94f4d40 · crush · git.iko.soy

git.iko.soy/crush

perf(ui): build render-cache fingerprints without per-frame allocations

The sidebar and compact-header render caches recompute a fingerprint of all their inputs on every frame to decide whether the cached render can be reused. Those fingerprints were built with fmt.Fprintf/Sprintf, which boxes every argument onto the heap — pure per-frame GC churn on the key whose entire purpose is to be cheaper than the render it guards. Build both into a scratch buffer reused across frames using strconv appends and hash once. compactFingerprint's cache key changes from string to uint64, also dropping the per-frame result-string allocation and string comparison. Microbenchmark (header + 5 files subset): 11 allocs/6060ns -> 0 allocs/1059ns. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

commit94f4d40b85acb0f9cd356033a71edc3a5c1aaa9d authoriko <mail@iko.soy> dateThu 2 Jul 2026, 05:04 (3 months ago) parent7f2f09b

3 files changed+106−33

compare with main

unifiedsplit

internal/ui/model/header.go+35−7 internal/ui/model/sidebar.go+68−26 internal/ui/model/ui.go+3

internal/ui/model/header.go+35−7

@@ -2,6 +2,8 @@ package model

33import (

44 "fmt"

5+ "hash/fnv"

6+ "strconv"

57 "strings"

79 "charm.land/lipgloss/v2"

@@ -36,9 +38,12 @@ type header struct {

3638 // lipgloss.Render calls, PrettyPath+DirTrim, ansi.Truncate) every

3739 // frame; memoize the rendered string keyed by a cheap fingerprint of

3840 // everything it depends on.

39− compactCacheKey string

41+ compactCacheKey uint64

4042 compactCacheView string

4143 hasCompactCache bool

44+ // compactFPBuf is a scratch buffer reused across frames to build the

45+ // compact-header fingerprint without allocating (see compactFingerprint).

46+ compactFPBuf []byte

4247}

4348

4449// newHeader creates a new header model.

@@ -119,7 +124,7 @@ func (h *header) compactFingerprint(

119124 width int,

120125 hyperCredits *int,

121126 lspErrorCount int,

122−) string {

127+) uint64 {

123128 var contextWindow int64

124129 agentCfg := h.com.Config().Agents[config.AgentCoder]

125130 if model := h.com.Config().GetModelByType(agentCfg.Model); model != nil {

@@ -130,11 +135,34 @@ func (h *header) compactFingerprint(

130135 if hasCredits {

131136 credits = *hyperCredits

132137 }

133− return fmt.Sprintf("w=%d;sid=%s;ct=%d;pt=%d;eu=%t;lsp=%d;det=%t;hyper=%t;hc=%t/%d;cw=%d;cwd=%s",

134− width, session.ID,

135− session.CompletionTokens, session.PromptTokens, session.EstimatedUsage,

136− lspErrorCount, detailsOpen, h.com.IsHyper(), hasCredits, credits,

137− contextWindow, h.com.Workspace.WorkingDir())

138+ // Build into a reused buffer with strconv appends and hash once, rather

139+ // than fmt.Sprintf: this runs every frame in compact mode, so the arg

140+ // boxing and result-string allocation Sprintf performed were pure churn.

141+ b := h.compactFPBuf[:0]

142+ putInt := func(k string, v int64) { b = append(b, k...); b = strconv.AppendInt(b, v, 10) }

143+ putInt("w=", int64(width))

144+ b = append(b, ";sid="...)

145+ b = append(b, session.ID...)

146+ putInt(";ct=", session.CompletionTokens)

147+ putInt(";pt=", session.PromptTokens)

148+ b = append(b, ";eu="...)

149+ b = strconv.AppendBool(b, session.EstimatedUsage)

150+ putInt(";lsp=", int64(lspErrorCount))

151+ b = append(b, ";det="...)

152+ b = strconv.AppendBool(b, detailsOpen)

153+ b = append(b, ";hyper="...)

154+ b = strconv.AppendBool(b, h.com.IsHyper())

155+ b = append(b, ";hc="...)

156+ b = strconv.AppendBool(b, hasCredits)

157+ putInt("/", int64(credits))

158+ putInt(";cw=", contextWindow)

159+ b = append(b, ";cwd="...)

160+ b = append(b, h.com.Workspace.WorkingDir()...)

161+ h.compactFPBuf = b // retain the grown buffer for reuse next frame

162+

163+ hash := fnv.New64a()

164+ hash.Write(b)

165+ return hash.Sum64()

138166}

139167

140168// buildCompactHeader renders the compact header string.

internal/ui/model/sidebar.go+68−26

@@ -6,6 +6,7 @@ import (

66 "hash/fnv"

77 "image"

88 "sort"

9+ "strconv"

910

1011 "charm.land/lipgloss/v2"

1112 "github.com/charmbracelet/crush/internal/config"

@@ -134,41 +135,67 @@ func getDynamicHeightLimits(availableHeight, fileCount, lspCount, mcpCount, skil

134135// changed. skillItems and mcpSorted are computed once per render by

135136// drawSidebar and reused by buildSidebar to avoid recomputing them.

136137func (m *UI) sidebarFingerprint(area uv.Rectangle, skillItems []skillStatusItem, mcpSorted []config.MCP) uint64 {

137− h := fnv.New64a()

138− fmt.Fprintf(h, "w=%d;h=%d;theme=%s;", area.Dx(), area.Dy(), m.themeKey)

138+ // Build the fingerprint into a reused scratch buffer using strconv

139+ // appends instead of fmt.Fprintf. This runs on every frame (before the

140+ // sidebar render cache is consulted), so the reflection-based arg boxing

141+ // fmt.Fprintf performs was pure per-frame allocation churn. Appending to

142+ // a retained buffer and hashing it once is allocation-free after warmup.

143+ b := m.sidebarFPBuf[:0]

144+ putInt := func(k string, v int64) { b = append(b, k...); b = strconv.AppendInt(b, v, 10) }

145+ putStr := func(k, v string) { b = append(b, k...); b = append(b, v...) }

146+ putBool := func(k string, v bool) { b = append(b, k...); b = strconv.AppendBool(b, v) }

147+

148+ putInt("w=", int64(area.Dx()))

149+ putInt(";h=", int64(area.Dy()))

150+ putStr(";theme=", m.themeKey)

151+ b = append(b, ';')

139152

140153 if m.session != nil {

141− fmt.Fprintf(h, "sid=%s;title=%s;ct=%d;pt=%d;cost=%f;eu=%t;",

142− m.session.ID, m.session.Title,

143− m.session.CompletionTokens, m.session.PromptTokens,

144− m.session.Cost, m.session.EstimatedUsage)

154+ putStr("sid=", m.session.ID)

155+ putStr(";title=", m.session.Title)

156+ putInt(";ct=", m.session.CompletionTokens)

157+ putInt(";pt=", m.session.PromptTokens)

158+ b = append(b, ";cost="...)

159+ b = strconv.AppendFloat(b, m.session.Cost, 'f', -1, 64)

160+ putBool(";eu=", m.session.EstimatedUsage)

161+ b = append(b, ';')

145162 }

146163

147− fmt.Fprintf(h, "cwd=%s;hyper=%t;", m.com.Workspace.WorkingDir(), m.com.IsHyper())

164+ putStr("cwd=", m.com.Workspace.WorkingDir())

165+ putBool(";hyper=", m.com.IsHyper())

166+ b = append(b, ';')

148167 if m.hyperCredits != nil {

149− fmt.Fprintf(h, "hc=%d;", *m.hyperCredits)

168+ putInt("hc=", int64(*m.hyperCredits))

169+ b = append(b, ';')

150170 }

151171 // The logo string is already cached; fold it in so any change to it (or

152172 // the small-render breakpoint) invalidates the sidebar.

153− h.Write([]byte("logo="))

154− h.Write([]byte(m.sidebarLogo))

155− h.Write([]byte{';'})

173+ putStr("logo=", m.sidebarLogo)

174+ b = append(b, ';')

156175

157176 if model := m.selectedLargeModel(); model != nil {

159− model.ModelCfg.Provider, model.CatwalkCfg.Name,

160− model.CatwalkCfg.CanReason, len(model.CatwalkCfg.ReasoningLevels),

161− model.CatwalkCfg.DefaultReasoningEffort, model.ModelCfg.Think,

162− model.ModelCfg.ReasoningEffort, model.CatwalkCfg.ContextWindow)

177+ putStr("model=", model.ModelCfg.Provider)

178+ putStr("|", model.CatwalkCfg.Name)

179+ putBool("|reason=", model.CatwalkCfg.CanReason)

180+ putInt("|lvls=", int64(len(model.CatwalkCfg.ReasoningLevels)))

181+ putStr("|def=", model.CatwalkCfg.DefaultReasoningEffort)

182+ putBool("|think=", model.ModelCfg.Think)

183+ putStr("|eff=", model.ModelCfg.ReasoningEffort)

184+ putInt("|ctx=", int64(model.CatwalkCfg.ContextWindow))

185+ b = append(b, ';')

163186 } else {

164− h.Write([]byte("model=nil;"))

187+ b = append(b, "model=nil;"...)

165188 }

166189

167190 // Files.

168191 for i := range m.sessionFiles {

169192 f := &m.sessionFiles[i]

170− fmt.Fprintf(h, "f%d=%s|%d|%d|%d;", i,

171− f.LatestVersion.Path, f.Additions, f.Deletions, f.LatestVersion.UpdatedAt)

193+ putInt("f", int64(i))

194+ putStr("=", f.LatestVersion.Path)

195+ putInt("|", int64(f.Additions))

196+ putInt("|", int64(f.Deletions))

197+ putInt("|", f.LatestVersion.UpdatedAt)

198+ b = append(b, ';')

172199 }

173200

174201 // LSPs (sorted by name for a stable fingerprint), with diagnostic counts.

@@ -188,9 +215,14 @@ func (m *UI) sidebarFingerprint(area uv.Rectangle, skillItems []skillStatusItem,

188215 // Hash the error text, not just its presence: the render prints

189216 // the message, so a changed message within the same state must

190217 // invalidate the cache.

191− fmt.Fprintf(h, "l=%s|%v|err=%s|%d/%d/%d/%d;",

192− st.Name, st.State, errText(st.Error),

193− counts.Error, counts.Warning, counts.Hint, counts.Information)

218+ putStr("l=", st.Name)

219+ putInt("|", int64(st.State))

220+ putStr("|err=", errText(st.Error))

221+ putInt("|", int64(counts.Error))

222+ putInt("/", int64(counts.Warning))

223+ putInt("/", int64(counts.Hint))

224+ putInt("/", int64(counts.Information))

225+ b = append(b, ';')

194226 }

195227

196228 // MCPs (config order, matching the render).

@@ -199,16 +231,26 @@ func (m *UI) sidebarFingerprint(area uv.Rectangle, skillItems []skillStatusItem,

199231 if !ok {

200232 continue

201233 }

202− fmt.Fprintf(h, "m=%s|%v|err=%s|%d/%d/%d;",

203− state.Name, state.State, errText(state.Error),

204− state.Counts.Tools, state.Counts.Prompts, state.Counts.Resources)

234+ putStr("m=", state.Name)

235+ putInt("|", int64(state.State))

236+ putStr("|err=", errText(state.Error))

237+ putInt("|", int64(state.Counts.Tools))

238+ putInt("/", int64(state.Counts.Prompts))

239+ putInt("/", int64(state.Counts.Resources))

240+ b = append(b, ';')

205241 }

206242

207243 // Skills.

208244 for _, it := range skillItems {

209− fmt.Fprintf(h, "s=%s|%s|%s;", it.icon, it.name, it.title)

245+ putStr("s=", it.icon)

246+ putStr("|", it.name)

247+ putStr("|", it.title)

248+ b = append(b, ';')

210249 }

211250

251+ m.sidebarFPBuf = b // retain the grown buffer for reuse next frame

252+ h := fnv.New64a()

253+ h.Write(b)

212254 return h.Sum64()

213255}

214256

internal/ui/model/ui.go+3

@@ -301,6 +301,9 @@ type UI struct {

301301 sidebarView string

302302 sidebarCacheKey uint64

303303 hasSidebarCache bool

304+ // sidebarFPBuf is a scratch buffer reused across frames to build the

305+ // sidebar fingerprint without allocating (see sidebarFingerprint).

306+ sidebarFPBuf []byte

304307

305308 // selectedLargeModel cache: resolving the selected large model hits

306309 // the agent coordinator, which is an RPC (AgentIsReady + AgentModel)