Struct PgListener 

pub struct PgListener { /* private fields */ }

A stream of asynchronous notifications from Postgres.

This listener will auto-reconnect. If the active connection being used ever dies, this listener will detect that event, create a new connection, will re-subscribe to all of the originally specified channels, and will resume operations as normal.

Implementations

impl PgListener

pub fn connect(uri: &str) -> Result<Self, Error>

pub fn connect_with(pool: &Pool<Postgres>) -> Result<Self, Error>

pub fn listen(&mut self, channel: &str) -> Result<(), Error>

Starts listening for notifications on a channel. The channel name is quoted here to ensure case sensitivity.

pub fn listen_all<'a>( &mut self, channels: impl IntoIterator<Item = &'a str>, ) -> Result<(), Error>

Starts listening for notifications on all channels.

pub fn unlisten(&mut self, channel: &str) -> Result<(), Error>

Stops listening for notifications on a channel. The channel name is quoted here to ensure case sensitivity.

pub fn unlisten_all(&mut self) -> Result<(), Error>

Stops listening for notifications on all channels.

pub fn recv(&mut self) -> Result<PgNotification, Error>

Receives the next notification available from any of the subscribed channels.

If the connection to PostgreSQL is lost, it is automatically reconnected on the next call to recv(), and should be entirely transparent (as long as it was just an intermittent network failure or long-lived connection reaper).

As notifications are transient, any received while the connection was lost, will not be returned. If you’d prefer the reconnection to be explicit and have a chance to do something before, please see try_recv.

Example

loop {
    // ask for next notification, re-connecting (transparently) if needed
    let notification = listener.recv()?;

    // handle notification, do something interesting
}

pub fn try_recv(&mut self) -> Result<Option<PgNotification>, Error>

Receives the next notification available from any of the subscribed channels.

If the connection to PostgreSQL is lost, None is returned, and the connection is reconnected on the next call to try_recv().

Example

loop {
    // start handling notifications, connecting if needed
    while let Some(notification) = listener.try_recv()? {
        // handle notification
    }

    // connection lost, do something interesting
}

pub fn into_stream(self) -> ChanStream<PgNotification>

Consume this listener, returning a Stream of notifications.

The backing connection will be automatically reconnected should it be lost.

This has the same potential drawbacks as recv.

Trait Implementations

impl Debug for PgListener

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Drop for PgListener

fn drop(&mut self)

Executes the destructor for this type.

impl<'c> Executor for &'c mut PgListener

type Database = Postgres

fn fetch_many<'q, E>( &mut self, query: E, ) -> ChanStream<Either<PgQueryResult, PgRow>>

where E: Execute<'q, Self::Database> + 'q,

Execute multiple queries and return the generated results as a stream from each query, in a stream.

fn fetch_optional<'q, E>(&mut self, query: E) -> Result<Option<PgRow>, Error>

where E: Execute<'q, Self::Database> + 'q,

Execute the query and returns at most one row.

fn prepare_with<'q>( &mut self, query: &'q str, parameters: &'q [PgTypeInfo], ) -> Result<PgStatement, Error>

Prepare the SQL query, with parameter type information, to inspect the type information about its parameters and results.

fn execute<'q, E>( &mut self, query: E, ) -> Result<<Self::Database as Database>::QueryResult, Error>

where E: 'q + Execute<'q, Self::Database>,

Execute the query and return the total number of rows affected.

fn execute_many<'q, E>( &mut self, query: E, ) -> ChanStream<<Self::Database as Database>::QueryResult>

where E: 'q + Execute<'q, Self::Database>,

Execute multiple queries and return the rows affected from each query, in a stream.

fn fetch<'q, E>( &mut self, query: E, ) -> ChanStream<<Self::Database as Database>::Row>

where E: 'q + Execute<'q, Self::Database>,

Execute the query and return the generated results as a stream.

fn fetch_all<'q, E>( &mut self, query: E, ) -> Result<Vec<<Self::Database as Database>::Row>, Error>

where E: 'q + Execute<'q, Self::Database>,

Execute the query and return all the generated results, collected into a Vec.

fn fetch_one<'q, E>( &mut self, query: E, ) -> Result<<Self::Database as Database>::Row, Error>

where E: 'q + Execute<'q, Self::Database>,

Execute the query and returns exactly one row.

fn prepare<'q>( &mut self, query: &'q str, ) -> Result<<Self::Database as HasStatement>::Statement, Error>

Prepare the SQL query to inspect the type information of its parameters and results.