open-nomad/ui/app/utils/classes/stream-logger.js
2022-01-20 09:46:45 -05:00

94 lines
2.6 KiB
JavaScript

import EmberObject, { computed } from '@ember/object';
import { task } from 'ember-concurrency';
import TextDecoder from 'nomad-ui/utils/classes/text-decoder';
import { decode } from 'nomad-ui/utils/stream-frames';
import AbstractLogger from './abstract-logger';
import { fetchFailure } from './log';
import classic from 'ember-classic-decorator';
@classic
export default class StreamLogger extends EmberObject.extend(AbstractLogger) {
reader = null;
@computed()
get additionalParams() {
return {
follow: true,
};
}
start() {
return this.poll.perform();
}
stop() {
const reader = this.reader;
if (reader) {
reader.cancel();
}
return this.poll.cancelAll();
}
@task(function* () {
const url = this.fullUrl;
const logFetch = this.logFetch;
const reader = yield logFetch(url).then((res) => {
const reader = res.body.getReader();
// It's possible that the logger was stopped between the time
// polling was started and the log request responded.
// If the logger was stopped, the reader needs to be immediately
// canceled to prevent an endless request running in the background.
if (this.poll.isRunning) {
return reader;
}
reader.cancel();
}, fetchFailure(url));
if (!reader) {
return;
}
this.set('reader', reader);
let streamClosed = false;
let buffer = '';
const decoder = new TextDecoder();
while (!streamClosed) {
yield reader.read().then(({ value, done }) => {
streamClosed = done;
// There is no guarantee that value will be a complete JSON object,
// so it needs to be buffered.
buffer += decoder.decode(value, { stream: true });
// Only when the buffer contains a close bracket can we be sure the buffer
// is in a complete state
if (buffer.indexOf('}') !== -1) {
// The buffer can be one or more complete frames with additional text for the
// next frame
const [, chunk, newBuffer] = buffer.match(/(.*\})(.*)$/);
// Peel chunk off the front of the buffer (since it represents complete frames)
// and set the buffer to be the remainder
buffer = newBuffer;
// Assuming the logs endpoint never returns nested JSON (it shouldn't), at this
// point chunk is a series of valid JSON objects with no delimiter.
const { offset, message } = decode(chunk);
if (message) {
this.set('endOffset', offset);
this.write(message);
}
}
});
}
})
poll;
}
StreamLogger.reopenClass({
isSupported: !!window.ReadableStream,
});