EventLoop

Listens for events and returns when any WebSocket has readable data or when concurrent tasks such as exchange.Go(), HttpQuery_Go(), etc. are completed.

    
    
    
EventLoop()

    
    
    
EventLoop(timeout)

Examples

    javascript
    
    
function main() {
    var routine_getTicker = exchange.Go("GetTicker")
    var routine_getDepth = exchange.Go("GetDepth")
    var routine_getTrades = exchange.Go("GetTrades")

    // Sleep(2000), if you use the Sleep statement here, it will cause the subsequent EventLoop function to miss previous events, because after waiting for 2 seconds, the concurrent functions have already received data, and the EventLoop listening mechanism starts afterwards, thus missing these events
    // Unless you call EventLoop(-1) at the very first line of code to initialize the EventLoop listening mechanism first, then these events will not be missed

    // Log("GetDepth:", routine_getDepth.wait()) If you call the wait function here in advance to retrieve the result of the GetDepth concurrent call, the event of GetDepth function receiving the request result will not be returned in the EventLoop function
    var ts1 = new Date().getTime()
    var ret1 = EventLoop(0)

    var ts2 = new Date().getTime()
    var ret2 = EventLoop(0)

    var ts3 = new Date().getTime()
    var ret3 = EventLoop(0)

    Log("First concurrent task completed:", _D(ts1), ret1)
    Log("Second concurrent task completed:", _D(ts2), ret2)
    Log("Third concurrent task completed:", _D(ts3), ret3)

    Log("GetTicker:", routine_getTicker.wait())
    Log("GetDepth:", routine_getDepth.wait())
    Log("GetTrades:", routine_getTrades.wait())
}

    python
    
    
import time
def main():
    routine_getTicker = exchange.Go("GetTicker")
    routine_getDepth = exchange.Go("GetDepth")
    routine_getTrades = exchange.Go("GetTrades")

    ts1 = time.time()
    ret1 = EventLoop(0)

    ts2 = time.time()
    ret2 = EventLoop(0)

    ts3 = time.time()
    ret3 = EventLoop(0)

    Log("First concurrent task completed:", _D(ts1), ret1)
    Log("Second concurrent task completed:", _D(ts2), ret2)
    Log("Third concurrent task completed:", _D(ts3), ret3)

    Log("GetTicker:", routine_getTicker.wait())
    Log("GetDepth:", routine_getDepth.wait())
    Log("GetTrades:", routine_getTrades.wait())

    c++
    
    
void main() {
    auto routine_getTicker = exchange.Go("GetTicker");
    auto routine_getDepth = exchange.Go("GetDepth");
    auto routine_getTrades = exchange.Go("GetTrades");

    auto ts1 = Unix() * 1000;
    auto ret1 = EventLoop(0);

    auto ts2 = Unix() * 1000;
    auto ret2 = EventLoop(0);

    auto ts3 = Unix() * 1000;
    auto ret3 = EventLoop(0);

    Log("First concurrent task completed:", _D(ts1), ret1);
    Log("Second concurrent task completed:", _D(ts2), ret2);
    Log("Third concurrent task completed:", _D(ts3), ret3);

    Ticker ticker;
    Depth depth;
    Trades trades;
    routine_getTicker.wait(ticker);
    routine_getDepth.wait(depth);
    routine_getTrades.wait(trades);

    Log("GetTicker:", ticker);
    Log("GetDepth:", depth);
    Log("GetTrades:", trades);
}

Returns

            json
            
            
{"Seq":1,"Event":"Exchange_GetTrades","ThreadId":0,"Index":3,"Nano":1682068771309583400}

Arguments

See Also

Remarks

The event listening mechanism is initialized only when the EventLoop() function is called for the first time in the code. If EventLoop() is called for the first time after event callbacks have occurred, previous events will be missed. The underlying system's encapsulated queue structure caches up to 500 event callbacks. If the EventLoop() function is not called in time during program execution to retrieve events, later event callbacks exceeding the 500 cache limit will be lost.
Calling the EventLoop() function does not affect the underlying system's WebSocket cache queue, nor does it affect the cache of concurrent functions such as exchange.Go(). For these caches, you still need to use their respective methods to retrieve data. Data that has been retrieved before the EventLoop() function returns will not generate return events in the EventLoop() function.
The main purpose of the EventLoop() function is to notify the strategy layer that the underlying system has received new network data, driving the entire strategy through events. When the EventLoop() function returns an event, simply iterate through all data sources, such as WebSocket connections and objects created by exchange.Go(), to attempt to retrieve data.
The EventLoop() function only supports live trading environments.

When called in the main function main(), it listens for events in the main thread. In strategies written in JavaScript, threads created by the threading.Thread() function can call this function within their execution functions to listen for events in the current thread.