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import type {LogContext} from '@rocicorp/logger';import type {ClientID} from '../sync/client-id';import type * as dag from '../dag/mod';import {  ClientMap,  ClientStateNotFoundError,  noUpdates,  updateClients,} from './clients';import {initBgIntervalProcess} from './bg-interval';
const HEARTBEAT_INTERVAL_MS = 60 * 1000;
export let latestHeartbeatUpdate: Promise<ClientMap> | undefined;
export function startHeartbeats(  clientID: ClientID,  dagStore: dag.Store,  onClientStateNotFound: () => void,  lc: LogContext,  signal: AbortSignal,): void {  initBgIntervalProcess(    'Heartbeat',    async () => {      latestHeartbeatUpdate = writeHeartbeat(clientID, dagStore);      try {        return await latestHeartbeatUpdate;      } catch (e) {        if (e instanceof ClientStateNotFoundError) {          onClientStateNotFound();          return;        }        throw e;      }    },    HEARTBEAT_INTERVAL_MS,    lc,    signal,  );}
export async function writeHeartbeat(  clientID: ClientID,  dagStore: dag.Store,): Promise<ClientMap> {  const updatedClients = await updateClients(clients => {    const client = clients.get(clientID);    if (!client) {      return noUpdates;    }    return {      clients: new Map(clients).set(clientID, {        heartbeatTimestampMs: Date.now(),        headHash: client.headHash,        mutationID: client.mutationID,        lastServerAckdMutationID: client.lastServerAckdMutationID,      }),    };  }, dagStore);  if (updatedClients.get(clientID) === undefined) {    throw new ClientStateNotFoundError(clientID);  }  return updatedClients;}