Struct PqsClient 

pub struct PqsClient { /* private fields */ }

A read client for a PQS database.

Cloning is cheap and clones share the connection, which pipelines concurrent queries — so pooling is the application’s decision rather than this crate’s, as telemetry is.

Implementations

impl PqsClient

pub async fn connect(config: &str) -> Result<Self>

Connect without TLS.

config is a libpq connection string — host=… user=… password=… dbname=… — or a postgres:// URL. The connection is driven on a spawned task; dropping every clone of the client ends it.

Errors

Error::Connection if the store cannot be reached, and Error::InvalidRequest if it refuses the connection for a reason waiting will not change — a wrong password, an unknown database.

pub async fn connect_with_timeout( config: &str, timeout: Duration, ) -> Result<Self>

connect with an explicit deadline for the attempt, which also becomes the per-query timeout.

Errors

As connect, plus Error::Timeout if the store did not answer within timeout.

pub async fn connect_tls(config: &str) -> Result<Self>

Available on crate feature tls only.

Connect over TLS, with the platform’s root certificates.

Errors

Error::Connection if the store cannot be reached, and Error::InvalidRequest if no root certificates can be loaded, if the certificate cannot be verified, or if the store refuses the connection for a reason waiting will not change.

pub async fn connect_tls_with_timeout( config: &str, timeout: Duration, ) -> Result<Self>

Available on crate feature tls only.

connect_tls with an explicit deadline for the attempt, which also becomes the per-query timeout.

TLS is required, not preferred: a store that answers the TLS request with “no” is an error here, never a silent plaintext session. tokio-postgres’s own default is sslmode=prefer, which is exactly that silent fallback, and a connection string carrying sslmode=disable would otherwise turn this method into connect.

Errors

As connect_tls, plus Error::Timeout if the store did not answer within timeout.

pub fn with_timeout(self, timeout: Duration) -> Self

Change the deadline for every query (and reconnect) on this client and its clones. The default is DEFAULT_TIMEOUT.

pub async fn run<T>(&self, query: &Query<T>) -> Result<Vec<Contract<T>>>

where T: ContractType + DeserializeOwned,

Run a query and decode every row.

Errors

Error::Connection if the query fails, or a decoding error if a row does not match T.

pub async fn active<T>(&self) -> Result<Vec<Contract<T>>>

where T: ContractType + DeserializeOwned,

The active contracts of a template, unfiltered.

Errors

As run.

pub async fn lookup<T>(&self, contract_id: &str) -> Result<Option<Contract<T>>>

where T: ContractType + DeserializeOwned,

One contract by id, or None if PQS does not have it.

Reads lookup_contract, which finds a contract whether it is active or archived — unlike a filter on active().

Errors

As run.

pub async fn exercises<T, C>( &self, from: Option<i64>, to: Option<i64>, ) -> Result<Vec<Exercise<C>>>

where T: ContractType, C: Choice<T> + DeserializeOwned,

The exercises of one choice, in a range of offsets.

The choice’s name is taken from the type, as a template’s qname is.

Errors

As run.

pub async fn latest_offset(&self) -> Result<i64>

The latest offset PQS has ingested.

What a caller reads to know how far behind the store is, and what to pass to Query::active_at for a stable read.

Errors

As run.

pub async fn query(&self, sql: &Sql) -> Result<Vec<Row>>

Run a compiled statement.

Errors

Error::Connection if the query fails.

Trait Implementations

impl Clone for PqsClient

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for PqsClient

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

Formats the value using the given formatter.