giffer

commit 9c31647f1afb84c2c640c9a952dde7ceccf740d8
parent 8ee99c1e8c615e9c56c5a5bc91c9f53c5a4c3680
Author: Jack Mordaunt <jackmordaunt@gmail.com>
Date:   Mon, 19 Nov 2018 22:57:47 +1300

[+] Hash the output of `yarn build` to speed up builds.

Diffstat:
A
cmd/build/hash.go
 | 
101
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
M
cmd/build/main.go
 | 
17
+++++++++++++++++

2 files changed, 118 insertions(+), 0 deletions(-)
diff --git a/cmd/build/hash.go b/cmd/build/hash.go
@@ -0,0 +1,101 @@
+package main
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"sort"
+	"sync"
+	"unicode"
+
+	"github.com/OneOfOne/xxhash"
+	"github.com/pkg/errors"
+)
+
+// Hash recusively and concurrently hashes a fileEntry or directory.
+func Hash(path string) (uint64, error) {
+	var (
+		found = make(chan fileEntry)
+		wg    = &sync.WaitGroup{}
+	)
+	walk := func(path string, info os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+		if info.IsDir() {
+			return nil
+		}
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			by, err := ioutil.ReadFile(path)
+			found <- fileEntry{
+				Path:    path,
+				Content: by,
+				Err:     err,
+			}
+		}()
+		return nil
+	}
+	if err := filepath.Walk(path, walk); err != nil {
+		return 0, err
+	}
+	go func() {
+		wg.Wait()
+		close(found)
+	}()
+	var files []fileEntry
+	for f := range found {
+		if f.Err != nil {
+			return 0, f.Err
+		}
+		files = append(files, f)
+	}
+	sort.Sort(alphabetical(files))
+	hash := xxhash.New64()
+	for _, f := range files {
+		if _, err := hash.Write(f.Content); err != nil {
+			return 0, errors.Wrap(err, "hashing")
+		}
+	}
+	return hash.Sum64(), nil
+}
+
+type fileEntry struct {
+	Path    string
+	Content []byte
+	Err     error
+}
+
+type alphabetical []fileEntry
+
+func (a alphabetical) Len() int {
+	return len(a)
+}
+
+func (a alphabetical) Swap(ii, jj int) {
+	a[ii], a[jj] = a[jj], a[ii]
+}
+
+func (a alphabetical) Less(ii, jj int) bool {
+	iRunes := []rune(a[ii].Path)
+	jRunes := []rune(a[jj].Path)
+	max := len(iRunes)
+	if max > len(jRunes) {
+		max = len(jRunes)
+	}
+	for idx := 0; idx < max; idx++ {
+		ir := iRunes[idx]
+		jr := jRunes[idx]
+		lir := unicode.ToLower(ir)
+		ljr := unicode.ToLower(jr)
+		if lir != ljr {
+			return lir < ljr
+		}
+		// the lowercase runes are the same, so compare the original
+		if ir != jr {
+			return ir < jr
+		}
+	}
+	return false
+}
diff --git a/cmd/build/main.go b/cmd/build/main.go
@@ -4,6 +4,7 @@ package main
 import (
 	"archive/zip"
 	"bytes"
+	"encoding/binary"
 	"flag"
 	"fmt"
 	"image/png"
@@ -96,6 +97,22 @@ func main() {
 			Task{
 				Name: "compile ui",
 				Op: func() error {
+					var (
+						uiFiles      = "/Users/jack/dev/personal/giffer/cmd/desktop/ui/src"
+						checksumFile = "/Users/jack/dev/personal/giffer/cmd/desktop/ui/checksum"
+					)
+					h, err := Hash(uiFiles)
+					if err != nil {
+						return errors.Wrap(err, "hashing ui files")
+					}
+					checksum, err := ioutil.ReadFile(checksumFile)
+					if err != nil && !os.IsNotExist(err) {
+						return errors.Wrap(err, "reading checksum file")
+					}
+					if !os.IsNotExist(err) && h == binary.LittleEndian.Uint64(checksum) {
+						return nil
+					}
+					fmt.Printf("compile ui: checksum mismatch: recompiling\n")
 					cmd := exec.Command("yarn", "build")
 					cmd.Dir = "/Users/jack/dev/personal/giffer/cmd/desktop/ui"
 					if out, err := cmd.CombinedOutput(); err != nil {