62 lines
2.1 KiB
JavaScript
62 lines
2.1 KiB
JavaScript
import { Crc32 } from "@aws-crypto/crc32";
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import { HeaderMarshaller } from "./HeaderMarshaller";
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import { splitMessage } from "./splitMessage";
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export class EventStreamCodec {
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constructor(toUtf8, fromUtf8) {
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this.headerMarshaller = new HeaderMarshaller(toUtf8, fromUtf8);
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this.messageBuffer = [];
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this.isEndOfStream = false;
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}
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feed(message) {
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this.messageBuffer.push(this.decode(message));
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}
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endOfStream() {
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this.isEndOfStream = true;
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}
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getMessage() {
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const message = this.messageBuffer.pop();
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const isEndOfStream = this.isEndOfStream;
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return {
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getMessage() {
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return message;
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},
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isEndOfStream() {
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return isEndOfStream;
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},
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};
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}
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getAvailableMessages() {
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const messages = this.messageBuffer;
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this.messageBuffer = [];
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const isEndOfStream = this.isEndOfStream;
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return {
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getMessages() {
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return messages;
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},
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isEndOfStream() {
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return isEndOfStream;
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},
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};
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}
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encode({ headers: rawHeaders, body }) {
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const headers = this.headerMarshaller.format(rawHeaders);
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const length = headers.byteLength + body.byteLength + 16;
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const out = new Uint8Array(length);
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const view = new DataView(out.buffer, out.byteOffset, out.byteLength);
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const checksum = new Crc32();
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view.setUint32(0, length, false);
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view.setUint32(4, headers.byteLength, false);
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view.setUint32(8, checksum.update(out.subarray(0, 8)).digest(), false);
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out.set(headers, 12);
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out.set(body, headers.byteLength + 12);
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view.setUint32(length - 4, checksum.update(out.subarray(8, length - 4)).digest(), false);
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return out;
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}
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decode(message) {
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const { headers, body } = splitMessage(message);
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return { headers: this.headerMarshaller.parse(headers), body };
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}
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formatHeaders(rawHeaders) {
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return this.headerMarshaller.format(rawHeaders);
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}
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}
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