GI.Gio.Objects.IOStream

GIOStream represents an object that has both read and write streams. Generally the two streams act as separate input and output streams, but they share some common resources and state. For instance, for seekable streams, both streams may use the same position.

Examples of IOStream objects are SocketConnection, which represents a two-way network connection; and FileIOStream, which represents a file handle opened in read-write mode.

To do the actual reading and writing you need to get the substreams with iOStreamGetInputStream and iOStreamGetOutputStream.

The IOStream object owns the input and the output streams, not the other way around, so keeping the substreams alive will not keep the IOStream object alive. If the IOStream object is freed it will be closed, thus closing the substreams, so even if the substreams stay alive they will always return IOErrorEnumClosed for all operations.

To close a stream use iOStreamClose which will close the common stream object and also the individual substreams. You can also close the substreams themselves. In most cases this only marks the substream as closed, so further I/O on it fails but common state in the IOStream may still be open. However, some streams may support "half-closed" states where one direction of the stream is actually shut down.

Operations on GIOStreams cannot be started while another operation on the IOStream or its substreams is in progress. Specifically, an application can read from the InputStream and write to the OutputStream simultaneously (either in separate threads, or as asynchronous operations in the same thread), but an application cannot start any IOStream operation while there is a IOStream, InputStream or OutputStream operation in progress, and an application can’t start any InputStream or OutputStream operation while there is a IOStream operation in progress.

This is a product of individual stream operations being associated with a given MainContext (the thread-default context at the time the operation was started), rather than entire streams being associated with a single MainContext.

GIO may run operations on GIOStreams from other (worker) threads, and this may be exposed to application code in the behaviour of wrapper streams, such as BufferedInputStream or TlsConnection. With such wrapper APIs, application code may only run operations on the base (wrapped) stream when the wrapper stream is idle. Note that the semantics of such operations may not be well-defined due to the state the wrapper stream leaves the base stream in (though they are guaranteed not to crash).

Since: 2.22

Exported types

newtype IOStream

Memory-managed wrapper type.

Constructors

IOStream (ManagedPtr IOStream)

Instances

Eq IOStream

Defined in GI.Gio.Objects.IOStream

Methods

(==) :: IOStream -> IOStream -> Bool

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

GObject IOStream

Defined in GI.Gio.Objects.IOStream

Methods

gobjectType :: IO GType

IsGValue IOStream

Convert IOStream to and from GValue with toGValue and fromGValue.

Defined in GI.Gio.Objects.IOStream

Methods

toGValue :: IOStream -> IO GValue

fromGValue :: GValue -> IO IOStream

HasParentTypes IOStream

Defined in GI.Gio.Objects.IOStream

type ParentTypes IOStream

Defined in GI.Gio.Objects.IOStream

type ParentTypes IOStream = '[Object]

class (GObject o, IsDescendantOf IOStream o) => IsIOStream o

Type class for types which can be safely cast to IOStream, for instance with toIOStream.

Instances

(GObject o, IsDescendantOf IOStream o) => IsIOStream o

Defined in GI.Gio.Objects.IOStream

toIOStream :: (MonadIO m, IsIOStream o) => o -> m IOStream

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

noIOStream :: Maybe IOStream

A convenience alias for Nothing :: Maybe IOStream.

Methods

Overloaded methods

clearPending

iOStreamClearPending

Arguments

:: (HasCallStack, MonadIO m, IsIOStream a)

=> a

stream: a IOStream

-> m ()

Clears the pending flag on stream.

Since: 2.22

close

iOStreamClose

Arguments

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

=> a

stream: a IOStream

-> Maybe b

cancellable: optional Cancellable object, Nothing to ignore

-> m ()

(Can throw GError)

Closes the stream, releasing resources related to it. This will also close the individual input and output streams, if they are not already closed.

Once the stream is closed, all other operations will return IOErrorEnumClosed. Closing a stream multiple times will not return an error.

Closing a stream will automatically flush any outstanding buffers in the stream.

Streams will be automatically closed when the last reference is dropped, but you might want to call this function to make sure resources are released as early as possible.

Some streams might keep the backing store of the stream (e.g. a file descriptor) open after the stream is closed. See the documentation for the individual stream for details.

On failure the first error that happened will be reported, but the close operation will finish as much as possible. A stream that failed to close will still return IOErrorEnumClosed for all operations. Still, it is important to check and report the error to the user, otherwise there might be a loss of data as all data might not be written.

If cancellable is not NULL, then the operation can be cancelled by triggering the cancellable object from another thread. If the operation was cancelled, the error IOErrorEnumCancelled will be returned. Cancelling a close will still leave the stream closed, but some streams can use a faster close that doesn't block to e.g. check errors.

The default implementation of this method just calls close on the individual input/output streams.

Since: 2.22

closeAsync

iOStreamCloseAsync

Arguments

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

=> a

stream: a IOStream

-> Int32

ioPriority: the io priority of the request

-> Maybe b

cancellable: optional cancellable object

-> Maybe AsyncReadyCallback

callback: callback to call when the request is satisfied

-> m ()

Requests an asynchronous close of the stream, releasing resources related to it. When the operation is finished callback will be called. You can then call iOStreamCloseFinish to get the result of the operation.

For behaviour details see iOStreamClose.

The asynchronous methods have a default fallback that uses threads to implement asynchronicity, so they are optional for inheriting classes. However, if you override one you must override all.

Since: 2.22

closeFinish

iOStreamCloseFinish

Arguments

:: (HasCallStack, MonadIO m, IsIOStream a, IsAsyncResult b)

=> a

stream: a IOStream

-> b

result: a AsyncResult

-> m ()

(Can throw GError)

Closes a stream.

Since: 2.22

getInputStream

iOStreamGetInputStream

Arguments

:: (HasCallStack, MonadIO m, IsIOStream a)

=> a

stream: a IOStream

-> m InputStream

Returns: a InputStream, owned by the IOStream. Do not free.

Gets the input stream for this object. This is used for reading.

Since: 2.22

getOutputStream

iOStreamGetOutputStream

Arguments

:: (HasCallStack, MonadIO m, IsIOStream a)

=> a

stream: a IOStream

-> m OutputStream

Returns: a OutputStream, owned by the IOStream. Do not free.

Gets the output stream for this object. This is used for writing.

Since: 2.22

hasPending

iOStreamHasPending

Arguments

:: (HasCallStack, MonadIO m, IsIOStream a)

=> a

stream: a IOStream

-> m Bool

Returns: True if stream has pending actions.

Checks if a stream has pending actions.

Since: 2.22

isClosed

iOStreamIsClosed

Arguments

:: (HasCallStack, MonadIO m, IsIOStream a)

=> a

stream: a IOStream

-> m Bool

Returns: True if the stream is closed.

Checks if a stream is closed.

Since: 2.22

setPending

iOStreamSetPending

Arguments

:: (HasCallStack, MonadIO m, IsIOStream a)

=> a

stream: a IOStream

-> m ()

(Can throw GError)

Sets stream to have actions pending. If the pending flag is already set or stream is closed, it will return False and set error.

Since: 2.22

spliceAsync

iOStreamSpliceAsync

Arguments

:: (HasCallStack, MonadIO m, IsIOStream a, IsIOStream b, IsCancellable c)

=> a

stream1: a IOStream.

-> b

stream2: a IOStream.

-> [IOStreamSpliceFlags]

flags: a set of IOStreamSpliceFlags.

-> Int32

ioPriority: the io priority of the request.

-> Maybe c

cancellable: optional Cancellable object, Nothing to ignore.

-> Maybe AsyncReadyCallback

callback: a AsyncReadyCallback.

-> m ()

Asyncronously splice the output stream of stream1 to the input stream of stream2, and splice the output stream of stream2 to the input stream of stream1.

When the operation is finished callback will be called. You can then call iOStreamSpliceFinish to get the result of the operation.

Since: 2.28

spliceFinish

iOStreamSpliceFinish

Arguments

:: (HasCallStack, MonadIO m, IsAsyncResult a)

=> a

result: a AsyncResult.

-> m ()

(Can throw GError)

Finishes an asynchronous io stream splice operation.

Since: 2.28

Properties

closed

No description available in the introspection data.

getIOStreamClosed :: (MonadIO m, IsIOStream o) => o -> m Bool

Get the value of the “closed” property. When overloading is enabled, this is equivalent to

get iOStream #closed

inputStream

No description available in the introspection data.

getIOStreamInputStream :: (MonadIO m, IsIOStream o) => o -> m InputStream

Get the value of the “input-stream” property. When overloading is enabled, this is equivalent to

get iOStream #inputStream

outputStream

No description available in the introspection data.

getIOStreamOutputStream :: (MonadIO m, IsIOStream o) => o -> m OutputStream

Get the value of the “output-stream” property. When overloading is enabled, this is equivalent to

get iOStream #outputStream