21647993278

Committed 03 Feb 2026 09:10PM UTC coverage: 44.408% (-0.07%) from 44.475%

Build # 21647993278

Build Type

push

github

Committed by

web-flow

Commit Message

ssh tui: fix data races related to model updates (#6077)

This fixes several data races related to concurrent rendering and model
updating. Some model callbacks were changed to be propagated using
tea.Msg instead, and the top level model uses a new double-buffer
drawable to ensure View() is always called from the same thread as
Update.

Run Details

0 of 248 new or added lines in 15 files covered. (0.0%)

33 existing lines in 11 files now uncovered.

31413 of 70737 relevant lines covered (44.41%)

115.64 hits per line

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0.0

/pkg/ssh/tui/core/double_buffer.go

package core

import (
        "sync"
        "sync/atomic"

        uv "github.com/charmbracelet/ultraviolet"
)

type buffer struct {
        uv.ScreenBuffer
        width, height int
        mu            sync.Mutex
        _             [24]byte // pad to cache line
}

type DoubleBuffer struct {
        buffers [2]buffer
        back    *buffer
        front   atomic.Pointer[buffer]
}

func NewDoubleBuffer() *DoubleBuffer {
        db := &DoubleBuffer{
                buffers: [2]buffer{
                        {
                                ScreenBuffer: uv.NewScreenBuffer(0, 0),
                        },
                        {
                                ScreenBuffer: uv.NewScreenBuffer(0, 0),
                        },
                },
        }
        db.back = &db.buffers[0]
        db.back.mu.Lock()
        db.front.Store(&db.buffers[1])
        return db
}

func (db *DoubleBuffer) UpdateView(width, height int, drawable uv.Drawable) {
        back := db.back
        if back.width != width || back.height != height {
                back.width = width
                back.height = height
                back.ScreenBuffer = uv.NewScreenBuffer(width, height)
        }
        drawable.Draw(back, uv.Rect(0, 0, back.width, back.height))
        db.swap()
}

func (db *DoubleBuffer) Draw(scr uv.Screen, area uv.Rectangle) {
        front := db.front.Load()
        front.mu.Lock()
        defer front.mu.Unlock()
        front.Draw(scr, area)
}

func (db *DoubleBuffer) swap() {
        db.back.mu.Unlock()              // unlock the current back buffer
        db.back = db.front.Swap(db.back) // swap the front and back buffers
        db.back.mu.Lock()                // wait for the previous frame to finish rendering
}

1	package core
2
3	import (
4	"sync"
5	"sync/atomic"
6
7	uv "github.com/charmbracelet/ultraviolet"
8	)
9
10	type buffer struct {
11	uv.ScreenBuffer
12	width, height int
13	mu sync.Mutex
14	_ [24]byte // pad to cache line
15	}
16
17	type DoubleBuffer struct {
18	buffers [2]buffer
19	back *buffer
20	front atomic.Pointer[buffer]
21	}
22
NEW 23	func NewDoubleBuffer() *DoubleBuffer {	×
NEW 24	db := &DoubleBuffer{	×
NEW 25	buffers: [2]buffer{	×
NEW 26	{	×
NEW 27	ScreenBuffer: uv.NewScreenBuffer(0, 0),	×
NEW 28	},	×
NEW 29	{	×
NEW 30	ScreenBuffer: uv.NewScreenBuffer(0, 0),	×
NEW 31	},	×
NEW 32	},	×
NEW 33	}	×
NEW 34	db.back = &db.buffers[0]	×
NEW 35	db.back.mu.Lock()	×
NEW 36	db.front.Store(&db.buffers[1])	×
NEW 37	return db	×
NEW 38	}	×
39
NEW 40	func (db *DoubleBuffer) UpdateView(width, height int, drawable uv.Drawable) {	×
NEW 41	back := db.back	×
NEW 42	if back.width != width \|\| back.height != height {	×
NEW 43	back.width = width	×
NEW 44	back.height = height	×
NEW 45	back.ScreenBuffer = uv.NewScreenBuffer(width, height)	×
NEW 46	}	×
NEW 47	drawable.Draw(back, uv.Rect(0, 0, back.width, back.height))	×
NEW 48	db.swap()	×
49	}
50
NEW 51	func (db *DoubleBuffer) Draw(scr uv.Screen, area uv.Rectangle) {	×
NEW 52	front := db.front.Load()	×
NEW 53	front.mu.Lock()	×
NEW 54	defer front.mu.Unlock()	×
NEW 55	front.Draw(scr, area)	×
NEW 56	}	×
57
NEW 58	func (db *DoubleBuffer) swap() {	×
NEW 59	db.back.mu.Unlock() // unlock the current back buffer	×
NEW 60	db.back = db.front.Swap(db.back) // swap the front and back buffers	×
NEW 61	db.back.mu.Lock() // wait for the previous frame to finish rendering	×
NEW 62	}	×

pomerium / pomerium / 21647993278

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