RecvError

RecvError is an error type in the Rust standard library related to the multi-producer, single-consumer (mpsc) channel API. It represents the situation where a blocking receive operation cannot yield a value because the channel has been closed. In Rust, a channel is closed when all senders have been dropped, after which no new messages will arrive.

A receiver can obtain a RecvError by calling the blocking recv method on the channel’s receiving end. When the channel is closed, subsequent calls to recv return Err(RecvError). The error itself carries no additional information about the channel; it simply signals that no more messages are available.

Handling RecvError typically involves pattern matching on the result of recv and terminating or propagating the error when it occurs. For example, a loop that processes incoming messages would break when Err(RecvError) is encountered, since that indicates the channel has been closed. If you need non-blocking behavior, the try_recv method returns a different error type, TryRecvError, which has variants such as Empty (no data available yet) and Disconnected (the channel is closed).

RecvError is distinct from TryRecvError and is specifically tied to the blocking receive path. It is part of the standard library’s mpsc channel module, and knowledge of its occurrence helps in designing graceful shutdown and channel lifecycle logic in concurrent Rust programs.

See also: Rust standard library, std::sync::mpsc, channel lifecycles, TryRecvError, concurrency patterns.