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Add the network object status service (#652)
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,51 @@ | ||
| import { NetworkObjectDetails } from '@shared/models/network-object.model'; | ||
| import logger from '@shared/services/logger.service'; | ||
| import { | ||
| NetworkObjectStatusRemoteServiceType, | ||
| networkObjectStatusServiceNetworkObjectName, | ||
| } from '@shared/services/network-object-status.service-model'; | ||
| import networkObjectService, { | ||
| onDidCreateNetworkObject, | ||
| onDidDisposeNetworkObject, | ||
| } from '@shared/services/network-object.service'; | ||
|
|
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| // We are assuming these events get hooked up before any network objects get registered. That allows | ||
| // us to start from a clean map. If somehow network objects can be registered before we hook up | ||
| // the events, then we have to figure out a way to insert pre-existing objects into the map in a way | ||
| // that avoids race conditions with the events that fire around the same time. | ||
| const networkObjectIDsToDetails = new Map<string, NetworkObjectDetails>(); | ||
|
|
||
| onDidCreateNetworkObject((networkObjectDetails) => { | ||
| if (networkObjectIDsToDetails.has(networkObjectDetails.id)) | ||
| logger.warn(`Re-saving network object details for ${networkObjectDetails.id}`); | ||
| networkObjectIDsToDetails.set(networkObjectDetails.id, networkObjectDetails); | ||
| }); | ||
|
|
||
| onDidDisposeNetworkObject((networkObjectId) => { | ||
| if (!networkObjectIDsToDetails.delete(networkObjectId)) | ||
| logger.warn(`Notification of disposed object ${networkObjectId} that was previously unknown`); | ||
| }); | ||
|
|
||
| // Making this async to align with the service model even though it could really be synchronous | ||
| async function getAllNetworkObjectDetails(): Promise<Record<string, NetworkObjectDetails>> { | ||
| const allNetworkObjectDetails: Record<string, NetworkObjectDetails> = {}; | ||
| networkObjectIDsToDetails.forEach((value: NetworkObjectDetails, key: string) => { | ||
| allNetworkObjectDetails[key] = value; | ||
| }); | ||
| return Promise.resolve(allNetworkObjectDetails); | ||
| } | ||
|
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| const networkObjectStatusService: NetworkObjectStatusRemoteServiceType = { | ||
| getAllNetworkObjectDetails, | ||
| }; | ||
|
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| /** Register the network object that backs the network object status service */ | ||
| // This doesn't really represent this service module, so we're not making it default. To use this | ||
| // service, you should use `network-object-status.service.ts` | ||
| // eslint-disable-next-line import/prefer-default-export | ||
| export async function startNetworkObjectStatusService(): Promise<void> { | ||
| await networkObjectService.set<NetworkObjectStatusRemoteServiceType>( | ||
| networkObjectStatusServiceNetworkObjectName, | ||
| networkObjectStatusService, | ||
| ); | ||
| } |
27 changes: 27 additions & 0 deletions
27
src/shared/services/network-object-status.service-model.ts
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,27 @@ | ||
| import { NetworkObjectDetails } from '@shared/models/network-object.model'; | ||
|
|
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| // Functions that are exposed through the network object | ||
| export interface NetworkObjectStatusRemoteServiceType { | ||
| /** | ||
| * Get details about all available network objects | ||
| * | ||
| * @returns Object whose keys are the names of the network objects and whose values are the | ||
| * {@link NetworkObjectDetails} for each network object | ||
| */ | ||
| getAllNetworkObjectDetails: () => Promise<Record<string, NetworkObjectDetails>>; | ||
| } | ||
|
|
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| // Functions that are added in the service client on top of what is provided by the network object | ||
| /** Provides functions related to the set of available network objects */ | ||
| export interface NetworkObjectStatusServiceType extends NetworkObjectStatusRemoteServiceType { | ||
| /** | ||
| * Get a promise that resolves when a network object is registered or rejects if a timeout is hit | ||
| * | ||
| * @returns Promise that either resolves to the {@link NetworkObjectDetails} for a network object | ||
| * once the network object is registered, or rejects if a timeout is provided and the timeout is | ||
| * reached before the network object is registered | ||
| */ | ||
| waitForNetworkObject: (id: string, timeoutInMS?: number) => Promise<NetworkObjectDetails>; | ||
| } | ||
|
|
||
| export const networkObjectStatusServiceNetworkObjectName = 'NetworkObjectStatusService'; |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,77 @@ | ||
| import { NetworkObjectDetails } from '@shared/models/network-object.model'; | ||
| import { | ||
| networkObjectStatusServiceNetworkObjectName, | ||
| NetworkObjectStatusRemoteServiceType, | ||
| NetworkObjectStatusServiceType, | ||
| } from '@shared/services/network-object-status.service-model'; | ||
| import networkObjectService, { | ||
| onDidCreateNetworkObject, | ||
| } from '@shared/services/network-object.service'; | ||
| import AsyncVariable from '@shared/utils/async-variable'; | ||
|
|
||
| let networkObject: NetworkObjectStatusRemoteServiceType; | ||
| let initializationPromise: Promise<void>; | ||
| async function initialize(): Promise<void> { | ||
| if (!initializationPromise) { | ||
| initializationPromise = new Promise<void>((resolve, reject) => { | ||
| const executor = async () => { | ||
| try { | ||
| const localNetworkObjectStatusService = | ||
| await networkObjectService.get<NetworkObjectStatusServiceType>( | ||
| networkObjectStatusServiceNetworkObjectName, | ||
| ); | ||
| if (!localNetworkObjectStatusService) | ||
| throw new Error( | ||
| `${networkObjectStatusServiceNetworkObjectName} is not available as a network object`, | ||
| ); | ||
| networkObject = localNetworkObjectStatusService; | ||
| resolve(); | ||
| } catch (error) { | ||
| reject(error); | ||
| } | ||
| }; | ||
| executor(); | ||
| }); | ||
| } | ||
| return initializationPromise; | ||
| } | ||
|
|
||
| // If we ever want to be more clever, we could just keep a local (to this process) cache of the | ||
| // active network objects. If we do that, we'll have to deal with initial race conditions around | ||
| // getting a network object disposed message in this process before handling the snapshot from | ||
| // the service host that includes the (now disposed) network object. Just asking the remote service | ||
| // is less error prone, but slower, whenever we get a request for the latest network objects. | ||
| async function getAllNetworkObjectDetails(): Promise<Record<string, NetworkObjectDetails>> { | ||
| await initialize(); | ||
| return networkObject.getAllNetworkObjectDetails(); | ||
| } | ||
|
|
||
| // Ideally we would use this inside the network object service to be event-based instead of polling | ||
| // while waiting for network objects to be created. That would create a circular dependency between | ||
| // this service and the network object service, though, which is most easily resolved by merging | ||
| // this code into the network object service. That service is pretty big as it is, so to optimize | ||
| // for code understandability we'll just leave it as-is and poll inside the network object service | ||
| // `get` for now. Other services will have to call this directly if they want to be event based. | ||
| async function waitForNetworkObject( | ||
| id: string, | ||
| timeoutInMS?: number, | ||
| ): Promise<NetworkObjectDetails> { | ||
| const asyncVar = new AsyncVariable<NetworkObjectDetails>(`waiting-for-${id}`, timeoutInMS ?? -1); | ||
| // Watch the stream of incoming network objects before getting a snapshot to avoid race conditions | ||
| const unsub = onDidCreateNetworkObject((networkObjectDetails) => { | ||
| if (networkObjectDetails.id === id) asyncVar.resolveToValue(networkObjectDetails, false); | ||
| if (asyncVar.hasSettled) unsub(); | ||
| }); | ||
| // Now check if the needed network object has already been created | ||
| const existingNetworkObjectDetails = await getAllNetworkObjectDetails(); | ||
| if (existingNetworkObjectDetails[id]) | ||
| asyncVar.resolveToValue(existingNetworkObjectDetails[id], false); | ||
| return asyncVar.promise; | ||
| } | ||
|
|
||
| const networkObjectStatusService: NetworkObjectStatusServiceType = { | ||
| getAllNetworkObjectDetails, | ||
| waitForNetworkObject, | ||
| }; | ||
|
|
||
| export default networkObjectStatusService; |
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