# README

Go VShard Router

Translations:

Русский

go-vshard-router is a library for sending requests to a sharded tarantool cluster directly, without using tarantool-router. go-vshard-router takes a new approach to creating your cluster

Old cluster schema

graph TD
    subgraph Tarantool Database Cluster
        subgraph Replicaset 1
            Master_001_1
            Replica_001_2
        end

    end

ROUTER1["Tarantool vshard-router 1_1"] --> Master_001_1
ROUTER2["Tarantool vshard-router 1_2"] --> Master_001_1
ROUTER3["Tarantool vshard-router 1_3"] --> Master_001_1
ROUTER1["Tarantool vshard-router 1_1"] --> Replica_001_2
ROUTER2["Tarantool vshard-router 1_2"] --> Replica_001_2
ROUTER3["Tarantool vshard-router 1_3"] --> Replica_001_2

GO["Golang service"]
GO --> ROUTER1
GO --> ROUTER2
GO --> ROUTER3

New cluster schema

graph TD
    subgraph Application Host
        Golang-Service
    end

    Golang-Service --> |iproto| MASTER1
    Golang-Service --> |iproto| REPLICA1
    
    MASTER1["Master 001_1"]
    REPLICA1["Replica 001_2"]
    
    subgraph Tarantool Database Cluster
        subgraph Replicaset 1
            MASTER1
            REPLICA1
        end
    end

    ROUTER1["Tarantool vshard-router(As contorol plane)"]
    ROUTER1 --> MASTER1
    ROUTER1 --> REPLICA1

Getting started

Prerequisites

Go: any one of the two latest major releases (we test it with these).

Getting Go-Vshard-Router

With Go module support, simply add the following import

import "github.com/hackallcode/go-vshard-router"

to your code, and then go [build|run|test] will automatically fetch the necessary dependencies.

Otherwise, run the following Go command to install the go-vshard-router package:

$ go get -u github.com/hackallcode/go-vshard-router

Running Go-Vshard-Router

First you need to import Go-Vshard-Router package for using Go-Vshard-Router

package main

import (
  "context"
  "fmt"
  "strconv"
  "time"

  vshardrouter "github.com/hackallcode/go-vshard-router"
  "github.com/hackallcode/go-vshard-router/providers/static"

  "github.com/google/uuid"
  "github.com/tarantool/go-tarantool/v2"
  "github.com/tarantool/go-tarantool/v2/pool"
)

func main() {
  ctx := context.Background()

  directRouter, err := vshardrouter.NewRouter(ctx, vshardrouter.Config{
    DiscoveryTimeout: time.Minute,
    DiscoveryMode:    vshardrouter.DiscoveryModeOn,
    TopologyProvider: static.NewProvider(map[vshardrouter.ReplicasetInfo][]vshardrouter.InstanceInfo{
      vshardrouter.ReplicasetInfo{
        Name: "replcaset_1",
        UUID: uuid.New(),
      }: {
        {
          Addr: "127.0.0.1:1001",
          UUID: uuid.New(),
        },
        {
          Addr: "127.0.0.1:1002",
          UUID: uuid.New(),
        },
      },
      vshardrouter.ReplicasetInfo{
        Name: "replcaset_2",
        UUID: uuid.New(),
      }: {
        {
          Addr: "127.0.0.1:2001",
          UUID: uuid.New(),
        },
        {
          Addr: "127.0.0.1:2002",
          UUID: uuid.New(),
        },
      },
    }),
    TotalBucketCount: 128000,
    PoolOpts: tarantool.Opts{
      Timeout: time.Second,
    },
  })
  if err != nil {
    panic(err)
  }

  user := struct {
    ID uint64
  }{
    ID: 123,
  }

  bucketID := vshardrouter.BucketIDStrCRC32(strconv.FormatUint(user.ID, 10), directRouter.RouterBucketCount())

  interfaceResult, getTyped, err := directRouter.RouterCallImpl(
    ctx,
    bucketID,
    vshardrouter.CallOpts{VshardMode: vshardrouter.ReadMode, PoolMode: pool.PreferRO, Timeout: time.Second * 2},
    "storage.api.get_user_info",
    []interface{}{&struct {
      BucketID uint64                 `msgpack:"bucket_id" json:"bucket_id,omitempty"`
      Body     map[string]interface{} `msgpack:"body"`
    }{
      BucketID: bucketID,
      Body: map[string]interface{}{
        "user_id": "123456",
      },
    }},
  )

  info := &struct {
    BirthDay int
  }{}

  err = getTyped(&[]interface{}{info})
  if err != nil {
    panic(err)
  }

  fmt.Printf("interface result: %v", interfaceResult)
  fmt.Printf("get typed result: %v", info)
}