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159(function Feeds(){
"use strict";
var Ar = ASQ.react, // namespace shortcut
// signal sequence(s)
item_feed;
EVT.on("setup-feeds",setupFeeds);
// ***********************************
function setupFeeds() {
// setup fake item feed
item_feed = Ar(fakeItemFeed);
// setup slow feed (feed 1)
var slow_feed_toggle = setupFeed(/*feedID=*/1,/*delay=*/2000);
// setup fast feed (feed 2)
var fast_feed_toggle = setupFeed(/*feedID=*/2,/*delay=*/1300);
// monitor feed status
Ar.latest(
slow_feed_toggle, fast_feed_toggle
)
.val(monitorFeedStatus);
// setup my feed (duplicate checking)
setupMyFeed();
}
// fake a network stream of data
function fakeItemFeed(next,registerTeardown) {
// fake a delay
var intv = setInterval(function timer(){
// signal a new item
next( ItemsText.more() );
},50);
registerTeardown(function teardown(){
clearInterval(intv);
});
}
function setupFeed(feedID,delay) {
// setup feed reactive sequences
var feed_toggle = Ar.distinctConsecutive(
fromEvent("status-" + feedID)
);
var feed = sampledStream(item_feed,delay)
.val(function val(itemText){
EVT.emit("feed-insertion",feedID,itemText);
});
feed_toggle.val(handleFeedToggle);
return feed_toggle;
// ***********************************
function handleFeedToggle(st){
if (st) feed.resume();
else feed.pause();
return st;
}
}
function sampledStream(stream,delay) {
var saveLatest = true, latest;
// observe the stream's messages as they go by
stream.val(observeStream);
return Ar(interval);
// ***********************************
function interval(next,registerTeardown) {
saveLatest = true;
// throttle feed sampling
var intv = setInterval(function timer(){
// signal a new feed item
next.apply(null,latest);
},delay);
registerTeardown(function teardown(){
saveLatest = false;
clearInterval(intv);
});
}
function observeStream() {
var args = ASQ.messages.apply(null,arguments);
if (saveLatest) latest = args;
return args;
}
}
function monitorFeedStatus(running1,running2) {
// both feeds paused?
if (!running1 && !running2) {
// protect the CPU!
item_feed.pause();
}
// keep calm and carry on
else {
item_feed.resume();
}
}
function setupMyFeed() {
var my_feed_text = {};
Ar(function reactor(next){
// wait for item-selection signal
EVT.on("item-selection",next);
})
.val(handleItemSelection);
// ***********************************
function handleItemSelection(feedID,itemText,$item) {
// not a duplicate message?
if (!(itemText in my_feed_text)) {
my_feed_text[itemText] = true;
// signal my-feed insertion
EVT.emit("my-feed-insertion",feedID,$item);
}
else {
// signal kill (duplicate) item
EVT.emit("feed-kill",$item);
}
}
}
function fromEvent(evtName) {
return Ar(listen);
// ***********************************
function listen(next,registerTeardown) {
EVT.on(evtName,next);
registerTeardown(function teardown(){
EVT.off(evtName,next);
});
}
}
})();