chore(endpoint-cache): expose getEndpoint as a separate API

In future, the callee may want to get all unexpired endpoints
and add their own logic as more weights and priorities are added.

Author: trivikr

packages/endpoint-cache/src/EndpointCache.spec.ts

@@ -103,26 +103,28 @@ describe(EndpointCache.name, () => {
       expect(set).toHaveBeenCalledWith(key, []);
     });
 
-    it("returns one of the un-expired endpoints", () => {
-      expect(mockEndpoints.map((endpoint) => endpoint.Address)).toContain(endpointCache.get(key));
-      verifyHasAndGetCalls();
-      expect(set).not.toHaveBeenCalled();
-    });
-
-    it("returns un-expired endpoint", () => {
-      jest.spyOn(Date, "now").mockImplementation(() => now + 90 * 1000);
-      expect(endpointCache.get(key)).toEqual(mockEndpoints[1].Address);
-      verifyHasAndGetCalls();
-      expect(set).not.toHaveBeenCalled();
-    });
+    describe("getEndpoint", () => {
+      it("returns one of the un-expired endpoints", () => {
+        expect(mockEndpoints.map((endpoint) => endpoint.Address)).toContain(endpointCache.getEndpoint(key));
+        verifyHasAndGetCalls();
+        expect(set).not.toHaveBeenCalled();
+      });
 
-    [0, 1].forEach((index) => {
-      it(`returns un-expired endpoint at index ${index}`, () => {
-        jest.spyOn(Math, "floor").mockImplementation(() => index);
-        expect(mockEndpoints.map((endpoint) => endpoint.Address)).toContain(endpointCache.get(key));
+      it("returns un-expired endpoint", () => {
+        jest.spyOn(Date, "now").mockImplementation(() => now + 90 * 1000);
+        expect(endpointCache.getEndpoint(key)).toEqual(mockEndpoints[1].Address);
         verifyHasAndGetCalls();
         expect(set).not.toHaveBeenCalled();
       });
+
+      [0, 1].forEach((index) => {
+        it(`returns un-expired endpoint at index ${index}`, () => {
+          jest.spyOn(Math, "floor").mockImplementation(() => index);
+          expect(mockEndpoints.map((endpoint) => endpoint.Address)).toContain(endpointCache.getEndpoint(key));
+          verifyHasAndGetCalls();
+          expect(set).not.toHaveBeenCalled();
+        });
+      });
     });
   });
 

packages/endpoint-cache/src/EndpointCache.ts

@@ -2,7 +2,7 @@ import { LRUCache } from "mnemonist";
 
 import { Endpoint } from "./Endpoint";
 
-interface EndpointWithExpiry extends Pick<Endpoint, "Address"> {
+export interface EndpointWithExpiry extends Pick<Endpoint, "Address"> {
   Expires: number;
 }
 
@@ -13,16 +13,23 @@ export class EndpointCache {
     this.cache = new LRUCache(capacity);
   }
 
-  private getEndpoint(endpointsWithExpiry: EndpointWithExpiry[]) {
-    const now = Date.now();
-    const endpoints = endpointsWithExpiry
-      .filter((endpoint) => now < endpoint.Expires)
-      .map((endpoint) => endpoint.Address);
+  /**
+   * Returns an un-expired endpoint for the given key.
+   *
+   * @param endpointsWithExpiry
+   * @returns
+   */
+  getEndpoint(key: string) {
+    const endpointsWithExpiry = this.get(key);
+    if (!endpointsWithExpiry || endpointsWithExpiry.length === 0) {
+      return undefined;
+    }
+    const endpoints = endpointsWithExpiry.map((endpoint) => endpoint.Address);
     return endpoints[Math.floor(Math.random() * endpoints.length)];
   }
 
   /**
-   * Returns an un-expired endpoint for the given key.
+   * Returns un-expired endpoints for the given key.
    *
    * @param key
    * @returns
@@ -32,16 +39,19 @@ export class EndpointCache {
       return;
     }
 
-    const endpointsWithExpiry = this.cache.get(key);
-    if (!endpointsWithExpiry) {
+    const value = this.cache.get(key);
+    if (!value) {
       return;
     }
 
-    const endpoint = this.getEndpoint(endpointsWithExpiry);
-    if (endpoint === undefined) {
+    const now = Date.now();
+    const endpointsWithExpiry = value.filter((endpoint) => now < endpoint.Expires);
+    if (endpointsWithExpiry.length === 0) {
       this.delete(key);
+      return undefined;
     }
-    return endpoint;
+
+    return endpointsWithExpiry;
   }
 
   /**