From d292e084a3bb27b55ee01f30d28e22f5f5adce63 Mon Sep 17 00:00:00 2001
From: Robert Nagy <ronagy@icloud.com>
Date: Wed, 13 Nov 2024 21:24:59 +0100
Subject: [PATCH] fix: memory store

Simplify and fix memory leak
---
 lib/cache/memory-cache-store.js | 123 +++++++-------------------------
 1 file changed, 24 insertions(+), 99 deletions(-)

diff --git a/lib/cache/memory-cache-store.js b/lib/cache/memory-cache-store.js
index 6a00568ca22..67b32f6962f 100644
--- a/lib/cache/memory-cache-store.js
+++ b/lib/cache/memory-cache-store.js
@@ -103,11 +103,7 @@ class MemoryCacheStore {
 
     const values = this.#getValuesForRequest(key, true)
 
-    /**
-     * @type {(MemoryStoreValue & { index: number }) | undefined}
-     */
     let value = this.#findValue(key, values)
-    let valueIndex = value?.index
     if (!value) {
       // The value doesn't already exist, meaning we haven't cached this
       //  response before. Let's assign it a value and insert it into our data
@@ -118,53 +114,12 @@ class MemoryCacheStore {
         return undefined
       }
 
-      this.#entryCount++
-
-      value = {
-        locked: true,
-        opts
+      if (this.#entryCount++ > this.#maxEntries) {
+        this.#prune()
       }
 
-      // We want to sort our responses in decending order by their deleteAt
-      //  timestamps so that deleting expired responses is faster
-      if (
-        values.length === 0 ||
-        opts.deleteAt < values[values.length - 1].deleteAt
-      ) {
-        // Our value is either the only response for this path or our deleteAt
-        //  time is sooner than all the other responses
-        values.push(value)
-        valueIndex = values.length - 1
-      } else if (opts.deleteAt >= values[0].deleteAt) {
-        // Our deleteAt is later than everyone elses
-        values.unshift(value)
-        valueIndex = 0
-      } else {
-        // We're neither in the front or the end, let's just binary search to
-        //  find our stop we need to be in
-        let startIndex = 0
-        let endIndex = values.length
-        while (true) {
-          if (startIndex === endIndex) {
-            values.splice(startIndex, 0, value)
-            break
-          }
-
-          const middleIndex = Math.floor((startIndex + endIndex) / 2)
-          const middleValue = values[middleIndex]
-          if (opts.deleteAt === middleIndex) {
-            values.splice(middleIndex, 0, value)
-            valueIndex = middleIndex
-            break
-          } else if (opts.deleteAt > middleValue.opts.deleteAt) {
-            endIndex = middleIndex
-            continue
-          } else {
-            startIndex = middleIndex
-            continue
-          }
-        }
-      }
+      value = { locked: true, opts }
+      values.push(value)
     } else {
       // Check if there's already another request writing to the value or
       //  a request reading from it
@@ -180,7 +135,7 @@ class MemoryCacheStore {
     /**
      * @type {Buffer[] | null}
      */
-    let body = key.method !== 'HEAD' ? [] : null
+    let body = []
     const maxEntrySize = this.#maxEntrySize
 
     const writable = new Writable({
@@ -202,7 +157,6 @@ class MemoryCacheStore {
         if (currentSize >= maxEntrySize) {
           body = null
           this.end()
-          shiftAtIndex(values, valueIndex)
           return callback()
         }
 
@@ -263,63 +217,34 @@ class MemoryCacheStore {
    *  to respond with.
    * @param {import('../../types/cache-interceptor.d.ts').default.CacheKey} req
    * @param {MemoryStoreValue[]} values
-   * @returns {(MemoryStoreValue & { index: number }) | undefined}
+   * @returns {(MemoryStoreValue) | undefined}
    */
   #findValue (req, values) {
-    /**
-     * @type {MemoryStoreValue | undefined}
-     */
-    let value
     const now = Date.now()
-    for (let i = values.length - 1; i >= 0; i--) {
-      const current = values[i]
-      const currentCacheValue = current.opts
-      if (now >= currentCacheValue.deleteAt) {
-        // We've reached expired values, let's delete them
-        this.#entryCount -= values.length - i
-        values.length = i
-        break
-      }
-
-      let matches = true
-
-      if (currentCacheValue.vary) {
-        if (!req.headers) {
-          matches = false
-          break
-        }
+    return values.find(({ opts: { deleteAt, vary }, body }) => (
+      body != null &&
+      deleteAt > now &&
+      (!vary || Object.keys(vary).every(key => vary[key] === req.headers?.[key]))
+    ))
+  }
 
-        for (const key in currentCacheValue.vary) {
-          if (currentCacheValue.vary[key] !== req.headers[key]) {
-            matches = false
-            break
+  #prune () {
+    const now = Date.now()
+    for (const [key, cachedPaths] of this.#data) {
+      for (const [method, prev] of cachedPaths) {
+        const next = prev.filter(({ opts, body }) => body == null || opts.deleteAt > now)
+        if (next.length === 0) {
+          cachedPaths.delete(method)
+          if (cachedPaths.size === 0) {
+            this.#data.delete(key)
           }
+        } else if (next.length !== prev.length) {
+          this.#entryCount -= prev.length - next.length
+          cachedPaths.set(method, next)
         }
       }
-
-      if (matches) {
-        value = {
-          ...current,
-          index: i
-        }
-        break
-      }
     }
-
-    return value
   }
 }
 
-/**
- * @param {any[]} array Array to modify
- * @param {number} idx Index to delete
- */
-function shiftAtIndex (array, idx) {
-  for (let i = idx + 1; idx < array.length; i++) {
-    array[i - 1] = array[i]
-  }
-
-  array.length--
-}
-
 module.exports = MemoryCacheStore