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