private DbRateLimiterConfig GetDbConfig(RateLimiterConfig config)
{
var dbConfig = new DbRateLimiterConfig
{
RequestTimeout = config.RequestTimeout
};
switch (config.RateLimiterType)
{
case RateLimiterType.Burst:
dbConfig.MaxTokens = config.IntervalCount;
dbConfig.OperationsInterval = config.IntervalRange;
break;
case RateLimiterType.Interval:
dbConfig.MaxTokens = 1;
dbConfig.OperationsInterval = TimeSpanDivision(config.IntervalRange, config.IntervalCount);
break;
default:
throw new ArgumentOutOfRangeException($"Unknown RateLimiter type of {config.RateLimiterType:G}");
}
dbConfig.StorageKey = GetStorageKey(
config.Key,
dbConfig.MaxTokens,
dbConfig.OperationsInterval.Milliseconds);
return(dbConfig);
}
private DateTimeOffset TryAllocateToken(DbRateLimiterConfig config)
{
var startDate = DateTimeOffset.UtcNow;
for (var current = startDate;
current - startDate < config.RequestTimeout;
current = DateTimeOffset.UtcNow)
{
var expirationDate = current.Subtract(config.OperationsInterval);
var tokenCount = _repo.GetTokenCount(config.StorageKey, expirationDate);
if (tokenCount >= config.MaxTokens)
{
//TODO: dynamic backoff sleep or retry class (move to top)
System.Threading.Thread.Sleep(TimeSpan.FromSeconds(5));
continue;
}
_repo.AllocateToken(config);
return(current);
}
throw new RateLimitTimeoutException($"Could not get a token in '{config.RequestTimeout.Seconds}' seconds");
}