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//! An asynchronous, pipelined, PostgreSQL client. //! //! # Example //! //! ```no_run //! use futures::{Future, Stream}; //! use tokio_postgres::NoTls; //! //! # #[cfg(not(feature = "runtime"))] //! # let fut = futures::future::ok(()); //! # #[cfg(feature = "runtime")] //! let fut = //! // Connect to the database //! tokio_postgres::connect("host=localhost user=postgres", NoTls) //! //! .map(|(client, connection)| { //! // The connection object performs the actual communication with the database, //! // so spawn it off to run on its own. //! let connection = connection.map_err(|e| eprintln!("connection error: {}", e)); //! tokio::spawn(connection); //! //! // The client is what you use to make requests. //! client //! }) //! //! .and_then(|mut client| { //! // Now we can prepare a simple statement that just returns its parameter. //! client.prepare("SELECT $1::TEXT") //! .map(|statement| (client, statement)) //! }) //! //! .and_then(|(mut client, statement)| { //! // And then execute it, returning a Stream of Rows which we collect into a Vec //! client.query(&statement, &[&"hello world"]).collect() //! }) //! //! // Now we can check that we got back the same string we sent over. //! .map(|rows| { //! let value: &str = rows[0].get(0); //! assert_eq!(value, "hello world"); //! }) //! //! // And report any errors that happened. //! .map_err(|e| { //! eprintln!("error: {}", e); //! }); //! //! // By default, tokio_postgres uses the tokio crate as its runtime. //! tokio::run(fut); //! ``` //! //! # Behavior //! //! Calling a method like `Client::query` on its own does nothing. The associated request is not sent to the database //! until the future returned by the method is first polled. Requests are executed in the order that they are first //! polled, not in the order that their futures are created. //! //! # Pipelining //! //! The client supports *pipelined* requests. Pipelining can improve performance in use cases in which multiple, //! independent queries need to be executed. In a traditional workflow, each query is sent to the server after the //! previous query completes. In contrast, pipelining allows the client to send all of the queries to the server up //! front, minimizing time spent by one side waiting for the other to finish sending data: //! //! ```not_rust //! Sequential Pipelined //! | Client | Server | | Client | Server | //! |----------------|-----------------| |----------------|-----------------| //! | send query 1 | | | send query 1 | | //! | | process query 1 | | send query 2 | process query 1 | //! | receive rows 1 | | | send query 3 | process query 2 | //! | send query 2 | | | receive rows 1 | process query 3 | //! | | process query 2 | | receive rows 2 | | //! | receive rows 2 | | | receive rows 3 | | //! | send query 3 | | //! | | process query 3 | //! | receive rows 3 | | //! ``` //! //! In both cases, the PostgreSQL server is executing the queries sequentially - pipelining just allows both sides of //! the connection to work concurrently when possible. //! //! Pipelining happens automatically when futures are polled concurrently (for example, by using the futures `join` //! combinator): //! //! ```rust //! use futures::Future; //! use tokio_postgres::{Client, Error, Statement}; //! //! fn pipelined_prepare( //! client: &mut Client, //! ) -> impl Future<Item = (Statement, Statement), Error = Error> //! { //! client.prepare("SELECT * FROM foo") //! .join(client.prepare("INSERT INTO bar (id, name) VALUES ($1, $2)")) //! } //! ``` //! //! # Runtime //! //! The client works with arbitrary `AsyncRead + AsyncWrite` streams. Convenience APIs are provided to handle the //! connection process, but these are gated by the `runtime` Cargo feature, which is enabled by default. If disabled, //! all dependence on the tokio runtime is removed. #![doc(html_root_url = "https://docs.rs/tokio-postgres/0.4.0-rc.1")] #![warn(rust_2018_idioms, clippy::all, missing_docs)] use bytes::IntoBuf; use futures::{Future, Poll, Stream}; use std::error::Error as StdError; use std::sync::atomic::{AtomicUsize, Ordering}; use tokio_io::{AsyncRead, AsyncWrite}; pub use crate::config::Config; use crate::error::DbError; pub use crate::error::Error; pub use crate::row::{Row, SimpleQueryRow}; #[cfg(feature = "runtime")] pub use crate::socket::Socket; pub use crate::stmt::Column; #[cfg(feature = "runtime")] use crate::tls::MakeTlsConnect; pub use crate::tls::NoTls; use crate::tls::TlsConnect; use crate::types::{ToSql, Type}; pub mod config; pub mod error; pub mod impls; mod proto; pub mod row; #[cfg(feature = "runtime")] mod socket; mod stmt; pub mod tls; pub mod types; fn next_statement() -> String { static ID: AtomicUsize = AtomicUsize::new(0); format!("s{}", ID.fetch_add(1, Ordering::SeqCst)) } fn next_portal() -> String { static ID: AtomicUsize = AtomicUsize::new(0); format!("p{}", ID.fetch_add(1, Ordering::SeqCst)) } /// A convenience function which parses a connection string and connects to the database. /// /// See the documentation for [`Config`] for details on the connection string format. /// /// Requires the `runtime` Cargo feature (enabled by default). /// /// [`Config`]: ./Config.t.html #[cfg(feature = "runtime")] pub fn connect<T>(config: &str, tls: T) -> impls::Connect<T> where T: MakeTlsConnect<Socket>, { impls::Connect(proto::ConnectFuture::new(tls, config.parse())) } /// An asynchronous PostgreSQL client. /// /// The client is one half of what is returned when a connection is established. Users interact with the database /// through this client object. pub struct Client(proto::Client); impl Client { /// Creates a new prepared statement. /// /// Prepared statements can be executed repeatedly, and may contain query parameters (indicated by `$1`, `$2`, etc), /// which are set when executed. Prepared statements can only be used with the connection that created them. pub fn prepare(&mut self, query: &str) -> impls::Prepare { self.prepare_typed(query, &[]) } /// Like `prepare`, but allows the types of query parameters to be explicitly specified. /// /// The list of types may be smaller than the number of parameters - the types of the remaining parameters will be /// inferred. For example, `client.prepare_typed(query, &[])` is equivalent to `client.prepare(query)`. pub fn prepare_typed(&mut self, query: &str, param_types: &[Type]) -> impls::Prepare { impls::Prepare(self.0.prepare(next_statement(), query, param_types)) } /// Executes a statement, returning the number of rows modified. /// /// If the statement does not modify any rows (e.g. `SELECT`), 0 is returned. /// /// # Panics /// /// Panics if the number of parameters provided does not match the number expected. pub fn execute(&mut self, statement: &Statement, params: &[&dyn ToSql]) -> impls::Execute { impls::Execute(self.0.execute(&statement.0, params)) } /// Executes a statement, returning a stream of the resulting rows. /// /// # Panics /// /// Panics if the number of parameters provided does not match the number expected. pub fn query(&mut self, statement: &Statement, params: &[&dyn ToSql]) -> impls::Query { impls::Query(self.0.query(&statement.0, params)) } /// Binds a statement to a set of parameters, creating a `Portal` which can be incrementally queried. /// /// Portals only last for the duration of the transaction in which they are created - in particular, a portal /// created outside of a transaction is immediately destroyed. Portals can only be used on the connection that /// created them. /// # Panics /// /// Panics if the number of parameters provided does not match the number expected. pub fn bind(&mut self, statement: &Statement, params: &[&dyn ToSql]) -> impls::Bind { impls::Bind(self.0.bind(&statement.0, next_portal(), params)) } /// Continues execution of a portal, returning a stream of the resulting rows. /// /// Unlike `query`, portals can be incrementally evaluated by limiting the number of rows returned in each call to /// query_portal. If the requested number is negative or 0, all rows will be returned. pub fn query_portal(&mut self, portal: &Portal, max_rows: i32) -> impls::QueryPortal { impls::QueryPortal(self.0.query_portal(&portal.0, max_rows)) } /// Executes a `COPY FROM STDIN` statement, returning the number of rows created. /// /// The data in the provided stream is passed along to the server verbatim; it is the caller's responsibility to /// ensure it uses the proper format. pub fn copy_in<S>( &mut self, statement: &Statement, params: &[&dyn ToSql], stream: S, ) -> impls::CopyIn<S> where S: Stream, S::Item: IntoBuf, <S::Item as IntoBuf>::Buf: Send, // FIXME error type? S::Error: Into<Box<dyn StdError + Sync + Send>>, { impls::CopyIn(self.0.copy_in(&statement.0, params, stream)) } /// Executes a `COPY TO STDOUT` statement, returning a stream of the resulting data. pub fn copy_out(&mut self, statement: &Statement, params: &[&dyn ToSql]) -> impls::CopyOut { impls::CopyOut(self.0.copy_out(&statement.0, params)) } /// Executes a sequence of SQL statements using the simple query protocol. /// /// Statements should be separated by semicolons. If an error occurs, execution of the sequence will stop at that /// point. The simple query protocol returns the values in rows as strings rather than in their binary encodings, /// so the associated row type doesn't work with the `FromSql` trait. Rather than simply returning a stream over the /// rows, this method returns a stream over an enum which indicates either the completion of one of the commands, /// or a row of data. This preserves the framing between the separate statements in the request. /// /// # Warning /// /// Prepared statements should be use for any query which contains user-specified data, as they provided the /// functionality to safely imbed that data in the request. Do not form statements via string concatenation and pass /// them to this method! pub fn simple_query(&mut self, query: &str) -> impls::SimpleQuery { impls::SimpleQuery(self.0.simple_query(query)) } /// A utility method to wrap a future in a database transaction. /// /// The returned future will start a transaction and then run the provided future. If the future returns `Ok`, it /// will commit the transaction, and if it returns `Err`, it will roll the transaction back. /// /// This is simply a convenience API; it's roughly equivalent to: /// /// ```ignore /// client.batch_execute("BEGIN") /// .and_then(your_future) /// .and_then(client.batch_execute("COMMIT")) /// .or_else(|e| client.batch_execute("ROLLBACK").then(|_| Err(e))) /// ``` /// /// # Warning /// /// Unlike the other futures created by a client, this future is *not* atomic with respect to other requests. If you /// attempt to execute it concurrently with other futures created by the same connection, they will interleave! pub fn build_transaction(&mut self) -> TransactionBuilder { TransactionBuilder(self.0.clone()) } /// Attempts to cancel an in-progress query. /// /// The server provides no information about whether a cancellation attempt was successful or not. An error will /// only be returned if the client was unable to connect to the database. /// /// Requires the `runtime` Cargo feature (enabled by default). #[cfg(feature = "runtime")] pub fn cancel_query<T>(&mut self, make_tls_mode: T) -> impls::CancelQuery<T> where T: MakeTlsConnect<Socket>, { impls::CancelQuery(self.0.cancel_query(make_tls_mode)) } /// Like `cancel_query`, but uses a stream which is already connected to the server rather than opening a new /// connection itself. pub fn cancel_query_raw<S, T>(&mut self, stream: S, tls_mode: T) -> impls::CancelQueryRaw<S, T> where S: AsyncRead + AsyncWrite, T: TlsConnect<S>, { impls::CancelQueryRaw(self.0.cancel_query_raw(stream, tls_mode)) } /// Determines if the connection to the server has already closed. /// /// In that case, all future queries will fail. pub fn is_closed(&self) -> bool { self.0.is_closed() } /// Polls the client to check if it is idle. /// /// A connection is idle if there are no outstanding requests, whether they have begun being polled or not. For /// example, this can be used by a connection pool to ensure that all work done by one checkout is done before /// making the client available for a new request. Otherwise, any non-completed work from the first request could /// interleave with the second. pub fn poll_idle(&mut self) -> Poll<(), Error> { self.0.poll_idle() } } /// A connection to a PostgreSQL database. /// /// This is one half of what is returned when a new connection is established. It performs the actual IO with the /// server, and should generally be spawned off onto an executor to run in the background. /// /// `Connection` implements `Future`, and only resolves when the connection is closed, either because a fatal error has /// occurred, or because its associated `Client` has dropped and all outstanding work has completed. #[must_use = "futures do nothing unless polled"] pub struct Connection<S, T>(proto::Connection<proto::MaybeTlsStream<S, T>>); impl<S, T> Connection<S, T> where S: AsyncRead + AsyncWrite, T: AsyncRead + AsyncWrite, { /// Returns the value of a runtime parameter for this connection. pub fn parameter(&self, name: &str) -> Option<&str> { self.0.parameter(name) } /// Polls for asynchronous messages from the server. /// /// The server can send notices as well as notifications asynchronously to the client. Applications which wish to /// examine those messages should use this method to drive the connection rather than its `Future` implementation. pub fn poll_message(&mut self) -> Poll<Option<AsyncMessage>, Error> { self.0.poll_message() } } impl<S, T> Future for Connection<S, T> where S: AsyncRead + AsyncWrite, T: AsyncRead + AsyncWrite, { type Item = (); type Error = Error; fn poll(&mut self) -> Poll<(), Error> { self.0.poll() } } /// An asynchronous message from the server. #[allow(clippy::large_enum_variant)] pub enum AsyncMessage { /// A notice. /// /// Notices use the same format as errors, but aren't "errors" per-se. Notice(DbError), /// A notification. /// /// Connections can subscribe to notifications with the `LISTEN` command. Notification(Notification), #[doc(hidden)] __NonExhaustive, } /// A prepared statement. /// /// Prepared statements can only be used with the connection that created them. #[derive(Clone)] pub struct Statement(proto::Statement); impl Statement { /// Returns the expected types of the statement's parameters. pub fn params(&self) -> &[Type] { self.0.params() } /// Returns information about the columns returned when the statement is queried. pub fn columns(&self) -> &[Column] { self.0.columns() } } /// A portal. /// /// Portals can only be used with the connection that created them, and only exist for the duration of the transaction /// in which they were created. pub struct Portal(proto::Portal); /// A builder type which can wrap a future in a database transaction. pub struct TransactionBuilder(proto::Client); impl TransactionBuilder { /// Returns a future which wraps another in a database transaction. pub fn build<T>(self, future: T) -> impls::Transaction<T> where T: Future, // FIXME error type? T::Error: From<Error>, { impls::Transaction(proto::TransactionFuture::new(self.0, future)) } } /// Message returned by the `SimpleQuery` stream. pub enum SimpleQueryMessage { /// A row of data. Row(SimpleQueryRow), /// A statement in the query has completed. /// /// The number of rows modified or selected is returned. CommandComplete(u64), #[doc(hidden)] __NonExhaustive, } /// An asynchronous notification. #[derive(Clone, Debug)] pub struct Notification { process_id: i32, channel: String, payload: String, } impl Notification { /// The process ID of the notifying backend process. pub fn process_id(&self) -> i32 { self.process_id } /// The name of the channel that the notify has been raised on. pub fn channel(&self) -> &str { &self.channel } /// The "payload" string passed from the notifying process. pub fn payload(&self) -> &str { &self.payload } }