Add extras/dialer

Based on the dialer.sh script by @alban:
https://gist.github.com/alban/7abe7f6307184c58be7429e63a2d9053

Signed-off-by: Michael Schubert <michael@kinvolk.io>

extras/dialer/.gitignore

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+bin/

extras/dialer/Dockerfile

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+FROM golang:1.7
+ADD ./bin/dialer /go/bin

extras/dialer/README.md

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+## Overview
+
+The dialer scripts can be used to test Scope with a high number of
+containers and connections.
+
+The dialer server is a TCP server that holds incoming connections
+forever.
+
+The dialer client is a TCP client that opens n connection to a server
+and holds them forever.
+
+The `listener` script starts a dialer server and prints its address for
+usage with the `dialer` script. The `dialer` scripts starts up to n
+(default 50) client containers, each opening a random (1-20) number of
+connections.
+
+`time-scope-probe` then can be used to measure the scheduled time
+(utime + stime) of the scope-probe process on the host. The results
+can be used to compare performance under different scenarios/branches.
+
+## Usage example
+
+```
+# Start a listener
+./tools/dialer/listener
+Listening on :8082
+IP addr + port: 172.17.0.2:8082
+
+
+# Start the dialer script with a maximum of 10 dialer containers
+# (default 50)
+./tools/dialer/dialer 172.17.0.2:8082 10
+
+
+# Start time-scope-probe to measure the scheduled time of scope-probe
+# every 3 seconds (default 10 seconds) for 3 times (default 60 times)
+sudo ./tools/dialer/time-scope-probe 3 3
+...
+```
+
+## Build dialer container
+
+```
+go build -o bin/dialer
+docker build -t dialer .
+```

extras/dialer/dialer

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+#!/bin/bash
+set -eu
+if [ $# -lt 1 ]; then
+  echo "Usage: $0 <ip:port> [<max_dialer>]" >&2
+  exit 1
+fi
+
+readonly addr=$1
+readonly max_dialer=${2:-50}
+
+dialer=()
+trap 'echo -n "stopping ... "; for c in "${dialer[@]}"; do docker rm -f "$c" >/dev/null; done; echo "done"' EXIT
+
+while true; do
+  rand=$(( ( RANDOM % max_dialer )  + 1 ))
+  dialer+=("$(docker run -d dialer /go/bin/dialer connect "$addr" "$rand")")
+
+  if [ ${#dialer[@]} -gt "$max_dialer" ]; then
+    container=${dialer[$rand]}
+    docker rm -f "$container" >/dev/null &
+    unset dialer[$rand]
+    dialer=("${dialer[@]}")
+  fi
+
+  sleep $(( rand % 3 ))
+done

extras/dialer/dialer.go

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+package main
+
+import (
+	"fmt"
+	"net"
+	"os"
+	"strconv"
+)
+
+func connect(url string, numConn int) {
+	fmt.Printf("Establishing %d TCP connections to %s\n", numConn, url)
+	for x := 0; x < numConn; x++ {
+		_, err := net.Dial("tcp", url)
+
+		if err != nil {
+			fmt.Printf("Error: %v\n", err)
+			os.Exit(1)
+		}
+	}
+
+	// wait forever
+	select {}
+}
+
+func listen(url string) {
+	l, err := net.Listen("tcp", url)
+	if err != nil {
+		fmt.Println("Error listening:", err.Error())
+		os.Exit(1)
+	}
+	defer l.Close()
+	fmt.Println("Listening on " + url)
+	for {
+		_, err := l.Accept()
+		if err != nil {
+			fmt.Println("Error accepting: ", err.Error())
+			os.Exit(1)
+		}
+	}
+
+}
+
+func main() {
+	if len(os.Args) < 2 {
+		fmt.Println("Not enough arguments")
+		os.Exit(1)
+	}
+
+	verb := os.Args[1]
+
+	if verb == "connect" {
+		if len(os.Args) != 4 {
+			fmt.Println("Not enough arguments")
+			os.Exit(1)
+		}
+
+		url := os.Args[2]
+		numConn, err := strconv.Atoi(os.Args[3])
+		if err != nil {
+			fmt.Printf("Error with second argument\n")
+			os.Exit(1)
+		}
+
+		connect(url, numConn)
+	}
+	if verb == "listen" {
+		if len(os.Args) != 3 {
+			fmt.Println("Not enough arguments")
+			os.Exit(1)
+		}
+
+		port := os.Args[2]
+		listen(":" + port)
+	}
+
+}

extras/dialer/listener

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+#!/bin/bash
+set -eu
+readonly port=${1:-8082}
+(
+sleep 5 # wait for dialerserver to start
+echo "IP addr + port: $(docker inspect -f '{{ .NetworkSettings.IPAddress }}' dialerserver):$port"
+) &
+docker run --rm --name dialerserver dialer /go/bin/dialer listen "$port"

extras/dialer/time-scope-probe

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+#!/bin/bash
+set -eu
+if [ $EUID -ne 0 ]; then
+  echo "You must be root!" >&2
+  exit 1
+fi
+
+readonly interval_num=${1:-60}
+readonly interval_sleep=${2:-10}
+
+TIME_U1=0
+TIME_K1=0
+TIME_T1=0
+TIME_U2=0
+TIME_K2=0
+TIME_T2=0
+
+if [ "$(pidof scope-probe)" == "" ]; then
+  echo "No scope-probe process running - aborting" >&2
+  exit 1
+fi
+
+for ((i=0; i<"$interval_num"; i++)); do
+  sleep "$interval_sleep"
+  TIME_U1=$TIME_U2
+  TIME_K1=$TIME_K2
+  TIME_T1=$TIME_T2
+
+  TIME_U2=$(gawk '{print $14"*10"}'<"/proc/$(pidof scope-probe)/stat" | bc)
+  TIME_K2=$(gawk '{print $15"*10"}'<"/proc/$(pidof scope-probe)/stat" | bc)
+  TIME_T2=$(( TIME_U2 + TIME_K2 ))
+  echo "utime $(( TIME_U2 - TIME_U1)) + stime $(( TIME_K2 - TIME_K1 )) = $(( TIME_T2 - TIME_T1 ))"
+done