gio::prelude

Trait PollableOutputStreamExt

Source 
pub trait PollableOutputStreamExt:
    IsA<PollableOutputStream>
    + Sealed
    + 'static {
    // Provided 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

Provided Methods§

Source

fn can_poll(&self) -> bool

Checks if @self is actually pollable. Some classes may implement #GPollableOutputStream but have only certain instances of that class be pollable. If this method returns false, then the behavior of other #GPollableOutputStream 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

true if @self is pollable, false if not.

Source

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 g_output_stream_write() after this returns true would still block. To guarantee non-blocking behavior, you should always use g_pollable_output_stream_write_nonblocking(), which will return a IOErrorEnum::WouldBlock error rather than blocking.

The behaviour of this method is undefined if g_pollable_output_stream_can_poll() returns false for @self.

§Returns

true if @self is writable, false if not. If an error has occurred on @self, this will result in g_pollable_output_stream_is_writable() returning true, and the next attempt to write will return the error.

Source

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 g_output_stream_write(). If @self is not currently writable, this will immediately return IOErrorEnum::WouldBlock, and you can use g_pollable_output_stream_create_source() to create a #GSource 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.

The behaviour of this method is undefined if g_pollable_output_stream_can_poll() returns false for @self.

§buffer

a buffer to write data from

§cancellable

a #GCancellable, or None

§Returns

the number of bytes written, or -1 on error (including IOErrorEnum::WouldBlock).

Dyn Compatibility§

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors§