initial commit

.github/workflows/go.yml

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+name: CI
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  testandinstall:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+
+    - name: Ensure all files were formatted as per gofmt
+      run: |
+        gofmt -l $(find . -name '*.go') >/dev/null
+
+    - name: run tests
+      run: go test ./...
+
+    - name: install binaries
+      run: go install github.com/gokrazy/stat/cmd/...

LICENSE

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+Copyright (c) 2017 the gokrazy authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of gokrazy nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

README.md

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+# gokrazy/stat
+
+`gokrazy/stat` is a program to visualize resource usage, producing output that
+looks very similar to [Dag Wieers’s
+`dstat`](https://github.com/dstat-real/dstat) default output.
+
+As the repository path implies, this program is meant to be used on the
+https://gokrazy.org/ Raspberry Pi platform, so it does not have any external
+runtime dependencies and is implemented natively in Go (not using any cgo). The
+resulting static binary might come in handy in other Linux environments, too!
+
+
+## github.com/gokrazy/stat/cmd/gokr-webstat
+
+`gokr-webstat` displays system resource usage in your browser, with output
+matching `gokr-stat` or `dstat`!
+
+It uses the [EventSource
+API](https://developer.mozilla.org/en-US/docs/Web/API/EventSource) to stream new
+lines into your browser.
+
+![webstat screenshot](2020-06-27-midna-webstat.jpg)
+
+## github.com/gokrazy/stat/cmd/gokr-stat
+
+The `gokr-stat` program is a terminal program that displays system resource
+usage, like `dstat`.
+
+Here is the `gokr-stat` terminal output (via
+[`gokrazy/breakglass`](https://github.com/gokrazy/breakglass)) when scanning one
+double-sided piece of A4 paper with
+[scan2drive](https://github.com/stapelberg/scan2drive) on a Raspberry Pi 4:
+
+![stat terminal output](2020-06-27-scan2drive-scan-gokrazy-stat.jpg)

cmd/gokr-stat/stat.go

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+package main
+
+import (
+	"flag"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"log"
+	"os"
+	"os/signal"
+	"strings"
+	"sync"
+	"syscall"
+	"time"
+	"unsafe"
+
+	"github.com/gokrazy/stat"
+	"github.com/gokrazy/stat/internal/cpu"
+	"github.com/gokrazy/stat/internal/disk"
+	"github.com/gokrazy/stat/internal/mem"
+	"github.com/gokrazy/stat/internal/net"
+	"github.com/gokrazy/stat/internal/sys"
+)
+
+func formatCols(cols []stat.Col) string {
+	formatted := make([]string, len(cols))
+	for idx, col := range cols {
+		formatted[idx] = col.String()
+	}
+	return strings.Join(formatted, " ")
+}
+
+const (
+	TIOCGWINSZ = 0x5413
+)
+
+type window struct {
+	Row    uint16
+	Col    uint16
+	Xpixel uint16
+	Ypixel uint16
+}
+
+func terminalSize() (*window, error) {
+	w := new(window)
+	tio := syscall.TIOCGWINSZ
+	res, _, err := syscall.Syscall(syscall.SYS_IOCTL,
+		uintptr(syscall.Stdin),
+		uintptr(tio),
+		uintptr(unsafe.Pointer(w)),
+	)
+	if int(res) == -1 {
+		if err == syscall.ENOTTY {
+			return &window{Row: 80}, nil
+		}
+		return nil, err
+	}
+	return w, nil
+}
+
+func printStats() error {
+	flag.Parse()
+
+	ts, err := terminalSize()
+	if err != nil {
+		return err
+	}
+	var rowsMu sync.Mutex
+	rows := int(ts.Row) - 1
+	ch := make(chan os.Signal, 1)
+	signal.Notify(ch, syscall.SIGWINCH)
+	go func() {
+		for range ch {
+			ts, err := terminalSize()
+			if err != nil {
+				log.Print(err)
+				continue
+			}
+			rowsMu.Lock()
+			rows = int(ts.Row) - 1
+			rowsMu.Unlock()
+		}
+	}()
+
+	type processAndFormatter interface {
+		ProcessAndFormat(map[string][]byte) []stat.Col
+	}
+	modules := []processAndFormatter{
+		&cpu.Stats{},
+		&disk.Stats{},
+		&sys.Stats{},
+		&net.Stats{},
+		&mem.Stats{},
+	}
+	header := func() {
+		const blue = "\033[1;34m"
+		fmt.Printf(blue + "usr sys idl wai stl | ")
+		fmt.Printf("_read _writ | ")
+		fmt.Printf("_int_ _csw_ | ")
+		fmt.Printf("_recv _send | ")
+		fmt.Printf("_used _free _buff _cach\n")
+	}
+	parts := make([]string, len(modules))
+	files := make(map[string]*os.File)
+	for _, mod := range modules {
+		// When a stats module implements the FileContents() interface, we
+		// ensure all returned file contents are read and passed to
+		// ProcessAndFormat.
+		fc, ok := mod.(interface{ FileContents() []string })
+		if !ok {
+			continue
+		}
+		for _, f := range fc.FileContents() {
+			if _, ok := files[f]; ok {
+				continue // already requested
+			}
+			fl, err := os.Open(f)
+			if err != nil {
+				return err
+			}
+			files[f] = fl
+		}
+	}
+	for i := 0; ; i++ {
+		rowsMu.Lock()
+		showHeader := i%(int(rows)-1) == 0
+		rowsMu.Unlock()
+		if showHeader {
+			header()
+		}
+		contents := make(map[string][]byte)
+		for path, fl := range files {
+			if _, err := fl.Seek(0, io.SeekStart); err != nil {
+				return err
+			}
+			b, err := ioutil.ReadAll(fl)
+			if err != nil {
+				return err
+			}
+			contents[path] = b
+		}
+
+		for idx, mod := range modules {
+			parts[idx] = formatCols(mod.ProcessAndFormat(contents))
+		}
+
+		if i > 0 {
+			const darkblue = "\033[0;34m"
+			fmt.Println(strings.Join(parts, darkblue+" | "))
+			// TODO: clear colors at the end of line so that program can be interrupted
+		}
+
+		time.Sleep(1 * time.Second)
+	}
+}
+
+func main() {
+	if os.Getenv("GOKRAZY_FIRST_START") == "1" {
+		// Do not supervise this process: it is meant for interactive usage on a
+		// terminal. If you are looking for a daemon, use gokr-webstat instead.
+		os.Exit(125)
+	}
+
+	if err := printStats(); err != nil {
+		log.Fatal(err)
+	}
+}

cmd/gokr-webstat/statustmpl.go

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+package main
+
+const statusTmpl = `<!DOCTYPE html>
+<html>
+  <head>
+    <title>{{ .Hostname }} - webstat</title>
+<style type="text/css">
+body {
+  background-color: #eee;
+}
+#readings {
+  background-color: black;
+  border: 1px solid grey;
+  font-family: monospace;
+}
+th {
+  color: white;
+  text-align: left;
+}
+</style>
+  </head>
+  <body>
+<h1>{{ .Hostname }} - webstat</h1>
+<table id="readings">
+<thead>
+<tr>
+{{ range $idx, $val := .Headers }}
+<th>{{ $val }}</th>
+{{ end }}
+</tr>
+</thead>
+<tbody>
+<tr><td>&nbsp;</td></tr>
+<tr><td>&nbsp;</td></tr>
+<tr><td>&nbsp;</td></tr>
+<tr><td>&nbsp;</td></tr>
+<tr><td>&nbsp;</td></tr>
+<tr><td>&nbsp;</td></tr>
+<tr><td>&nbsp;</td></tr>
+<tr><td>&nbsp;</td></tr>
+<tr><td>&nbsp;</td></tr>
+<tr><td>&nbsp;</td></tr>
+<tr><td>&nbsp;</td></tr>
+<tr><td>&nbsp;</td></tr>
+<tr><td>&nbsp;</td></tr>
+<tr><td>&nbsp;</td></tr>
+<tr><td>&nbsp;</td></tr>
+<tr><td>&nbsp;</td></tr>
+<tr><td>&nbsp;</td></tr>
+<tr><td>&nbsp;</td></tr>
+<tr><td>&nbsp;</td></tr>
+<tr><td>&nbsp;</td></tr>
+</tbody>
+</table>
+<script type="text/javascript">
+var readingstbody = document.getElementById('readings').children[1];
+var readings = new EventSource('/readings');
+readings.onmessage = function(e) {
+  var parts = JSON.parse(e.data);
+  var innerHTML = '';
+
+  for (part of parts) {
+    innerHTML += part;
+  }
+  for (var i = 0; i < 19; i++) {
+    // copy from i+1 to i, overwriting the oldest entry
+    readingstbody.children[i].innerHTML = readingstbody.children[i+1].innerHTML
+  }
+  readingstbody.children[19].innerHTML = innerHTML;
+}
+</script>
+  </body>
+</html>`