zio.blocks.async

Constructors for Async values.

An Async[A] is created with one of succeed, fail, attempt, or promise (a bare A is not itself an Async[A]). The transformation and combination operators (map, flatMap, catchAll, await, ...) become available as extension methods on Async[A] after importing zio.blocks.async._.

A repeatable, round-robin selector for independently pending computations.

Eligibility means that a slot is armed (initially, or by replace) and its computation has completed. Among eligible slots selection scans cyclically from the slot after the previous winner. Consequently a continuously eligible slot wins within at most armedCount successful selections.

The selector registers one stable waker per armed slot, rather than a new loser waker per call to select. A winning slot is disarmed atomically and cannot win twice. shutdown is idempotent and does not finish until cleanup for every still-armed loser has finished.

This object was generated by sbt-buildinfo.

Companion for Cancelable, providing the no-op handle.

Handle returned by Async.start (via Async.Running) that stops a running Async.

Calling cancel() is idempotent and synchronous. It prevents a terminal value from being published if cancellation linearizes before the run reaches completion, and it is a no-op once the run has completed.

When cancellation wins, the driver also signals Pollable.cancel on the active pending operation. A source that can abort an in-flight socket read, timer, or callback registration implements that hook; the default hook is a no-op. Cancellation does not wait for an already-running Pollable.poll invocation to return.

Extends java.lang.AutoCloseable so a Async.Running handle can be used as a managed resource (scala.util.Using, Java try-with-resources): close simply delegates to cancel(). cancel remains the canonical verb — it names the domain operation (stop an in-flight computation) and, unlike AutoCloseable.close, declares no checked exception.

The completion capability handed to an Async.promise block: complete the resulting Async by calling succeed (with a value) or fail (with a cause), typically from an I/O callback.

Thread-safe and '''one-shot''': the first call to succeed or fail wins; all subsequent calls are silent no-ops, regardless of which thread they come from.

Failure outcome of an Async. Constructed via Async.fail (or by Completer.fail, or captured from thrown code by Async.attempt); recovered via the .catchAll / .mapError / .orElse extensions or surfaced as a thrown Throwable by .block.

A failure is terminal: once an Async has failed, it stays failed with the same cause unless a handler such as .catchAll recovers it.

NOTE: errors thrown by user code inside .map(f) / .flatMap(f) are NOT captured — Async is eager, so a throw in f escapes through the call site before any later .catchAll runs. To convert thrown exceptions into a Failure, wrap the work in Async.attempt.

The implementation point for a custom suspended Async leaf (a timer, a socket read, a callback bridge, ...). A Pollable[A] is itself an Async[A], so it can be used wherever an Async[A] is expected.

Implementors define poll: when asked for its value, a pollable either returns the completed result (a value, or a failed Async) or, if it is still pending, stashes the supplied java.lang.Runnable and returns a pending Async (typically itself). When the value later becomes available it must invoke onComplete.run() to ask the scheduler to poll again.

A possibly-suspended computation that will eventually yield an A (or fail with a Throwable). A async.Pollable may be used wherever an Async[A] is expected.

Async is a restricted monad: A must not itself be an Async (nor a async.Pollable). Compose effects with flatMap rather than nesting them as success values; Async[Async[A]] is unsupported.

Complete the surrounding Async.promise block with a failure.

Complete the surrounding Async.promise block with value.

Inverse of when: evaluate fa only when cond is false.

Conditionally evaluate fa. Returns fa.unit when cond is true, Async.succeed(()) otherwise. The unevaluated fa is by-name so it is not constructed when the condition is false.