Add ability to detect when MemoryCacheStore reaches max size (#4224)

* Initial impl

* modified failing test

* modified a comment

* moved tests in memory-cache-store-size.js to memory-cache-store-tests.js

Author: FelixVaughan

docs/docs/api/CacheStore.md

@@ -13,8 +13,28 @@ The `MemoryCacheStore` stores the responses in-memory.
 
 **Options**
 
+- `maxSize` - The maximum total size in bytes of all stored responses. Default `Infinity`.
 - `maxCount` - The maximum amount of responses to store. Default `Infinity`.
-- `maxEntrySize` - The maximum size in bytes that a response's body can be. If a response's body is greater than or equal to this, the response will not be cached.
+- `maxEntrySize` - The maximum size in bytes that a response's body can be. If a response's body is greater than or equal to this, the response will not be cached. Default `Infinity`.
+
+### Getters
+
+#### `MemoryCacheStore.size`
+
+Returns the current total size in bytes of all stored responses.
+
+### Methods
+
+#### `MemoryCacheStore.isFull()`
+
+Returns a boolean indicating whether the cache has reached its maximum size or count.
+
+### Events
+
+#### `'maxSizeExceeded'`
+
+Emitted when the cache exceeds its maximum size or count limits. The event payload contains `size`, `maxSize`, `count`, and `maxCount` properties.
+
 
 ### `SqliteCacheStore`
 
@@ -26,7 +46,7 @@ The `SqliteCacheStore` is only exposed if the `node:sqlite` api is present.
 
 - `location` - The location of the SQLite database to use. Default `:memory:`.
 - `maxCount` - The maximum number of entries to store in the database. Default `Infinity`.
-- `maxEntrySize` - The maximum size in bytes that a resposne's body can be. If a response's body is greater than or equal to this, the response will not be cached. Default `Infinity`.
+- `maxEntrySize` - The maximum size in bytes that a response's body can be. If a response's body is greater than or equal to this, the response will not be cached. Default `Infinity`.
 
 ## Defining a Custom Cache Store
 

lib/cache/memory-cache-store.js

@@ -1,6 +1,7 @@
 'use strict'
 
 const { Writable } = require('node:stream')
+const { EventEmitter } = require('node:events')
 const { assertCacheKey, assertCacheValue } = require('../util/cache.js')
 
 /**
@@ -12,20 +13,23 @@ const { assertCacheKey, assertCacheValue } = require('../util/cache.js')
 
 /**
  * @implements {CacheStore}
+ * @extends {EventEmitter}
  */
-class MemoryCacheStore {
+class MemoryCacheStore extends EventEmitter {
   #maxCount = Infinity
   #maxSize = Infinity
   #maxEntrySize = Infinity
 
   #size = 0
   #count = 0
   #entries = new Map()
+  #hasEmittedMaxSizeEvent = false
 
   /**
    * @param {import('../../types/cache-interceptor.d.ts').default.MemoryCacheStoreOpts | undefined} [opts]
    */
   constructor (opts) {
+    super()
     if (opts) {
       if (typeof opts !== 'object') {
         throw new TypeError('MemoryCacheStore options must be an object')
@@ -66,6 +70,22 @@ class MemoryCacheStore {
     }
   }
 
+  /**
+   * Get the current size of the cache in bytes
+   * @returns {number} The current size of the cache in bytes
+   */
+  get size () {
+    return this.#size
+  }
+
+  /**
+   * Check if the cache is full (either max size or max count reached)
+   * @returns {boolean} True if the cache is full, false otherwise
+   */
+  isFull () {
+    return this.#size >= this.#maxSize || this.#count >= this.#maxCount
+  }
+
   /**
    * @param {import('../../types/cache-interceptor.d.ts').default.CacheKey} req
    * @returns {import('../../types/cache-interceptor.d.ts').default.GetResult | undefined}
@@ -144,7 +164,20 @@ class MemoryCacheStore {
 
         store.#size += entry.size
 
+        // Check if cache is full and emit event if needed
         if (store.#size > store.#maxSize || store.#count > store.#maxCount) {
+          // Emit maxSizeExceeded event if we haven't already
+          if (!store.#hasEmittedMaxSizeEvent) {
+            store.emit('maxSizeExceeded', {
+              size: store.#size,
+              maxSize: store.#maxSize,
+              count: store.#count,
+              maxCount: store.#maxCount
+            })
+            store.#hasEmittedMaxSizeEvent = true
+          }
+
+          // Perform eviction
           for (const [key, entries] of store.#entries) {
             for (const entry of entries.splice(0, entries.length / 2)) {
               store.#size -= entry.size
@@ -154,6 +187,11 @@ class MemoryCacheStore {
               store.#entries.delete(key)
             }
           }
+
+          // Reset the event flag after eviction
+          if (store.#size < store.#maxSize && store.#count < store.#maxCount) {
+            store.#hasEmittedMaxSizeEvent = false
+          }
         }
 
         callback(null)

test/cache-interceptor/memory-cache-store-tests.js

@@ -1,6 +1,124 @@
 'use strict'
 
+const { test } = require('node:test')
+const { equal } = require('node:assert')
 const MemoryCacheStore = require('../../lib/cache/memory-cache-store')
 const { cacheStoreTests } = require('./cache-store-test-utils.js')
 
 cacheStoreTests(MemoryCacheStore)
+
+test('size getter returns correct total size', async () => {
+  const store = new MemoryCacheStore()
+  const testData = 'test data'
+
+  equal(store.size, 0, 'Initial size should be 0')
+
+  const writeStream = store.createWriteStream(
+    { origin: 'test', path: '/', method: 'GET' },
+    {
+      statusCode: 200,
+      statusMessage: 'OK',
+      headers: {},
+      cachedAt: Date.now(),
+      staleAt: Date.now() + 1000,
+      deleteAt: Date.now() + 2000
+    }
+  )
+
+  writeStream.write(testData)
+  writeStream.end()
+
+  equal(store.size, testData.length, 'Size should match written data length')
+})
+
+test('isFull returns false when under limits', () => {
+  const store = new MemoryCacheStore({
+    maxSize: 1000,
+    maxCount: 10
+  })
+
+  equal(store.isFull(), false, 'Should not be full when empty')
+})
+
+test('isFull returns true when maxSize reached', async () => {
+  const maxSize = 10
+  const store = new MemoryCacheStore({ maxSize })
+  const testData = 'x'.repeat(maxSize + 1) // Exceed maxSize
+
+  const writeStream = store.createWriteStream(
+    { origin: 'test', path: '/', method: 'GET' },
+    {
+      statusCode: 200,
+      statusMessage: 'OK',
+      headers: {},
+      cachedAt: Date.now(),
+      staleAt: Date.now() + 1000,
+      deleteAt: Date.now() + 2000
+    }
+  )
+
+  writeStream.write(testData)
+  writeStream.end()
+
+  equal(store.isFull(), true, 'Should be full when maxSize exceeded')
+})
+
+test('isFull returns true when maxCount reached', async () => {
+  const maxCount = 2
+  const store = new MemoryCacheStore({ maxCount })
+
+  // Add maxCount + 1 entries
+  for (let i = 0; i <= maxCount; i++) {
+    const writeStream = store.createWriteStream(
+      { origin: 'test', path: `/${i}`, method: 'GET' },
+      {
+        statusCode: 200,
+        statusMessage: 'OK',
+        headers: {},
+        cachedAt: Date.now(),
+        staleAt: Date.now() + 1000,
+        deleteAt: Date.now() + 2000
+      }
+    )
+    writeStream.end('test')
+  }
+
+  equal(store.isFull(), true, 'Should be full when maxCount exceeded')
+})
+
+test('emits maxSizeExceeded event when limits exceeded', async () => {
+  const maxSize = 10
+  const store = new MemoryCacheStore({ maxSize })
+
+  let eventFired = false
+  let eventPayload = null
+
+  store.on('maxSizeExceeded', (payload) => {
+    eventFired = true
+    eventPayload = payload
+  })
+
+  const testData = 'x'.repeat(maxSize + 1) // Exceed maxSize
+
+  const writeStream = store.createWriteStream(
+    { origin: 'test', path: '/', method: 'GET' },
+    {
+      statusCode: 200,
+      statusMessage: 'OK',
+      headers: {},
+      cachedAt: Date.now(),
+      staleAt: Date.now() + 1000,
+      deleteAt: Date.now() + 2000
+    }
+  )
+
+  writeStream.write(testData)
+  writeStream.end()
+
+  equal(eventFired, true, 'maxSizeExceeded event should fire')
+  equal(typeof eventPayload, 'object', 'Event should have payload')
+  equal(typeof eventPayload.size, 'number', 'Payload should have size')
+  equal(typeof eventPayload.maxSize, 'number', 'Payload should have maxSize')
+  equal(typeof eventPayload.count, 'number', 'Payload should have count')
+  equal(typeof eventPayload.maxCount, 'number', 'Payload should have maxCount')
+})

test/fixtures/wpt/xhr/formdata/append.any.js

@@ -19,13 +19,13 @@
         assert_equals(create_formdata(['key', null], ['key', 'value1']).get('key'), "null");
     }, 'testFormDataAppendNull2');
     test(function() {
-        var before = new Date(new Date().getTime() - 2000); // two seconds ago, in case there's clock drift
+        var before = Date.now() - 2000; // Two seconds ago,(in case there's clock drift) using timestamp number
         var fd = create_formdata(['key', new Blob(), 'blank.txt']).get('key');
         assert_equals(fd.name, "blank.txt");
         assert_equals(fd.type, "");
         assert_equals(fd.size, 0);
         assert_greater_than_equal(fd.lastModified, before);
-        assert_less_than_equal(fd.lastModified, new Date());
+        assert_less_than_equal(fd.lastModified, Date.now());
     }, 'testFormDataAppendEmptyBlob');
 
     function create_formdata() {