js-csp operations.mult doesn't distribute a value across the channels

Question

I was playing with js-csp library and it's mult function specifically. I setup a test with a source channel, a couple of channels tapped into mult and a result channel. Yet somehow not all values were distributed to the channels. Here's the code:

import csp from 'js-csp';

describe('Dispatcher', function() {
    let source, broadcast, listeners, result;

    beforeEach(function() {
        source = csp.chan();

        broadcast = csp.operations.mult(source);

        result = csp.chan();
        csp.operations.mult.tap(broadcast, result);

        listeners = Array(csp.chan(), csp.chan(), csp.chan()).map((chan) => {
            csp.operations.mult.tap(broadcast, chan);
            return chan;
        });
    });

    it('should broadcast the payload to all listeners', function(done) {
        this.timeout(0);

        let counter = 0;
        csp.go(function*() {
            let payload = yield result;
            while (payload !== csp.CLOSED) {
                console.log('[result]', payload);
                if (payload.name === 'done') {
                    counter++;
                    console.log('[result]', counter);
                    if (counter === listeners.length) {
                        done();
                    }
                }
                payload = yield result;
            }
        });

        listeners.forEach((chan, idx) => {
            csp.go(function*() {
                let payload = yield chan;
                while (payload !== csp.CLOSED) {
                    if (payload.name !== 'done') {
                        console.log('[listener]', payload);
                        yield csp.put(source, {name: 'done'});
                    }
                    payload = yield chan;
                }
            });
        });

        csp.putAsync(source, {name: 'test'}, () => console.log('putAsync callback'));
    });
});

I'm using Webpack with Babel.js and their version of Renegerator to transform this code into ES5. Once I run it (in the browser) the {name: 'test'} message delivered to every channel, but {name: 'done'} is delivered to result channel only once.

I checked the source channel in debugger and it has a puts buffer which contains two remaining {name: 'done'} values.

So I'm wondering what I'm doing wrong.

Answer 1

Each mult waits for all of its tap's to consume a payload before moving to the next. In this case it is waiting for 2 of the taps while they are in turn waiting for it.