117 lines
2.3 KiB
Markdown
117 lines
2.3 KiB
Markdown
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# Sync
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Sync is a synchronization library for distributed systems.
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## Overview
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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
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e.g Availability and Partitional tolerance but sacrificing consistency. In the case of microservices we often offload this concern to
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an external database or eventing system. Go Sync provides a framework for synchronization which can be used in the application by the developer.
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## Getting Started
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- [Leader](#leader) - leadership election for group coordination
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- [Lock](#lock) - distributed locking for exclusive resource access
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- [Task](#task) - distributed job execution
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- [Time](#time) - provides synchronized time
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## Lock
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The Lock interface provides distributed locking. Multiple instances attempting to lock the same id will block until available.
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```go
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import "github.com/micro/go-micro/sync/lock/consul"
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lock := consul.NewLock()
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// acquire lock
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err := lock.Acquire("id")
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// handle err
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// release lock
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err = lock.Release("id")
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// handle err
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```
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## Leader
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Leader provides leadership election. Useful where one node needs to coordinate some action.
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```go
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import (
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"github.com/micro/go-micro/sync/leader"
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"github.com/micro/go-micro/sync/leader/consul"
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)
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l := consul.NewLeader(
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leader.Group("name"),
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)
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// elect leader
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e, err := l.Elect("id")
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// handle err
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// operate while leader
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revoked := e.Revoked()
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for {
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select {
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case <-revoked:
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// re-elect
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e.Elect("id")
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default:
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// leader operation
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}
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}
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// resign leadership
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e.Resign()
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```
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## Task
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Task provides distributed job execution. It's a simple way to distribute work across a coordinated pool of workers.
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```go
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import (
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"github.com/micro/go-micro/sync/task"
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"github.com/micro/go-micro/sync/task/local"
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)
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t := local.NewTask(
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task.WithPool(10),
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)
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err := t.Run(task.Command{
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Name: "atask",
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Func: func() error {
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// exec some work
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return nil
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},
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})
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if err != nil {
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// do something
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}
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```
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## Time
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Time provides synchronized time. Local machines may have clock skew and time cannot be guaranteed to be the same everywhere.
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Synchronized Time allows you to decide how time is defined for your applications.
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```go
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import (
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"github.com/micro/go-micro/sync/time/ntp"
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)
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t := ntp.NewTime()
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time, err := t.Now()
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```
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## TODO
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- Event package - strongly consistent event stream e.g kafka
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