internal async Task CreateAsync(UrlItem urlItem)
{
// Add item to database
_dbContext.Urls.Add(urlItem);
var success = false;
Exception?lastException = null;
// Try max 10 times before giving up
string key = null;
for (var i = 0; i < 10; i++)
{
// Create random id
key = Helpers.GetRandomKey(_config.Url);
// Try to add item to database
urlItem.Key = key;
try
{
await _dbContext.SaveChangesAsync();
success = true;
}
catch (DbUpdateException dbUpdateException) when((dbUpdateException.InnerException as SqlException)?.Number == 2601)
{
// Already exists: We need to retry
_logger.LogInformation(dbUpdateException, $"Collision creating ShortUrl: {urlItem.Key}");
lastException = dbUpdateException;
continue;
}
catch (Exception exception)
{
// Not sure what is wrong, log it and try again
_logger.LogError(exception, $"Creating new ShortUrl: {JsonSerializer.Serialize(urlItem)}");
lastException = exception;
continue;
}
}
// Not success: Throw last error
if (!success)
{
throw lastException !;
}
// Success: Add item to recent used cache since it will probably be used immediately
var cacheEntryOptions = new MemoryCacheEntryOptions();
cacheEntryOptions.Size = 1;
_cache.Set <UrlItem>(key, urlItem, cacheEntryOptions);
}
internal Task Save()
{
return(ShortUrlDbContext.SaveChangesAsync());
}