buffer-writer.js•2.77 kB
"use strict";
//binary data writer tuned for encoding binary specific to the postgres binary protocol
Object.defineProperty(exports, "__esModule", { value: true });
exports.Writer = void 0;
class Writer {
constructor(size = 256) {
this.size = size;
this.offset = 5;
this.headerPosition = 0;
this.buffer = Buffer.allocUnsafe(size);
}
ensure(size) {
const remaining = this.buffer.length - this.offset;
if (remaining < size) {
const oldBuffer = this.buffer;
// exponential growth factor of around ~ 1.5
// https://stackoverflow.com/questions/2269063/buffer-growth-strategy
const newSize = oldBuffer.length + (oldBuffer.length >> 1) + size;
this.buffer = Buffer.allocUnsafe(newSize);
oldBuffer.copy(this.buffer);
}
}
addInt32(num) {
this.ensure(4);
this.buffer[this.offset++] = (num >>> 24) & 0xff;
this.buffer[this.offset++] = (num >>> 16) & 0xff;
this.buffer[this.offset++] = (num >>> 8) & 0xff;
this.buffer[this.offset++] = (num >>> 0) & 0xff;
return this;
}
addInt16(num) {
this.ensure(2);
this.buffer[this.offset++] = (num >>> 8) & 0xff;
this.buffer[this.offset++] = (num >>> 0) & 0xff;
return this;
}
addCString(string) {
if (!string) {
this.ensure(1);
}
else {
const len = Buffer.byteLength(string);
this.ensure(len + 1); // +1 for null terminator
this.buffer.write(string, this.offset, 'utf-8');
this.offset += len;
}
this.buffer[this.offset++] = 0; // null terminator
return this;
}
addString(string = '') {
const len = Buffer.byteLength(string);
this.ensure(len);
this.buffer.write(string, this.offset);
this.offset += len;
return this;
}
add(otherBuffer) {
this.ensure(otherBuffer.length);
otherBuffer.copy(this.buffer, this.offset);
this.offset += otherBuffer.length;
return this;
}
join(code) {
if (code) {
this.buffer[this.headerPosition] = code;
//length is everything in this packet minus the code
const length = this.offset - (this.headerPosition + 1);
this.buffer.writeInt32BE(length, this.headerPosition + 1);
}
return this.buffer.slice(code ? 0 : 5, this.offset);
}
flush(code) {
const result = this.join(code);
this.offset = 5;
this.headerPosition = 0;
this.buffer = Buffer.allocUnsafe(this.size);
return result;
}
}
exports.Writer = Writer;
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