Fix all possible data races

- Update to go 1.19 for new atomic types
- Use atomic for StitchedImage query counter
- Make sure that we don't copy any tile objects

bin/stitch/image-tile.go

@@ -28,8 +28,8 @@ type ImageTile struct {
 
 	scaleDivider int // Downscales the coordinates and images on the fly.
 
-	image      image.Image   // Either a rectangle or an RGBA image. The bounds of this image are determined by the filename.
-	imageMutex *sync.RWMutex //
+	image      image.Image // Either a rectangle or an RGBA image. The bounds of this image are determined by the filename.
+	imageMutex *sync.RWMutex
 
 	invalidationChan chan struct{} // Used to send invalidation requests to the tile's goroutine.
 	timeoutChan      chan struct{} // Used to determine whether the tile is still being accessed or not.

bin/stitch/image-tiles.go

@@ -39,7 +39,8 @@ func LoadImageTiles(path string, scaleDivider int) (ImageTiles, error) {
 
 // InvalidateAboveY invalidates all cached images that have no pixel at the given y coordinate or below.
 func (it ImageTiles) InvalidateAboveY(y int) {
-	for _, tile := range it {
+	for i := range it {
+		tile := &it[i] // Need to copy a reference.
 		if tile.Bounds().Max.Y <= y {
 			tile.Invalidate()
 		}

bin/stitch/stitched-image-cache.go

@@ -54,10 +54,10 @@ func (sic *StitchedImageCache) Regenerate() *image.RGBA {
 
 	// List of tiles that intersect with the to be generated cache image.
 	intersectingTiles := []*ImageTile{}
-	for i, tile := range si.tiles {
+	for i := range si.tiles {
+		tile := &si.tiles[i]
 		if tile.Bounds().Overlaps(sic.rect) {
-			tilePtr := &si.tiles[i]
-			intersectingTiles = append(intersectingTiles, tilePtr)
+			intersectingTiles = append(intersectingTiles, tile)
 		}
 	}
 

bin/stitch/stitched-image.go

@@ -9,6 +9,7 @@ import (
 	"fmt"
 	"image"
 	"image/color"
+	"sync/atomic"
 )
 
 // StitchedImageCacheGridSize defines the worker chunk size when the cache image is regenerated.
@@ -37,7 +38,7 @@ type StitchedImage struct {
 	cacheRowYOffset int // Defines the pixel offset of the first cache row.
 
 	oldCacheRowIndex int
-	queryCounter     int
+	queryCounter     atomic.Int64
 }
 
 // NewStitchedImage creates a new image from several single image tiles.
@@ -98,7 +99,7 @@ func (si *StitchedImage) At(x, y int) color.Color {
 //	At(Bounds().Max.X-1, Bounds().Max.Y-1) // returns the bottom-right pixel.
 func (si *StitchedImage) RGBAAt(x, y int) color.RGBA {
 	// Assume that every pixel is only queried once.
-	si.queryCounter++
+	si.queryCounter.Add(1)
 
 	// Determine the cache rowIndex index.
 	rowIndex := (y + si.cacheRowYOffset) / si.cacheRowHeight
@@ -142,5 +143,5 @@ func (si *StitchedImage) Opaque() bool {
 func (si *StitchedImage) Progress() (value, max int) {
 	size := si.Bounds().Size()
 
-	return si.queryCounter, size.X * size.Y
+	return int(si.queryCounter.Load()), size.X * size.Y
 }

go.mod

@@ -1,6 +1,6 @@
 module github.com/Dadido3/noita-mapcap
 
-go 1.18
+go 1.19
 
 require (
 	github.com/1lann/promptui v0.8.1-0.20220708222609-81fad96dd5e1