109 lines
3.5 KiB
JavaScript
109 lines
3.5 KiB
JavaScript
"use strict";
|
|
//binary data writer tuned for creating
|
|
//postgres message packets as effeciently as possible by reusing the
|
|
//same buffer to avoid memcpy and limit memory allocations
|
|
Object.defineProperty(exports, "__esModule", { value: true });
|
|
class Writer {
|
|
constructor(size = 1024) {
|
|
this.offset = 5;
|
|
this.headerPosition = 0;
|
|
this.encoding = 'utf-8';
|
|
this.buffer = Buffer.alloc(size + 5);
|
|
}
|
|
_ensure(size) {
|
|
var remaining = this.buffer.length - this.offset;
|
|
if (remaining < size) {
|
|
var oldBuffer = this.buffer;
|
|
// exponential growth factor of around ~ 1.5
|
|
// https://stackoverflow.com/questions/2269063/buffer-growth-strategy
|
|
var newSize = oldBuffer.length + (oldBuffer.length >> 1) + size;
|
|
this.buffer = Buffer.alloc(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) {
|
|
//just write a 0 for empty or null strings
|
|
if (!string) {
|
|
this._ensure(1);
|
|
}
|
|
else {
|
|
var len = Buffer.byteLength(string);
|
|
this._ensure(len + 1); //+1 for null terminator
|
|
this.buffer.write(string, this.offset, this.encoding);
|
|
this.offset += len;
|
|
}
|
|
this.buffer[this.offset++] = 0; // null terminator
|
|
return this;
|
|
}
|
|
// note: this assumes character is 1 byte - used for writing protocol charcodes
|
|
addChar(c) {
|
|
this._ensure(1);
|
|
this.buffer.write(c, this.offset);
|
|
this.offset++;
|
|
return this;
|
|
}
|
|
addString(string = "") {
|
|
var len = Buffer.byteLength(string);
|
|
this._ensure(len);
|
|
this.buffer.write(string, this.offset);
|
|
this.offset += len;
|
|
return this;
|
|
}
|
|
getByteLength() {
|
|
return this.offset - 5;
|
|
}
|
|
add(otherBuffer) {
|
|
this._ensure(otherBuffer.length);
|
|
otherBuffer.copy(this.buffer, this.offset);
|
|
this.offset += otherBuffer.length;
|
|
return this;
|
|
}
|
|
clear() {
|
|
this.offset = 5;
|
|
this.headerPosition = 0;
|
|
}
|
|
//appends a header block to all the written data since the last
|
|
//subsequent header or to the beginning if there is only one data block
|
|
addHeader(code, last = false) {
|
|
var origOffset = this.offset;
|
|
this.offset = this.headerPosition;
|
|
this.buffer[this.offset++] = code;
|
|
//length is everything in this packet minus the code
|
|
this.addInt32(origOffset - (this.headerPosition + 1));
|
|
//set next header position
|
|
this.headerPosition = origOffset;
|
|
//make space for next header
|
|
this.offset = origOffset;
|
|
if (!last) {
|
|
this._ensure(5);
|
|
this.offset += 5;
|
|
}
|
|
}
|
|
join(code) {
|
|
if (code) {
|
|
this.addHeader(code, true);
|
|
}
|
|
return this.buffer.slice(code ? 0 : 5, this.offset);
|
|
}
|
|
flush(code) {
|
|
var result = this.join(code);
|
|
this.clear();
|
|
return result;
|
|
}
|
|
}
|
|
exports.Writer = Writer;
|
|
//# sourceMappingURL=BufferWriter.js.map
|