Trait gio::prelude::PollableOutputStreamExt
source · pub trait PollableOutputStreamExt: 'static {
// Required methods
fn can_poll(&self) -> bool;
fn is_writable(&self) -> bool;
fn write_nonblocking(
&self,
buffer: &[u8],
cancellable: Option<&impl IsA<Cancellable>>
) -> Result<isize, Error>;
}
Expand description
Trait containing all PollableOutputStream
methods.
Implementors
ConverterOutputStream
, MemoryOutputStream
, PollableOutputStream
, UnixOutputStream
Required Methods§
sourcefn can_poll(&self) -> bool
fn can_poll(&self) -> bool
Checks if self
is actually pollable. Some classes may implement
PollableOutputStream
but have only certain instances of that
class be pollable. If this method returns false
, then the behavior
of other PollableOutputStream
methods is undefined.
For any given stream, the value returned by this method is constant; a stream cannot switch from pollable to non-pollable or vice versa.
Returns
sourcefn is_writable(&self) -> bool
fn is_writable(&self) -> bool
Checks if self
can be written.
Note that some stream types may not be able to implement this 100%
reliably, and it is possible that a call to OutputStreamExt::write()
after this returns true
would still block. To guarantee
non-blocking behavior, you should always use
write_nonblocking()
, which will return a
IOErrorEnum::WouldBlock
error rather than blocking.
Returns
true
if self
is writable, false
if not. If an error
has occurred on self
, this will result in
is_writable()
returning true
, and the
next attempt to write will return the error.
sourcefn write_nonblocking(
&self,
buffer: &[u8],
cancellable: Option<&impl IsA<Cancellable>>
) -> Result<isize, Error>
fn write_nonblocking( &self, buffer: &[u8], cancellable: Option<&impl IsA<Cancellable>> ) -> Result<isize, Error>
Attempts to write up to count
bytes from buffer
to self
, as
with OutputStreamExt::write()
. If self
is not currently writable,
this will immediately return IOErrorEnum::WouldBlock
, and you can
use PollableOutputStreamExtManual::create_source()
to create a glib::Source
that will be triggered when self
is writable.
Note that since this method never blocks, you cannot actually
use cancellable
to cancel it. However, it will return an error
if cancellable
has already been cancelled when you call, which
may happen if you call this method after a source triggers due
to having been cancelled.
Also note that if IOErrorEnum::WouldBlock
is returned some underlying
transports like D/TLS require that you re-send the same buffer
and
count
in the next write call.
buffer
a buffer to write data from
cancellable
a Cancellable
, or None
Returns
the number of bytes written, or -1 on error (including
IOErrorEnum::WouldBlock
).