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sparkles:event-horizon ​

sparkles:event-horizon is a completion-first event loop for D: io_uring on Linux, kqueue on macOS and the BSDs, IOCP on Windows (in progress), driven in three tiers — a callback loop, direct-style fibers with structured concurrency, and an Effect!T veneer — with process supervision, channels, retry schedules and a bounded pool for the few host calls a completion backend cannot express.

Use it when a program has to wait on many things at once — sockets, files, timers, child processes, signals — and you want that waiting to read as ordinary sequential code, with cancellation, timeouts and cleanup that cannot be forgotten.

d
import sparkles.event_horizon;
import core.time : msecs;

LoopGroup group;
if (LoopGroup.start(group).hasError)
    assert(false, "no completion backend");
scope (exit) group.shutdown();

auto outcome = group.run((ref RootScope sc, ref Env env) {
    cast(void) env.clock.sleep(10.msecs); // parks the fiber, not the thread
    return 42;
});
assert(outcome.value == 42);

How this documentation is organised ​

These docs follow the Diátaxis framework.

Tutorial ​

Learning-oriented.

  • Coming from Node.js — the event loop you already know, mapped concept by concept onto fibers, scopes, channels and supervised processes, with runnable programs for each.
  • Coming from eventcore — proactor drivers, callbacks, and handle ownership mapped to scoped fibers and I/O results.
  • Coming from vibe-core — direct-style fibers and task handles mapped to explicit scope ownership and cancellation.
  • Coming from libasync — comparing callback I/O, file workers, and cross-thread notifications with scoped I/O.
  • Coming from Photon — comparing Photon's syscall interception and fibers with explicit capabilities and scopes.
  • Coming from collie — Netty/Finagle-style channel pipelines and readiness loops compared with completion-first fibers, move-only buffers, and structured concurrency.
  • Coming from hunt-net — Java/Netty/Vert.x-inspired asynchronous networking, codecs, and connection handlers mapped to stream primitives.
  • Coming from EVE — layered backends and runtime facilities mapped to scoped fibers, outcomes, and bounded channels.
  • Running the examples — Linux prerequisites, executable shared examples, partial I/O, error handling, and support boundaries.

Reference ​

Information-oriented. The normative surface lives in the specification for now: SPEC.md (public API in §16) and the delivery status in PLAN.md.

Explanation ​

Understanding-oriented. The research behind the design: Async I/O & Event Loops and Process Supervision.