79 lines
2.0 KiB
Markdown
79 lines
2.0 KiB
Markdown
---
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summary: WASM build constraints and patterns for kreuzberg-wasm crate
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---
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# WASM Build Constraints
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## Overview
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WASM target in `crates/kreuzberg-wasm/`. Uses wasm-bindgen with sync-only internal APIs.
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## Feature Flags
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```toml
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[features]
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wasm-target = ["pdf", "html", "xml", "email", "language-detection", "chunking", "quality", "office"]
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wasm-threads = ["dep:wasm-bindgen-rayon"] # Optional
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```
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## Critical Constraints
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### 1. No Tokio Runtime
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All operations must be synchronous internally. Use `#[cfg(not(feature = "tokio-runtime"))]` paths.
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### 2. SyncExtractor Required
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Every WASM-compatible extractor MUST implement `SyncExtractor`:
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```rust
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impl SyncExtractor for MyExtractor {
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fn extract_sync(&self, content: &[u8], mime_type: &str, config: &ExtractionConfig)
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-> Result<ExtractionResult> { /* sync implementation */ }
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}
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impl DocumentExtractor for MyExtractor {
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fn as_sync_extractor(&self) -> Option<&dyn SyncExtractor> {
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Some(self) // MUST return Some for WASM
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}
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}
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```
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### 3. HTML Size Limit
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```rust
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const MAX_HTML_SIZE: usize = 2 * 1024 * 1024; // 2MB - stack constraint
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```
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## Build Config
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```toml
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[lib]
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crate-type = ["cdylib", "rlib"]
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[profile.release.package.kreuzberg-wasm]
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opt-level = "z" # Size optimization
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codegen-units = 1
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```
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## API Pattern
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```rust
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#[wasm_bindgen]
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pub async fn extract_from_bytes(content: Vec<u8>, config: JsValue) -> Result<JsValue, JsValue> {
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let config: ExtractionConfig = serde_wasm_bindgen::from_value(config)?;
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let result = extract_bytes_sync(&content, mime_type, &config)?;
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Ok(serde_wasm_bindgen::to_value(&result)?)
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}
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```
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Functions can be `async` for JS compatibility, but internal extraction is sync.
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## Critical Rules
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1. **No tokio** -- all operations synchronous
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2. **Implement SyncExtractor** for all WASM-compatible extractors
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3. **HTML limited to 2MB** due to stack constraints
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4. **Size optimization** via `opt-level = "z"`
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5. **Feature gate** with `#[cfg(target_arch = "wasm32")]`
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