Bug 1562305 - Make browser.cache.disk.metadata_memory_limit a static pref. r=michal

Differential Revision: https://phabricator.services.mozilla.com/D37179

--HG--
extra : moz-landing-system : lando

modules/libpref/init/StaticPrefList.h

@@ -726,6 +726,14 @@ VARCACHE_PREF(
   RelaxedAtomicBool, true
 )
 
+// Limit of recent metadata we keep in memory for faster access, in KB.
+VARCACHE_PREF(
+  Live,
+  "browser.cache.disk.metadata_memory_limit",
+   browser_cache_disk_metadata_memory_limit,
+  RelaxedAtomicUint32, 250 // 0.25 MB
+)
+
 // Whether Content Blocking Third-Party Cookies UI has been enabled.
 VARCACHE_PREF(
   Live,

modules/libpref/init/all.js

@@ -62,8 +62,6 @@ pref("browser.cache.disk.max_priority_chunks_memory_usage", 40960);
 pref("browser.cache.disk_cache_ssl",        true);
 // 0 = once-per-session, 1 = each-time, 2 = never, 3 = when-appropriate/automatically
 pref("browser.cache.check_doc_frequency",   3);
-// Limit of recent metadata we keep in memory for faster access, in Kb
-pref("browser.cache.disk.metadata_memory_limit", 250); // 0.25 MB
 // The number of chunks we preload ahead of read.  One chunk has currently 256kB.
 pref("browser.cache.disk.preload_chunk_count", 4); // 1 MB of read ahead
 // The half life used to re-compute cache entries frecency in hours.

netwerk/cache2/CacheObserver.cpp

@@ -26,9 +26,6 @@ StaticRefPtr<CacheObserver> CacheObserver::sSelf;
 static float const kDefaultHalfLifeHours = 24.0F;  // 24 hours
 float CacheObserver::sHalfLifeHours = kDefaultHalfLifeHours;
 
-static uint32_t const kDefaultMetadataMemoryLimit = 250;  // 0.25 MB
-uint32_t CacheObserver::sMetadataMemoryLimit = kDefaultMetadataMemoryLimit;
-
 static int32_t const kDefaultMemoryCacheCapacity = -1;  // autodetect
 int32_t CacheObserver::sMemoryCacheCapacity = kDefaultMemoryCacheCapacity;
 // Cache of the calculated memory capacity based on the system memory size in KB
@@ -140,10 +137,6 @@ nsresult CacheObserver::Shutdown() {
 }
 
 void CacheObserver::AttachToPreferences() {
-  mozilla::Preferences::AddUintVarCache(
-      &sMetadataMemoryLimit, "browser.cache.disk.metadata_memory_limit",
-      kDefaultMetadataMemoryLimit);
-
   mozilla::Preferences::AddAtomicUintVarCache(&sDiskCacheCapacity,
                                               "browser.cache.disk.capacity",
                                               kDefaultDiskCacheCapacity);

netwerk/cache2/CacheObserver.h

@@ -34,7 +34,7 @@ class CacheObserver : public nsIObserver, public nsSupportsWeakReference {
   }
   static uint32_t MetadataMemoryLimit()  // result in kilobytes.
   {
-    return sMetadataMemoryLimit;
+    return StaticPrefs::browser_cache_disk_metadata_memory_limit();
   }
   static uint32_t MemoryCacheCapacity();  // result in kilobytes.
   static uint32_t DiskCacheCapacity()     // result in kilobytes.
@@ -103,7 +103,6 @@ class CacheObserver : public nsIObserver, public nsSupportsWeakReference {
   void StoreCacheAmountWritten();
   void AttachToPreferences();
 
-  static uint32_t sMetadataMemoryLimit;
   static int32_t sMemoryCacheCapacity;
   static int32_t sAutoMemoryCacheCapacity;
   static Atomic<uint32_t, Relaxed> sDiskCacheCapacity;