micro/sync
2019-10-03 11:26:24 +01:00
..
event Add sync => go-sync 2019-05-31 00:43:23 +01:00
leader Move the remaining consul cruft to go-plugins 2019-10-03 11:22:35 +01:00
lock Move out consul sync/lock and store. Move data/store to store 2019-10-03 09:46:20 +01:00
task Change Publication to Event 2019-07-07 12:44:09 +01:00
time Add sync => go-sync 2019-05-31 00:43:23 +01:00
cron.go Fix breaking import 2019-10-03 11:26:24 +01:00
map.go Rename Dump to Sync 2019-10-03 09:56:25 +01:00
options.go Move out consul sync/lock and store. Move data/store to store 2019-10-03 09:46:20 +01:00
README.md Move data to top level 2019-06-11 17:20:52 +01:00
sync.go Move out consul sync/lock and store. Move data/store to store 2019-10-03 09:46:20 +01:00

Sync

Sync is a synchronization library for distributed systems.

Overview

Distributed systems by their very nature are decoupled and independent. In most cases they must honour 2 out of 3 letters of the CAP theorem e.g Availability and Partitional tolerance but sacrificing consistency. In the case of microservices we often offload this concern to an external database or eventing system. Go Sync provides a framework for synchronization which can be used in the application by the developer.

Getting Started

  • Leader - leadership election for group coordination
  • Lock - distributed locking for exclusive resource access
  • Task - distributed job execution
  • Time - provides synchronized time

Lock

The Lock interface provides distributed locking. Multiple instances attempting to lock the same id will block until available.

import "github.com/micro/go-micro/sync/lock/consul"

lock := consul.NewLock()

// acquire lock
err := lock.Acquire("id")
// handle err

// release lock
err = lock.Release("id")
// handle err

Leader

Leader provides leadership election. Useful where one node needs to coordinate some action.

import (
	"github.com/micro/go-micro/sync/leader"
	"github.com/micro/go-micro/sync/leader/consul"
)

l := consul.NewLeader(
	leader.Group("name"),
)

// elect leader
e, err := l.Elect("id")
// handle err


// operate while leader
revoked := e.Revoked()

for {
	select {
	case <-revoked:
		// re-elect
		e.Elect("id")
	default:
		// leader operation
	}
}

// resign leadership
e.Resign() 

Task

Task provides distributed job execution. It's a simple way to distribute work across a coordinated pool of workers.

import (
	"github.com/micro/go-micro/sync/task"
	"github.com/micro/go-micro/sync/task/local"
)

t := local.NewTask(
	task.WithPool(10),
)

err := t.Run(task.Command{
	Name: "atask",
	Func: func() error {
		// exec some work
		return nil
	},
})

if err != nil {
	// do something
}

Time

Time provides synchronized time. Local machines may have clock skew and time cannot be guaranteed to be the same everywhere. Synchronized Time allows you to decide how time is defined for your applications.

import (
	"github.com/micro/go-micro/sync/time/ntp"
)


t := ntp.NewTime()
time, err := t.Now()

TODO

  • Event package - strongly consistent event stream e.g kafka