PHP Async Core RFC

A thin, policy-free concurrency core for PHP. The PHP engine standardises one thing: how a scheduler is activated and which component is in charge. Everything user-facing (coroutine classes, spawn()/await(), channels, event loops) stays with the scheduler and the ecosystem.

// The whole activation surface: one call.
Async\SchedulerHook::register('my-scheduler', new MyScheduler());

With no scheduler registered, PHP behaves exactly as it does today.

Documents

Document	What is inside
scheduler_rfc.md	The RFC: Async Scheduler Hook API. The activation contract, the hook set, a minimal scheduler, worked examples. Start here.
SCHEDULER.md	The exact engine invocation points, for scheduler implementers.
scheduler_rfc_examples.md	Worked examples with real code: per-coroutine contexts (ob_start(), gethostbyname()) and the microtask-driven concurrent iterator.
reactor.md	Reactor C interface, a discussion draft: a callback-first io_* API (poll, streaming IO, timers, filesystem, DNS) and how it feeds the scheduler. Not an RFC.
example/	Runnable schedulers: the same cooperative scheduler on plain Fibers and on Continuations.

Implementation

• Proof of concept: php/php-src#22561, branch async-core: the core, the engine invocation points, the PHP registration bridge and its tests.
• Reference C scheduler: the TrueAsync extension.
• The full stack the core was extracted from: the TrueAsync project.