如何解决Kotlin中的Nio HTTP Server与协程
我正在用协同程序在kotlin中编写一个非常简单的nio HTTP服务器(将“ Hello World!”传送到任何请求)。
首先,我仅使用一个线程来处理选择,读取和写入作业。一切顺利。
result in browser
然后,我使用withTimeoutOrNull(timeout)
来限制服务器无限地运行。我将超时限制设置为10s,而我的选择者将选择阻塞3秒。
...
while (selector.select(3000) == 0) {
println("HttServer is waiting")
continue
}
...
但是时间到了,什么也没发生。
Running endless
这是我的第一个问题:我的代码中withTimeoutOrNull(timeout)
发生了什么事?
忽略该问题,我尝试使用主线程进行选择,并使用线程池作为读取和写入的调度程序。但是该程序仅输出“ HttpServer正在等待”,而无需等待我设置的3秒(几乎每微秒)。
HttpServer
class HttpServer(
val port: Int,val dispatcher: CoroutineDispatcher,) {
val selector = Selector.open()
val ssChannel: ServerSocketChannel = ServerSocketChannel.open()
init {
ssChannel.configureBlocking(false)
}
val htmlBuffer: ByteBuffer
init {
HttpServer::class.java.getResourceAsStream("/nio/index.html").use {
htmlBuffer = ByteBuffer.allocate(it.available())
htmlBuffer.clear()
htmlBuffer.put(it.readBytes())
}
}
suspend fun run(timeout: Long) {
ssChannel.register(selector,SelectionKey.OP_ACCEPT)
ssChannel.bind(InetSocketAddress(port))
withTimeoutOrNull(timeout) {
while (isActive) {
while (selector.select(3000) == 0) {
println("HttpServer is waiting")
continue
}
// launch(dispatcher) { // Something went wrong when uncomment this
val keys = selector.selectedKeys()
val iterator = keys.iterator()
while (iterator.hasNext()) {
val key = iterator.next()
if (key.isAcceptable) {
val serverSocketChannel = key.channel() as ServerSocketChannel
val socketChannel = serverSocketChannel.accept()
socketChannel.configureBlocking(false)
socketChannel.register(selector,SelectionKey.OP_READ,ByteBuffer.allocate(1024))
println("A client is connected")
} else if (key.isWritable) {
val socketChannel = key.channel() as SocketChannel
val httpBuffer = key.attachment() as ByteBuffer
httpBuffer.clear()
val stringBuilder = StringBuilder()
stringBuilder.append("HTTP/1.1 200 OK\n")
stringBuilder.append("Content-Type: text/html\n")
stringBuilder.append("\r\n")
stringBuilder.append(String(htmlBuffer.array()))
httpBuffer.put(stringBuilder.toString().toByteArray())
httpBuffer.flip()
socketChannel.write(httpBuffer)
httpBuffer.rewind()
println("Send message: ${String(httpBuffer.array())}")
key.cancel()
socketChannel.close()
} else if (key.isReadable) {
val socketChannel = key.channel() as SocketChannel
val httpBuffer = key.attachment() as ByteBuffer
httpBuffer.clear()
socketChannel.read(httpBuffer)
httpBuffer.flip()
println("Receive message: ${String(httpBuffer.array())}")
key.channel()
socketChannel.register(selector,SelectionKey.OP_WRITE,ByteBuffer.allocate(1024))
}
iterator.remove()
}
// }
}
}
}
fun shutdown() {
selector.close()
ssChannel.close()
}
}
测试部分(kotest):
class HttpServerTest : FunSpec({
test("HttpServer") {
val tpcontext = newFixedThreadPoolContext(2,"worker")
runBlocking {
val server = HttpServer(2333,tpcontext)
server.run(1000)
server.shutdown()
}
tpcontext.close()
}
})
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