refactor(experimental): create a deduplication key getter specifically for subscriptions

packages/library/src/__tests__/rpc-request-deduplication-test.ts

@@ -1,4 +1,7 @@
-import { getSolanaRpcPayloadDeduplicationKey } from '../rpc-request-deduplication';
+import {
+    getSolanaRpcPayloadDeduplicationKey,
+    getSolanaRpcSubscriptionPayloadDeduplicationKey,
+} from '../rpc-request-deduplication';
 
 describe('getSolanaRpcPayloadDeduplicationKey', () => {
     it('produces no key for undefined payloads', () => {
@@ -52,3 +55,66 @@ describe('getSolanaRpcPayloadDeduplicationKey', () => {
         );
     });
 });
+
+describe('getSolanaRpcSubscriptionPayloadDeduplicationKey', () => {
+    it('produces no key for undefined payloads', () => {
+        expect(getSolanaRpcSubscriptionPayloadDeduplicationKey(undefined)).toBeUndefined();
+    });
+    it('produces no key for null payloads', () => {
+        expect(getSolanaRpcSubscriptionPayloadDeduplicationKey(null)).toBeUndefined();
+    });
+    it('produces no key for array payloads', () => {
+        expect(getSolanaRpcSubscriptionPayloadDeduplicationKey([])).toBeUndefined();
+    });
+    it('produces no key for string payloads', () => {
+        expect(getSolanaRpcSubscriptionPayloadDeduplicationKey('o hai')).toBeUndefined();
+    });
+    it('produces no key for numeric payloads', () => {
+        expect(getSolanaRpcSubscriptionPayloadDeduplicationKey(123)).toBeUndefined();
+    });
+    it('produces no key for bigint payloads', () => {
+        expect(getSolanaRpcSubscriptionPayloadDeduplicationKey(123n)).toBeUndefined();
+    });
+    it('produces no key for object payloads that are not JSON-RPC payloads', () => {
+        expect(getSolanaRpcSubscriptionPayloadDeduplicationKey({})).toBeUndefined();
+    });
+    it("produces a key for a JSON-RPC payload whose method ends in 'Subscribe'", () => {
+        expect(
+            getSolanaRpcSubscriptionPayloadDeduplicationKey({
+                id: 1,
+                jsonrpc: '2.0',
+                method: 'fooSubscribe',
+                params: 'foo',
+            })
+        ).toMatchInlineSnapshot(`"["fooSubscribe","foo"]"`);
+    });
+    it("produces no key for a JSON-RPC payload whose method does not end in 'Subscribe'", () => {
+        expect(
+            getSolanaRpcSubscriptionPayloadDeduplicationKey({
+                id: 1,
+                jsonrpc: '2.0',
+                method: 'getFoo',
+                params: 'foo',
+            })
+        ).toBeUndefined();
+    });
+    it('produces identical keys for two materially identical JSON-RPC payloads', () => {
+        expect(
+            getSolanaRpcSubscriptionPayloadDeduplicationKey({
+                id: 1,
+                jsonrpc: '2.0',
+                method: 'fooSubscribe',
+                params: { a: 1, b: { c: [2, 3], d: 4 } },
+            })
+        ).toEqual(
+            /* eslint-disable sort-keys-fix/sort-keys-fix */
+            getSolanaRpcSubscriptionPayloadDeduplicationKey({
+                jsonrpc: '2.0',
+                method: 'fooSubscribe',
+                params: { b: { d: 4, c: [2, 3] }, a: 1 },
+                id: 2,
+            })
+            /* eslint-enable sort-keys-fix/sort-keys-fix */
+        );
+    });
+});

packages/library/src/rpc-request-deduplication.ts

@@ -2,11 +2,25 @@
 // @ts-ignore
 import fastStableStringify from 'fast-stable-stringify';
 
-export function getSolanaRpcPayloadDeduplicationKey(payload: unknown): string | undefined {
+function isJsonRpcPayload(payload: unknown): payload is Readonly<{ method: string; params: unknown }> {
     if (payload == null || typeof payload !== 'object' || Array.isArray(payload)) {
-        return;
-    }
-    if ('jsonrpc' in payload && payload.jsonrpc === '2.0' && 'method' in payload && 'params' in payload) {
-        return fastStableStringify([payload.method, payload.params]);
+        return false;
     }
+    return (
+        'jsonrpc' in payload &&
+        payload.jsonrpc === '2.0' &&
+        'method' in payload &&
+        typeof payload.method === 'string' &&
+        'params' in payload
+    );
+}
+
+export function getSolanaRpcPayloadDeduplicationKey(payload: unknown): string | undefined {
+    return isJsonRpcPayload(payload) ? fastStableStringify([payload.method, payload.params]) : undefined;
+}
+
+export function getSolanaRpcSubscriptionPayloadDeduplicationKey(payload: unknown): string | undefined {
+    return isJsonRpcPayload(payload) && payload.method.endsWith('Subscribe')
+        ? fastStableStringify([payload.method, payload.params])
+        : undefined;
 }