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Introduce RequestTimer for per-request phase tracking (init, backend, process, total) exposed via Server-Timing response headers. Add benchmark tooling with --profile mode for collecting timing data. Document phased optimization plan covering streaming architecture, code-level fixes, and open design questions for team review.
Introduce RequestTimer for per-request phase tracking (init, backend, process, total) exposed via Server-Timing response headers. Add benchmark tooling with --profile mode for collecting timing data. Document phased optimization plan covering streaming architecture, code-level fixes, and open design questions for team review.
RequestTimer and Server-Timing header were premature — WASM guest profiling via profile.sh gives better per-function visibility without runtime overhead. Also strips dead --profile mode from benchmark.sh.
build.rs already resolves trusted-server.toml + env vars at compile time and embeds the result. Replace Settings::from_toml() with direct toml::from_str() to skip the config crate pipeline on every request. Profiling confirms: ~5-8% → ~3.3% CPU per request.
- OPTIMIZATION.md: profiling results, CPU breakdown, phased optimization plan covering streaming fixes, config crate elimination, and stream_to_client() architecture - scripts/profile.sh: WASM guest profiling via --profile-guest with Firefox Profiler-compatible output - scripts/benchmark.sh: TTFB analysis, cold start detection, endpoint latency breakdown, and load testing with save/compare support
…ding HTML and RSC Flight URL rewriting, to avoid full-body buffering
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Summary
This PR fundamentally shifts the Trusted Server’s publisher proxy path from a fully buffered model to a chunked streaming architecture, delivering Phase 1 and 2.1 of the performance optimization plan.
By replacing response buffering with Fastly’s
stream_to_client()API and optimizing thelol_htmloutput pipeline for true incremental streaming, response headers and initial HTML chunks are now dispatched to the client as soon as they are processed. This significantly reduces Time-To-First-Byte (TTFB) and unblocks early client-side subresource discovery.Additionally, WASM hostcalls have been batched to improve throughput and reduce memory pressure.
Key Changes
stream_to_client()Integration (publisher.rs)Replaced fully buffered response collection with
stream_to_client()to enable immediate header dispatch and incremental chunk streaming.lol_htmlOutput Pipeline (streaming_processor.rs)Refactored the
HtmlRewriteradapter to implement theOutputSinktrait using a sharedRc<RefCell<Vec<u8>>>buffer, enabling true incremental streaming.Buffer Pre-allocation
Replaced
std::mem::takewithVec::with_capacityandstd::mem::replaceto eliminate reallocation churn during chunk processing.WASM Hostcall Batching
Wrapped the
StreamingBodyoutput in an 8KBstd::io::BufWriterto reduce expensive WASM-to-host boundary crossings.Code Health
# Errorsdocumentation sections to the streaming handlerTest Plan
Local Unit & Workspace Tests
Run:
cargo test --workspaceto ensure all functionality remains intact.
TypeScript Bundle Build
Run:
in
crates/js/libto verify successful generation of integration modules.Local Fastly Simulation
Run:
Verify:
curl)Staging Load Testing
Execute:
against staging to quantify external TTFB and Time-to-Last-Byte (TTLB) improvements under concurrent traffic.