Bug 559942 - RE-LAND- Heuristic to pick default HTTP cache size. r=dwitte, gavin, ui=limi, a=blocks-beta7

browser/components/preferences/advanced.js

@@ -70,6 +70,7 @@ var gAdvancedPane = {
 #ifdef MOZ_CRASHREPORTER
     this.initSubmitCrashes();
 #endif
+    this.updateActualCacheSize();
   },
 
   /**
@@ -190,6 +191,8 @@ var gAdvancedPane = {
    *
    * browser.cache.disk.capacity
    * - the size of the browser cache in KB
+   * browser.cache.disk.smart_size.enabled
+   * - If disabled, disk.capacity is used
    */
 
   /**
@@ -201,6 +204,49 @@ var gAdvancedPane = {
                                            "", null);
   },
  
+  // Retrieves the amount of space currently used by disk cache
+  updateActualCacheSize: function ()
+  {
+    var visitor = {
+      visitDevice: function (deviceID, deviceInfo)
+      {
+        if (deviceID == "disk") {
+          var actualSizeLabel = document.getElementById("actualCacheSize");
+          var sizeStrings = DownloadUtils.convertByteUnits(deviceInfo.totalSize);
+          var prefStrBundle = document.getElementById("bundlePreferences");
+          var sizeStr = prefStrBundle.getFormattedString("actualCacheSize",
+                                                          sizeStrings);
+          actualSizeLabel.value = sizeStr;
+        }
+        // Do not enumerate entries
+        return false;
+      },
+
+      visitEntry: function (deviceID, entryInfo)
+      {
+        // Do not enumerate entries.
+        return false;
+      }
+    };
+    var cacheService =
+      Components.classes["@mozilla.org/network/cache-service;1"]
+                .getService(Components.interfaces.nsICacheService);
+    cacheService.visitEntries(visitor);
+  },
+
+  updateCacheSizeUI: function (smartSizeEnabled)
+  {
+    document.getElementById("useCacheBefore").disabled = smartSizeEnabled;
+    document.getElementById("cacheSize").disabled = smartSizeEnabled;
+    document.getElementById("useCacheAfter").disabled = smartSizeEnabled;
+  },
+
+  readSmartSizeEnabled: function ()
+  {
+    var enabled = document.getElementById("browser.cache.disk.smart_size.enabled").value;
+    this.updateCacheSizeUI(enabled);
+  },
+  
   /**
    * Converts the cache size from units of KB to units of MB and returns that
    * value.
@@ -232,6 +278,7 @@ var gAdvancedPane = {
     try {
       cacheService.evictEntries(Components.interfaces.nsICache.STORE_ANYWHERE);
     } catch(ex) {}
+    this.updateActualCacheSize();
   },
 
   readOfflineNotify: function()

browser/components/preferences/advanced.xul

@@ -86,7 +86,11 @@
       <preference id="browser.cache.disk.capacity"     name="browser.cache.disk.capacity"     type="int"/>
       <preference id="browser.offline-apps.notify"     name="browser.offline-apps.notify"     type="bool"/>
  
-      <!-- Update tab -->
+      <preference id="browser.cache.disk.smart_size.enabled"
+                  name="browser.cache.disk.smart_size.enabled"
+                  type="bool"/>
+ 
+     <!-- Update tab -->
 #ifdef MOZ_UPDATER
       <preference id="app.update.enabled"              name="app.update.enabled"              type="bool"
                   onchange="gAdvancedPane.updateAppUpdateItems();
@@ -214,65 +218,71 @@
         <!-- Network -->
         <tabpanel id="networkPanel" orient="vertical">
 
-           <!-- Connection -->
-           <groupbox id="connectionGroup">
-             <caption label="&connection.label;"/>
+          <!-- Connection -->
+          <groupbox id="connectionGroup">
+            <caption label="&connection.label;"/>
 
-             <hbox align="center">
-               <description flex="1" control="connectionSettings">&connectionDesc.label;</description>
-               <button id="connectionSettings" icon="network" label="&connectionSettings.label;"
-                       accesskey="&connectionSettings.accesskey;"
-                       oncommand="gAdvancedPane.showConnections();"/>
-             </hbox>
-           </groupbox>
+            <hbox align="center">
+              <description flex="1" control="connectionSettings">&connectionDesc.label;</description>
+              <button id="connectionSettings" icon="network" label="&connectionSettings.label;"
+                      accesskey="&connectionSettings.accesskey;"
+                      oncommand="gAdvancedPane.showConnections();"/>
+            </hbox>
+          </groupbox>
 
-           <!-- Cache/Offline apps -->
-           <groupbox id="offlineGroup">
-             <caption label="&offlineStorage.label;"/>
+          <!-- Cache/Offline apps -->
+          <groupbox id="offlineGroup">
+            <caption label="&offlineStorage.label;"/>
  
-             <hbox align="center">
-               <label id="useCacheBefore" control="cacheSize"
-                      accesskey="&useCacheBefore.accesskey;" value="&useCacheBefore.label;"/>
-               <textbox id="cacheSize" type="number" size="2"
-                        preference="browser.cache.disk.capacity"
-                        onsyncfrompreference="return gAdvancedPane.readCacheSize();"
-                        onsynctopreference="return gAdvancedPane.writeCacheSize();"
-                        aria-labelledby="useCacheBefore cacheSize useCacheAfter"/>
-               <label id="useCacheAfter" flex="1">&useCacheAfter.label;</label>
-               <button id="clearCacheButton" icon="clear"
-                       label="&clearCacheNow.label;" accesskey="&clearCacheNow.accesskey;"
-                       oncommand="gAdvancedPane.clearCache();"/>
-             </hbox>
-	     <hbox align="center">
-	       <checkbox id="offlineNotify" flex="1"
-			 label="&offlineNotify.label;" accesskey="&offlineNotify.accesskey;"
-			 preference="browser.offline-apps.notify"
-			 onsyncfrompreference="return gAdvancedPane.readOfflineNotify();"/>
-	       <button id="offlineNotifyExceptions"
-		       label="&offlineNotifyExceptions.label;"
-		       accesskey="&offlineNotifyExceptions.accesskey;"
-		       oncommand="gAdvancedPane.showOfflineExceptions();"/>
-	     </hbox>
-	     <hbox>
-	       <vbox flex="1">
-
-		 <label id="offlineAppsListLabel">&offlineAppsList.label;</label>
-		 <listbox id="offlineAppsList"
-			  style="height: &offlineAppsList.height;;"
-			  flex="1"
-			  aria-labelledby="offlineAppsListLabel"
-			  onselect="gAdvancedPane.offlineAppSelected(event);">
-		 </listbox>
-	       </vbox>
-	       <vbox pack="end">
-		 <button id="offlineAppsListRemove"
-			 disabled="true"
-			 label="&offlineAppsListRemove.label;"
-			 accesskey="&offlineAppsListRemove.accesskey;" 
-			 oncommand="gAdvancedPane.removeOfflineApp();"/>
-	       </vbox>
-	     </hbox>
-	   </groupbox>
+            <hbox align="center">
+              <label id="actualCacheSize" flex="1"/>
+              <button id="clearCacheButton" icon="clear"
+                      label="&clearCacheNow.label;" accesskey="&clearCacheNow.accesskey;"
+                      oncommand="gAdvancedPane.clearCache();"/>
+            </hbox>
+            <checkbox preference="browser.cache.disk.smart_size.enabled"
+                      id="allowSmartSize" flex="1"
+                      onsyncfrompreference="return gAdvancedPane.readSmartSizeEnabled();"
+                      label="&smartSizeCache.label;"/>
+            <hbox align="center" class="indent">
+              <label id="useCacheBefore" control="cacheSize"
+                     accesskey="&useCacheBefore.accesskey;" value="&useCacheBefore.label;"/>
+              <textbox id="cacheSize" type="number" size="2"
+                       preference="browser.cache.disk.capacity"
+                       onsyncfrompreference="return gAdvancedPane.readCacheSize();"
+                       onsynctopreference="return gAdvancedPane.writeCacheSize();"
+                       aria-labelledby="useCacheBefore cacheSize useCacheAfter"/>
+              <label id="useCacheAfter" flex="1">&useCacheAfter.label;</label>
+            </hbox>
+            <hbox align="center">
+              <checkbox id="offlineNotify" flex="1"
+                        label="&offlineNotify.label;" accesskey="&offlineNotify.accesskey;"
+                        preference="browser.offline-apps.notify"
+                        onsyncfrompreference="return gAdvancedPane.readOfflineNotify();"/>
+              <button id="offlineNotifyExceptions"
+                      label="&offlineNotifyExceptions.label;"
+                      accesskey="&offlineNotifyExceptions.accesskey;"
+                      oncommand="gAdvancedPane.showOfflineExceptions();"/>
+            </hbox>
+            <hbox>
+              <vbox flex="1">
+                <label id="offlineAppsListLabel">&offlineAppsList.label;</label>
+                <listbox id="offlineAppsList"
+                         style="height: &offlineAppsList.height;;"
+                         flex="1"
+                         aria-labelledby="offlineAppsListLabel"
+                         onselect="gAdvancedPane.offlineAppSelected(event);">
+                </listbox>
+              </vbox>
+              <vbox pack="end">
+                <button id="offlineAppsListRemove"
+                        disabled="true"
+                        label="&offlineAppsListRemove.label;"
+                        accesskey="&offlineAppsListRemove.accesskey;" 
+                        oncommand="gAdvancedPane.removeOfflineApp();"/>
+              </vbox>
+            </hbox>
+          </groupbox>
         </tabpanel>
 
         <!-- Update -->

browser/locales/en-US/chrome/browser/preferences/advanced.dtd

@@ -51,6 +51,7 @@
 <!ENTITY useCacheAfter.label             "MB of space for the cache">
 <!ENTITY clearCacheNow.label             "Clear Now">
 <!ENTITY clearCacheNow.accesskey         "C">
+<!ENTITY smartSizeCache.label            "Let &brandShortName; manage the size of my cache">
 
 <!ENTITY updateTab.label                 "Update">
 

browser/locales/en-US/chrome/browser/preferences/preferences.properties

@@ -104,6 +104,12 @@ offlineAppUsage=%1$S %2$S
 offlinepermissionstext=The following websites are not allowed to store data for offline use:
 offlinepermissionstitle=Offline Data
 
+####Preferences::Advanced::Network
+#LOCALIZATION NOTE: The next string is for the disk usage of the http cache.
+#   e.g., "Your cache is currently using 200 MB"
+#   %1$S = size
+#   %2$S = unit (MB, KB, etc.)
+actualCacheSize=Your cache is currently using %1$S %2$S of disk space
 
 #### Syncing
 connect.label=Connect

modules/libpref/src/init/all.js

@@ -60,6 +60,11 @@ pref("general.warnOnAboutConfig", true);
 pref("browser.bookmarks.max_backups",       5);
 
 pref("browser.cache.disk.enable",           true);
+// Is this the first-time smartsizing has been introduced?
+pref("browser.cache.disk.smart_size.first_run", true);
+// Does the user want smart-sizing?
+pref("browser.cache.disk.smart_size.enabled", true);
+// Size explicitly set by the user. Used when smart_size.enabled == false
 #ifndef WINCE
 pref("browser.cache.disk.capacity",         256000);
 #else

netwerk/cache/nsCacheService.cpp

@@ -84,6 +84,11 @@
 
 #define DISK_CACHE_ENABLE_PREF      "browser.cache.disk.enable"
 #define DISK_CACHE_DIR_PREF         "browser.cache.disk.parent_directory"
+#define DISK_CACHE_SMART_SIZE_FIRST_RUN_PREF\
+    "browser.cache.disk.smart_size.first_run"
+#define DISK_CACHE_SMART_SIZE_ENABLED_PREF \
+    "browser.cache.disk.smart_size.enabled"
+#define DISK_CACHE_SMART_SIZE_PREF "browser.cache.disk.smart_size_cached_value"
 #define DISK_CACHE_CAPACITY_PREF    "browser.cache.disk.capacity"
 #define DISK_CACHE_MAX_ENTRY_SIZE_PREF "browser.cache.disk.max_entry_size"
 #define DISK_CACHE_CAPACITY         256000
@@ -106,6 +111,7 @@ static const char * observerList[] = {
 static const char * prefList[] = { 
 #ifdef NECKO_DISK_CACHE
     DISK_CACHE_ENABLE_PREF,
+    DISK_CACHE_SMART_SIZE_ENABLED_PREF,
     DISK_CACHE_CAPACITY_PREF,
     DISK_CACHE_DIR_PREF,
 #endif
@@ -118,6 +124,12 @@ static const char * prefList[] = {
     MEMORY_CACHE_CAPACITY_PREF
 };
 
+// Let our base line be 250MB. 
+const PRInt32 BASE_LINE = 250 * 1024 * 1024;
+const PRInt32 MIN_SIZE = 50 * 1024 * 1024;
+const PRInt32 MAX_SIZE = 1024 * 1024 * 1024;
+
+
 class nsCacheProfilePrefObserver : public nsIObserver
 {
 public:
@@ -144,6 +156,7 @@ public:
     
     PRBool          DiskCacheEnabled();
     PRInt32         DiskCacheCapacity()         { return mDiskCacheCapacity; }
+    void            SetDiskCacheCapacity(PRInt32);
     nsILocalFile *  DiskCacheParentDirectory()  { return mDiskCacheParentDirectory; }
 
     PRBool          OfflineCacheEnabled();
@@ -153,7 +166,10 @@ public:
     PRBool          MemoryCacheEnabled();
     PRInt32         MemoryCacheCapacity();
 
+    static PRUint32 GetSmartCacheSize(void);
+
 private:
+    bool                    PermittedToSmartSize(nsIPrefBranch*, PRBool firstRun);
     PRBool                  mHaveProfile;
     
     PRBool                  mDiskCacheEnabled;
@@ -170,7 +186,85 @@ private:
     PRBool                  mInPrivateBrowsing;
 };
 
-NS_IMPL_ISUPPORTS1(nsCacheProfilePrefObserver, nsIObserver)
+NS_IMPL_THREADSAFE_ISUPPORTS1(nsCacheProfilePrefObserver, nsIObserver)
+
+// Runnable sent to main thread after the cache IO thread calculates available
+// disk space, so that there is no race in setting mDiskCacheCapacity.
+class nsSetSmartSizeEvent: public nsRunnable 
+{
+public:
+    nsSetSmartSizeEvent(bool firstRun, 
+                        PRInt32 smartSize, 
+                        nsIPrefBranch* branch,
+                        nsCacheProfilePrefObserver* observer) 
+        : mFirstRun(firstRun)
+        , mSmartSize(smartSize)
+        , mBranch(branch)
+        , mObserver(observer)
+    {
+    }
+
+    NS_IMETHOD Run() 
+    {
+        nsresult rv;
+        NS_ASSERTION(NS_IsMainThread(), 
+                     "Setting smart size data off the main thread");
+        PRBool smartSizeEnabled;
+        rv = mBranch->GetBoolPref(DISK_CACHE_SMART_SIZE_ENABLED_PREF,
+                                  &smartSizeEnabled);
+        if (NS_FAILED(rv)) smartSizeEnabled = PR_FALSE;
+        // ensure smart sizing wasn't switched off while event was pending
+        if (smartSizeEnabled) {
+            // must set both fields to be safe
+            nsCacheService::SetDiskCacheCapacity(mSmartSize);
+            mObserver->SetDiskCacheCapacity(mSmartSize);
+            rv = mBranch->SetIntPref(DISK_CACHE_SMART_SIZE_PREF, mSmartSize);
+            if (NS_FAILED(rv)) NS_WARNING("Failed to set smart size pref");
+        }
+        return rv;
+    }
+
+private: 
+    bool mFirstRun;
+    PRInt32 mSmartSize;
+    nsCOMPtr<nsIPrefBranch> mBranch;
+    nsRefPtr<nsCacheProfilePrefObserver> mObserver;
+};
+
+
+// Runnable sent from main thread to cacheIO thread
+class nsGetSmartSizeEvent: public nsRunnable
+{
+public:
+    nsGetSmartSizeEvent(bool firstRun, 
+                        nsIPrefBranch* branch,
+                        nsCacheProfilePrefObserver* observer) 
+        : mFirstRun(firstRun)
+        , mSmartSize(0)  
+        , mBranch(branch)
+        , mObserver(observer)
+    {
+    }
+   
+    // Calculates user's disk space available on a background thread and
+    // dispatches this value back to the main thread.
+    NS_IMETHOD Run()
+    {
+        mSmartSize = nsCacheProfilePrefObserver::GetSmartCacheSize() / 1024;
+        nsCOMPtr<nsIRunnable> event = new nsSetSmartSizeEvent(mFirstRun,
+                                                              mSmartSize,
+                                                              mBranch, 
+                                                              mObserver);
+        NS_DispatchToMainThread(event);
+        return NS_OK;
+    }
+
+private: 
+    bool mFirstRun;
+    PRInt32 mSmartSize;
+    nsCOMPtr<nsIPrefBranch> mBranch;
+    nsRefPtr<nsCacheProfilePrefObserver> mObserver;
+};
 
 
 nsresult
@@ -246,6 +340,12 @@ nsCacheProfilePrefObserver::Remove()
         prefs->RemoveObserver(prefList[i], this); // remove cache pref observers
 }
 
+void
+nsCacheProfilePrefObserver::SetDiskCacheCapacity(PRInt32 capacity)
+{
+    mDiskCacheCapacity = PR_MAX(0, capacity);
+}
+
 
 NS_IMETHODIMP
 nsCacheProfilePrefObserver::Observe(nsISupports *     subject,
@@ -302,6 +402,31 @@ nsCacheProfilePrefObserver::Observe(nsISupports *     subject,
             if (NS_FAILED(rv))  return rv;
             mDiskCacheCapacity = PR_MAX(0, capacity);
             nsCacheService::SetDiskCacheCapacity(mDiskCacheCapacity);
+       
+        // Update the cache capacity when smart sizing is turned on/off 
+        } else if (!strcmp(DISK_CACHE_SMART_SIZE_ENABLED_PREF, data.get())) {
+            // Is the update because smartsizing was turned on, or off?
+            PRBool smartSizeEnabled;
+            rv = branch->GetBoolPref(DISK_CACHE_SMART_SIZE_ENABLED_PREF,
+                                     &smartSizeEnabled);
+            if (NS_FAILED(rv)) return rv;
+            PRInt32 newCapacity = 0;
+            if (smartSizeEnabled) {
+                // Smart sizing switched on: recalculate the capacity.
+                nsCOMPtr<nsIRunnable> event = new nsGetSmartSizeEvent(false,
+                                                  branch, this);
+                rv = nsCacheService::DispatchToCacheIOThread(event);
+                // If the dispatch failed, just use our base line for the size
+                if (NS_FAILED(rv)) mDiskCacheCapacity = BASE_LINE;
+            } else {
+                // Smart sizing switched off: use user specified size
+                rv = branch->GetIntPref(DISK_CACHE_CAPACITY_PREF, &newCapacity);
+                if (NS_FAILED(rv)) return rv;
+                mDiskCacheCapacity = PR_MAX(0, newCapacity);
+                nsCacheService::SetDiskCacheCapacity(mDiskCacheCapacity);
+            } 
+            
+               
 #if 0            
         } else if (!strcmp(DISK_CACHE_DIR_PREF, data.get())) {
             // XXX We probaby don't want to respond to this pref except after
@@ -399,6 +524,108 @@ nsCacheProfilePrefObserver::Observe(nsISupports *     subject,
 }
  
  
+
+ /* Computes our best guess for the default size of the user's disk cache, 
+  * based on the amount of space they have free on their hard drive. 
+  * We use a tiered scheme: the more space available, 
+  * the larger the disk cache will be. However, we do not want
+  * to enable the disk cache to grow to an unbounded size, so the larger the
+  * user's available space is, the smaller of a percentage we take. We set a
+  * lower bound of 50MB and an upper bound of 1GB.  
+  *
+  *@param:  None.
+  *@return: The size that the user's disk cache should default to, in bytes.
+  */
+PRUint32
+nsCacheProfilePrefObserver::GetSmartCacheSize(void) {
+  // Get a handle to disk where cache lives, so we can check for free space
+  nsresult rv;
+  nsCOMPtr<nsIFile> profileDirectory;
+  rv = NS_GetSpecialDirectory(NS_APP_USER_PROFILE_50_DIR,
+                              getter_AddRefs(profileDirectory));
+  if (NS_FAILED(rv)) { 
+    return BASE_LINE;
+  }
+  nsCOMPtr<nsILocalFile> diskHandle = do_QueryInterface(profileDirectory);
+  PRInt64 bytesAvailable;
+  diskHandle->GetDiskSpaceAvailable(&bytesAvailable);
+  
+  /* 0MB <= Available < 500MB
+   * Use between 50MB  and 200MB
+   */ 
+  if (bytesAvailable < BASE_LINE * 2) {
+    return PR_MAX(MIN_SIZE, bytesAvailable * 4 / 10);
+  }
+  
+  /* 500MB <= Available < 2500MB
+   * Use 250MB 
+   */
+  if (bytesAvailable < static_cast<PRInt64>(BASE_LINE) * 10) {
+    return BASE_LINE;
+  }
+
+  /* 2500MB <= Available < 5000MB 
+   * Use between 250MB and 500MB
+   */
+  if (bytesAvailable < static_cast<PRInt64>(BASE_LINE) * 20) {
+    return bytesAvailable / 10;
+  }
+
+  /* 5000MB <= Available < 50000MB 
+   * Use 625MB
+   */
+  if (bytesAvailable < static_cast<PRInt64>(BASE_LINE) * 200 ) {
+    return BASE_LINE * 5 / 2;
+  }
+
+  /* 50000MB <= Available < 75000MB
+   * Use 800MB
+   */
+  if (bytesAvailable < static_cast<PRInt64>(BASE_LINE) * 300) {
+    return BASE_LINE / 5 * 16;  
+  }
+  
+  /* We have come within range of the ceiling
+   * Use 1GB
+   */
+  return MAX_SIZE;
+}
+
+/* Determine if we are permitted to dynamically size the user's disk cache based
+ * on their disk space available. We may do this so long as the pref 
+ * smart_size.enabled is true.
+ */
+bool
+nsCacheProfilePrefObserver::PermittedToSmartSize(nsIPrefBranch* branch, PRBool
+                                                 firstRun)
+{
+    nsresult rv;
+    // If user has explicitly set cache size to be smaller than previous default
+    // of 250MB, then smart sizing is off by default. Otherwise, smart sizing is
+    // on by default.
+    if (firstRun) {
+        // check if user has set cache size in the past
+        PRBool userSet;
+        rv = branch->PrefHasUserValue(DISK_CACHE_CAPACITY_PREF, &userSet);
+        if (NS_FAILED(rv)) userSet = PR_TRUE;
+        if (userSet) {
+            PRInt32 oldCapacity;
+            rv = branch->GetIntPref(DISK_CACHE_CAPACITY_PREF, &oldCapacity);
+            if (oldCapacity < BASE_LINE / 1024) {
+                branch->SetBoolPref(DISK_CACHE_SMART_SIZE_ENABLED_PREF, 
+                                    PR_FALSE);
+                return false;
+            }
+        }
+    }
+    PRBool smartSizeEnabled; 
+    rv = branch->GetBoolPref(DISK_CACHE_SMART_SIZE_ENABLED_PREF,
+                             &smartSizeEnabled);
+    if (NS_FAILED(rv)) return false;
+    return !!smartSizeEnabled;
+}
+
+
 nsresult
 nsCacheProfilePrefObserver::ReadPrefs(nsIPrefBranch* branch)
 {
@@ -456,6 +683,37 @@ nsCacheProfilePrefObserver::ReadPrefs(nsIPrefBranch* branch)
         if (directory)
             mDiskCacheParentDirectory = do_QueryInterface(directory, &rv);
     }
+    if (mDiskCacheParentDirectory) {
+        PRBool firstSmartSizeRun;
+        rv = branch->GetBoolPref(DISK_CACHE_SMART_SIZE_FIRST_RUN_PREF, 
+                                 &firstSmartSizeRun); 
+        if (NS_FAILED(rv)) firstSmartSizeRun = PR_FALSE;
+        if (PermittedToSmartSize(branch, firstSmartSizeRun)) {
+            // Prevent unnecessary eviction before smart size event returns 
+            if (!firstSmartSizeRun) {
+                PRInt32 oldSmartSize;
+                rv = branch->GetIntPref(DISK_CACHE_SMART_SIZE_PREF,
+                                        &oldSmartSize);
+                mDiskCacheCapacity = oldSmartSize;
+            } else {
+                rv = branch->SetIntPref(DISK_CACHE_CAPACITY_PREF, 
+                                        MAX_SIZE / 1024);
+                if (NS_FAILED(rv)) NS_WARNING("Failed setting capacity pref");
+            }
+            nsCOMPtr<nsIRunnable> event = 
+                new nsGetSmartSizeEvent(!!firstSmartSizeRun, branch, this);
+            rv = nsCacheService::DispatchToCacheIOThread(event);
+            if (NS_FAILED(rv)) mDiskCacheCapacity = BASE_LINE;
+        }
+
+        if (firstSmartSizeRun) {
+            // It is no longer our first run
+            rv = branch->SetBoolPref(DISK_CACHE_SMART_SIZE_FIRST_RUN_PREF, 
+                                     PR_FALSE);
+            if (NS_FAILED(rv)) 
+                NS_WARNING("Failed setting first_run pref in ReadPrefs.");
+        }
+    }
 #endif // !NECKO_DISK_CACHE
 
 #ifdef NECKO_OFFLINE_CACHE
@@ -513,6 +771,13 @@ nsCacheProfilePrefObserver::ReadPrefs(nsIPrefBranch* branch)
     return rv;
 }
 
+nsresult
+nsCacheService::DispatchToCacheIOThread(nsIRunnable* event)
+{
+    if (!gService->mCacheIOThread) return NS_ERROR_NOT_AVAILABLE;
+    return gService->mCacheIOThread->Dispatch(event, NS_DISPATCH_NORMAL);
+}
+
 
 PRBool
 nsCacheProfilePrefObserver::DiskCacheEnabled()

netwerk/cache/nsCacheService.h

@@ -143,6 +143,9 @@ public:
     static void      ReleaseObject_Locked(nsISupports *    object,
                                           nsIEventTarget * target = nsnull);
 
+    static nsresult DispatchToCacheIOThread(nsIRunnable* event);
+
+
     /**
      * Methods called by nsCacheProfilePrefObserver
      */