node-binance-api: Problems with Depth Cache

The ‘if’ that i added revolved completely the issue in my software. We are still developing using this library and the error did not happen again 😃

Still, i hope someone test it too! Pretty fast to test it if you already have the request implemented.

Thank you very much @josepgomes If that code is tested and working I can include it in the next release

@jmarto Excellent, thanks for the update. That makes sense that it would cause the same error. If you delayed that second call however, it would work, but then you’d have two sockets open providing duplicate data.

@jaggedsoft Perhaps as a more bulletproof fix, we can discuss having the API throw a more descriptive error when:

1. Attempting to subscribe to, technically, a duplicate data stream, or
2. A symbol appears more than once in any of the applicable websockets functions.

I say technically above as it would only detect exact duplicate subscriptions as an error. ie.

// Fine: This is the first call, so no possible duplicates
websockets.depthCache(['BNBBTC'], ...);

// Error: Subscription results in a duplicate data stream
websockets.depthCache(['BNBBTC'], ...);

// Fine: You are essentially receiving duplicate data for BNBBTC on this socket,
// but overall, the stream is not a duplicate
websockets.depthCache(['BNBBTC', 'XRPBTC'], ...);

The alternative to point 1, if we don’t want to restrict users to only a single point of subscription, would be to just attach their callback to the already existing WebSocket instance.

What do you think?

It wasn’t. I was initially passing in as per my edit with simply ['XRPBTC','LTCBTC']. But would you believe that it has just decided to work with v0.4.11? Can’t figure out why, but I’m sure it was my fault. Sorry to bother! Thanks for following up so quickly.

@jmarto @jaggedsoft I’ll have a look at this right now. Will provide updates on my findings as soon as I have any.

@jmarto Could you please provide a snippet of what your call to websockets.depthCache looks like, along with what your first parameter (symbols) is? Thanks.

Hi,

Don’t know if this is the perfect way to correct this problem, but can help a lot of people until official fix is released:

line 603

info[symbol].firstUpdateId = json.lastUpdateId;
depthCache[symbol] = depthData(json);
for ( let depth of messageQueue[symbol] ) {
    depthHandler(depth, json.lastUpdateId);
}
delete messageQueue[symbol];
if ( callback ) callback(symbol, depthCache[symbol]);

To

if (messageQueue != null && typeof messageQueue[symbol] === 'object') {
    info[symbol].firstUpdateId = json.lastUpdateId;
    depthCache[symbol] = depthData(json);
    for ( let depth of messageQueue[symbol] ) {
        depthHandler(depth, json.lastUpdateId);
    }
    delete messageQueue[symbol];
    if ( callback ) callback(symbol, depthCache[symbol]);
}

PS: It worked for me, no more errors 😃