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/// !example
/// ## Sending events both ways between the main thread and a worker thread
///
/// This third example demonstrates how we can use events to communicate in both directions
/// between main thread and worker thread.
///
/// Like before, we create a worker thread and we define the fibonacci function:
var Threads = require('webworker-threads');
var t = Threads.create();
function fibo(n) {
return n > 1 ? fibo(n - 1) + fibo(n - 2) : 1;
}
/// In the previous example we were running a loop that generates fibonacci numbers in the worker thread.
/// This is fine if the generator produces the number at a slower rate than the main thread can consume them
/// but it will hog memory if the main thread is too busy and cannot consume the data events fast enough.
/// We can improve this by controlling the flow with events in both directions.
///
/// The `thread` global variable that **webworker-threads** predefines in every worker thread is also an `EventEmitter`.
/// So we will use it to send events in the other direction, from the main thread to the worker thread.
///
/// Our modified generator does not use a loop any more. Instead, it generates numbers in response to `next` events
/// sent from the main thread. Here is the new generator:
function generateFibos() {
var i = 1;
thread.on('next', function() {
thread.emit('data', i, fibo(i));
i++;
});
}
/// From the main thread, we listen for the `data` events emitted by the worker thread.
/// Every time we get a `data` event from the worker thread, we print the result and we `emit` a
/// `next` event into the worker thread (stopping at 40):
t.on('data', function(n, result) {
console.log('fibo(' + n + ') = ' + result);
if (n < 40) t.emit('next');
else console.log('bye!'), t.destroy();
});
/// We now have all we need for our little ping-pong game. We load the two functions into the thread:
t.eval(fibo);
t.eval(generateFibos);
/// We start the generator in the worker thread:
t.eval("generateFibos()");
/// And we start the game by emitting the first `next` event:
t.emit('next');
/// ### Output
///
/// ```
/// fibo(1) = 1
/// fibo(2) = 2
/// fibo(3) = 3
/// fibo(4) = 5
/// ...
/// fibo(39) = 102334155
/// fibo(40) = 165580141
/// bye!
/// ```
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