What is a nice Kotlin way of copying data from a ByteArrayOutputStream in chunks to an OutputStream?...

# announcements

[janvladimirmostert]

What is a nice Kotlin way of copying data from a ByteArrayOutputStream in chunks to an OutputStream?
the non-chunked way seems to be outputStream.use { out -> baos.writeTo(out) }

[diesieben07]

copyTo already copies in chunks (it has a bufferSize parameter). Or what do you mean by "chunked"?

[janvladimirmostert]

writeTo writes the whole thing when looking at the source:

public synchronized void writeTo(OutputStream out) throws IOException {
        out.write(this.buf, 0, this.count);
    }

Kinda looking for something where I can yield inbetween each chunk to prevent a Blocking.IO coroutine from being hogged if somebody has a very slow internet connection

outputStream.use { out ->
baos.window(BufferSize) { chunk ->
chunk.writeTo(out)
yield()
}
}

[diesieben07]

ByteArrayInputStream(baos.toByteArray()).use { 
        it.copyTo(output)
    }

[diesieben07]

That is chunkced, but yeah... not really in a way that lets you yield

[janvladimirmostert]

that looks like a good place to start, thanks for this!

[janvladimirmostert]

could make use of channels from here on

[janvladimirmostert]

this works well

val buffer = ByteArray(DEFAULT_BUFFER_SIZE)
		val yieldSize: Int = 1 * 1024 * 1024
		var bytesCopied = 0L
		var bytesAfterYield = 0L
		this.respondOutputStream {
			this.use { output ->
				ByteArrayInputStream(result.data?.toByteArray() ?: byteArrayOf()).use { input ->
					while (true) {
						val bytes = input.read(buffer).takeIf { it >= 0 } ?: break
						<http://LulaServer.log.info|LulaServer.log.info>("[${result.fileName}] writing: $bytes")
						output.write(buffer)
						if (bytesAfterYield >= yieldSize) {
							yield()
							bytesAfterYield %= yieldSize
						}
						bytesCopied += bytes
						bytesAfterYield += bytes
					}
				}
			}
		}