_G

Persistently save data. This function implements a savable global dictionary feature. The data structure is a key-value pair table, permanently saved in the docker's local database file.

    
    
    
_G()

    
    
    
_G(k)

    
    
    
_G(k, v)

Examples

    javascript
    
    
function main(){
    // 设置一个全局变量num，值为1
    _G("num", 1)
    // 更改一个全局变量num，值为字符串ok
    _G("num", "ok")
    // 删除全局变量num
    _G("num", null)
    // 返回全局变量num的值
    Log(_G("num"))
    // 删除所有全局变量
    _G(null)
    // 返回实盘ID
    var robotId = _G()
}

    python
    
    
def main():
    _G("num", 1)
    _G("num", "ok")
    _G("num", None)
    Log(_G("num"))
    _G(None)
    robotId = _G()

    c++
    
    
void main() {
    _G("num", 1);
    _G("num", "ok");
    _G("num", NULL);
    Log(_G("num"));
    _G(NULL);
    // 不支持 auto robotId = _G();
}

Returns

Arguments

See Also

Remarks

Each live trading uses a separate database. When the strategy restarts or the docker stops running, the data saved by the _G() function will persist. If the backtest ends, the data saved by the _G() function in the backtest system will be cleared. When using the _G() function to persistently save data, it should be used reasonably according to the memory and disk space of the hardware device to avoid abuse.

In live trading, when calling the _G() function without passing any parameters, the _G() function returns the Id of the current live trading.

When calling the _G() function, passing null for parameter v means deleting the k-v key-value pair.

When calling the _G() function and only passing parameter k (string type), the _G() function returns the saved key value corresponding to parameter k.

When calling the _G() function and only passing null for parameter k, it means deleting all recorded k-v key-value pairs.

After a k-v key-value pair has been persistently saved, calling the _G() function again with the already persistently saved key name as parameter k and a new key value as parameter v will update the k-v key-value pair.

Taking live trading Id 123456 as an example, the key-value pair data persistently saved using the _G() function is stored in the database file /logs/storage/123456/123456.db3 under the docker directory to which the live trading (i.e., strategy instance program) belongs, and the data is recorded in the kvdb table.