WASI 0.3 prep: 0.2 component build, scheduler timer queue, async design notes#497
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WASI 0.3 prep: 0.2 component build, scheduler timer queue, async design notes#497stevedekorte wants to merge 4 commits into
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make component builds build/bin/io_component.wasm via wasi-sdk's wasm32-wasip2 target and wasm-component-ld; make check-component runs the Io correctness suite against it under wasmtime. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Object wait now parks the calling coroutine on a Scheduler timer queue with a deadline. Expired timers re-enter the run queue on yield/pause; when nothing is runnable but timers are pending, the VM blocks in a single host wait until the nearest deadline (Scheduler idleUntilNextTimer). That idle point is where a WASI 0.3 future<T> will be awaited once host/toolchain support lands. Timed coroutines now run concurrently (two overlapping 1s waits: ~1.1s wall, ~4% CPU, previously a 100% CPU busy-spin or fully serialized sleeps). wait uses condition-variable semantics — a finished child coroutine resumes its parent directly, so pause can return early; wait re-parks for the remaining time and removes stale timer entries. Two eval-loop fixes this exposed: - Dead-ancestor walk: when a coroutine finishes after the coroutine that started it already finished, the parent-resume walk hit the dead link and took the nestedEvalDepth early-return, stranding all parked coroutines. The walk now skips ancestors with no saved frames. - Stale run-queue entries: a coroutine woken by the child-death walk while still queued in yieldingCoros leaves a stale entry; resuming it after it finished restarted its body (frameless coros look never-started). IoCoroutineData gains a hasFinished flag set by the eval loop on body completion (cleared at every deliberate restart site), exposed as Coroutine isFinished; pause/yield drop finished entries instead of resuming them. Adds SchedulerTimerTest covering concurrent waits, timer wakeups during yields, actor waits, and a regression test for the dead-ancestor walk (verified to fail with the walk disabled). Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Adds a WASI 0.3 section to the Technical Notes WASM page evaluating how the native-async component model fits Io (stackless evaluator, actor futures, the new scheduler idle point) and records the landed migration steps. agents/WASI_ASYNC_PLAN.md maps future<T>/stream<T> onto the scheduler seam, documents the VM contracts to preserve, and lists the upgrade triggers (wasmtime 46, C toolchain async support). Static HTML and llms-full.txt regenerated. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Adds the source JPEGs for the chapter art (_originals), unused assets (_unused), and the previous Introduction image. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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Summary
Prep work toward WASI 0.3's native async, implementing the two migration steps that are buildable and testable with today's toolchain (wasi-sdk 25, wasmtime 42), plus a design doc for the 0.3 step itself.
make componentproducesbuild/bin/io_component.wasm(a real layer-1 component viawasm32-wasip2+wasm-component-ld);make check-componentruns the full Io suite against it.Object waitparks the calling coroutine with a deadline instead of busy-yielding. Expired timers re-enter the run queue onyield/pause; when nothing is runnable the VM blocks in one host wait until the nearest deadline (Scheduler idleUntilNextTimer) — the exact seam where a WASI 0.3future<T>plugs in later. Two overlapping 1s waits: ~1.1s wall at ~4% CPU (previously 100% CPU spin or serialized sleeps).hasFinishedflag on coroutines (exposed asCoroutine isFinished);pause/yielddrop stale run-queue entries instead of resuming a finished coroutine, which restarted its body.agents/WASI_ASYNC_PLAN.mdwith the 0.3 integration design, VM contracts to preserve, and upgrade triggers (wasmtime ≥ 46, wit-bindgen C async support).Test plan
io_static: 243/243 (238 existing + 5 new inSchedulerTimerTest)🤖 Generated with Claude Code