Persisted Query Link: improve memory management

.api-reports/api-report-link_persisted-queries.md

@@ -57,7 +57,9 @@ interface BaseOptions {
 // Warning: (ae-forgotten-export) The symbol "ApolloLink" needs to be exported by the entry point index.d.ts
 //
 // @public (undocumented)
-export const createPersistedQueryLink: (options: PersistedQueryLink.Options) => ApolloLink;
+export const createPersistedQueryLink: (options: PersistedQueryLink.Options) => ApolloLink & {
+    resetHashCache: () => void;
+};
 
 // @public (undocumented)
 interface DefaultContext extends Record<string, any> {

.changeset/thick-tips-cry.md

@@ -0,0 +1,9 @@
+---
+"@apollo/client": patch
+---
+
+Persisted Query Link: improve memory management
+* use LRU `WeakCache` instead of `WeakMap` to keep a limited number of hash results
+* hash cache is initiated lazily, only when needed
+* expose `persistedLink.resetHashCache()` method
+* reset hash cache if the upstream server reports it doesn't accept persisted queries

.size-limits.json

@@ -1,4 +1,4 @@
 {
-  "dist/apollo-client.min.cjs": 38589,
-  "import { ApolloClient, InMemoryCache, HttpLink } from \"dist/index.js\" (production)": 32365
+  "dist/apollo-client.min.cjs": 38535,
+  "import { ApolloClient, InMemoryCache, HttpLink } from \"dist/index.js\" (production)": 32310
 }

src/link/persisted-queries/__tests__/persisted-queries.test.ts

@@ -66,7 +66,7 @@ const giveUpResponse = JSON.stringify({ errors: giveUpErrors });
 const giveUpResponseWithCode = JSON.stringify({ errors: giveUpErrorsWithCode });
 const multiResponse = JSON.stringify({ errors: multipleErrors });
 
-export function sha256(data: string) {
+function sha256(data: string) {
   const hash = crypto.createHash("sha256");
   hash.update(data);
   return hash.digest("hex");
@@ -151,6 +151,32 @@ describe("happy path", () => {
     }, reject);
   });
 
+  it("clears the cache when calling `resetHashCache`", async () => {
+    fetchMock.post(
+      "/graphql",
+      () => new Promise((resolve) => resolve({ body: response })),
+      { repeat: 1 }
+    );
+
+    const hashRefs: WeakRef<String>[] = [];
+    function hash(query: string) {
+      const newHash = new String(query);
+      hashRefs.push(new WeakRef(newHash));
+      return newHash as string;
+    }
+    const persistedLink = createPersistedQuery({ sha256: hash });
+    await new Promise<void>((complete) =>
+      execute(persistedLink.concat(createHttpLink()), {
+        query,
+        variables,
+      }).subscribe({ complete })
+    );
+
+    await expect(hashRefs[0]).not.toBeGarbageCollected();
+    persistedLink.resetHashCache();
+    await expect(hashRefs[0]).toBeGarbageCollected();
+  });
+
   itAsync("supports loading the hash from other method", (resolve, reject) => {
     fetchMock.post(
       "/graphql",
@@ -517,6 +543,41 @@ describe("failure path", () => {
       })
   );
 
+  it.each([
+    ["error message", giveUpResponse],
+    ["error code", giveUpResponseWithCode],
+  ] as const)(
+    "clears the cache when receiving NotSupported error (%s)",
+    async (_description, failingResponse) => {
+      fetchMock.post(
+        "/graphql",
+        () => new Promise((resolve) => resolve({ body: failingResponse })),
+        { repeat: 1 }
+      );
+      fetchMock.post(
+        "/graphql",
+        () => new Promise((resolve) => resolve({ body: response })),
+        { repeat: 1 }
+      );
+
+      const hashRefs: WeakRef<String>[] = [];
+      function hash(query: string) {
+        const newHash = new String(query);
+        hashRefs.push(new WeakRef(newHash));
+        return newHash as string;
+      }
+      const persistedLink = createPersistedQuery({ sha256: hash });
+      await new Promise<void>((complete) =>
+        execute(persistedLink.concat(createHttpLink()), {
+          query,
+          variables,
+        }).subscribe({ complete })
+      );
+
+      await expect(hashRefs[0]).toBeGarbageCollected();
+    }
+  );
+
   itAsync("works with multiple errors", (resolve, reject) => {
     fetchMock.post(
       "/graphql",

src/link/persisted-queries/__tests__/react.test.tsx

@@ -4,6 +4,7 @@ import * as ReactDOM from "react-dom/server";
 import gql from "graphql-tag";
 import { print } from "graphql";
 import fetchMock from "fetch-mock";
+import crypto from "crypto";
 
 import { ApolloProvider } from "../../../react/context";
 import { InMemoryCache as Cache } from "../../../cache/inmemory/inMemoryCache";
@@ -12,7 +13,12 @@ import { createHttpLink } from "../../http/createHttpLink";
 import { graphql } from "../../../react/hoc/graphql";
 import { getDataFromTree } from "../../../react/ssr/getDataFromTree";
 import { createPersistedQueryLink as createPersistedQuery, VERSION } from "..";
-import { sha256 } from "./persisted-queries.test";
+
+function sha256(data: string) {
+  const hash = crypto.createHash("sha256");
+  hash.update(data);
+  return hash.digest("hex");
+}
 
 // Necessary configuration in order to mock multiple requests
 // to a single (/graphql) endpoint