发布于 2016-08-25 01:05:05 | 135 次阅读 | 评论: 0 | 来源: 网友投递
Node.js 服务器端的JavaScript
Node.js 是一个基于Chrome JavaScript 运行时建立的一个平台, 用来方便地搭建快速的 易于扩展的网络应用· Node.js 借助事件驱动, 非阻塞I/O 模型变得轻量和高效, 非常适合 运行在分布式设备 的 数据密集型 的实时应用
function longPoll (data) {
//....此处省略**行
$.ajax({ cache: false
, type: "GET"
, url: "/recv"
, dataType: "json"
, data: { since: CONFIG.last_message_time, id: CONFIG.id }
, error: function () {
addMessage("", "long poll error. trying again...", new Date(), "error");
transmission_errors += 1;
//don't flood the servers on error, wait 10 seconds before retrying
setTimeout(longPoll, 10*1000);
}
, success: function (data) {
transmission_errors = 0;
//if everything went well, begin another request immediately
//the server will take a long time to respond
//how long? well, it will wait until there is another message
//and then it will return it to us and close the connection.
//since the connection is closed when we get data, we longPoll again
longPoll(data);
}
});
}
fu.get("/recv", function (req, res) {
//对session的验证和更新......
channel.query(since, function (messages) {
if (session) session.poke();
res.simpleJSON(200, { messages: messages, rss: mem.rss });
});
});
var MESSAGE_BACKLOG = 200,
SESSION_TIMEOUT = 60 * 1000;
var channel = new function () {
var messages = [],
callbacks = [];
this.appendMessage = function (nick, type, text) {
var m = { nick: nick
, type: type // "msg", "join", "part"
, text: text
, timestamp: (new Date()).getTime()
};
switch (type) {
case "msg":
sys.puts("<" + nick + "> " + text);
break;
case "join":
sys.puts(nick + " join");
break;
case "part":
sys.puts(nick + " part");
break;
}
messages.push( m );
while (callbacks.length > 0) {
//shift() 方法用于把数组的第一个元素从其中删除,并返回第一个元素的值
callbacks.shift().callback([m]);
}
while (messages.length > MESSAGE_BACKLOG)
messages.shift();
};
this.query = function (since, callback) {
var matching = [];
for (var i = 0; i < messages.length; i++) {
var message = messages[i];
if (message.timestamp > since)
matching.push(message)
}
if (matching.length != 0) {
callback(matching);
} else {
callbacks.push({ timestamp: new Date(), callback: callback });
}
};
// clear old callbacks
// they can hang around for at most 30 seconds.
setInterval(function () {
var now = new Date();
while (callbacks.length > 0 && now - callbacks[0].timestamp > 30*1000) {
callbacks.shift().callback([]);
}
}, 3000);
};
if (matching.length != 0) {
callback(matching);
} else {
callbacks.push({ timestamp: new Date(), callback: callback });
}
while (callbacks.length > 0) {
//shift() 方法用于把数组的第一个元素从其中删除,并返回第一个元素的值
callbacks.shift().callback([m]);
}