Fix 100% CPU problem

Author: testn

lib/commands/query.js

@@ -212,7 +212,7 @@ class Query extends Command {
     if (this._receivedFieldsCount === this._fieldCount) {
       const fields = this._fields[this._resultIndex];
       this.emit('fields', fields);
-      this._rowParser = new (getTextParser(fields, this.options, connection.config))();
+      this._rowParser = new (getTextParser(fields, this.options, connection.config))(fields);
       return Query.prototype.fieldsEOF;
     }
     return Query.prototype.readField;

lib/parsers/text_parser.js

@@ -78,6 +78,25 @@ function compile(fields, options, config) {
     options.typeCast = config.typeCast;
   }
 
+  function wrap(field, _this) {
+    return {
+      type: typeNames[field.columnType],
+      length: field.columnLength,
+      db: field.schema,
+      table: field.table,
+      name: field.name,
+      string: function() {
+        return _this.packet.readLengthCodedString(field.encoding);
+      },
+      buffer: function() {
+        return _this.packet.readLengthCodedBuffer();
+      },
+      geometry: function() {
+        return _this.packet.parseGeometryValue();
+      }
+    };
+  }
+
   const parserFn = genFunc();
 
   /* eslint-disable no-trailing-spaces */
@@ -88,42 +107,14 @@ function compile(fields, options, config) {
   );
 
   // constructor method
-  parserFn('constructor() {');
+  parserFn('constructor(fields) {');
   // node-mysql typeCast compatibility wrapper
   // see https://github.com/mysqljs/mysql/blob/96fdd0566b654436624e2375c7b6604b1f50f825/lib/protocol/packets/Field.js
   if (typeof options.typeCast === 'function') {
     parserFn('const _this = this;');
-    for(let i=0; i<fields.length; ++i) {
-      const field = fields[i];
-      const encodingExpr = helpers.srcEscape(field.encoding);
-      const readCode = readCodeFor(
-        fields[i].columnType,
-        fields[i].characterSet,
-        encodingExpr,
-        config,
-        options
-      );
-      parserFn(`this.wrap${i} = {
-        type: ${helpers.srcEscape(typeNames[field.columnType])},
-        length: ${field.columnLength},
-        db: ${helpers.srcEscape(field.schema)},
-        table: ${helpers.srcEscape(field.table)},
-        name: ${helpers.srcEscape(field.name)},
-        string: function() {
-          return _this.packet.readLengthCodedString(${encodingExpr});
-        },
-        buffer: function() {
-          return _this.packet.readLengthCodedBuffer();
-        },
-        geometry: function() {
-          return _this.packet.parseGeometryValue();
-        },
-        readNext: function() {
-          const packet = _this.packet;
-          return ${readCode};
-        }
-      };`);
-    }
+    parserFn('for(let i=0; i<fields.length; ++i) {');
+    parserFn('this[`wrap${i}`] = wrap(fields[i], _this);');
+    parserFn('}');
   }
   parserFn('}');
 
@@ -165,9 +156,7 @@ function compile(fields, options, config) {
     } else {
       lvalue = `result[${fieldName}]`;
     }
-    if (typeof options.typeCast === 'function') {
-      parserFn(`${lvalue} = options.typeCast(this.wrap${i}, this.wrap${i}.readNext);`);
-    } else if (options.typeCast === false) {
+    if (options.typeCast === false) {
       parserFn(`${lvalue} = packet.readLengthCodedBuffer();`);
     } else {
       const encodingExpr = `fields[${i}].encoding`;
@@ -178,8 +167,12 @@ function compile(fields, options, config) {
         config,
         options
       );
-      parserFn(`${lvalue} = ${readCode};`);
-    }
+      if (typeof options.typeCast === 'function') {
+        parserFn(`${lvalue} = options.typeCast(this.wrap${i}, function() { return ${readCode} });`);
+      }  else {
+        parserFn(`${lvalue} = ${readCode};`);
+      }
+    }  
   }
 
   parserFn('return result;');
@@ -196,6 +189,9 @@ function compile(fields, options, config) {
       parserFn.toString()
     );
   }
+  if (typeof options.typeCast === 'function') {
+    return parserFn.toFunction({wrap});
+  } 
   return parserFn.toFunction();
 }