kotlinx-io-core/kotlinx.io/Source/request

request

abstract fun request(byteCount: Long): Boolean(source)

Attempts to fill the buffer with at least byteCount bytes of data from the underlying source and returns a value indicating if the requirement was successfully fulfilled.

false value returned by this method indicates that the underlying source was exhausted before filling the buffer with byteCount bytes of data.

Parameters

byteCount

the number of bytes that the buffer should contain.

Throws

when byteCount is negative.

when the source is closed.

when some I/O error occurs.

Samples

import kotlinx.io.*
import kotlin.test.*

fun main() { 
   //sampleStart 
   val singleByteSource = object : RawSource {
    private var exhausted = false
    override fun readAtMostTo(sink: Buffer, byteCount: Long): Long = when {
        byteCount == 0L -> 0L
        exhausted -> -1L
        else -> {
            exhausted = true
            sink.writeByte(42)
            1L
        }
    }

    override fun close() = Unit
}

val source = singleByteSource.buffered()

assertTrue(source.request(1))
// The request call already soaked all the data from the source
assertEquals(-1, singleByteSource.readAtMostTo(Buffer(), 1))
// There is only one byte, so we can't request more
assertFalse(source.request(2))
// But we didn't consume single byte yet, so request(1) will succeed
assertTrue(source.request(1))
assertEquals(42, source.readByte())
assertFalse(source.request(1)) 
   //sampleEnd
}