`(sigil async core)`

Cooperative scheduling and external waits. Host I/O, timers and signals are installed by (sigil async).

Exports

make-schedulerprocedure

Create a new scheduler.

scheduler-spawnprocedure

Add a new task to the scheduler.

scheduler-runprocedure

Run all scheduler tasks until completion or deadlock.

*current-scheduler* is restored on EVERY exit — the normal return branches AND the exception path when a task raises uncaught and the error unwinds through scheduler-run. Restoring only on the normal branches (the historical bug) leaked the scheduler during unwinding, which is the precondition that let an async-port write (e.g. a logger in a dynamic-wind cleanup, or an outer exception handler) attempt to abort-to-prompt with no live prompt — the async-port logging-recursion class.

We use a guard (catch → restore → re-raise), NOT dynamic-wind: a dynamic-wind after-thunk is silently SKIPPED when an exception unwinds through the call-with-prompt that run-task installs around each task body (a VM unwind quirk — guard, being an exception handler, still fires across the prompt). Task yields use abort-to-prompt to that per-task prompt installed BELOW this frame, so they never reach this guard; only a genuinely uncaught task exception does.

yieldprocedure

Yield control to the scheduler.

Allows other tasks to run before continuing.

in-async-context?procedure

Check if currently running in an async context.

Returns #t if running inside with-async, #f otherwise. Useful for writing code that behaves differently in sync vs async contexts.

(if (in-async-context?)
    (display "running async\n")
    (display "running sync\n"))

current-schedulervariable

(No description)

scheduler?variable

(No description)

with-asyncvariable

(No description)

%run-asyncvariable

(No description)

resume-asyncvariable

(No description)

govariable

(No description)

%go-spawnvariable

(No description)

when-asyncvariable

(No description)

if-asyncvariable

(No description)

await-externalvariable

(No description)

scheduler-task-countvariable

(No description)

scheduler-blocked-countvariable

(No description)

async-prompt-tagvariable

(No description)

scheduler-enqueue!variable

(No description)

scheduler-dec-blocked!variable

(No description)

%async-has-io-waiters?variable

(No description)

%async-has-fd-waiters?variable

(No description)

%async-has-timer-waiters?variable

(No description)

%async-has-external-waiters?variable

(No description)

%async-scheduler-empty?variable

(No description)

%async-process-external-waiters!variable

(No description)

%async-install-poll-service!variable

(No description)

%async-install-external-service!variable

(No description)

%async-install-timer-service!variable

(No description)

%async-install-signal-service!variable

(No description)

%async-service-signals!variable

(No description)