impl pg-pulse

cmd/pg-pulse/main.go

@@ -0,0 +1,114 @@
+package main
+
+import (
+	"context"
+	"database/sql"
+	"flag"
+	"fmt"
+	"log"
+	"os"
+	"os/signal"
+	"syscall"
+	"time"
+
+	_ "github.com/lib/pq"
+)
+
+func main() {
+	ctx, can := signal.NotifyContext(context.Background(), syscall.SIGINT)
+	defer can()
+
+	fs := flag.NewFlagSet(os.Args[0], flag.ContinueOnError)
+	c := fs.String("c", "postgresql://pulsegres:pulsegres@localhost:15432", "conn string")
+	d := fs.Duration("d", time.Second, "interval")
+	if err := fs.Parse(os.Args[1:]); err != nil {
+		panic(err)
+	}
+
+	log.Println("opening...")
+	pg, err := sql.Open("postgres", *c)
+	if err != nil {
+		panic(err)
+	}
+	defer func() {
+		log.Println("closed:", pg.Close())
+	}()
+
+	func() {
+		pinged := make(chan bool)
+		defer close(pinged)
+		for {
+			log.Println("pinging...")
+			go func() {
+				err := pg.PingContext(ctx)
+				if err != nil {
+					log.Println("!", err)
+				}
+				select {
+				case pinged <- err == nil:
+				case <-ctx.Done():
+				case <-time.After(time.Second * 5):
+				}
+			}()
+			select {
+			case <-ctx.Done():
+				return
+			case ok := <-pinged:
+				if ok {
+					return
+				}
+			case <-time.After(time.Second * 5):
+			}
+		}
+	}()
+
+	log.Println("staging...")
+	if _, err := pg.ExecContext(ctx, `
+		CREATE TABLE IF NOT EXISTS "pg-pulse" (k TEXT);
+	`); err != nil {
+		panic(err)
+	}
+
+	log.Println("spamming...")
+	pticker := time.NewTicker(5 * time.Second)
+	defer pticker.Stop()
+	ticker := time.NewTicker(*d)
+	defer ticker.Stop()
+	n := 0
+	for ctx.Err() == nil {
+		func() {
+			ctx, can := context.WithCancel(ctx)
+			defer can()
+
+			done := make(chan struct{})
+			go func() {
+				defer close(done)
+
+				if _, err := pg.ExecContext(ctx, fmt.Sprintf(`
+					INSERT INTO "pg-pulse" (k) SELECT substr(md5(random()::text), 1, 25)
+				`)); err != nil {
+					log.Println("\n! failed nonzero insert:", err)
+				}
+
+				ctx, can = context.WithTimeout(ctx, time.Second*5)
+				defer can()
+
+				n += 1
+				select {
+				case <-pticker.C:
+					log.Println(n)
+				default:
+				}
+			}()
+
+			select {
+			case <-ctx.Done():
+			case <-done:
+			}
+		}()
+		select {
+		case <-ctx.Done():
+		case <-ticker.C:
+		}
+	}
+}