/// <summary>
/// 异步计算查询表达式，进行学术文献直方图的检索。启用分页。
/// </summary>
private async Task CalcHistogramAsync(string expression, string attributes, ParitionedPromise <CalcHistogramResult> promise)
{
if (string.IsNullOrEmpty(attributes))
{
throw new ArgumentNullException(nameof(attributes));
}
if (promise == null)
{
throw new ArgumentNullException(nameof(promise));
}
Logger.AcademicSearch.Enter(this, $"{expression}, Paged");
var noMoreResults = false;
for (var offset = 0;; offset += PagingSize)
{
var result = await CalcHistogramAsync(expression, PagingSize, offset, attributes);
if (result.Histograms.Any(h => h.Entries.Count > 0))
{
promise.DeclarePartitionFinished(result);
}
if (result.Histograms.All(h => h.Entries.Count < PagingSize))
{
// 没有结果了。
noMoreResults = true;
break;
}
}
Logger.AcademicSearch.Exit(this, $"{expression}; {(noMoreResults ? "" : " Truncated.")}");
}
/// <summary>
/// 异步计算查询表达式，进行学术文献直方图的检索。启用分页。
/// </summary>
public ParitionedPromise <CalcHistogramResult> CalcHistogramAsync(string expression, string attributes)
{
var promise = new ParitionedPromise <CalcHistogramResult>();
promise.SetProducerTask(CalcHistogramAsync(expression, attributes, promise));
return(promise);
}
