scheduler

* Deadline

Dealine is a modified and well maitained hard fork of github.com/rakanalh/scheduler. Deadline does not seek to maintain backwards compatibility with the aformentiond libray. There are a few major differences in the api. There's also a few diffferences iin the storage engines supported out of the box, and plans to support many more.

Deadline is a small library that you can use within your application that enables you to execute callbacks (goroutines) after a pre-defined
amount of time. GTS also provides task storage which is used to invoke callbacks for tasks which couldn't be executed
during down-time as well as maintaining a history of the callbacks that got executed.

** Features
- Execute tasks based after a specific duration or at a specific point in time
- Job stores for history & recovery, provided stores out of the box:
 - Sqlite3
 - Redis (Coming soon)

* Installation
#+BEGIN_SRC shell
go get github.com/rakanalh/scheduler
#+END_SRC

* How To Use

Instantiate a scheduler as follows:

#+BEGIN_SRC go
s := scheduler.New(storage)
#+END_SRC

GTS currently supports 2 kinds of storages:
1. NoOpStorage: Does nothing
#+BEGIN_SRC go
noOpStorage := storage.NewNoOpStorage()
#+END_SRC
2. MemoryStorage: Does nothing
#+BEGIN_SRC go
memStorage := storage.NewMemoryStorage()
#+END_SRC
2. SqliteStorage: Persists tasks into a SQLite3 database.
#+BEGIN_SRC go
sqliteStorage := storage.NewSqlite3Storage()
#+END_SRC

Example:
#+BEGIN_SRC go
storage := storage.NewSqlite3Storage(
	storage.Sqlite3Config{
		DbName: "db.store",
	},
)
if err := storage.Connect(); err != nil {
	log.Fatal("Could not connect to db", err)
}

if err := storage.Initialize(); err != nil {
	log.Fatal("Could not intialize database", err)
}
#+END_SRC

and then pass it to the scheduler.

Scheduling tasks can be done in 3 ways:

** Execute a task after 5 seconds.
#+BEGIN_SRC go
func MyFunc(arg1 string, arg2 string)
taskID := s.RunAfter(5*time.Second, MyFunc, "Hello", "World")
#+END_SRC

** Execute a task at a specific time.
#+BEGIN_SRC go
func MyFunc(arg1 string, arg2 string)
taskID := s.RunAt(time.Now().Add(24 * time.Hour), MyFunc, "Hello", "World")
#+END_SRC

** Execute a task every 1 minute.
#+BEGIN_SRC go
func MyFunc(arg1 string, arg2 string)
taskID := s.RunEvery(1 * time.Minute, MyFunc, "Hello", "World")
#+END_SRC

* Examples

The [[https://github.com/rakanalh/scheduler/tree/master/_example/][Examples]] folder contains a bunch of code samples you can look into.

* Custom Storage

GTS supports the ability to provide a custom storage, the newly created storage has to implement the TaskStore interface

#+BEGIN_SRC go
type TaskStore interface {
	Store(task *TaskAttributes) error
        Remove(task *TaskAttributes) error
	Fetch() ([]TaskAttributes, error)
}
#+END_SRC

TaskAttributes looks as follows:
#+BEGIN_SRC go
type TaskAttributes struct {
	Hash        string
	Name        string
	LastRun     string
	NextRun     string
	Duration    string
	IsRecurring string
	Params      string
}
#+END_SRC

* TODOs
- [ ] Design a cron-like task schedule for RunEvery method

* Credit
This package is heavily inspired by [[https://github.com/agronholm/apscheduler/][APScheduler]] for Python & [[https://github.com/jasonlvhit/gocron][GoCron]]

* License

MIT