Joe
104 lines
3.7 KiB
JavaScript
104 lines
3.7 KiB
JavaScript
"use strict";
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//binary data writer tuned for encoding binary specific to the postgres binary protocol
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Object.defineProperty(exports, "__esModule", { value: true });
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exports.Writer = void 0;
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class Writer {
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constructor(size = 256) {
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this.size = size;
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this.offset = 5;
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this.headerPosition = 0;
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this.buffer = Buffer.allocUnsafe(size);
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}
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ensure(size) {
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const remaining = this.buffer.length - this.offset;
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if (remaining < size) {
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const oldBuffer = this.buffer;
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// exponential growth factor of around ~ 1.5
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// https://stackoverflow.com/questions/2269063/buffer-growth-strategy
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const newSize = oldBuffer.length + (oldBuffer.length >> 1) + size;
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this.buffer = Buffer.allocUnsafe(newSize);
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oldBuffer.copy(this.buffer);
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}
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}
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addInt32(num) {
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this.ensure(4);
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this.buffer[this.offset++] = (num >>> 24) & 0xff;
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this.buffer[this.offset++] = (num >>> 16) & 0xff;
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this.buffer[this.offset++] = (num >>> 8) & 0xff;
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this.buffer[this.offset++] = (num >>> 0) & 0xff;
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return this;
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}
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addInt16(num) {
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this.ensure(2);
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this.buffer[this.offset++] = (num >>> 8) & 0xff;
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this.buffer[this.offset++] = (num >>> 0) & 0xff;
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return this;
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}
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addCString(string) {
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if (!string) {
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this.ensure(1);
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}
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else {
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const len = Buffer.byteLength(string);
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this.ensure(len + 1); // +1 for null terminator
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this.buffer.write(string, this.offset, 'utf-8');
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this.offset += len;
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}
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this.buffer[this.offset++] = 0; // null terminator
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return this;
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}
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addString(string = '') {
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const len = Buffer.byteLength(string);
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this.ensure(len);
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this.buffer.write(string, this.offset);
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this.offset += len;
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return this;
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}
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// Write an Int32 byte-length prefix immediately followed by the string's UTF-8
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// bytes. Postgres' Bind wire format prefixes every parameter with its length,
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// and doing it in one method computes Buffer.byteLength ONCE — the previous
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// `addInt32(Buffer.byteLength(s)).addString(s)` pairing scanned the string
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// three times (byteLength for the prefix, byteLength again inside addString,
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// then the encode), which is costly for large text parameters.
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addInt32PrefixedString(string) {
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const len = Buffer.byteLength(string);
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this.ensure(4 + len);
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const buffer = this.buffer;
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let offset = this.offset;
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buffer[offset++] = (len >>> 24) & 0xff;
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buffer[offset++] = (len >>> 16) & 0xff;
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buffer[offset++] = (len >>> 8) & 0xff;
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buffer[offset++] = (len >>> 0) & 0xff;
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buffer.write(string, offset, 'utf-8');
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this.offset = offset + len;
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return this;
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}
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add(otherBuffer) {
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this.ensure(otherBuffer.length);
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otherBuffer.copy(this.buffer, this.offset);
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this.offset += otherBuffer.length;
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return this;
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}
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join(code) {
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if (code) {
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this.buffer[this.headerPosition] = code;
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//length is everything in this packet minus the code
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const length = this.offset - (this.headerPosition + 1);
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this.buffer.writeInt32BE(length, this.headerPosition + 1);
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}
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return this.buffer.slice(code ? 0 : 5, this.offset);
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}
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flush(code) {
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const result = this.join(code);
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this.offset = 5;
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this.headerPosition = 0;
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this.buffer = Buffer.allocUnsafe(this.size);
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return result;
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}
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clear() {
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this.offset = 5;
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this.headerPosition = 0;
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}
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}
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exports.Writer = Writer;
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//# sourceMappingURL=buffer-writer.js.map
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