| Copyright | Will Thompson Iñaki García Etxebarria and Jonas Platte |
|---|---|
| License | LGPL-2.1 |
| Maintainer | Iñaki García Etxebarria (garetxe@gmail.com) |
| Safe Haskell | None |
| Language | Haskell2010 |
GI.Gio.Interfaces.PollableOutputStream
Description
PollableOutputStream is implemented by GOutputStreams that
can be polled for readiness to write. This can be used when
interfacing with a non-GIO API that expects
UNIX-file-descriptor-style asynchronous I/O rather than GIO-style.
Since: 2.28
Synopsis
- newtype PollableOutputStream = PollableOutputStream (ManagedPtr PollableOutputStream)
- noPollableOutputStream :: Maybe PollableOutputStream
- class GObject o => IsPollableOutputStream o
- toPollableOutputStream :: (MonadIO m, IsPollableOutputStream o) => o -> m PollableOutputStream
- pollableOutputStreamCanPoll :: (HasCallStack, MonadIO m, IsPollableOutputStream a) => a -> m Bool
- pollableOutputStreamCreateSource :: (HasCallStack, MonadIO m, IsPollableOutputStream a, IsCancellable b) => a -> Maybe b -> m Source
- pollableOutputStreamIsWritable :: (HasCallStack, MonadIO m, IsPollableOutputStream a) => a -> m Bool
- pollableOutputStreamWriteNonblocking :: (HasCallStack, MonadIO m, IsPollableOutputStream a, IsCancellable b) => a -> Maybe ByteString -> Maybe b -> m Int64
Exported types
newtype PollableOutputStream Source #
Memory-managed wrapper type.
Constructors
| PollableOutputStream (ManagedPtr PollableOutputStream) |
Instances
noPollableOutputStream :: Maybe PollableOutputStream Source #
A convenience alias for Nothing :: Maybe PollableOutputStream.
class GObject o => IsPollableOutputStream o Source #
Type class for types which can be safely cast to PollableOutputStream, for instance with toPollableOutputStream.
Instances
toPollableOutputStream :: (MonadIO m, IsPollableOutputStream o) => o -> m PollableOutputStream Source #
Cast to PollableOutputStream, for types for which this is known to be safe. For general casts, use castTo.
Methods
canPoll
pollableOutputStreamCanPoll Source #
Arguments
| :: (HasCallStack, MonadIO m, IsPollableOutputStream a) | |
| => a |
|
| -> m Bool |
Checks if stream 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.
Since: 2.28
createSource
pollableOutputStreamCreateSource Source #
Arguments
| :: (HasCallStack, MonadIO m, IsPollableOutputStream a, IsCancellable b) | |
| => a |
|
| -> Maybe b |
|
| -> m Source | Returns: a new |
Creates a Source that triggers when stream can be written, or
cancellable is triggered or an error occurs. The callback on the
source is of the PollableSourceFunc type.
As with pollableOutputStreamIsWritable, it is possible that
the stream may not actually be writable even after the source
triggers, so you should use pollableOutputStreamWriteNonblocking
rather than outputStreamWrite from the callback.
Since: 2.28
isWritable
pollableOutputStreamIsWritable Source #
Arguments
| :: (HasCallStack, MonadIO m, IsPollableOutputStream a) | |
| => a |
|
| -> m Bool | Returns: |
Checks if stream 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 outputStreamWrite
after this returns True would still block. To guarantee
non-blocking behavior, you should always use
pollableOutputStreamWriteNonblocking, which will return a
IOErrorEnumWouldBlock error rather than blocking.
Since: 2.28
writeNonblocking
pollableOutputStreamWriteNonblocking Source #
Arguments
| :: (HasCallStack, MonadIO m, IsPollableOutputStream a, IsCancellable b) | |
| => a |
|
| -> Maybe ByteString |
|
| -> Maybe b |
|
| -> m Int64 | Returns: the number of bytes written, or -1 on error (including
|
Attempts to write up to count bytes from buffer to stream, as
with outputStreamWrite. If stream is not currently writable,
this will immediately return IOErrorEnumWouldBlock, and you can
use pollableOutputStreamCreateSource to create a Source
that will be triggered when stream 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 IOErrorEnumWouldBlock is returned some underlying
transports like D/TLS require that you send the same buffer and count.