Struct MessageReader 

pub struct MessageReader { /* private fields */ }

Cancellation-safe backend message reader.

PostgreSQL backend messages span multiple read operations (5-byte header, then a variable payload). A naive implementation using read_exact is not cancellation-safe: if the future is dropped between reads (e.g. by tokio::select! or tokio::time::timeout), bytes already pulled from the underlying stream are lost and the next read mis-parses the wire stream.

MessageReader externalizes the partial-read state so it survives across dropped futures. Each call to read uses one-shot AsyncReadExt::read (which is cancel-safe) and accumulates progress on self. If the returned future is dropped, no bytes are lost; the next invocation resumes from where the previous one left off.

Implementations

impl MessageReader

pub fn new() -> Self

pub fn with_capacity(capacity: usize) -> Self

pub async fn read<R: AsyncRead + Unpin>( &mut self, rd: &mut R, ) -> Result<BackendMessage>

Read the next complete backend message.

Cancellation-safe: dropping the returned future preserves all progress so far on self. Re-call to resume.

Trait Implementations

impl Default for MessageReader

fn default() -> Self

Returns the “default value” for a type.