Package org.gnome.gio

Interface PollableInputStream

All Superinterfaces:

Proxy

All Known Implementing Classes:

ConverterInputStream, MemoryInputStream, MultipartInputStream, PollableInputStream.PollableInputStream$Impl

@Generated("io.github.jwharm.JavaGI")
public interface PollableInputStream
extends Proxy

GPollableInputStream is implemented by InputStreams that can be polled for readiness to read. This can be used when interfacing with a non-GIO API that expects UNIX-file-descriptor-style asynchronous I/O rather than GIO-style.

Some classes may implement GPollableInputStream but have only certain instances of that class be pollable. If canPoll() returns false, then the behavior of other GPollableInputStream methods is undefined.

Since:

2.28

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static class	PollableInputStream.PollableInputStream$Impl	The PollableInputStream$Impl type represents a native instance of the PollableInputStream interface.
static class	PollableInputStream.PollableInputStreamInterface	The interface for pollable input streams.

Method Summary

Modifier and Type	Method	Description
default boolean	canPoll()	Checks if this PollableInputStream is actually pollable.
default Source	createSource(@Nullable Cancellable cancellable)	Creates a GSource that triggers when this PollableInputStream can be read, or cancellable is triggered or an error occurs.
static @Nullable Type	getType()	Get the GType of the PollableInputStream class
default boolean	isReadable()	Checks if this PollableInputStream can be read.
default long	readNonblocking(@Nullable Out<byte[]> buffer, @Nullable Cancellable cancellable)	Attempts to read up to count bytes from this PollableInputStream into buffer, as with g_input_stream_read().

Methods inherited from interface org.javagi.base.Proxy

handle

Method Details

getType

static @Nullable Type getType()

Get the GType of the PollableInputStream class

Returns:

the GType

canPoll

default boolean canPoll()

Checks if this PollableInputStream is actually pollable. Some classes may implement GPollableInputStream but have only certain instances of that class be pollable. If this method returns false, then the behavior of other GPollableInputStream 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 this PollableInputStream is pollable, false if not.

Since:

2.28

createSource

default Source createSource(@Nullable Cancellable cancellable)

Creates a GSource that triggers when this PollableInputStream can be read, or cancellable is triggered or an error occurs. The callback on the source is of the GPollableSourceFunc type.

As with g_pollable_input_stream_is_readable(), it is possible that the stream may not actually be readable even after the source triggers, so you should use g_pollable_input_stream_read_nonblocking() rather than g_input_stream_read() from the callback.

The behaviour of this method is undefined if g_pollable_input_stream_can_poll() returns false for stream.

Parameters:

cancellable - a GCancellable, or null

Returns:

a new GSource

Since:

2.28

isReadable

default boolean isReadable()

Checks if this PollableInputStream can be read.

Note that some stream types may not be able to implement this 100% reliably, and it is possible that a call to g_input_stream_read() after this returns true would still block. To guarantee non-blocking behavior, you should always use g_pollable_input_stream_read_nonblocking(), which will return a IOErrorEnum.WOULD_BLOCK error rather than blocking.

The behaviour of this method is undefined if g_pollable_input_stream_can_poll() returns false for stream.

Returns:

true if this PollableInputStream is readable, false if not. If an error has occurred on stream, this will result in g_pollable_input_stream_is_readable() returning true, and the next attempt to read will return the error.

Since:

2.28

readNonblocking

default long readNonblocking(@Nullable Out<byte[]> buffer,
 @Nullable Cancellable cancellable)
                      throws GErrorException

Attempts to read up to count bytes from this PollableInputStream into buffer, as with g_input_stream_read(). If this PollableInputStream is not currently readable, this will immediately return IOErrorEnum.WOULD_BLOCK, and you can use g_pollable_input_stream_create_source() to create a GSource that will be triggered when this PollableInputStream is readable.

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.

The behaviour of this method is undefined if g_pollable_input_stream_can_poll() returns false for stream.

Parameters:

buffer - a buffer to read data into (which should be at least count bytes long).

cancellable - a GCancellable, or null

Returns:

the number of bytes read, or -1 on error (including IOErrorEnum.WOULD_BLOCK).

Throws:

GErrorException - see GError