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