Package io.vertx.core.streams

Interface ReadStream<T>

All Superinterfaces:

StreamBase

All Known Subinterfaces:

AmqpReceiver, AsyncFile, CassandraRowStream, ClientWebSocket, GrpcClientResponse<Req,Resp>, GrpcReadStream<T>, GrpcServerRequest<Req,Resp>, HttpClientResponse, HttpServerFileUpload, HttpServerRequest, JsonParser, KafkaConsumer<K,V>, KafkaReadStream<K,V>, MessageConsumer<T>, NetSocket, PgChannel, RabbitMQConsumer, ReactiveReadStream<T>, RecordParser, RedisConnection, RowStream<T>, ServerWebSocket, SockJSSocket, TestSuiteReport, WebServerRequest, WebSocket, WebSocketBase

public interface ReadStream<T>
extends StreamBase

Represents a stream of items that can be read from.

Any class that implements this interface can be used by a Pipe to pipe data from it to a WriteStream.

Streaming mode

The stream is either in flowing or fetch mode.

Initially the stream is in flowing mode.
• When the stream is in flowing mode, elements are delivered to the handler.
• When the stream is in fetch mode, only the number of requested elements will be delivered to the handler.

The mode can be changed with the pause(), resume() and fetch(long) methods:

• Calling resume() sets the flowing mode
• Calling pause() sets the fetch mode and resets the demand to 0
• Calling fetch(long) requests a specific amount of elements and adds it to the actual demand

Author:

Tim Fox

Method Summary

Modifier and Type	Method	Description
default <R,A> Future<R>	collect(java.util.stream.Collector<T,A,R> collector)	Apply a collector to this stream, the obtained result is returned as a future.
ReadStream<T>	endHandler(Handler<Void> endHandler)	Set an end handler.
ReadStream<T>	exceptionHandler(Handler<Throwable> handler)	Set an exception handler on the read stream.
ReadStream<T>	fetch(long amount)	Fetch the specified amount of elements.
ReadStream<T>	handler(Handler<T> handler)	Set a data handler.
ReadStream<T>	pause()	Pause the ReadStream, it sets the buffer in fetch mode and clears the actual demand.
default Pipe<T>	pipe()	Pause this stream and return a Pipe to transfer the elements of this stream to a destination WriteStream.
default Future<Void>	pipeTo(WriteStream<T> dst)	Pipe this ReadStream to the WriteStream.
ReadStream<T>	resume()	Resume reading, and sets the buffer in flowing mode.

Method Detail

exceptionHandler

ReadStream<T> exceptionHandler(Handler<Throwable> handler)

Set an exception handler on the read stream.

Specified by:

exceptionHandler in interface StreamBase

Parameters:

handler - the exception handler

Returns:

a reference to this, so the API can be used fluently

handler

ReadStream<T> handler(Handler<T> handler)

Set a data handler. As data is read, the handler will be called with the data.

Returns:

a reference to this, so the API can be used fluently

pause

ReadStream<T> pause()

Pause the ReadStream, it sets the buffer in fetch mode and clears the actual demand.

While it's paused, no data will be sent to the data handler.

Returns:

a reference to this, so the API can be used fluently

resume

ReadStream<T> resume()

Resume reading, and sets the buffer in flowing mode.

If the ReadStream has been paused, reading will recommence on it.

Returns:

a reference to this, so the API can be used fluently

fetch

ReadStream<T> fetch(long amount)

Fetch the specified amount of elements. If the ReadStream has been paused, reading will recommence with the specified amount of items, otherwise the specified amount will be added to the current stream demand.

Returns:

a reference to this, so the API can be used fluently

endHandler

ReadStream<T> endHandler(Handler<Void> endHandler)

Set an end handler. Once the stream has ended, and there is no more data to be read, this handler will be called.

Returns:

a reference to this, so the API can be used fluently

pipe

default Pipe<T> pipe()

Pause this stream and return a Pipe to transfer the elements of this stream to a destination WriteStream.

The stream will be resumed when the pipe will be wired to a WriteStream.

Returns:

a pipe

collect

default <R,A> Future<R> collect(java.util.stream.Collector<T,A,R> collector)

Apply a collector to this stream, the obtained result is returned as a future.

Handlers of this stream are affected by this operation.

Returns:

a future notified with result produced by the collector applied to this stream

pipeTo

default Future<Void> pipeTo(WriteStream<T> dst)

Pipe this ReadStream to the WriteStream.

Elements emitted by this stream will be written to the write stream until this stream ends or fails.

Parameters:

dst - the destination write stream

Returns:

a future notified when the write stream will be ended with the outcome