override fun writeAvailable()

in ktor-io/jvm/src/io/ktor/utils/io/ByteBufferChannel.kt [1572:1612]

• 24 lines of code
• 6 McCabe index (conditional complexity)

    override fun writeAvailable(min: Int, block: (ByteBuffer) -> Unit): Int {
        require(min > 0) { "min should be positive" }
        require(min <= BYTE_BUFFER_CAPACITY) { "Min($min) shouldn't be greater than $BYTE_BUFFER_CAPACITY" }

        var result = 0
        var written = false

        writing { dst, state ->
            val locked = state.tryWriteAtLeast(min)

            if (locked > 0) {
                // here we have locked all remaining for write bytes
                // however we don't know how many bytes will be actually written
                // so later we have to return (locked - actuallyWritten) bytes back

                // it is important to lock bytes to fail concurrent tryLockForRelease
                // once we have locked some bytes, tryLockForRelease will fail so it is safe to use buffer

                val position = dst.position()
                val l = dst.limit()
                block(dst)
                if (l != dst.limit()) throw IllegalStateException("buffer limit modified")

                result = dst.position() - position
                if (result < 0) throw IllegalStateException("position has been moved backward: pushback is not supported")

                dst.bytesWritten(state, result)

                if (result < locked) {
                    state.completeRead(locked - result) // return back extra bytes (see note above)
                    // we use completeRead in spite of that it is write block
                    // we don't need to resume write as we are already in writing block
                }

                written = true
            }
        }

        if (!written) return -1
        return result
    }