vertx / io.vertx.core.streams / Pump

# Pump

`interface Pump`

Pumps data from a ReadStream to a WriteStream and performs flow control where necessary to prevent the write stream buffer from getting overfull.

Instances of this class read items from a ReadStream and write them to a WriteStream. If data can be read faster than it can be written this could result in the write queue of the WriteStream growing without bound, eventually causing it to exhaust all available RAM.

To prevent this, after each write, instances of this class check whether the write queue of the is full, and if so, the ReadStream is paused, and a `drainHandler` is set on the WriteStream.

When the WriteStream has processed half of its backlog, the `drainHandler` will be called, which results in the pump resuming the ReadStream.

This class can be used to pump from any ReadStream to any WriteStream, e.g. from an io.vertx.core.http.HttpServerRequest to an io.vertx.core.file.AsyncFile, or from io.vertx.core.net.NetSocket to a io.vertx.core.http.WebSocket.

Please see the documentation for more information.

Author
Tim Fox

### Properties

factory | `static val factory: PumpFactory`

### Functions

numberPumped | `abstract fun numberPumped(): Int` Return the total number of items pumped by this pump.
pump | `open static fun <T : Any> pump(rs: ReadStream<T>, ws: WriteStream<T>): Pump` Create a new `Pump` with the given `ReadStream` and `WriteStream` `open static fun <T : Any> pump(rs: ReadStream<T>, ws: WriteStream<T>, writeQueueMaxSize: Int): Pump` Create a new `Pump` with the given `ReadStream` and `WriteStream` and `writeQueueMaxSize`
setWriteQueueMaxSize | `abstract fun setWriteQueueMaxSize(maxSize: Int): Pump` Set the write queue max size to `maxSize`
start | `abstract fun start(): Pump` Start the Pump. The Pump can be started and stopped multiple times.
stop | `abstract fun stop(): Pump` Stop the Pump. The Pump can be started and stopped multiple times.