'use strict'; const Packet = require('../packets/packet'); const StringParser = require('../parsers/string'); const CharsetToEncoding = require('../constants/charset_encodings.js'); const fields = ['catalog', 'schema', 'table', 'orgTable', 'name', 'orgName']; // creating JS string is relatively expensive (compared to // reading few bytes from buffer) because all string properties // except for name are unlikely to be used we postpone // string conversion until property access // // TODO: watch for integration benchmarks (one with real network buffer) // there could be bad side effect as keeping reference to a buffer makes it // sit in the memory longer (usually until final .query() callback) // Latest v8 perform much better in regard to bufferer -> string conversion, // at some point of time this optimisation might become unnecessary // see https://github.com/sidorares/node-mysql2/pull/137 // class ColumnDefinition { constructor(packet, clientEncoding) { this._buf = packet.buffer; this._clientEncoding = clientEncoding; this._catalogLength = packet.readLengthCodedNumber(); this._catalogStart = packet.offset; packet.offset += this._catalogLength; this._schemaLength = packet.readLengthCodedNumber(); this._schemaStart = packet.offset; packet.offset += this._schemaLength; this._tableLength = packet.readLengthCodedNumber(); this._tableStart = packet.offset; packet.offset += this._tableLength; this._orgTableLength = packet.readLengthCodedNumber(); this._orgTableStart = packet.offset; packet.offset += this._orgTableLength; // name is always used, don't make it lazy const _nameLength = packet.readLengthCodedNumber(); const _nameStart = packet.offset; packet.offset += _nameLength; this._orgNameLength = packet.readLengthCodedNumber(); this._orgNameStart = packet.offset; packet.offset += this._orgNameLength; packet.skip(1); // length of the following fields (always 0x0c) this.characterSet = packet.readInt16(); this.encoding = CharsetToEncoding[this.characterSet]; this.name = StringParser.decode( this._buf, this.encoding === 'binary' ? this._clientEncoding : this.encoding, _nameStart, _nameStart + _nameLength ); this.columnLength = packet.readInt32(); this.columnType = packet.readInt8(); this.flags = packet.readInt16(); this.decimals = packet.readInt8(); } inspect() { return { catalog: this.catalog, schema: this.schema, name: this.name, orgName: this.orgName, table: this.table, orgTable: this.orgTable, characterSet: this.characterSet, columnLength: this.columnLength, columnType: this.columnType, flags: this.flags, decimals: this.decimals }; } static toPacket(column, sequenceId) { let length = 17; // = 4 padding + 1 + 12 for the rest fields.forEach(field => { length += Packet.lengthCodedStringLength( column[field], CharsetToEncoding[column.characterSet] ); }); const buffer = Buffer.allocUnsafe(length); const packet = new Packet(sequenceId, buffer, 0, length); function writeField(name) { packet.writeLengthCodedString( column[name], CharsetToEncoding[column.characterSet] ); } packet.offset = 4; fields.forEach(writeField); packet.writeInt8(0x0c); packet.writeInt16(column.characterSet); packet.writeInt32(column.columnLength); packet.writeInt8(column.columnType); packet.writeInt16(column.flags); packet.writeInt8(column.decimals); packet.writeInt16(0); // filler return packet; } // node-mysql compatibility: alias "db" to "schema" get db() { return this.schema; } } const addString = function(name) { Object.defineProperty(ColumnDefinition.prototype, name, { get: function() { const start = this[`_${name}Start`]; const end = start + this[`_${name}Length`]; const val = StringParser.decode( this._buf, this.encoding === 'binary' ? this._clientEncoding : this.encoding, start, end ); Object.defineProperty(this, name, { value: val, writable: false, configurable: false, enumerable: false }); return val; } }); }; addString('catalog'); addString('schema'); addString('table'); addString('orgTable'); addString('orgName'); module.exports = ColumnDefinition;