+}
+
+func init() {
+	log.Register("test", testlogger.NewTestLogger)
 }
diff --git a/tests/testlogger.go b/tests/testlogger.go
deleted file mode 100644
index 7cac5bbe33..0000000000
--- a/tests/testlogger.go
+++ /dev/null
@@ -1,201 +0,0 @@
-// Copyright 2019 The Gitea Authors. All rights reserved.
-// SPDX-License-Identifier: MIT
-
-package tests
-
-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
-}
-
-func (w *testLoggerWriterCloser) Reset() {
-	w.Lock()
-	if len(w.t) > 0 {
-		for _, t := range w.t {
-			if t == nil {
-				continue
-			}
-			fmt.Fprintf(os.Stdout, "Unclosed logger writer in test: %s", (*t).Name())
-			(*t).Errorf("Unclosed logger writer in test: %s", (*t).Name())
-		}
-		w.t = nil
-	}
-	w.Unlock()
-}
-
-// 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(), 2*time.Minute); 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"
-}
-
-func init() {
-	log.Register("test", NewTestLogger)
-	_, filename, _, _ := runtime.Caller(0)
-	prefix = strings.TrimSuffix(filename, "tests/integration/testlogger.go")
-}