Csv解析性能优化

MesETL.App/Services/ETL/CsvReader.cs

@@ -49,43 +49,44 @@ public class CsvReader : IDataReader
         if (string.IsNullOrWhiteSpace(str))
             return false;
 
-        var fields = ParseRow(str, QuoteChar, Delimiter);
+        var fields = ParseRow(str, QuoteChar, Delimiter[0]);
         Current = new DataRecord(fields, TableName, Headers);
         return true;
     }
 
-    public string[] ParseRow(ReadOnlySpan<char> source, char quoteChar, string delimiter)
+    public static string[] ParseRow(ReadOnlySpan<char> source, char quoteChar, char delimiter)
     {
         var result = new List<string>();
         var index = -1;
-        var current = new StringBuilder();
+        var current = new StringBuilder(source.Length);
         var hasQuote = false;
         var hasSlash = false;
         while (index < source.Length - 1)
         {
             index++;
-            if (hasSlash == false && source[index] == '\\')
+            var currChar = source[index];
+            if (hasSlash == false && currChar == '\\')
             {
                 hasSlash = true;
                 current.Append('\\');
                 continue;
             }
 
-            if (hasSlash == false && source[index] == quoteChar)
+            if (hasSlash == false && currChar == quoteChar)
             {
                 hasQuote = !hasQuote;
-                current.Append(source[index]);
+                current.Append(currChar);
                 continue;
             }
 
-            if (hasQuote == false && source[index] == delimiter[0])
+            if (hasQuote == false && currChar == delimiter)
             {
                 result.Add(current.ToString());
                 current.Clear();
             }
             else
             {
-                current.Append(source[index]);
+                current.Append(currChar);
             }
 
             hasSlash = false;
@@ -94,6 +95,54 @@ public class CsvReader : IDataReader
         result.Add(current.ToString());
         return result.ToArray();
     }
+    
+    public static List<string> ParseRowFaster(ReadOnlySpan<char> source, char quoteChar, char delimiter, int columnCount = 10)
+    {
+        var result = new List<string>(columnCount);
+        var index = -1;
+        var hasQuote = false;
+        var hasSlash = false;
+        var start = 0;
+        var end = 0;
+        var len = source.Length - 1;
+        while (index < len)
+        {
+            ++index;
+            var currChar = source[index];
+            
+            if (!hasSlash)
+            {
+                if (currChar is '\\')
+                {
+                    hasSlash = true;
+                    ++end;
+                    continue;
+                }
+
+                if (currChar == quoteChar)
+                {
+                    hasQuote = !hasQuote;
+                    ++end;
+                    continue;
+                }
+            }
+            
+            if (!hasQuote && currChar == delimiter)
+            {
+                result.Add(source[start..(end + 1)].ToString());
+                start = end + 2;
+            }
+            else
+            {
+                ++end;
+            }
+
+            hasSlash = false;
+        }
+
+        result.Add(source[start..(end + 1)].ToString());
+        return result;
+    }
 
     public virtual void Dispose()
     {

MesETL.App/Services/ETL/ZstReader.cs

@@ -31,7 +31,7 @@ public class ZstReader : CsvReader
         if (string.IsNullOrWhiteSpace(str))
             return false;
 
-        var fields = ParseRow(str, QuoteChar, Delimiter);
+        var fields = ParseRow(str, QuoteChar, Delimiter[0]);
         Current = new DataRecord(fields, TableName, Headers);
         return true;
     }