_C

A retry function used for fault-tolerant handling of interface calls.

    
    
    
_C(pfn)

    
    
    
_C(pfn, ...args)

Examples

• Apply fault-tolerant handling to a function without parameters:

  • javascript
  • python
  • rust
  • cpp

  
      javascript
      
      
  function main(){
      var ticker = _C(exchange.GetTicker)
      // Change the retry interval of the _C() function to 2 seconds
      _CDelay(2000)
      var depth = _C(exchange.GetDepth)
      Log(ticker)
      Log(depth)
  }
  

  
      python
      
      
  def main():
      ticker = _C(exchange.GetTicker)
      _CDelay(2000)
      depth = _C(exchange.GetDepth)
      Log(ticker)
      Log(depth)
  

  
      rust
      
      
  fn main() {
      let ticker = _C!(exchange.GetTicker(None));
      // Change the retry interval of the _C!() macro to 2 seconds
      _CDelay(2000);
      let depth = _C!(exchange.GetDepth(None));
      Log!(ticker);
      Log!(depth);
  }
  

  
      c++
      
      
  void main() {
      auto ticker = _C(exchange.GetTicker);
      _CDelay(2000);
      auto depth = _C(exchange.GetDepth);
      Log(ticker);
      Log(depth);
  }
  

• Apply fault-tolerant handling to a function with parameters:

  • javascript
  • python
  • rust
  • cpp

  
      javascript
      
      
  function main(){
      var records = _C(exchange.GetRecords, PERIOD_D1)
      Log(records)
  }
  

  
      python
      
      
  def main():
      records = _C(exchange.GetRecords, PERIOD_D1)
      Log(records)
  

  
      rust
      
      
  fn main() {
      let records = _C!(exchange.GetRecords(None, PERIOD_D1, None));
      Log!(records);
  }
  

  
      c++
      
      
  void main() {
      auto records = _C(exchange.GetRecords, PERIOD_D1);
      Log(records);
  }
  

• It can also be used to apply fault-tolerant handling to custom functions:

  • javascript
  • python
  • rust
  • cpp

  
      javascript
      
      
  var test = function(a, b){
      var time = new Date().getTime() / 1000
      if(time % b == 3){
          Log("Condition met!", "#FF0000")
          return true
      }
      Log("Retrying!", "#FF0000")
      return false
  }
  
  function main(){
      var ret = _C(test, 1, 5)
      Log(ret)
  }
  

  
      python
      
      
  import time
  def test(a, b):
      ts = time.time()
      if ts % b == 3:
          Log("Condition met!", "#FF0000")
          return True
      Log("Retrying!", "#FF0000")
      return False
  
  def main():
      ret = _C(test, 1, 5)
      Log(ret)
  

  
      rust
      
      
  fn test(a: i64, b: i64) -> Result<bool> {
      let time = Unix();
      if time % b == 3 {
          Log!("Condition met!", "#FF0000");
          return Ok(true);
      }
      Log!("Retrying!", "#FF0000");
      Err(Error::Api("retry".to_string()))
  }
  
  fn main() {
      // In Rust, a custom function can use the _C! macro for fault tolerance as long as it returns a Result type; it will retry when Err is returned
      let ret = _C!(test(1, 5));
      Log!(ret);
  }
  

  
      c++
      
      
  // C++ does not support this way of applying fault tolerance to custom functions

Returns

Arguments

Remarks

The _C() function repeatedly calls the specified function until it returns successfully (when the function referenced by the parameter pfn returns a null value or a false value upon being called, the call to pfn will be retried).

For example, _C(exchange.GetTicker). The default retry interval is 3 seconds, and you can call the _CDelay() function to set the retry interval.

For example, _CDelay(1000) means changing the retry interval of the _C() function to 1 second.

Fault-tolerant handling can be applied to the following functions (but is not limited to them):

• exchange.GetTicker()
• exchange.GetDepth()
• exchange.GetTrades()
• exchange.GetRecords()
• exchange.GetAccount()
• exchange.GetOrders()
• exchange.GetOrder()
• exchange.GetPositions()

All of the above functions can be called through the _C() function to achieve fault tolerance. The fault tolerance of the _C() function is not limited to the functions listed above. Please note that the parameter pfn is a function reference rather than a function call, i.e. it should be written as _C(exchange.GetTicker), not _C(exchange.GetTicker()).