Possible to get 'total bytes sent' and 'stream end' from ctx.seekableStream ?

I’m using ctx.seekableStream(file.inputStream(), "audio/mpeg") to stream files to the client and I’m planning to log some statistics about how many bytes have actually been sent. As far as I understand the browser it will call the endpoint multiple times to get a small chunk on every request. Is it possible to get this information from the seekable stream somehow? And is it possible to identify when the stream (chunk) ended?

Ty for any information.

[tipsy]

Nice ! I’ll add an “info” tag to the issue 😃

[fq-selbach]

I think I solved the “mystery” 🙂.

CountingInputStream counts the skipped bytes as well meaning each request that reads only a chunk of the file is counted as “read bytes” + “skipped bytes” to find position. In the case where the whole file was read at once I was simply counting the bytes too early since the stream is read after ctx.result(inputStream) returned.

So I ended up writing a new CountingInputStream implementation instead of a new SeekableWriter like this:

import static org.apache.commons.io.IOUtils.EOF;
import java.io.IOException;
import java.io.InputStream;
import java.util.function.Consumer;
import org.apache.commons.io.input.CountingInputStream;

/**
 * Adapted version of {@link CountingInputStream} to get download statistics.
 */
public class DownloadCounterStream extends CountingInputStream {
	
    private long totalBytesRead = 0l;
    private Consumer<Long> onClose;
    
    /**
    * Constructs a new DownloadCounterStream.
    * @param in - the input stream
    * @param onClose - callback on stream close with totalBytesRead
    */
    public DownloadCounterStream(final InputStream in, Consumer<Long> onClose) {
        super(in);
        this.onClose = onClose;
    }
    
    /**
     * Get total bytes actually read by this stream 
     * (without skipped bytes like {@link #getByteCount()}).
     */
    public long getTotalBytesRead(){
    	return this.totalBytesRead;
    }
    
    /**
     * Adds the number of read bytes to the count.
     */
    @Override
    protected synchronized void afterRead(final int n) {
        if (n != EOF) {
            this.totalBytesRead += n;
        }
        super.afterRead(n);
    }
    
    @Override 
    public void close() throws IOException {
    	super.close();
    	this.onClose.accept(this.totalBytesRead);
    }
}

And I’m using it like this:

DownloadCounterStream is = new DownloadCounterStream(Files.newInputStream(file.toPath()), total -> {
    System.out.println("Total bytes sent: " + total);
});
ctx.seekableStream(is, ct);