perf(desktop): 200-entry LRU cache for highlight.js output#3117
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HUQIANTAO wants to merge 1 commit into
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perf(desktop): 200-entry LRU cache for highlight.js output#3117HUQIANTAO wants to merge 1 commit into
HUQIANTAO wants to merge 1 commit into
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highlight.highlight() runs a real lexer walk over the source. The same code block re-renders many times in normal use — a streaming update on the *next* block still re-runs the parent transcript, the React StrictMode double-invoke in dev re-renders every block, and the code-block toolbar's hover-reveal re-renders the block's wrapper. Add a 200-entry LRU keyed on a djb2 hash of (lang + code). The cache stores the original source alongside the rendered HTML and verifies the source matches before serving — a hash collision (vanishingly unlikely with djb2 on multi-KB code) returns a cache miss instead of the wrong highlight. Map iteration is insertion-order, so the oldest entry is at the head; eviction is a single delete(). Size 200 covers the visible viewport (~30 blocks) plus an overshoot for the transcript's re-render window. Memory is bounded: each entry is the (code, html) pair, so worst case is ~200 * average-block-size bytes; in practice 50KB total for a busy transcript. Public API is unchanged. tsc --noEmit passes.
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highlight.highlight()runs a real lexer walk over the source. The same code block re-renders many times in normal use — a streaming update on the next block still re-runs the parent transcript, the React StrictMode double-invoke in dev re-renders every block, and the code-block toolbar's hover-reveal re-renders the block's wrapper.Add a 200-entry LRU keyed on a djb2 hash of (lang + code). The cache stores the original source alongside the rendered HTML and verifies the source matches before serving — a hash collision returns a cache miss instead of the wrong highlight. Map iteration is insertion-order, so the oldest entry is at the head; eviction is a single
delete(). Public API is unchanged.