Bug 1645051 - Calculated smart max cache size shouldn't overwrite browser.cache.disk.capacity pref r=necko-reviewers,mayhemer

Differential Revision: https://phabricator.services.mozilla.com/D83377

modules/libpref/init/StaticPrefList.yaml

@@ -760,6 +760,13 @@
   value: true
   mirror: always
 
+# Disk cache capacity in kilobytes. It's used only when
+# browser.cache.disk.smart_size.enabled == false
+- name: browser.cache.disk.capacity
+  type: RelaxedAtomicUint32
+  value: 256000
+  mirror: always
+
 # Enable/Disable Origin based cache isolation
 - name: browser.cache.cache_isolation
   type: RelaxedAtomicBool

modules/libpref/init/all.js

@@ -241,9 +241,6 @@ pref("general.warnOnAboutConfig", true);
 // maximum number of dated backups to keep at any time
 pref("browser.bookmarks.max_backups",       5);
 
-// Size (in KB) explicitly set by the user. Used when smart_size.enabled == false
-pref("browser.cache.disk.capacity",         256000);
-
 pref("browser.cache.disk_cache_ssl",        true);
 // The half life used to re-compute cache entries frecency in hours.
 pref("browser.cache.frecency_half_life_hours", 6);

netwerk/cache2/CacheFileIOManager.cpp

@@ -4132,7 +4132,7 @@ nsresult CacheFileIOManager::UpdateSmartCacheSize(int64_t aFreeSpace) {
     return NS_OK;
   }
 
-  CacheObserver::SetDiskCacheCapacity(smartSize);
+  CacheObserver::SetSmartDiskCacheCapacity(smartSize);
 
   return NS_OK;
 }

netwerk/cache2/CacheObserver.cpp

@@ -29,9 +29,11 @@ float CacheObserver::sHalfLifeHours = kDefaultHalfLifeHours;
 // Cache of the calculated memory capacity based on the system memory size in KB
 int32_t CacheObserver::sAutoMemoryCacheCapacity = -1;
 
-static uint32_t const kDefaultDiskCacheCapacity = 250 * 1024;  // 250 MB
-Atomic<uint32_t, Relaxed> CacheObserver::sDiskCacheCapacity(
-    kDefaultDiskCacheCapacity);
+// The default value will be overwritten as soon as the correct smart size is
+// calculated by CacheFileIOManager::UpdateSmartCacheSize(). It's limited to 1GB
+// just for case the size is never calculated which might in theory happen if
+// GetDiskSpaceAvailable() always fails.
+Atomic<uint32_t, Relaxed> CacheObserver::sSmartDiskCacheCapacity(1024 * 1024);
 
 static bool kDefaultCacheFSReported = false;
 bool CacheObserver::sCacheFSReported = kDefaultCacheFSReported;
@@ -87,10 +89,6 @@ nsresult CacheObserver::Shutdown() {
 }
 
 void CacheObserver::AttachToPreferences() {
-  mozilla::Preferences::AddAtomicUintVarCache(&sDiskCacheCapacity,
-                                              "browser.cache.disk.capacity",
-                                              kDefaultDiskCacheCapacity);
-
   mozilla::Preferences::GetComplex(
       "browser.cache.disk.parent_directory", NS_GET_IID(nsIFile),
       getter_AddRefs(mCacheParentDirectoryOverride));
@@ -140,26 +138,14 @@ uint32_t CacheObserver::MemoryCacheCapacity() {
 }
 
 // static
-void CacheObserver::SetDiskCacheCapacity(uint32_t aCapacity) {
-  sDiskCacheCapacity = aCapacity;
-
-  if (!sSelf) {
-    return;
-  }
-
-  if (NS_IsMainThread()) {
-    sSelf->StoreDiskCacheCapacity();
-  } else {
-    nsCOMPtr<nsIRunnable> event =
-        NewRunnableMethod("net::CacheObserver::StoreDiskCacheCapacity",
-                          sSelf.get(), &CacheObserver::StoreDiskCacheCapacity);
-    NS_DispatchToMainThread(event);
-  }
+void CacheObserver::SetSmartDiskCacheCapacity(uint32_t aCapacity) {
+  sSmartDiskCacheCapacity = aCapacity;
 }
 
-void CacheObserver::StoreDiskCacheCapacity() {
-  mozilla::Preferences::SetInt("browser.cache.disk.capacity",
-                               sDiskCacheCapacity);
+// static
+uint32_t CacheObserver::DiskCacheCapacity() {
+  return SmartCacheSizeEnabled() ? sSmartDiskCacheCapacity
+                                 : StaticPrefs::browser_cache_disk_capacity();
 }
 
 // static

netwerk/cache2/CacheObserver.h

@@ -38,11 +38,8 @@ class CacheObserver : public nsIObserver, public nsSupportsWeakReference {
     return StaticPrefs::browser_cache_disk_metadata_memory_limit();
   }
   static uint32_t MemoryCacheCapacity();            // result in kilobytes.
-  static uint32_t DiskCacheCapacity()     // result in kilobytes.
-  {
-    return sDiskCacheCapacity;
-  }
-  static void SetDiskCacheCapacity(uint32_t);  // parameter in kilobytes.
+  static uint32_t DiskCacheCapacity();              // result in kilobytes.
+  static void SetSmartDiskCacheCapacity(uint32_t);  // parameter in kilobytes.
   static uint32_t DiskFreeSpaceSoftLimit()          // result in kilobytes.
   {
     return StaticPrefs::browser_cache_disk_free_space_soft_limit();
@@ -103,14 +100,13 @@ class CacheObserver : public nsIObserver, public nsSupportsWeakReference {
  private:
   static StaticRefPtr<CacheObserver> sSelf;
 
-  void StoreDiskCacheCapacity();
   void StoreCacheFSReported();
   void StoreHashStatsReported();
   void StoreCacheAmountWritten();
   void AttachToPreferences();
 
   static int32_t sAutoMemoryCacheCapacity;
-  static Atomic<uint32_t, Relaxed> sDiskCacheCapacity;
+  static Atomic<uint32_t, Relaxed> sSmartDiskCacheCapacity;
   static float sHalfLifeHours;
   static bool sCacheFSReported;
   static bool sHashStatsReported;