internal/graphics: Bug fix: Race condition at QuadVertices

QuadVertices or verticesBackend.slice reused its backend slice.
This caused a race condition. QuadVertices can be accessed from
multiple goroutines, and resetting the head and copying the data
at internal/graphicscommand might not be synced.

This change fixes this issue by basically reverting
9cb631e30f.

Closes #1546
This commit is contained in:
Hajime Hoshi 2021-03-20 16:18:50 +09:00
parent 80645ad4dc
commit 26b9fa20c1
6 changed files with 31 additions and 81 deletions

View File

@ -203,7 +203,7 @@ func (i *Image) DrawImage(img *Image, options *DrawImageOptions) {
sy0 := float32(bounds.Min.Y)
sx1 := float32(bounds.Max.X)
sy1 := float32(bounds.Max.Y)
vs := graphics.QuadVertices(sx0, sy0, sx1, sy1, a, b, c, d, tx, ty, 1, 1, 1, 1, i.screen)
vs := graphics.QuadVertices(sx0, sy0, sx1, sy1, a, b, c, d, tx, ty, 1, 1, 1, 1)
is := graphics.QuadIndices()
srcs := [graphics.ShaderImageNum]*mipmap.Mipmap{img.mipmap}
@ -327,6 +327,7 @@ func (i *Image) DrawTriangles(vertices []Vertex, indices []uint16, img *Image, o
filter := driver.Filter(options.Filter)
// TODO: Use the same backend as graphics.QuadVertices.
vs := make([]float32, len(vertices)*graphics.VertexFloatNum)
for i, v := range vertices {
vs[i*graphics.VertexFloatNum] = v.DstX
@ -566,7 +567,7 @@ func (i *Image) DrawRectShader(width, height int, shader *Shader, options *DrawR
}
a, b, c, d, tx, ty := options.GeoM.elements32()
vs := graphics.QuadVertices(sx, sy, sx+float32(width), sy+float32(height), a, b, c, d, tx, ty, 1, 1, 1, 1, false)
vs := graphics.QuadVertices(sx, sy, sx+float32(width), sy+float32(height), a, b, c, d, tx, ty, 1, 1, 1, 1)
is := graphics.QuadIndices()
var sr driver.Region

View File

@ -301,7 +301,7 @@ func (i *Image) putOnAtlas() error {
// If the underlying graphics driver doesn't require restoring from the context lost, just a regular
// rendering works.
w, h := float32(i.width), float32(i.height)
vs := graphics.QuadVertices(0, 0, w, h, 1, 0, 0, 1, 0, 0, 1, 1, 1, 1, false)
vs := graphics.QuadVertices(0, 0, w, h, 1, 0, 0, 1, 0, 0, 1, 1, 1, 1)
is := graphics.QuadIndices()
dr := driver.Region{
X: 0,

View File

@ -14,6 +14,10 @@
package graphics
import (
"sync"
)
const (
ShaderImageNum = 4
@ -50,46 +54,45 @@ func QuadIndices() []uint16 {
}
var (
theVerticesBackend = &verticesBackend{
backend: make([]float32, VertexFloatNum*1024),
}
theVerticesBackend = &verticesBackend{}
)
type verticesBackend struct {
backend []float32
head int
m sync.Mutex
}
func (v *verticesBackend) slice(n int, last bool) []float32 {
// As this is called only on browsers, mutex is not required.
func (v *verticesBackend) slice(n int) []float32 {
v.m.Lock()
defer v.m.Unlock()
need := n * VertexFloatNum
if l := len(v.backend); v.head+need > l {
for v.head+need > l {
l *= 2
}
v.backend = make([]float32, l)
if v.head+need > len(v.backend) {
v.backend = nil
v.head = 0
}
if v.backend == nil {
l := 1024
if n > l {
l = n
}
v.backend = make([]float32, VertexFloatNum*l)
}
s := v.backend[v.head : v.head+need]
if last {
// If last is true, the vertices backend is sent to GPU and it is fine to reuse the slice.
v.head = 0
} else {
v.head += need
}
v.head += need
return s
}
func QuadVertices(sx0, sy0, sx1, sy1 float32, a, b, c, d, tx, ty float32, cr, cg, cb, ca float32, last bool) []float32 {
func QuadVertices(sx0, sy0, sx1, sy1 float32, a, b, c, d, tx, ty float32, cr, cg, cb, ca float32) []float32 {
x := sx1 - sx0
y := sy1 - sy0
ax, by, cx, dy := a*x, b*y, c*x, d*y
u0, v0, u1, v1 := float32(sx0), float32(sy0), float32(sx1), float32(sy1)
// Use the vertex backend instead of calling make to reduce GCs (#1521).
vs := theVerticesBackend.slice(4, last)
vs := theVerticesBackend.slice(4)
// This function is very performance-sensitive and implement in a very dumb way.
_ = vs[:32]

View File

@ -187,7 +187,7 @@ func (m *Mipmap) level(level int) *buffered.Image {
switch {
case level == 1:
src = m.orig
vs = graphics.QuadVertices(0, 0, float32(m.width), float32(m.height), 0.5, 0, 0, 0.5, 0, 0, 1, 1, 1, 1, false)
vs = graphics.QuadVertices(0, 0, float32(m.width), float32(m.height), 0.5, 0, 0, 0.5, 0, 0, 1, 1, 1, 1)
filter = driver.FilterLinear
case level > 1:
src = m.level(level - 1)
@ -197,7 +197,7 @@ func (m *Mipmap) level(level int) *buffered.Image {
}
w := sizeForLevel(m.width, level-1)
h := sizeForLevel(m.height, level-1)
vs = graphics.QuadVertices(0, 0, float32(w), float32(h), 0.5, 0, 0, 0.5, 0, 0, 1, 1, 1, 1, false)
vs = graphics.QuadVertices(0, 0, float32(w), float32(h), 0.5, 0, 0, 0.5, 0, 0, 1, 1, 1, 1)
filter = driver.FilterLinear
default:
panic(fmt.Sprintf("ebiten: invalid level: %d", level))

View File

@ -400,15 +400,16 @@ func (i *Image) appendDrawTrianglesHistory(srcs [graphics.ShaderImageNum]*Image,
// All images must be resolved and not stale each after frame.
// So we don't have to care if image is stale or not here.
vs := make([]float32, len(vertices))
copy(vs, vertices)
// vertices is generated at ebiten package and doesn't have to be copied so far.
// This depends on the implementation of graphics.QuadVertices.
is := make([]uint16, len(indices))
copy(is, indices)
item := &drawTrianglesHistoryItem{
images: srcs,
offsets: offsets,
vertices: vs,
vertices: vertices,
indices: is,
colorm: colorm,
mode: mode,

View File

@ -861,58 +861,3 @@ func TestClearPixels(t *testing.T) {
// After clearing, the regions will be available again.
img.ReplacePixels(make([]byte, 4*8*4), 0, 0, 8, 4)
}
func TestMutateSlices(t *testing.T) {
const w, h = 16, 16
dst := NewImage(w, h)
src := NewImage(w, h)
pix := make([]byte, 4*w*h)
for i := 0; i < w*h; i++ {
pix[4*i] = byte(i)
pix[4*i+1] = byte(i)
pix[4*i+2] = byte(i)
pix[4*i+3] = 0xff
}
src.ReplacePixels(pix, 0, 0, w, h)
vs := quadVertices(w, h, 0, 0)
is := make([]uint16, len(graphics.QuadIndices()))
copy(is, graphics.QuadIndices())
dr := driver.Region{
X: 0,
Y: 0,
Width: w,
Height: h,
}
dst.DrawTriangles([graphics.ShaderImageNum]*Image{src}, [graphics.ShaderImageNum - 1][2]float32{}, vs, is, nil, driver.CompositeModeSourceOver, driver.FilterNearest, driver.AddressUnsafe, dr, driver.Region{}, nil, nil)
for i := range vs {
vs[i] = 0
}
for i := range is {
is[i] = 0
}
if err := ResolveStaleImages(); err != nil {
t.Fatal(err)
}
if err := RestoreIfNeeded(); err != nil {
t.Fatal(err)
}
for j := 0; j < h; j++ {
for i := 0; i < w; i++ {
r, g, b, a, err := src.At(i, j)
if err != nil {
t.Fatal(err)
}
want := color.RGBA{r, g, b, a}
r, g, b, a, err = dst.At(i, j)
if err != nil {
t.Fatal(err)
}
got := color.RGBA{r, g, b, a}
if !sameColors(got, want, 1) {
t.Errorf("(%d, %d): got %v, want %v", i, j, got, want)
}
}
}
}