Refactor Cron and merge dashboard tasks (#10745)

* Refactor Cron and merge dashboard tasks

* Merge Cron and Dashboard tasks
* Make every cron task report a system notice on completion
* Refactor the creation of these tasks
* Ensure that execution counts of tasks is correct
* Allow cron tasks to be started from the cron page

* golangci-lint fixes

* Enforce that only one task with the same name can be registered

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

* fix name check

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

* as per @guillep2k

* as per @lafriks

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

* Add git.CommandContext variants

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

Co-authored-by: Lauris BH <lauris@nix.lv>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>

modules/cron/tasks.go

@@ -0,0 +1,166 @@
+// Copyright 2020 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package cron
+
+import (
+	"context"
+	"fmt"
+	"reflect"
+	"sync"
+
+	"code.gitea.io/gitea/models"
+	"code.gitea.io/gitea/modules/graceful"
+	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/process"
+	"code.gitea.io/gitea/modules/setting"
+)
+
+var lock = sync.Mutex{}
+var started = false
+var tasks = []*Task{}
+var tasksMap = map[string]*Task{}
+
+// Task represents a Cron task
+type Task struct {
+	lock      sync.Mutex
+	Name      string
+	config    Config
+	fun       func(context.Context, *models.User, Config) error
+	ExecTimes int64
+}
+
+// DoRunAtStart returns if this task should run at the start
+func (t *Task) DoRunAtStart() bool {
+	return t.config.DoRunAtStart()
+}
+
+// IsEnabled returns if this task is enabled as cron task
+func (t *Task) IsEnabled() bool {
+	return t.config.IsEnabled()
+}
+
+// GetConfig will return a copy of the task's config
+func (t *Task) GetConfig() Config {
+	if reflect.TypeOf(t.config).Kind() == reflect.Ptr {
+		// Pointer:
+		return reflect.New(reflect.ValueOf(t.config).Elem().Type()).Interface().(Config)
+	}
+	// Not pointer:
+	return reflect.New(reflect.TypeOf(t.config)).Elem().Interface().(Config)
+}
+
+// Run will run the task incrementing the cron counter with no user defined
+func (t *Task) Run() {
+	t.RunWithUser(&models.User{
+		ID:        -1,
+		Name:      "(Cron)",
+		LowerName: "(cron)",
+	}, t.config)
+}
+
+// RunWithUser will run the task incrementing the cron counter at the time with User
+func (t *Task) RunWithUser(doer *models.User, config Config) {
+	if !taskStatusTable.StartIfNotRunning(t.Name) {
+		return
+	}
+	t.lock.Lock()
+	if config == nil {
+		config = t.config
+	}
+	t.ExecTimes++
+	t.lock.Unlock()
+	defer func() {
+		taskStatusTable.Stop(t.Name)
+		if err := recover(); err != nil {
+			// Recover a panic within the
+			combinedErr := fmt.Errorf("%s\n%s", err, log.Stack(2))
+			log.Error("PANIC whilst running task: %s Value: %v", t.Name, combinedErr)
+		}
+	}()
+	graceful.GetManager().RunWithShutdownContext(func(baseCtx context.Context) {
+		ctx, cancel := context.WithCancel(baseCtx)
+		defer cancel()
+		pm := process.GetManager()
+		pid := pm.Add(config.FormatMessage(t.Name, "process", doer), cancel)
+		defer pm.Remove(pid)
+		if err := t.fun(ctx, doer, config); err != nil {
+			if models.IsErrCancelled(err) {
+				message := err.(models.ErrCancelled).Message
+				if err := models.CreateNotice(models.NoticeTask, config.FormatMessage(t.Name, "aborted", doer, message)); err != nil {
+					log.Error("CreateNotice: %v", err)
+				}
+				return
+			}
+			if err := models.CreateNotice(models.NoticeTask, config.FormatMessage(t.Name, "error", doer, err)); err != nil {
+				log.Error("CreateNotice: %v", err)
+			}
+			return
+		}
+		if err := models.CreateNotice(models.NoticeTask, config.FormatMessage(t.Name, "finished", doer)); err != nil {
+			log.Error("CreateNotice: %v", err)
+		}
+	})
+}
+
+// GetTask gets the named task
+func GetTask(name string) *Task {
+	lock.Lock()
+	defer lock.Unlock()
+	log.Info("Getting %s in %v", name, tasksMap[name])
+
+	return tasksMap[name]
+}
+
+// RegisterTask allows a task to be registered with the cron service
+func RegisterTask(name string, config Config, fun func(context.Context, *models.User, Config) error) error {
+	log.Debug("Registering task: %s", name)
+	_, err := setting.GetCronSettings(name, config)
+	if err != nil {
+		log.Error("Unable to register cron task with name: %s Error: %v", name, err)
+		return err
+	}
+
+	task := &Task{
+		Name:   name,
+		config: config,
+		fun:    fun,
+	}
+	lock.Lock()
+	locked := true
+	defer func() {
+		if locked {
+			lock.Unlock()
+		}
+	}()
+	if _, has := tasksMap[task.Name]; has {
+		log.Error("A task with this name: %s has already been registered", name)
+		return fmt.Errorf("duplicate task with name: %s", task.Name)
+	}
+
+	if config.IsEnabled() {
+		// We cannot use the entry return as there is no way to lock it
+		if _, err = c.AddJob(name, config.GetSchedule(), task); err != nil {
+			log.Error("Unable to register cron task with name: %s Error: %v", name, err)
+			return err
+		}
+	}
+
+	tasks = append(tasks, task)
+	tasksMap[task.Name] = task
+	if started && config.IsEnabled() && config.DoRunAtStart() {
+		lock.Unlock()
+		locked = false
+		task.Run()
+	}
+
+	return nil
+}
+
+// RegisterTaskFatal will register a task but if there is an error log.Fatal
+func RegisterTaskFatal(name string, config Config, fun func(context.Context, *models.User, Config) error) {
+	if err := RegisterTask(name, config, fun); err != nil {
+		log.Fatal("Unable to register cron task %s Error: %v", name, err)
+	}
+}