PHP Async Core RFC

A thin, policy-free concurrency core for PHP. The PHP engine standardizes 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.

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

Documents

Document	What is inside
scheduler_rfc.md	PHP RFC: Concurrency Support in the PHP Engine. The notifications, the granted operations, per-coroutine state and the request lifecycle changes. Start here.
SCHEDULER.md	The C-level interface and the exact engine invocation points, for scheduler implementers.
core-integration.md	Every place the integration touches php-src, file by file.
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.

Implementation

• Proof of concept: php/php-src#22561, branch async-core: the engine capabilities and the lifecycle points.
• Reference C scheduler: ext/test_scheduler, in the same tree.
• Scheduler bridge for PHP: ext-scheduler-hook, a separate extension, not part of the RFC.
• Reference production scheduler: true-async.
• The full stack the core was extracted from: the TrueAsync project.