From f04bc3182005d874a105592b201404448bdaf05d Mon Sep 17 00:00:00 2001
From: Mihai Parparita <mihai@tailscale.com>
Date: Tue, 2 Aug 2022 15:00:26 -0700
Subject: [PATCH] cmd/tsconnect: add -fast-compression option

Changes Gzip and Brotli to optimize for speed instead of size. This
signficantly speeds up Brotli, and is useful when iterating locally
or running the build during a CI job (where we just care that it
can successfully build).

Signed-off-by: Mihai Parparita <mihai@tailscale.com>
---
 .github/workflows/cross-wasm.yml |  2 +-
 cmd/tsconnect/build.go           | 20 ++++++++++++++------
 cmd/tsconnect/tsconnect.go       |  7 ++++---
 3 files changed, 19 insertions(+), 10 deletions(-)

diff --git a/.github/workflows/cross-wasm.yml b/.github/workflows/cross-wasm.yml
index 9d729a7f7..b188940fb 100644
--- a/.github/workflows/cross-wasm.yml
+++ b/.github/workflows/cross-wasm.yml
@@ -34,7 +34,7 @@ jobs:
     - name: tsconnect static build
       # Use our custom Go toolchain, we set build tags (to control binary size)
       # that depend on it.
-      run: ./tool/go run ./cmd/tsconnect build
+      run: ./tool/go run ./cmd/tsconnect --fast-compression build
 
     - uses: k0kubun/action-slack@v2.0.0
       with:
diff --git a/cmd/tsconnect/build.go b/cmd/tsconnect/build.go
index 570f3038a..933c953cb 100644
--- a/cmd/tsconnect/build.go
+++ b/cmd/tsconnect/build.go
@@ -71,7 +71,7 @@ func runBuild() {
 		log.Fatalf("Cannot write metadata: %v", err)
 	}
 
-	if er := precompressDist(); err != nil {
+	if er := precompressDist(*fastCompression); err != nil {
 		log.Fatalf("Cannot precompress resources: %v", er)
 	}
 }
@@ -125,7 +125,7 @@ func cleanDist() error {
 	return nil
 }
 
-func precompressDist() error {
+func precompressDist(fastCompression bool) error {
 	log.Printf("Pre-compressing files in %s/...\n", *distDir)
 	var eg errgroup.Group
 	err := fs.WalkDir(os.DirFS(*distDir), ".", func(p string, d fs.DirEntry, err error) error {
@@ -142,7 +142,7 @@ func precompressDist() error {
 		log.Printf("Pre-compressing %v\n", p)
 
 		eg.Go(func() error {
-			return precompress(p)
+			return precompress(p, fastCompression)
 		})
 		return nil
 	})
@@ -158,7 +158,7 @@ func precompressDist() error {
 	".wasm": true,
 }
 
-func precompress(path string) error {
+func precompress(path string, fastCompression bool) error {
 	contents, err := os.ReadFile(path)
 	if err != nil {
 		return err
@@ -168,14 +168,22 @@ func precompress(path string) error {
 		return err
 	}
 
+	gzipLevel := gzip.BestCompression
+	if fastCompression {
+		gzipLevel = gzip.BestSpeed
+	}
 	err = writeCompressed(contents, func(w io.Writer) (io.WriteCloser, error) {
-		return gzip.NewWriterLevel(w, gzip.BestCompression)
+		return gzip.NewWriterLevel(w, gzipLevel)
 	}, path+".gz", fi.Mode())
 	if err != nil {
 		return err
 	}
+	brotliLevel := brotli.BestCompression
+	if fastCompression {
+		brotliLevel = brotli.BestSpeed
+	}
 	return writeCompressed(contents, func(w io.Writer) (io.WriteCloser, error) {
-		return brotli.NewWriterLevel(w, brotli.BestCompression), nil
+		return brotli.NewWriterLevel(w, brotliLevel), nil
 	}, path+".br", fi.Mode())
 }
 
diff --git a/cmd/tsconnect/tsconnect.go b/cmd/tsconnect/tsconnect.go
index 1fb183deb..099cc973c 100644
--- a/cmd/tsconnect/tsconnect.go
+++ b/cmd/tsconnect/tsconnect.go
@@ -18,9 +18,10 @@
 )
 
 var (
-	addr     = flag.String("addr", ":9090", "address to listen on")
-	distDir  = flag.String("distdir", "./dist", "path of directory to place build output in")
-	yarnPath = flag.String("yarnpath", "../../tool/yarn", "path yarn executable used to install JavaScript dependencies")
+	addr            = flag.String("addr", ":9090", "address to listen on")
+	distDir         = flag.String("distdir", "./dist", "path of directory to place build output in")
+	yarnPath        = flag.String("yarnpath", "../../tool/yarn", "path yarn executable used to install JavaScript dependencies")
+	fastCompression = flag.Bool("fast-compression", false, "Use faster compression when building, to speed up build time. Meant to iterative/debugging use only.")
 )
 
 func main() {