我有一个非常独特的情况，我正在生成一个文件，我必须使用嵌套循环。
因此，对于当前文件，我有4级嵌套的foreach（）。当数据较少时，其性能还可以，ok类型仍然不好但是当数据开始增长时，循环因嵌套而呈指数级增长。
因此需要花费很多时间。请建议我一些替代方案或如何优化我的代码。
用例： 我试图打印的文件说有一个带有这些嵌套循环的结构的蓝色打印，所以我不得不使用嵌套。
例如：
Member Details (Level 1)
Health Coverage (Level 2)
Provider Information (Level 3)
BeneFits (Level 4)
因此，会员详细信息可以具有多个健康保险范围，其中每个健康保险范围可以包含多个提供商，其中每个提供商可以享有多种福利。
希望在实时示例中帮助我的情况
Level1
foreach()
{
//do some stuff
//writer.writeline();
level2
foreach()
{
//do some stuff
//writer.writeline();
level3
foreach()
{
//do some stuff
//writer.writeline();
level4
foreach()
{
//do some stuff
//writer.writeline();
}
}
}
}
在writeWholeLine（）下面使用的方法中，它为每个循环再次包含3个嵌套，由于正文的字符限制而无法在此处发布代码
private string TransactionsGeneration(StreamWriter writer, string line, int maximumCount)
{
#region Re-Generation
TransactionCounter = 0;
foreach (DataRow memRow in MemberTblMaster.Rows)
{
TransactionCounter++;
line = string.Empty; //begin of a new Transaction
//Counter
TotalLines = 0;
ST_SE_UniqueCode = 0;
// Fill the dataset based on the member id
MemberID = Convert.ToString(memRow[MEMBER_ID]).Trim();
HealthCoverageTbl = HealthCoverageTblMaster.AsEnumerable().Where(x => x.Field<string>(MEMBER_ID).Trim() == MemberID);
Associations834Tbl = Associations834TblMaster.AsEnumerable().Where(x => x.Field<string>(MEMBER_ID).Trim() == MemberID);
AddressTbl = AddressTblMaster.AsEnumerable().Where(x => x.Field<string>(MEMBER_ID).Trim() == MemberID);
GenNameInfoTbl = GenNameInfoTblMaster.AsEnumerable().Where(x => x.Field<string>(Gen_Name_ID).Trim() == memRow[Sponsor_ID].ToString().Trim() ||
x.Field<string>(Gen_Name_ID).Trim() == memRow[Payer_ID].ToString().Trim() ||
x.Field<string>(Gen_Name_ID).Trim() == memRow[TPA_Broker_ID].ToString().Trim()
);
ContactTbl = ContactTblMaster.AsEnumerable().Where(x => x.Field<string>(MEMBER_ID).Trim() == MemberID);
GenReferenceTbl = GenReferenceTblMaster.AsEnumerable().Where(x => x.Field<string>(MEMBER_ID).Trim() == MemberID);
MemberTbl = MemberTblMaster.AsEnumerable().Where(x => x.Field<string>(MEMBER_ID).Trim() == MemberID);
// Based on Health Coverage
//Provider , COB
var loopLevel1 = (from row in LoopOrder.AsEnumerable()
where row.Field<int>(HIERARCHY_LEVEL) == 1
&& !Header.Contains(row.Field<string>(LOOP_ID).Trim())
&& !Footer.Contains(row.Field<string>(LOOP_ID).Trim())
select row);
foreach (DataRow parentLoop in loopLevel1)
{
//Level 1
//TODO : Need to implement the parent loop functionality
ParentLoop = Convert.ToString(parentLoop[PARENT_LOOP]);
string loopIDofLoopOrder = parentLoop[LOOP_ID].ToString();
LoopID = loopIDofLoopOrder;
var resultLevel1 = (from row in ValidationElementAttribute.AsEnumerable()
where row.Field<string>(LoopIdSegment).Trim() == loopIDofLoopOrder
select row);
if (resultLevel1.Any())
{
int maxCount1;
if (String.IsNullOrEmpty(Convert.ToString(parentLoop[Repeat_max])))
maxCount1 = maximumCount; //Max_Repitition = NULL means infinite number of repititions allowed; no upper cap
else
maxCount1 = Convert.ToInt32(parentLoop[Repeat_max]);
for (int i = 0; i < maxCount1; i++) //until all the repititions are covered, keep repeating the same loop, else change the parent loop
{
SkipLine = false;
WriteWholeLine(line, i, resultLevel1, writer, memRow);
#region Level 2
var loopLevel2 = (from row in LoopOrder.AsEnumerable()
where row.Field<int>(HIERARCHY_LEVEL) == 2
&& row.Field<string>(PARENT_LOOP).Trim() == loopIDofLoopOrder.Trim()
select row);
foreach (DataRow level2 in loopLevel2)
{
//Level 2
// ChildLoop = Convert.ToString(level2["PARENT_LOOP"]);// 1000C
ChildLoop = Convert.ToString(level2[LOOP_ID]);// 1100C
LoopID = ChildLoop;
var resultLevel2 = (from row in ValidationElementAttribute.AsEnumerable()
where row.Field<string>(LoopIdSegment).Trim() == ChildLoop.Trim()
select row);
//var healthCoverageIdList = memberEnrollment.Select(x => x.Field<object>(Health_Coverage_ID)).Distinct().ToList();
if (resultLevel2.Any())
{
int maxCount2;
if (String.IsNullOrEmpty(Convert.ToString(level2[Repeat_max])))
maxCount2 = maximumCount;
else
maxCount2 = Convert.ToInt32(level2[Repeat_max]);
//Custom Code
// maxCount2= ChildLoop == _2300 ? healthCoverageIdList.Count : maxCount2;
for (int j = 0; j < maxCount2; j++)
{
SkipLine = false;
//Custom Code
//if (ChildLoop == "2300")
//{
// WriteWholeLine(line, j, resultLevel2, writer, memRow, memberEnrollment.Where(x => x.Field<object>(Health_Coverage_ID) == healthCoverageIdList[j]).Select(x => x));
//}
//else
//{
//WriteWholeLine(line, j, resultLevel2, writer, memRow, memberEnrollment);
//}
WriteWholeLine(line, j, resultLevel2, writer, memRow);
if (HealthCoverageTbl.Any() && HealthCoverageTbl.Count() > j)
{
HealthCoverageID = Convert.ToString(HealthCoverageTbl.ElementAt(j).Field<string>(Health_Coverage_ID)).Trim();
}
else
{
HealthCoverageID = string.Empty;
}
#region Level 3
var loopLevel3 = (from row in LoopOrder.AsEnumerable()
where row.Field<int>(HIERARCHY_LEVEL) == 3
&& row.Field<string>(PARENT_LOOP).Trim() == ChildLoop.Trim()
select row);
foreach (DataRow level3 in loopLevel3)
{
//Level 3
ChildLoopLevel3 = Convert.ToString(level3[LOOP_ID]);
LoopID = ChildLoopLevel3;
var resultLevel3 = (from row in ValidationElementAttribute.AsEnumerable()
where row.Field<string>(LoopIdSegment).Trim() == ChildLoopLevel3.Trim()
select row);
if (resultLevel3.Any())
{
CobInfoTbl = CobInfoTblMaster.AsEnumerable().Where(x => x.Field<string>(Health_Coverage_ID).Trim() == HealthCoverageID).Select(x => x);
ProviderTbl = ProviderTblMaster.AsEnumerable().Where(x => x.Field<string>(Health_Coverage_ID).Trim() == HealthCoverageID).Select(x => x);
LXcounter = 0;
int maxCount3;
if (String.IsNullOrEmpty(Convert.ToString(level3[Repeat_max])))
maxCount3 = maximumCount;
else
maxCount3 = Convert.ToInt32(level3[Repeat_max]);
for (int k = 0; k < maxCount3; k++)
{
SkipLine = false;
if (CobInfoTbl.Any() && CobInfoTbl.Count() > k)
{
CobInfoID = CobInfoTbl.ElementAt(k).Field<string>(COB_ID);
}
else
{
CobInfoID = Convert.ToString("0");
}
//Not used : uncomment if Provider ID needed.
if (ProviderTbl.Any() && ProviderTbl.Count() > k)
{
ProviderID = ProviderTbl.ElementAt(k).Field<string>(Provider_ID).Trim();
}
else
{
ProviderID = string.Empty;
}
WriteWholeLine(line, k, resultLevel3, writer, memRow);
#region Level 4
var loopLevel4 = (from row in LoopOrder.AsEnumerable()
where row.Field<int>(HIERARCHY_LEVEL) == 4
&& row.Field<string>(PARENT_LOOP).Trim() == ChildLoopLevel3.Trim()
select row);
foreach (DataRow level4 in loopLevel4)
{
//Level 4
ChildLoopLevel4 = Convert.ToString(level4[LOOP_ID]);
LoopID = ChildLoopLevel4;
var resultLevel4 = (from row in ValidationElementAttribute.AsEnumerable()
where row.Field<string>(LoopIdSegment).Trim() == ChildLoopLevel4.Trim()
select row);
if (resultLevel4.Any())
{
int maxCount4;
if (String.IsNullOrEmpty(Convert.ToString(level4[Repeat_max])))
maxCount4 = maximumCount;
else
maxCount4 = Convert.ToInt32(level4[Repeat_max]);
for (int l = 0; l < maxCount4; l++)
{
SkipLine = false;
WriteWholeLine(line, l, resultLevel4, writer, memRow);
}
}
}
#endregion
}
}
}
#endregion
}
}
}
#endregion
}
}
}
// TODO : remove below break
// break;
}
//end of Regeneration
#endregion
return line;
}
答案 0 :(得分：0)
如果条目的顺序无关紧要，因为每个嵌套循环的结果都不需要具有foreach源所具有的结构。
A-> B-> C-> D-> E每个代表一个嵌套循环，你可以并行执行。
因为所有数据操作都应该相同，所以将所有foreach重写为并行。将结果保存到ConcurrentDictionary之类的集合中