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grafana/public/app/core/services/FetchQueue.ts

94 lines
3.1 KiB

import { Observable, Subject } from 'rxjs';
import { BackendSrvRequest } from '@grafana/runtime';
export interface QueueState extends Record<string, { state: FetchStatus; options: BackendSrvRequest }> {}
export enum FetchStatus {
Pending,
InProgress,
Done,
}
export interface FetchQueueUpdate {
noOfInProgress: number;
noOfPending: number;
state: QueueState;
}
interface QueueStateEntry {
id: string;
options?: BackendSrvRequest;
state: FetchStatus;
}
export class FetchQueue {
private state: QueueState = {}; // internal queue state
private queue: Subject<QueueStateEntry> = new Subject<QueueStateEntry>(); // internal stream for requests that are to be queued
private updates: Subject<FetchQueueUpdate> = new Subject<FetchQueueUpdate>(); // external stream with updates to the queue state
constructor(debug = false) {
// This will create an implicit live subscription for as long as this class lives.
// But as FetchQueue is used by the singleton backendSrv that also lives for as long as Grafana app lives
// I think this ok. We could add some disposable pattern later if the need arises.
this.queue.subscribe((entry) => {
const { id, state, options } = entry;
if (!this.state[id]) {
this.state[id] = { state: FetchStatus.Pending, options: {} as BackendSrvRequest };
}
if (state === FetchStatus.Done) {
delete this.state[id];
const update = this.getUpdate(this.state);
this.publishUpdate(update, debug);
return;
}
this.state[id].state = state;
if (options) {
this.state[id].options = options;
}
const update = this.getUpdate(this.state);
this.publishUpdate(update, debug);
});
}
add = (id: string, options: BackendSrvRequest): void => this.queue.next({ id, options, state: FetchStatus.Pending });
setInProgress = (id: string): void => this.queue.next({ id, state: FetchStatus.InProgress });
setDone = (id: string): void => this.queue.next({ id, state: FetchStatus.Done });
getUpdates = (): Observable<FetchQueueUpdate> => this.updates.asObservable();
private getUpdate = (state: QueueState): FetchQueueUpdate => {
const noOfInProgress = Object.keys(state).filter((key) => state[key].state === FetchStatus.InProgress).length;
const noOfPending = Object.keys(state).filter((key) => state[key].state === FetchStatus.Pending).length;
return { noOfPending, noOfInProgress, state };
};
private publishUpdate = (update: FetchQueueUpdate, debug: boolean): void => {
this.printState(update, debug);
this.updates.next(update);
};
private printState = (update: FetchQueueUpdate, debug: boolean): void => {
if (!debug) {
return;
}
const entriesWithoutOptions = Object.keys(update.state).reduce((all, key) => {
const entry = { id: key, state: update.state[key].state };
all.push(entry);
return all;
}, [] as Array<{ id: string; state: FetchStatus }>);
console.log('FetchQueue noOfStarted', update.noOfInProgress);
console.log('FetchQueue noOfNotStarted', update.noOfPending);
console.log('FetchQueue state', entriesWithoutOptions);
};
}