packages/rpc-core/src/util/refCountDelay.ts
// Copyright 2017-2024 @polkadot/rpc-core authors & contributors
// SPDX-License-Identifier: Apache-2.0
import type { ConnectableObservable, MonoTypeOperatorFunction, TeardownLogic } from 'rxjs';
import { asapScheduler, Observable, Subscription } from 'rxjs';
/** @internal */
export function refCountDelay <T> (delay = 1750): MonoTypeOperatorFunction<T> {
return (source: Observable<T>): Observable<T> => {
// state: 0 = disconnected, 1 = disconnecting, 2 = connecting, 3 = connected
let [state, refCount, connection, scheduler] = [0, 0, Subscription.EMPTY, Subscription.EMPTY];
return new Observable((ob): TeardownLogic => {
source.subscribe(ob);
if (refCount++ === 0) {
if (state === 1) {
scheduler.unsubscribe();
} else {
// eslint-disable-next-line deprecation/deprecation
connection = (source as ConnectableObservable<T>).connect();
}
state = 3;
}
return (): void => {
if (--refCount === 0) {
if (state === 2) {
state = 0;
scheduler.unsubscribe();
} else {
// state === 3
state = 1;
scheduler = asapScheduler.schedule((): void => {
state = 0;
connection.unsubscribe();
}, delay);
}
}
};
});
};
}