From 23dda938943a7e3a4acdaf5b2b8de60820172e51 Mon Sep 17 00:00:00 2001
From: CanadaHonk <oj@oojmed.com>
Date: Wed, 5 Jul 2023 09:40:21 +0000
Subject: [PATCH] Bug 1841599 - Remove unused canvas.image.cache.limit pref
 r=gregp,emilio

It is not used anywhere currently and was added >10 years ago.

Differential Revision: https://phabricator.services.mozilla.com/D182749
---
 dom/canvas/CanvasImageCache.cpp          | 17 +----------------
 modules/libpref/init/StaticPrefList.yaml |  6 ------
 2 files changed, 1 insertion(+), 22 deletions(-)

diff --git a/dom/canvas/CanvasImageCache.cpp b/dom/canvas/CanvasImageCache.cpp
index 96a1505a40e3..fcbdf3978ee6 100644
--- a/dom/canvas/CanvasImageCache.cpp
+++ b/dom/canvas/CanvasImageCache.cpp
@@ -143,7 +143,6 @@ class ImageCache final : public nsExpirationTracker<ImageCacheEntryData, 4> {
   ~ImageCache();
 
   virtual void NotifyExpired(ImageCacheEntryData* aObject) override {
-    mTotal -= aObject->SizeInBytes();
     RemoveObject(aObject);
 
     // Remove from the all canvas cache entry first since nsExpirationTracker
@@ -158,7 +157,6 @@ class ImageCache final : public nsExpirationTracker<ImageCacheEntryData, 4> {
 
   nsTHashtable<ImageCacheEntry> mCache;
   nsTHashtable<AllCanvasImageCacheEntry> mAllCanvasCache;
-  size_t mTotal;
   RefPtr<ImageCacheObserver> mImageCacheObserver;
 };
 
@@ -232,8 +230,7 @@ class CanvasImageCacheShutdownObserver final : public nsIObserver {
 };
 
 ImageCache::ImageCache()
-    : nsExpirationTracker<ImageCacheEntryData, 4>(GENERATION_MS, "ImageCache"),
-      mTotal(0) {
+    : nsExpirationTracker<ImageCacheEntryData, 4>(GENERATION_MS, "ImageCache") {
   mImageCacheObserver = new ImageCacheObserver(this);
   MOZ_RELEASE_ASSERT(mImageCacheObserver,
                      "GFX: Can't alloc ImageCacheObserver");
@@ -295,7 +292,6 @@ void CanvasImageCache::NotifyDrawImage(Element* aImage,
   if (entry) {
     if (entry->mData->mSourceSurface) {
       // We are overwriting an existing entry.
-      gImageCache->mTotal -= entry->mData->SizeInBytes();
       gImageCache->RemoveObject(entry->mData.get());
       gImageCache->mAllCanvasCache.RemoveEntry(allCanvasCacheKey);
     }
@@ -304,7 +300,6 @@ void CanvasImageCache::NotifyDrawImage(Element* aImage,
     entry->mData->mSourceSurface = aSource;
     entry->mData->mSize = aSize;
     entry->mData->mIntrinsicSize = aIntrinsicSize;
-    gImageCache->mTotal += entry->mData->SizeInBytes();
 
     AllCanvasImageCacheEntry* allEntry =
         gImageCache->mAllCanvasCache.PutEntry(allCanvasCacheKey);
@@ -312,16 +307,6 @@ void CanvasImageCache::NotifyDrawImage(Element* aImage,
       allEntry->mSourceSurface = aSource;
     }
   }
-
-  if (!StaticPrefs::canvas_image_cache_limit()) {
-    return;
-  }
-
-  // Expire the image cache early if its larger than we want it to be.
-  while (gImageCache->mTotal >
-         size_t(StaticPrefs::canvas_image_cache_limit())) {
-    gImageCache->AgeOneGeneration();
-  }
 }
 
 SourceSurface* CanvasImageCache::LookupAllCanvas(Element* aImage,
diff --git a/modules/libpref/init/StaticPrefList.yaml b/modules/libpref/init/StaticPrefList.yaml
index 28bbc32db451..42687d4be3f0 100644
--- a/modules/libpref/init/StaticPrefList.yaml
+++ b/modules/libpref/init/StaticPrefList.yaml
@@ -1819,12 +1819,6 @@
 # Prefs starting with "canvas."
 #---------------------------------------------------------------------------
 
-# Limit for the canvas image cache. 0 means unlimited.
-- name: canvas.image.cache.limit
-  type: int32_t
-  value: 0
-  mirror: always
-
 # Add support for canvas path objects
 - name: canvas.path.enabled
   type: RelaxedAtomicBool