fix: let the provider decide when to reuse an existing subscription ID

docs/configuration.md

@@ -123,6 +123,7 @@ Unless you need to set a non-default value, it is recommended to only populate o
 | `WS_CACHE_TTL` | "20000" | The time to live for cached entries. |
 | `WS_NEW_HEADS_ENABLED`. | "true" | Enables subscriptions for the latest blocks, `newHeads`. |
 | `WS_PING_INTERVAL` | "100000" | Interval between ping messages. Set to `0` to disable pinger. |
+| `WS_SAME_SUB_FOR_SAME_EVENT` | "true" | The relay will return the same subscription ID when a client subscribes to the same event multiple times using a single connection. When set to false, the relay will always create a new subscription ID for each `eth_subscribe' request. |
 
 ## Sample for connecting to Hedera Environments
 

packages/relay/src/lib/subscriptionController.ts

@@ -41,6 +41,7 @@ export class SubscriptionController {
  private cache;
  private activeSubscriptionHistogram: Histogram;
  private resultsSentToSubscribersCounter: Counter;
+ private useTheSameSubscriptionForTheSameEvent: boolean;
 
  constructor(poller: Poller, logger: Logger, register: Registry) {
  this.poller = poller;
@@ -76,6 +77,9 @@ export class SubscriptionController {
  registers: [register],
  labelNames: ['subId', 'tag'],
  });
+
+ // Default: true
+ this.useTheSameSubscriptionForTheSameEvent = process.env.WS_SAME_SUB_FOR_SAME_EVENT?.toLowerCase() !== 'false';
  }
 
  createHash(data) {
@@ -99,11 +103,13 @@ export class SubscriptionController {
  this.subscriptions[tag] = [];
  }
 
- // Check if the connection is already subscribed to this event
- const existingSub = this.subscriptions[tag].find((sub) => sub.connection.id === connection.id);
- if (existingSub) {
- this.logger.debug(`Connection ${connection.id}: Attempting to subscribe to ${tag}; already subscribed`);
- return existingSub.subscriptionId;
+ if (this.useTheSameSubscriptionForTheSameEvent) {
+ // Check if the connection is already subscribed to this event
+ const existingSub = this.subscriptions[tag].find((sub) => sub.connection.id === connection.id);
+ if (existingSub) {
+ this.logger.debug(`Connection ${connection.id}: Attempting to subscribe to ${tag}; already subscribed`);
+ return existingSub.subscriptionId;
+ }
  }
 
  const subId = this.generateId();

packages/relay/tests/lib/subscriptionController.spec.ts

@@ -263,4 +263,39 @@ describe('subscriptionController', async function () {
  subscriptionController.unsubscribe(wsConnection, subId);
  subscriptionController.unsubscribe(wsConnection, subId2);
  });
+
+ describe('With WS_SAME_SUB_FOR_SAME_EVENT == `false`', async function () {
+ let originalEnv;
+ let originalSubscriptionController;
+
+ before(() => {
+ originalEnv = process.env.WS_SAME_SUB_FOR_SAME_EVENT;
+ originalSubscriptionController = subscriptionController;
+
+ process.env.WS_SAME_SUB_FOR_SAME_EVENT = 'false';
+ const registry = new Registry();
+ poller = new Poller(ethImpl, logger, registry);
+ subscriptionController = new SubscriptionController(poller, logger, registry);
+ });
+
+ after(() => {
+ process.env.WS_SAME_SUB_FOR_SAME_EVENT = originalEnv;
+ subscriptionController = originalSubscriptionController;
+ });
+
+ it('Subscribing to the same event and filters should return different subscription id', async function () {
+ const connectionId = '7';
+ const wsConnection = new MockWsConnection(connectionId);
+ const tag1 = {
+ event: 'logs',
+ filters: { topics: ['0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef'] },
+ };
+ const subId = subscriptionController.subscribe(wsConnection, tag1.event);
+ const subId2 = subscriptionController.subscribe(wsConnection, tag1.event);
+
+ expect(subId).to.be.not.eq(subId2);
+ subscriptionController.unsubscribe(wsConnection, subId);
+ subscriptionController.unsubscribe(wsConnection, subId2);
+ });
+ });
 });