# h2::client::Connection - Rust
API documentation for the Rust `Connection` struct in crate `h2`.
Keywords: rust, rustlang, rust-lang, Connection

# Struct h2::client::Connection [−] [src]

    #[must_use = "futures do nothing unless polled"]pub struct Connection<T, B: Buf = Bytes> { /* fields omitted */ }

Manages all state associated with an HTTP/2.0 client connection.

A `Connection` is backed by an I/O resource (usually a TCP socket) and implements the HTTP/2.0 client logic for that connection. It is responsible for driving the internal state forward, performing the work requested of the associated handles (`SendRequest`, `ResponseFuture`, `SendStream`, `RecvStream`).

`Connection` values are created by calling `handshake`. Once a `Connection` value is obtained, the caller must repeatedly call `poll` until `Ready` is returned. The easiest way to do this is to submit the `Connection` instance to an executor.

# Examples

        let (send_request, connection) = client::handshake(my_io).await?;
        // Submit the connection handle to an executor.
        tokio::spawn(async { connection.await.expect("connection failed"); });

        // Now, use `send_request` to initialize HTTP/2.0 streams.
        // ...

## Implementations

### `impl<T, B> Connection<T, B> where
T: AsyncRead + AsyncWrite + Unpin,
B: Buf + 'static,` [src]

#### `pub fn set_target_window_size(&mut self, size: u32)` [src]

Sets the target window size for the whole connection.

If `size` is greater than the current value, then a `WINDOW_UPDATE` frame will be immediately sent to the remote, increasing the connection level window by `size - current_value`.

If `size` is less than the current value, nothing will happen immediately. However, as window capacity is released by `FlowControl` instances, no `WINDOW_UPDATE` frames will be sent out until the number of "in flight" bytes drops below `size`.

The default value is 65,535.

See `FlowControl` documentation for more details.

#### `pub fn set_initial_window_size(&mut self, size: u32) -> Result<(), Error>` [src]

Set a new `INITIAL_WINDOW_SIZE` setting (in octets) for stream-level flow control for received data.

The `SETTINGS` will be sent to the remote, and only applied once the remote acknowledges the change.

This can be used to increase or decrease the window size for existing streams.

# Errors

Returns an error if a previous call is still pending acknowledgement from the remote endpoint.

#### `pub fn ping_pong(&mut self) -> Option<PingPong>` [src]

Takes a `PingPong` instance from the connection.

# Note

This may only be called once. Calling multiple times will return `None`.

#### `pub fn max_concurrent_send_streams(&self) -> usize` [src]

Returns the maximum number of concurrent streams that may be initiated by this client.

This limit is configured by the server peer by sending the [`SETTINGS_MAX_CONCURRENT_STREAMS` parameter][1] in a `SETTINGS` frame. This method returns the currently acknowledged value recieved from the remote.

#### `pub fn max_concurrent_recv_streams(&self) -> usize` [src]

Returns the maximum number of concurrent streams that may be initiated by the server on this connection.

This returns the value of the `SETTINGS_MAX_CONCURRENT_STREAMS` parameter sent in a `SETTINGS` frame that has been acknowledged by the remote peer. The value to be sent is configured by the `Builder::max_concurrent_streams` method before handshaking with the remote peer.

## Trait Implementations

### `impl<T, B> Debug for Connection<T, B> where
T: AsyncRead + AsyncWrite,
T: Debug,
B: Debug + Buf,` [src]

#### `fn fmt(&self, fmt: &mut Formatter<'_>) -> Result` [src]

Formats the value using the given formatter. Read more

### `impl<T, B> Future for Connection<T, B> where
T: AsyncRead + AsyncWrite + Unpin,
B: Buf + 'static,` [src]

#### `type Output = Result<(), Error>`

The type of value produced on completion.

#### `fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output>` [src]

Attempt to resolve the future to a final value, registering the current task for wakeup if the value is not yet available. Read more

## Auto Trait Implementations

### `impl<T, B = Bytes> !RefUnwindSafe for Connection<T, B>` [src]

### `impl<T, B> Send for Connection<T, B> where
B: Send,
T: Send,` [src]

### `impl<T, B> Sync for Connection<T, B> where
B: Send + Sync,
T: Sync,` [src]

### `impl<T, B> Unpin for Connection<T, B> where
T: Unpin,` [src]

### `impl<T, B = Bytes> !UnwindSafe for Connection<T, B>` [src]

## Blanket Implementations

### `impl<T> Any for T where
T: 'static + ?Sized,` [src]

#### `pub fn type_id(&self) -> TypeId` [src]

Gets the `TypeId` of `self`. Read more

### `impl<T> Borrow<T> for T where
T: ?Sized,` [src]

#### `pub fn borrow(&self) -> &T` [src]

Immutably borrows from an owned value. Read more

### `impl<T> BorrowMut<T> for T where
T: ?Sized,` [src]

#### `pub fn borrow_mut(&mut self) -> &mut T` [src]

Mutably borrows from an owned value. Read more

### `impl<T> From<T> for T` [src]

#### `pub fn from(t: T) -> T` [src]

Performs the conversion.

### `impl<T> FutureExt for T where
T: Future + ?Sized,` [src]

#### `pub fn map<U, F>(self, f: F) -> Map<Self, F> where
F: FnOnce(Self::Output) -> U,` [src]

Map this future's output to a different type, returning a new future of the resulting type. Read more

#### `pub fn map_into<U>(self) -> MapInto<Self, U> where
Self::Output: Into<U>,` [src]

Map this future's output to a different type, returning a new future of the resulting type. Read more

#### `pub fn then<Fut, F>(self, f: F) -> Then<Self, Fut, F> where
F: FnOnce(Self::Output) -> Fut,
Fut: Future,` [src]

Chain on a computation for when a future finished, passing the result of the future to the provided closure `f`. Read more

#### `pub fn left_future<B>(self) -> Either<Self, B> where
B: Future<Output = Self::Output>,` [src]

Wrap this future in an `Either` future, making it the left-hand variant of that `Either`. Read more

#### `pub fn right_future<A>(self) -> Either<A, Self> where
A: Future<Output = Self::Output>,` [src]

Wrap this future in an `Either` future, making it the right-hand variant of that `Either`. Read more

#### `pub fn into_stream(self) -> IntoStream<Self>` [src]

Convert this future into a single element stream. Read more

#### `pub fn flatten(self) -> Flatten<Self> where
Self::Output: Future,` [src]

Flatten the execution of this future when the output of this future is itself another future. Read more

#### `pub fn flatten_stream(self) -> FlattenStream<Self> where
Self::Output: Stream,` [src]

Flatten the execution of this future when the successful result of this future is a stream. Read more

#### `pub fn fuse(self) -> Fuse<Self>` [src]

Fuse a future such that `poll` will never again be called once it has completed. This method can be used to turn any `Future` into a `FusedFuture`. Read more

#### `pub fn inspect<F>(self, f: F) -> Inspect<Self, F> where
F: FnOnce(&Self::Output),` [src]

Do something with the output of a future before passing it on. Read more

#### `pub fn unit_error(self) -> UnitError<Self>` [src]

Turns a `Future<Output = T>` into a `TryFuture<Ok = T, Error = ()`>. Read more

#### `pub fn never_error(self) -> NeverError<Self>` [src]

Turns a `Future<Output = T>` into a `TryFuture<Ok = T, Error = Never`>. Read more

#### `pub fn poll_unpin(&mut self, cx: &mut Context<'_>) -> Poll<Self::Output> where
Self: Unpin,` [src]

A convenience for calling `Future::poll` on `Unpin` future types.

#### `pub fn now_or_never(self) -> Option<Self::Output>` [src]

Evaluates and consumes the future, returning the resulting output if the future is ready after the first call to `Future::poll`. Read more

### `impl<T> Instrument for T` [src]

#### `pub fn instrument(self, span: Span) -> Instrumented<Self>` [src]

Instruments this type with the provided `Span`, returning an `Instrumented` wrapper. Read more

#### `pub fn in_current_span(self) -> Instrumented<Self>` [src]

Instruments this type with the current `Span`, returning an `Instrumented` wrapper. Read more

### `impl<T, U> Into<U> for T where
U: From<T>,` [src]

#### `pub fn into(self) -> U` [src]

Performs the conversion.

### `impl<F> IntoFuture for F where
F: Future,` [src]

#### `type Output = <F as Future>::Output`

🔬 This is a nightly-only experimental API. (`into_future`)

The output that the future will produce on completion.

#### `type Future = F`

🔬 This is a nightly-only experimental API. (`into_future`)

Which kind of future are we turning this into?

#### `pub fn into_future(self) -> <F as IntoFuture>::Future` [src]

🔬 This is a nightly-only experimental API. (`into_future`)

Creates a future from a value.

### `impl<T, U> TryFrom<U> for T where
U: Into<T>,` [src]

#### `type Error = Infallible`

The type returned in the event of a conversion error.

#### `pub fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>` [src]

Performs the conversion.

### `impl<F, T, E> TryFuture for F where
F: Future<Output = Result<T, E>> + ?Sized,` [src]

#### `type Ok = T`

The type of successful values yielded by this future

#### `type Error = E`

The type of failures yielded by this future

#### `pub fn try_poll(
self: Pin<&mut F>,
cx: &mut Context<'_>
) -> Poll<<F as Future>::Output>` [src]

Poll this `TryFuture` as if it were a `Future`. Read more

### `impl<Fut> TryFutureExt for Fut where
Fut: TryFuture + ?Sized,` [src]

#### `pub fn map_ok<T, F>(self, f: F) -> MapOk<Self, F> where
F: FnOnce(Self::Ok) -> T,` [src]

Maps this future's success value to a different value. Read more

#### `pub fn map_ok_or_else<T, E, F>(self, e: E, f: F) -> MapOkOrElse<Self, F, E> where
E: FnOnce(Self::Error) -> T,
F: FnOnce(Self::Ok) -> T,` [src]

Maps this future's success value to a different value, and permits for error handling resulting in the same type. Read more

#### `pub fn map_err<E, F>(self, f: F) -> MapErr<Self, F> where
F: FnOnce(Self::Error) -> E,` [src]

Maps this future's error value to a different value. Read more

#### `pub fn err_into<E>(self) -> ErrInto<Self, E> where
Self::Error: Into<E>,` [src]

Maps this future's `Error` to a new error type using the `Into` trait. Read more

#### `pub fn ok_into<U>(self) -> OkInto<Self, U> where
Self::Ok: Into<U>,` [src]

Maps this future's `Ok` to a new type using the `Into` trait. Read more

#### `pub fn and_then<Fut, F>(self, f: F) -> AndThen<Self, Fut, F> where
F: FnOnce(Self::Ok) -> Fut,
Fut: TryFuture<Error = Self::Error>,` [src]

Executes another future after this one resolves successfully. The success value is passed to a closure to create this subsequent future. Read more

#### `pub fn or_else<Fut, F>(self, f: F) -> OrElse<Self, Fut, F> where
F: FnOnce(Self::Error) -> Fut,
Fut: TryFuture<Ok = Self::Ok>,` [src]

Executes another future if this one resolves to an error. The error value is passed to a closure to create this subsequent future. Read more

#### `pub fn inspect_ok<F>(self, f: F) -> InspectOk<Self, F> where
F: FnOnce(&Self::Ok),` [src]

Do something with the success value of a future before passing it on. Read more

#### `pub fn inspect_err<F>(self, f: F) -> InspectErr<Self, F> where
F: FnOnce(&Self::Error),` [src]

Do something with the error value of a future before passing it on. Read more

#### `pub fn try_flatten(self) -> TryFlatten<Self, Self::Ok> where
Self::Ok: TryFuture,
<Self::Ok as TryFuture>::Error == Self::Error,` [src]

Flatten the execution of this future when the successful result of this future is another future. Read more

#### `pub fn try_flatten_stream(self) -> TryFlattenStream<Self> where
Self::Ok: TryStream,
<Self::Ok as TryStream>::Error == Self::Error,` [src]

Flatten the execution of this future when the successful result of this future is a stream. Read more

#### `pub fn unwrap_or_else<F>(self, f: F) -> UnwrapOrElse<Self, F> where
F: FnOnce(Self::Error) -> Self::Ok,` [src]

Unwraps this future's output, producing a future with this future's `Ok` type as its `Output` type. Read more

#### `pub fn into_future(self) -> IntoFuture<Self>` [src]

Wraps a `TryFuture` into a type that implements `Future`. Read more

#### `pub fn try_poll_unpin(
&mut self,
cx: &mut Context<'_>
) -> Poll<Result<Self::Ok, Self::Error>> where
Self: Unpin,` [src]

A convenience method for calling `TryFuture::try_poll` on `Unpin` future types. Read more

### `impl<T, U> TryInto<U> for T where
U: TryFrom<T>,` [src]

#### `type Error = <U as TryFrom<T>>::Error`

The type returned in the event of a conversion error.

#### `pub fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>` [src]

Performs the conversion.