Author Archives: bullgare

Count lines in git repository

git ls-files | xargs wc -l

1	git ls-files \| xargs wc -l

https://stackoverflow.com/questions/4822471/count-number-of-lines-in-a-git-repository

Algorithms to find fastest route through network

This is a great article on that — https://www.redblobgames.com/pathfinding/a-star/introduction.html (in russain). It tells about Dijkstra, Breadth-first, Greedy and A* algorithms. It’s all about optimization of one travel. To optimize your entire network you should try to use Aint Colony algorithm — http://rain.ifmo.ru/cat/data/theory/unsorted/ant-algo-2006/article.pdf (it’s in russian). Another link to this PDF file — aca

How go code is being compiled to assembler code

https://go.godbolt.org/z/31FyJ3 I was interested in comparing line 15 vs line 17 of the following code:

package main

import "fmt"

type kv struct {
	key   []byte
	value []byte
}

type sliceMap []kv

func (sm *sliceMap) Add(k, v []byte) {
	kvs := *sm
	if cap(kvs) > len(kvs) {
		kvs = kvs[:len(kvs)+1]
	} else {
		kvs = append(kvs, kv{})
	}
	kv := &kvs[len(kvs)-1]
	kv.key = append(kv.key[:0], k...)
	kv.value = append(kv.value[:0], v...)
	*sm = kvs
}

func main() {
	sm := sliceMap{}
	sm.Add([]byte("foo"), []byte("bar"))
	fmt.Println(sm)
}

package main

import "fmt"

type kv struct {

key []byte

value []byte

}

type sliceMap []kv

func (sm *sliceMap) Add(k, v []byte) {

kvs := *sm

if cap(kvs) > len(kvs) {

kvs = kvs[:len(kvs)+1]

} else {

kvs = append(kvs, kv{})

}

kv := &kvs[len(kvs)-1]

kv.key = append(kv.key[:0], k...)

kv.value = append(kv.value[:0], v...)

*sm = kvs

}

func main() {

sm := sliceMap{}

sm.Add([]byte("foo"), []byte("bar"))

fmt.Println(sm)

}

E2E tests in go

I tried it via ginkgo and gomega. It has Agouti with WebDriver support out of the box, but I didn’t use it as we have grpc API. That’s the example (table tests):

var _ = Describe("GetRoute", func() {
	var (
		srClient sr.Client
		srErr    error
	)

	JustBeforeEach(func() {
		srClient, srErr = GetClient()
	})

	DescribeTable("positive cases",
		func(fromGeoPointID, toGeoPointID int, expectedUID string, expectedCostGreaterThan float64) {
			Expect(srErr).NotTo(HaveOccurred())
			Expect(srClient).NotTo(BeNil())

			response, err := srClient.GetRoute(context.TODO(), &sr.GetRouteRequest{
				FromGeoPointId: int64(fromGeoPointID),
				ToGeoPointId:   int64(toGeoPointID),
				Quantity:       1,
				Volume:         1,
				Weight:         1,
			})

			Expect(err).To(Succeed())
			Expect(response).NotTo(BeNil())
			Expect(response.RouteCost).NotTo(BeNil())
			Expect(response.RouteCost.RouteUid).To(HaveSuffix(expectedUID))
			Expect(response.RouteCost.GetCost()).To(BeNumerically(">", expectedCostGreaterThan))
		},
		Entry("from(geo=3)->to(geo=2)", 3, 2, "-3-2", float64(10)),
	)

var _ = Describe("GetRoute", func() {

var (

srClient sr.Client

srErr error

)

JustBeforeEach(func() {

srClient, srErr = GetClient()

})

DescribeTable("positive cases",

func(fromGeoPointID, toGeoPointID int, expectedUID string, expectedCostGreaterThan float64) {

Expect(srErr).NotTo(HaveOccurred())

Expect(srClient).NotTo(BeNil())

response, err := srClient.GetRoute(context.TODO(), &sr.GetRouteRequest{

FromGeoPointId: int64(fromGeoPointID),

ToGeoPointId: int64(toGeoPointID),

Quantity: 1,

Volume: 1,

Weight: 1,

})

Expect(err).To(Succeed())

Expect(response).NotTo(BeNil())

Expect(response.RouteCost).NotTo(BeNil())

Expect(response.RouteCost.RouteUid).To(HaveSuffix(expectedUID))

Expect(response.RouteCost.GetCost()).To(BeNumerically(">", expectedCostGreaterThan))

Entry("from(geo=3)->to(geo=2)", 3, 2, "-3-2", float64(10)),

)

What is teamlead’s first duty

Sarah Mei «We think awful code is written by awful devs. But in reality, it’s written by reasonable devs in awful circumstances.» (source) So, teamlead is there to improve circumstances.

ORM for go

https://github.com/Masterminds/squirrel Never used it as we always write SQL queries manually. But looks okay for ORM (well, actually a query-builder).

Kubernetes’ cronjobs

That’s what it is — https://kubernetes.io/docs/concepts/workloads/controllers/cron-jobs/ Get all cronjobs in env:

kubectl --kubeconfig ... --namespace platform -o wide get cronjobs

1	kubectl --kubeconfig ... --namespace platform -o wide get cronjobs

Get info on exact cronjob:

kubectl --kubeconfig ... --namespace platform describe cronjob/smartrouting-cron-import-from-bi

1	kubectl --kubeconfig ... --namespace platform describe cronjob/smartrouting-cron-import-from-bi

Get pods with this cronjob:

kubectl --kubeconfig ... --namespace platform  -o wide get pods|grep "rou"

1	kubectl --kubeconfig ... --namespace platform -o wide get pods\|grep "rou"

Get logs of cronjob

kubectl --kubeconfig ... --namespace platform logs smartrouting-cron-import-from-bi-1555060200-dqg5j

1	kubectl --kubeconfig ... --namespace platform logs smartrouting-cron-import-from-bi-1555060200-dqg5j

you can add -f for live updating logs and -p for watching logs of previous pod.

Crontab time format

That’s about it: min hour day/month month day/week Execution time 30 0 1 1,6,12 * — 00:30 Hrs on 1st of Jan, June & Dec. 0 20 * 10 1-5 –8.00 PM every weekday (Mon-Fri) only in Oct. 0 0 1,10,15 * * — midnight on 1st ,10th & 15th of month 5,10 0 10 …

How to make grpc call from shell

1 https://github.com/grpc/grpc/blob/master/doc/command_line_tool.md

grpc_cli call localhost:7020 ChatAPI.GetChats "external_user:{id:'30594028',type:1}, limit:10, offset:0, order:ORDER_DESC, requested_by_external_user:{id:'30594028',type:1},with_unread_count:true"

1	grpc_cli call localhost:7020 ChatAPI.GetChats "external_user:{id:'30594028',type:1}, limit:10, offset:0, order:ORDER_DESC, requested_by_external_user:{id:'30594028',type:1},with_unread_count:true"

2 https://github.com/fullstorydev/grpcurl

grpcurl -plaintext -emit-defaults -d '{"lozon_id": 15515160432000}' -H 'User-Name: grpcurl' localhost:7020 points/FindPointByLozonID

1	grpcurl -plaintext -emit-defaults -d '{"lozon_id": 15515160432000}' -H 'User-Name: grpcurl' localhost:7020 points/FindPointByLozonID

How to analyze the performance of your go application in production

You should definitely use chi’s middleware for running pprof and stuff in your admin panel. That’s the repo — https://github.com/go-chi/chi That’s the profiler — https://github.com/go-chi/chi/blob/master/middleware/profiler.go CPU profiling After that you can run something like this in shell:

go tool pprof -png ~/Downloads/profile

1	go tool pprof -png ~/Downloads/profile

Or just open it in the browser:

go tool pprof -http=:1234 ~/Downloads/profile

1	go tool pprof -http=:1234 ~/Downloads/profile

If it opens something different then your browser (sublime …