GI.Gio.Interfaces.PollableOutputStream

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

Exported types

newtype PollableOutputStream

Memory-managed wrapper type.

Constructors

PollableOutputStream (ManagedPtr PollableOutputStream)

Instances

Eq PollableOutputStream

Defined in GI.Gio.Interfaces.PollableOutputStream

Methods

(==) :: PollableOutputStream -> PollableOutputStream -> Bool

(/=) :: PollableOutputStream -> PollableOutputStream -> Bool

IsGValue PollableOutputStream

Convert PollableOutputStream to and from GValue with toGValue and fromGValue.

Defined in GI.Gio.Interfaces.PollableOutputStream

Methods

toGValue :: PollableOutputStream -> IO GValue

fromGValue :: GValue -> IO PollableOutputStream

ManagedPtrNewtype PollableOutputStream

Defined in GI.Gio.Interfaces.PollableOutputStream

Methods

toManagedPtr :: PollableOutputStream -> ManagedPtr PollableOutputStream

TypedObject PollableOutputStream

Defined in GI.Gio.Interfaces.PollableOutputStream

Methods

glibType :: IO GType

GObject PollableOutputStream

Defined in GI.Gio.Interfaces.PollableOutputStream

HasParentTypes PollableOutputStream

Defined in GI.Gio.Interfaces.PollableOutputStream

type ParentTypes PollableOutputStream

Defined in GI.Gio.Interfaces.PollableOutputStream

type ParentTypes PollableOutputStream = '[OutputStream, Object]

class (GObject o, IsDescendantOf PollableOutputStream o) => IsPollableOutputStream o

Type class for types which can be safely cast to PollableOutputStream, for instance with toPollableOutputStream.

Instances

(GObject o, IsDescendantOf PollableOutputStream o) => IsPollableOutputStream o

Defined in GI.Gio.Interfaces.PollableOutputStream

toPollableOutputStream :: (MonadIO m, IsPollableOutputStream o) => o -> m PollableOutputStream

Cast to PollableOutputStream, for types for which this is known to be safe. For general casts, use castTo.

Methods

Overloaded methods

canPoll

pollableOutputStreamCanPoll

Arguments

:: (HasCallStack, MonadIO m, IsPollableOutputStream a)

=> a

stream: a PollableOutputStream.

-> m Bool

Returns: True if stream is pollable, False if not.

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

Arguments

:: (HasCallStack, MonadIO m, IsPollableOutputStream a, IsCancellable b)

=> a

stream: a PollableOutputStream.

-> Maybe b

cancellable: a Cancellable, or Nothing

-> m Source

Returns: a new Source

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

Arguments

:: (HasCallStack, MonadIO m, IsPollableOutputStream a)

=> a

stream: a PollableOutputStream.

-> m Bool

Returns: True if stream is writable, False if not. If an error has occurred on stream, this will result in pollableOutputStreamIsWritable returning True, and the next attempt to write will return the error.

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

Arguments

:: (HasCallStack, MonadIO m, IsPollableOutputStream a, IsCancellable b)

=> a

stream: a PollableOutputStream

-> Maybe ByteString

buffer: a buffer to write data from

-> Maybe b

cancellable: a Cancellable, or Nothing

-> m Int64

Returns: the number of bytes written, or -1 on error (including IOErrorEnumWouldBlock). (Can throw GError)

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 re-send the same buffer and count in the next write call.

writevNonblocking

pollableOutputStreamWritevNonblocking

Arguments

:: (HasCallStack, MonadIO m, IsPollableOutputStream a, IsCancellable b)

=> a

stream: a PollableOutputStream

-> [OutputVector]

vectors: the buffer containing the GOutputVectors to write.

-> Maybe b

cancellable: a Cancellable, or Nothing

-> m (PollableReturn, Word64)

Returns: %gPOLLABLERETURNOK on success, PollableReturnWouldBlock if the stream is not currently writable (and error is *not* set), or PollableReturnFailed if there was an error in which case error will be set. (Can throw GError)

Attempts to write the bytes contained in the nVectors vectors to stream, as with outputStreamWritev. If stream is not currently writable, this will immediately return %gPOLLABLERETURNWOULDBLOCK, and you can use pollableOutputStreamCreateSource to create a Source that will be triggered when stream is writable. error will *not* be set in that case.

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 PollableReturnWouldBlock is returned some underlying transports like D/TLS require that you re-send the same vectors and nVectors in the next write call.

Since: 2.60