Merge pull request #379 from ardanlabs/shorts2

Second batch of "shorts" recordings

Author: ardan-bkennedy

go.mod

@@ -8,19 +8,23 @@ require (
 	github.com/patrickmn/go-cache v2.1.0+incompatible
 	github.com/pborman/uuid v1.2.1
 	github.com/pkg/errors v0.9.1
+	github.com/stretchr/testify v1.8.4
+	golang.org/x/exp v0.0.0-20230510235704-dd950f8aeaea
+	golang.org/x/text v0.10.0
 	gonum.org/v1/plot v0.13.0
 )
 
 require (
 	git.sr.ht/~sbinet/gg v0.5.0 // indirect
 	github.com/ajstarks/svgo v0.0.0-20211024235047-1546f124cd8b // indirect
 	github.com/campoy/embedmd v1.0.0 // indirect
+	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/go-fonts/liberation v0.3.1 // indirect
 	github.com/go-latex/latex v0.0.0-20230307184459-12ec69307ad9 // indirect
 	github.com/go-pdf/fpdf v0.8.0 // indirect
 	github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0 // indirect
 	github.com/google/uuid v1.3.0 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	golang.org/x/image v0.8.0 // indirect
-	golang.org/x/text v0.10.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

go.sum

@@ -10,6 +10,8 @@ github.com/braintree/manners v0.0.0-20160418043613-82a8879fc5fd h1:ePesaBzdTmoMQ
 github.com/braintree/manners v0.0.0-20160418043613-82a8879fc5fd/go.mod h1:TNehV1AhBwtT7Bd+rh8G6MoGDbBLNs/sKdk3nvr4Yzg=
 github.com/campoy/embedmd v1.0.0 h1:V4kI2qTJJLf4J29RzI/MAt2c3Bl4dQSYPuflzwFH2hY=
 github.com/campoy/embedmd v1.0.0/go.mod h1:oxyr9RCiSXg0M3VJ3ks0UGfp98BpSSGr0kpiX3MzVl8=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/go-fonts/dejavu v0.1.0 h1:JSajPXURYqpr+Cu8U9bt8K+XcACIHWqWrvWCKyeFmVQ=
 github.com/go-fonts/latin-modern v0.3.1 h1:/cT8A7uavYKvglYXvrdDw4oS5ZLkcOU22fa2HJ1/JVM=
 github.com/go-fonts/liberation v0.3.1 h1:9RPT2NhUpxQ7ukUvz3jeUckmN42T9D9TpjtQcqK/ceM=
@@ -34,13 +36,16 @@ github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
 github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=
+github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
 github.com/yuin/goldmark v1.2.1/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
 github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
 golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
 golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
 golang.org/x/exp v0.0.0-20230510235704-dd950f8aeaea h1:vLCWI/yYrdEHyN2JzIzPO3aaQJHQdp89IZBA/+azVC4=
+golang.org/x/exp v0.0.0-20230510235704-dd950f8aeaea/go.mod h1:V1LtkGg67GoY2N1AnLN78QLrzxkLyJw7RJb1gzOOz9w=
 golang.org/x/image v0.8.0 h1:agUcRXV/+w6L9ryntYYsF2x9fQTMd4T8fiiYXAVW6Jg=
 golang.org/x/image v0.8.0/go.mod h1:PwLxp3opCYg4WR2WO9P0L6ESnsD6bLTWcw8zanLMVFM=
 golang.org/x/mod v0.3.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
@@ -85,5 +90,9 @@ golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1/go.mod h1:I/5z698sn9Ka8T
 gonum.org/v1/gonum v0.13.0 h1:a0T3bh+7fhRyqeNbiC3qVHYmkiQgit3wnNan/2c0HMM=
 gonum.org/v1/plot v0.13.0 h1:yb2Z/b8bY5h/xC4uix+ujJ+ixvPUvBmUOtM73CJzpsw=
 gonum.org/v1/plot v0.13.0/go.mod h1:mV4Bpu4PWTgN2CETURNF8hCMg7EtlZqJYCcmYo/t4Co=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 honnef.co/go/tools v0.1.3/go.mod h1:NgwopIslSNH47DimFoV78dnkksY2EFtX0ajyb3K/las=
 rsc.io/pdf v0.1.1 h1:k1MczvYDUvJBe93bYd7wrZLLUEcLZAuF824/I4e5Xr4=

topics/go/videos/miki/shorts/client/client.go

@@ -0,0 +1,35 @@
+package client
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+)
+
+type Client struct {
+	baseURL string
+	client  http.Client
+}
+
+func NewAPIClient(baseURL string) Client {
+	return Client{baseURL: baseURL}
+}
+
+func (c *Client) Health(ctx context.Context) error {
+	url := fmt.Sprintf("%s/health", c.baseURL)
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return err
+	}
+
+	resp, err := c.client.Do(req)
+	if err != nil {
+		return err
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("%s", resp.Status)
+	}
+
+	return nil
+}

topics/go/videos/miki/shorts/client/client_test.go

@@ -0,0 +1,24 @@
+package client
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+type ErrTransport struct{}
+
+// implement http.RoundTripper
+func (e ErrTransport) RoundTrip(r *http.Request) (*http.Response, error) {
+	return nil, fmt.Errorf("%s", "connection error")
+}
+
+func TestHealthConnectionError(t *testing.T) {
+	c := NewAPIClient("https://example.com")
+	c.client.Transport = ErrTransport{}
+	err := c.Health(context.Background())
+	require.Error(t, err)
+}

topics/go/videos/miki/shorts/discard/main.go

@@ -0,0 +1,20 @@
+package main
+
+import (
+	"flag"
+	"io/ioutil"
+	"log"
+)
+
+func main() {
+	var config struct {
+		Verbose bool
+	}
+	flag.BoolVar(&config.Verbose, "verbose", false, "be more verbose")
+	flag.Parse()
+
+	if !config.Verbose {
+		log.SetOutput(ioutil.Discard)
+	}
+	log.Printf("Please reinstall universe and reboot")
+}

topics/go/videos/miki/shorts/fmt_num/main.go

@@ -0,0 +1,13 @@
+package main
+
+import (
+	"golang.org/x/text/language"
+	"golang.org/x/text/message"
+)
+
+func main() {
+	fmt := message.NewPrinter(language.English)
+
+	symbol, price := "BRK-A", 506_466.10 // circa 2023-03-22
+	fmt.Printf("%s is currently at $%.2f!\n", symbol, price)
+}

topics/go/videos/miki/shorts/for_range/main.go

@@ -0,0 +1,46 @@
+package main
+
+import (
+	"fmt"
+)
+
+const (
+	maxX = 1000
+	maxY = 600
+)
+
+type Point struct {
+	X int
+	Y int
+}
+
+func inBounds(p Point) bool {
+	return p.X >= 0 && p.X <= maxX && p.Y >= 0 && p.Y <= maxY
+}
+
+func main() {
+	ch := make(chan bool)
+	points := []Point{
+		{10, 20},
+		{900, 700},
+		{450, 353},
+	}
+
+	// fan out
+	for _, p := range points {
+		p := p // avoid closure capture
+		go func() {
+			ch <- inBounds(p)
+		}()
+	}
+
+	// collect
+	numOK := 0
+	for range points {
+		ok := <-ch
+		if ok {
+			numOK++
+		}
+	}
+	fmt.Println(numOK, "points in range")
+}

topics/go/videos/miki/shorts/json_stream/db.go

@@ -0,0 +1,41 @@
+// Dummy DB package
+package main
+
+import (
+	"fmt"
+	"time"
+)
+
+type DB struct{}
+
+func NewDB() *DB {
+	return &DB{}
+}
+
+func (d *DB) Query() *Rows {
+	return &Rows{max: 5}
+}
+
+type Rows struct {
+	max int
+	n   int
+}
+
+func (r *Rows) Next() bool {
+	r.n++
+	return r.n <= r.max
+}
+
+func (r *Rows) Event() Event {
+	t := time.Now().UTC().Add(-time.Duration((r.max-r.n-200)*527) * time.Millisecond)
+	return Event{
+		Time:   t,
+		User:   "elliot",
+		Action: "READ",
+		URI:    fmt.Sprintf("file:///reports/sec/%d.txt", r.n),
+	}
+}
+
+func (r *Rows) Err() error {
+	return nil
+}

topics/go/videos/miki/shorts/json_stream/main.go

@@ -0,0 +1,48 @@
+package main
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"log"
+	"time"
+)
+
+type Event struct {
+	Time   time.Time `json:"time"`
+	User   string    `json:"user"`
+	Action string    `json:"action"`
+	URI    string    `json:"uri"`
+}
+
+func main() {
+	db := NewDB()
+	rows := db.Query()
+
+	var net bytes.Buffer
+
+	// Server
+	enc := json.NewEncoder(&net)
+	for rows.Next() {
+		evt := rows.Event()
+		enc.Encode(evt)
+	}
+	if err := rows.Err(); err != nil {
+		log.Fatalf("error: %s", err)
+	}
+
+	// Client
+	dec := json.NewDecoder(&net)
+	var e Event
+	for {
+		err := dec.Decode(&e)
+		if err == io.EOF {
+			break
+		}
+		if err != nil {
+			log.Fatalf("error: %s", err)
+		}
+		fmt.Println(e)
+	}
+}

topics/go/videos/miki/shorts/limit/main.go

@@ -0,0 +1,33 @@
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"log"
+	"net/http"
+)
+
+const (
+	maxSize = 1 << 20 // 1MB
+)
+
+func handler(w http.ResponseWriter, r *http.Request) {
+	rdr := http.MaxBytesReader(w, r.Body, maxSize)
+	defer rdr.Close()
+	data, err := ioutil.ReadAll(rdr)
+	if err != nil {
+		http.Error(w, "can't read", http.StatusBadRequest)
+		return
+	}
+
+	fmt.Fprintf(w, "read %d bytes\n", len(data))
+}
+
+func main() {
+	http.HandleFunc("/", handler)
+	log.Printf("INFO: max request size = %d", maxSize)
+
+	if err := http.ListenAndServe(":8080", nil); err != nil {
+		log.Fatal(err)
+	}
+}