Update README and some fixes

README.md

@@ -1,15 +1,53 @@
+# StatusMonitor
 
+Simple command line app for monitoring CPU of the Status.im application running on the device (or simulator).
 
+---
+
+TODO:
+
+ - iOS support
+ - Add more metrics (memory, custom expvars, etc)
+ - Optimize for higher frequencies (now 1s resolution)
+
+---
+
+# Installation
+
+Just:
+
+```
+go get github.com/divan/statusmonitor
+```
+
+# Usage
+
+Just run `statusmonitor` binary. It will automatically connect to your device using `adb`, find the Status.im PID and start collecting data:
+```
+./statusmonitor
+```
+![](./demo/demo0.png)
+
+Press `q` to exit.
+
+If you want to analyze data after, use `-csv` switch — all data will be written in the CSV file. Name of the file is autogenerated in form `20160102_150405.csv` in the current folder.
+
+# Plot CSV with R
+To analyze the data, you may use R lang. Here is a sample code that works well in R Studio:
+
+Load data and convert UNIX timestamps into R's POSIXct object:
 ```
 df = read.csv("~/Downloads/data.csv")
 df$timestamp = as.POSIXct(df$timestamp, origin="1970-01-01")
 ```
 
-Draw the plot;
+Draw the plot:
+
 ```
 plot(df, type="l", main="status CPU usage", col = 'green', lwd=2, cex.main=1.5, cex.axis=1, xlab="time", xaxt="n")
 axis.POSIXct(1, df$timestamp, format="%H:%M:%S")
 ```
+![](./demo/demo1.png)
 
 or interactive version with plotly:
 
@@ -17,3 +55,4 @@ or interactive version with plotly:
 library(plotly)
 plot_ly(df, x = df$timestamp, y = df$cpu, type = 'scatter', mode = 'lines', fill = 'tozeroy')
 ```
+![](./demo/demo2.png)

adb_shell.go

@@ -5,7 +5,6 @@ import (
 	"errors"
 	"fmt"
 	"os/exec"
-	"strconv"
 	"strings"
 )
 
@@ -22,22 +21,12 @@ func adbCPU(pid int64) (float64, error) {
 		return 0, err
 	}
 
-	line := parseTopOutput(out)
+	top, err := NewTopOutput(out)
-
-	fields := strings.Fields(line)
-	if len(fields) < 10 {
-		fmt.Println("[ERROR]: wrong top output", fields)
-		return 0, ErrParse
-	}
-	cpu, err := strconv.ParseFloat(fields[9], 64)
 	if err != nil {
-		// this usually means that app is in background and top
+		return 0, err
-		// omits
-		fmt.Println("[ERROR] Parse CPU value:", err)
-		fmt.Println("Output:", fields)
-		return 0, ErrParse
 	}
-	return cpu, nil
+
+	return top.CPU, nil
 }
 
 // adbShell calls custom command via 'adb shell` and returns it's stdout output.
@@ -59,10 +48,3 @@ func adbShell(command string) (string, error) {
 
 	return buf.String(), nil
 }
-
-// parseTopOutput parses line from the android shell top's output.
-// It contains one line with data and many newlines.
-func parseTopOutput(data string) string {
-	lines := strings.Split(data, "\r")
-	return strings.Replace(lines[0], "\r", "", -1)
-}

top.go

@@ -0,0 +1,44 @@
+package main
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+// TopOutput represents data from 'top' command output
+// for single process.
+type TopOutput struct {
+	CPU float64
+}
+
+// NewTopOutput creates new TopOutput from raw stdout data.
+func NewTopOutput(data string) (*TopOutput, error) {
+	fields := parseTopOutput(data)
+	if len(fields) < 11 {
+		fmt.Println("[ERROR]: wrong top output", fields)
+		return nil, ErrParse
+	}
+
+	// eithh field is supposed to be CPU value
+	cpu, err := strconv.ParseFloat(fields[8], 64)
+	if err != nil {
+		// top output might be different from system to system, so log
+		// this verbosely
+		fmt.Println("[ERROR] Parse CPU value:", err)
+		fmt.Println("Output:", fields)
+		return nil, ErrParse
+	}
+
+	return &TopOutput{
+		CPU: cpu,
+	}, nil
+}
+
+func parseTopOutput(data string) []string {
+	lines := strings.Split(data, "\r")
+	line := strings.Replace(lines[0], "\r", "", -1)
+	line = strings.TrimSpace(line)
+	fields := strings.Fields(line)
+	return fields
+}