com.javanut.pronghorn.pipe.ChannelWriterController Maven / Gradle / Ivy

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Ring buffer based queuing utility for applications that require high performance and/or a small footprint. Well suited for embedded and stream based processing.

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package com.javanut.pronghorn.pipe;

public class ChannelWriterController {

	protected final Pipe pipe;
	private boolean isWriting = false;		
	
	public ChannelWriterController(Pipe pipe) {
		this.pipe = pipe;
	}
	
	/**
	 * check if connection data can take another message
	 * @return true if there is room for another write
	 */
	public boolean hasRoomForWrite() {
		return Pipe.hasRoomForWrite(pipe);
	}
	
	/**
	 * Open the message for writing
	 * @return returns the ChannelWriter or null if there is no room to write.
	 */
	public ChannelWriter beginWrite() {
		if (Pipe.hasRoomForWrite(pipe)) {
			Pipe.markHead(pipe);
			Pipe.addMsgIdx(pipe, RawDataSchema.MSG_CHUNKEDSTREAM_1);
			isWriting = true;
			return Pipe.openOutputStream(pipe);
		}
		return null;
	}
	
	/**
	 * Dispose of everything written and restore to the way it was before
	 * beginWrite() was called.
	 */
	public void abandonWrite() {
		if (isWriting) {
			DataOutputBlobWriter.closeLowLevelField(Pipe.outputStream(pipe));
			Pipe.resetHead(pipe);
		} else {
			isWriting=false;
		}
	}
	
	/**
	 * Store the message and move the pointers forward so the data can be
	 * consumed later.
	 */
	public void commitWrite() {
		if (isWriting) {
			DataOutputBlobWriter.closeLowLevelField(Pipe.outputStream(pipe));		
			
			Pipe.confirmLowLevelWrite(pipe, Pipe.sizeOf(RawDataSchema.instance,RawDataSchema.MSG_CHUNKEDSTREAM_1));
			Pipe.publishWrites(pipe);
		} else {
			isWriting = false;
		}
	}

}