Struct tokio_reactor::PollEvented
[−]
[src]
pub struct PollEvented<E: Evented> { /* fields omitted */ }
Associates an I/O resource that implements the std::Read
and / or
std::Write
traits with the reactor that drives it.
PollEvented
uses Registration
internally to take a type that
implements mio::Evented
as well as std::Read
and or std::Write
and associate it with a reactor that will drive it.
Once the mio::Evented
type is wrapped by PollEvented
, it can be
used from within the future's execution model. As such, the PollEvented
type provides AsyncRead
and AsyncWrite
implementations using the
underlying I/O resource as well as readiness events provided by the reactor.
Note: While PollEvented
is Sync
(if the underlying I/O type is
Sync
), the caller must ensure that there are at most two tasks that use a
PollEvented
instance concurrently. One for reading and one for writing.
While violating this requirement is "safe" from a Rust memory model point of
view, it will result in unexpected behavior in the form of lost
notifications and tasks hanging.
Readiness events
Besides just providing AsyncRead
and AsyncWrite
implementations,
this type also supports access to the underlying readiness event stream.
While similar in function to what Registration
provides, the semantics
are a bit different.
Two functions are provided to access the readiness events:
poll_read_ready
and poll_write_ready
. These functions return the
current readiness state of the PollEvented
instance. If
poll_read_ready
indicates read readiness, immediately calling
poll_read_ready
again will also indicate read readiness.
When the operation is attempted and is unable to succeed due to the I/O
resource not being ready, the caller must call clear_read_ready
or
[clear_write_ready
]. This clears the readiness state until a new readiness
event is received.
This allows the caller to implement additional functions. For example,
TcpListener
implements poll_accept by using poll_read_ready
and
clear_read_ready
.
pub fn poll_accept(&mut self) -> Poll<(net::TcpStream, SocketAddr), io::Error> { let ready = Ready::readable(); try_ready!(self.poll_evented.poll_read_ready(ready)); match self.poll_evented.get_ref().accept_std() { Ok(pair) => Ok(Async::Ready(pair)), Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => { self.poll_evented.clear_read_ready(ready); Ok(Async::NotReady) } Err(e) => Err(e), } }
Platform-specific events
PollEvented
also allows receiving platform-specific mio::Ready
events.
These events are included as part of the read readiness event stream. The
write readiness event stream is only for Ready::writable()
events.
Methods
impl<E> PollEvented<E> where
E: Evented,
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E: Evented,
ⓘImportant traits for PollEvented<E>pub fn new(io: E) -> PollEvented<E>
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Creates a new PollEvented
associated with the default reactor.
pub fn new_with_handle(io: E, handle: &Handle) -> Result<Self>
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Creates a new PollEvented
associated with the specified reactor.
pub fn get_ref(&self) -> &E
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Returns a shared reference to the underlying I/O object this readiness stream is wrapping.
pub fn get_mut(&mut self) -> &mut E
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Returns a mutable reference to the underlying I/O object this readiness stream is wrapping.
pub fn into_inner(self) -> Result<E>
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Consumes self, returning the inner I/O object
This function will deregister the I/O resource from the reactor before returning. If the deregistration operation fails, an error is returned.
Note that deregistering does not guarantee that the I/O resource can be registered with a different reactor. Some I/O resource types can only be associated with a single reactor instance for their lifetime.
pub fn poll_read_ready(&self, mask: Ready) -> Poll<Ready, Error>
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Check the I/O resource's read readiness state.
The mask argument allows specifying what readiness to notify on. This
can be any value, including platform specific readiness, except
writable
. HUP is always implicitly included on platforms that support
it.
If the resource is not ready for a read then Async::NotReady
is
returned and the current task is notified once a new event is received.
The I/O resource will remain in a read-ready state until readiness is
cleared by calling clear_read_ready
.
Panics
This function panics if:
ready
includes writable.- called from outside of a task context.
pub fn clear_read_ready(&self, ready: Ready) -> Result<()>
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Clears the I/O resource's read readiness state and registers the current task to be notified once a read readiness event is received.
After calling this function, poll_read_ready
will return NotReady
until a new read readiness event has been received.
The mask
argument specifies the readiness bits to clear. This may not
include writable
or hup
.
Panics
This function panics if:
ready
includes writable or HUP- called from outside of a task context.
pub fn poll_write_ready(&self) -> Poll<Ready, Error>
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Check the I/O resource's write readiness state.
This always checks for writable readiness and also checks for HUP readiness on platforms that support it.
If the resource is not ready for a write then Async::NotReady
is
returned and the current task is notified once a new event is received.
The I/O resource will remain in a write-ready state until readiness is
cleared by calling clear_write_ready
.
Panics
This function panics if:
ready
contains bits besideswritable
andhup
.- called from outside of a task context.
pub fn clear_write_ready(&self) -> Result<()>
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Resets the I/O resource's write readiness state and registers the current task to be notified once a write readiness event is received.
This only clears writable readiness. HUP (on platforms that support HUP) cannot be cleared as it is a final state.
After calling this function, poll_write_ready(Ready::writable())
will
return NotReady
until a new write readiness event has been received.
Panics
This function will panic if called from outside of a task context.
Trait Implementations
impl<E> Read for PollEvented<E> where
E: Evented + Read,
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E: Evented + Read,
fn read(&mut self, buf: &mut [u8]) -> Result<usize>
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Pull some bytes from this source into the specified buffer, returning how many bytes were read. Read more
unsafe fn initializer(&self) -> Initializer
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read_initializer
)Determines if this Read
er can work with buffers of uninitialized memory. Read more
fn read_to_end(&mut self, buf: &mut Vec<u8>) -> Result<usize, Error>
1.0.0[src]
Read all bytes until EOF in this source, placing them into buf
. Read more
fn read_to_string(&mut self, buf: &mut String) -> Result<usize, Error>
1.0.0[src]
Read all bytes until EOF in this source, appending them to buf
. Read more
fn read_exact(&mut self, buf: &mut [u8]) -> Result<(), Error>
1.6.0[src]
Read the exact number of bytes required to fill buf
. Read more
fn by_ref(&mut self) -> &mut Self
1.0.0[src]
Creates a "by reference" adaptor for this instance of Read
. Read more
fn bytes(self) -> Bytes<Self>
1.0.0[src]
Transforms this Read
instance to an [Iterator
] over its bytes. Read more
fn chars(self) -> Chars<Self>
[src]
🔬 This is a nightly-only experimental API. (io
)
the semantics of a partial read/write of where errors happen is currently unclear and may change
Transforms this Read
instance to an [Iterator
] over [char
]s. Read more
fn chain<R>(self, next: R) -> Chain<Self, R> where
R: Read,
1.0.0[src]
R: Read,
Creates an adaptor which will chain this stream with another. Read more
fn take(self, limit: u64) -> Take<Self>
1.0.0[src]
Creates an adaptor which will read at most limit
bytes from it. Read more
impl<E> Write for PollEvented<E> where
E: Evented + Write,
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E: Evented + Write,
fn write(&mut self, buf: &[u8]) -> Result<usize>
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Write a buffer into this object, returning how many bytes were written. Read more
fn flush(&mut self) -> Result<()>
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Flush this output stream, ensuring that all intermediately buffered contents reach their destination. Read more
fn write_all(&mut self, buf: &[u8]) -> Result<(), Error>
1.0.0[src]
Attempts to write an entire buffer into this write. Read more
fn write_fmt(&mut self, fmt: Arguments) -> Result<(), Error>
1.0.0[src]
Writes a formatted string into this writer, returning any error encountered. Read more
fn by_ref(&mut self) -> &mut Self
1.0.0[src]
Creates a "by reference" adaptor for this instance of Write
. Read more
impl<E> AsyncRead for PollEvented<E> where
E: Evented + Read,
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E: Evented + Read,
unsafe fn prepare_uninitialized_buffer(&self, buf: &mut [u8]) -> bool
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Prepares an uninitialized buffer to be safe to pass to read
. Returns true
if the supplied buffer was zeroed out. Read more
fn poll_read(&mut self, buf: &mut [u8]) -> Result<Async<usize>, Error>
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Attempt to read from the AsyncRead
into buf
. Read more
fn read_buf<B>(&mut self, buf: &mut B) -> Result<Async<usize>, Error> where
B: BufMut,
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B: BufMut,
Pull some bytes from this source into the specified Buf
, returning how many bytes were read. Read more
fn framed<T>(self, codec: T) -> Framed<Self, T> where
Self: AsyncWrite,
T: Decoder + Encoder,
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Self: AsyncWrite,
T: Decoder + Encoder,
: Use tokio_codec::Decoder::framed instead
Provides a Stream
and Sink
interface for reading and writing to this Io
object, using Decode
and Encode
to read and write the raw data. Read more
fn split(self) -> (ReadHalf<Self>, WriteHalf<Self>) where
Self: AsyncWrite,
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Self: AsyncWrite,
Helper method for splitting this read/write object into two halves. Read more
impl<E> AsyncWrite for PollEvented<E> where
E: Evented + Write,
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E: Evented + Write,
fn shutdown(&mut self) -> Poll<(), Error>
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Initiates or attempts to shut down this writer, returning success when the I/O connection has completely shut down. Read more
fn poll_write(&mut self, buf: &[u8]) -> Result<Async<usize>, Error>
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Attempt to write bytes from buf
into the object. Read more
fn poll_flush(&mut self) -> Result<Async<()>, Error>
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Attempt to flush the object, ensuring that any buffered data reach their destination. Read more
fn write_buf<B>(&mut self, buf: &mut B) -> Result<Async<usize>, Error> where
B: Buf,
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B: Buf,
Write a Buf
into this value, returning how many bytes were written. Read more
impl<'a, E> Read for &'a PollEvented<E> where
E: Evented,
&'a E: Read,
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E: Evented,
&'a E: Read,
fn read(&mut self, buf: &mut [u8]) -> Result<usize>
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Pull some bytes from this source into the specified buffer, returning how many bytes were read. Read more
unsafe fn initializer(&self) -> Initializer
[src]
read_initializer
)Determines if this Read
er can work with buffers of uninitialized memory. Read more
fn read_to_end(&mut self, buf: &mut Vec<u8>) -> Result<usize, Error>
1.0.0[src]
Read all bytes until EOF in this source, placing them into buf
. Read more
fn read_to_string(&mut self, buf: &mut String) -> Result<usize, Error>
1.0.0[src]
Read all bytes until EOF in this source, appending them to buf
. Read more
fn read_exact(&mut self, buf: &mut [u8]) -> Result<(), Error>
1.6.0[src]
Read the exact number of bytes required to fill buf
. Read more
fn by_ref(&mut self) -> &mut Self
1.0.0[src]
Creates a "by reference" adaptor for this instance of Read
. Read more
fn bytes(self) -> Bytes<Self>
1.0.0[src]
Transforms this Read
instance to an [Iterator
] over its bytes. Read more
fn chars(self) -> Chars<Self>
[src]
🔬 This is a nightly-only experimental API. (io
)
the semantics of a partial read/write of where errors happen is currently unclear and may change
Transforms this Read
instance to an [Iterator
] over [char
]s. Read more
fn chain<R>(self, next: R) -> Chain<Self, R> where
R: Read,
1.0.0[src]
R: Read,
Creates an adaptor which will chain this stream with another. Read more
fn take(self, limit: u64) -> Take<Self>
1.0.0[src]
Creates an adaptor which will read at most limit
bytes from it. Read more
impl<'a, E> Write for &'a PollEvented<E> where
E: Evented,
&'a E: Write,
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E: Evented,
&'a E: Write,
fn write(&mut self, buf: &[u8]) -> Result<usize>
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Write a buffer into this object, returning how many bytes were written. Read more
fn flush(&mut self) -> Result<()>
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Flush this output stream, ensuring that all intermediately buffered contents reach their destination. Read more
fn write_all(&mut self, buf: &[u8]) -> Result<(), Error>
1.0.0[src]
Attempts to write an entire buffer into this write. Read more
fn write_fmt(&mut self, fmt: Arguments) -> Result<(), Error>
1.0.0[src]
Writes a formatted string into this writer, returning any error encountered. Read more
fn by_ref(&mut self) -> &mut Self
1.0.0[src]
Creates a "by reference" adaptor for this instance of Write
. Read more
impl<'a, E> AsyncRead for &'a PollEvented<E> where
E: Evented,
&'a E: Read,
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E: Evented,
&'a E: Read,
unsafe fn prepare_uninitialized_buffer(&self, buf: &mut [u8]) -> bool
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Prepares an uninitialized buffer to be safe to pass to read
. Returns true
if the supplied buffer was zeroed out. Read more
fn poll_read(&mut self, buf: &mut [u8]) -> Result<Async<usize>, Error>
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Attempt to read from the AsyncRead
into buf
. Read more
fn read_buf<B>(&mut self, buf: &mut B) -> Result<Async<usize>, Error> where
B: BufMut,
[src]
B: BufMut,
Pull some bytes from this source into the specified Buf
, returning how many bytes were read. Read more
fn framed<T>(self, codec: T) -> Framed<Self, T> where
Self: AsyncWrite,
T: Decoder + Encoder,
[src]
Self: AsyncWrite,
T: Decoder + Encoder,
: Use tokio_codec::Decoder::framed instead
Provides a Stream
and Sink
interface for reading and writing to this Io
object, using Decode
and Encode
to read and write the raw data. Read more
fn split(self) -> (ReadHalf<Self>, WriteHalf<Self>) where
Self: AsyncWrite,
[src]
Self: AsyncWrite,
Helper method for splitting this read/write object into two halves. Read more
impl<'a, E> AsyncWrite for &'a PollEvented<E> where
E: Evented,
&'a E: Write,
[src]
E: Evented,
&'a E: Write,
fn shutdown(&mut self) -> Poll<(), Error>
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Initiates or attempts to shut down this writer, returning success when the I/O connection has completely shut down. Read more
fn poll_write(&mut self, buf: &[u8]) -> Result<Async<usize>, Error>
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Attempt to write bytes from buf
into the object. Read more
fn poll_flush(&mut self) -> Result<Async<()>, Error>
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Attempt to flush the object, ensuring that any buffered data reach their destination. Read more
fn write_buf<B>(&mut self, buf: &mut B) -> Result<Async<usize>, Error> where
B: Buf,
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B: Buf,
Write a Buf
into this value, returning how many bytes were written. Read more
impl<E: Evented + Debug> Debug for PollEvented<E>
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fn fmt(&self, f: &mut Formatter) -> Result
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Formats the value using the given formatter. Read more