官方API的 net.Server 中 server.listen 有个 demo
server.on('error', function (e) {
if (e.code == 'EADDRINUSE') {
console.log('Address in use, retrying...');
setTimeout(function () {
server.close();
server.listen(PORT, HOST);
}, 1000);
}
});
error 事件触发之后不是会马上触发 close 事件的么？在 setTimeout 的回调中加入 server.close() 不仅多余，而且如果 server 已经 close 掉不是还是抛出异常？
看起来是这样：调用server.close()方法会关闭server，如果成功关闭，触发close事件。官网对close()的解释如下：
server.close([callback]) Stops the server from accepting new connections and keeps existing connections. This function is asynchronous, the server is finally closed when all connections are ended and the server emits a ‘close’ event. Optionally, you can pass a callback to listen for the ‘close’ event.
Event: ‘error’# Error Object Emitted when an error occurs. The ‘close’ event will be called directly following this event. See example in discussion of server.listen. 可Server的error事件中说close事件会directly执行，我找源码没找出，但估计是在process.nextTick中执行的。如果是这样的话，那么在setTimeout延迟到来之前server已经被close了
