Bug 964561 - Part 5: Add a data threshold pref; r=asuth

dom/indexedDB/IndexedDatabaseManager.cpp

@@ -133,11 +133,17 @@ NS_DEFINE_IID(kIDBRequestIID, PRIVATE_IDBREQUEST_IID);
 
 const uint32_t kDeleteTimeoutMs = 1000;
 
+// The threshold we use for structured clone data storing.
+// Anything smaller than the threshold is compressed and stored in the database.
+// Anything larger is compressed and stored outside the database.
+const int32_t kDefaultDataThresholdBytes = 1024 * 1024; // 1MB
+
 #define IDB_PREF_BRANCH_ROOT "dom.indexedDB."
 
 const char kTestingPref[] = IDB_PREF_BRANCH_ROOT "testing";
 const char kPrefExperimental[] = IDB_PREF_BRANCH_ROOT "experimental";
 const char kPrefFileHandle[] = "dom.fileHandle.enabled";
+const char kDataThresholdPref[] = IDB_PREF_BRANCH_ROOT "dataThreshold";
 
 #define IDB_PREF_LOGGING_BRANCH_ROOT IDB_PREF_BRANCH_ROOT "logging."
 
@@ -159,6 +165,7 @@ Atomic<bool> gClosed(false);
 Atomic<bool> gTestingMode(false);
 Atomic<bool> gExperimentalFeaturesEnabled(false);
 Atomic<bool> gFileHandleEnabled(false);
+Atomic<int32_t> gDataThresholdBytes(0);
 
 class DeleteFilesRunnable final
   : public nsIRunnable
@@ -244,6 +251,17 @@ AtomicBoolPrefChangedCallback(const char* aPrefName, void* aClosure)
   *static_cast<Atomic<bool>*>(aClosure) = Preferences::GetBool(aPrefName);
 }
 
+void
+DataThresholdPrefChangedCallback(const char* aPrefName, void* aClosure)
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(!strcmp(aPrefName, kDataThresholdPref));
+  MOZ_ASSERT(!aClosure);
+
+  gDataThresholdBytes =
+    Preferences::GetInt(aPrefName, kDefaultDataThresholdBytes);
+}
+
 } // namespace
 
 IndexedDatabaseManager::IndexedDatabaseManager()
@@ -381,6 +399,9 @@ IndexedDatabaseManager::Init()
   Preferences::RegisterCallbackAndCall(LoggingModePrefChangedCallback,
                                        kPrefLoggingEnabled);
 
+  Preferences::RegisterCallbackAndCall(DataThresholdPrefChangedCallback,
+                                       kDataThresholdPref);
+
 #ifdef ENABLE_INTL_API
   const nsAdoptingCString& acceptLang =
     Preferences::GetLocalizedCString("intl.accept_languages");
@@ -441,6 +462,9 @@ IndexedDatabaseManager::Destroy()
   Preferences::UnregisterCallback(LoggingModePrefChangedCallback,
                                   kPrefLoggingEnabled);
 
+  Preferences::UnregisterCallback(DataThresholdPrefChangedCallback,
+                                  kDataThresholdPref);
+
   delete this;
 }
 
@@ -742,6 +766,16 @@ IndexedDatabaseManager::IsFileHandleEnabled()
   return gFileHandleEnabled;
 }
 
+// static
+uint32_t
+IndexedDatabaseManager::DataThreshold()
+{
+  MOZ_ASSERT(gDBManager,
+             "DataThreshold() called before indexedDB has been initialized!");
+
+  return gDataThresholdBytes;
+}
+
 void
 IndexedDatabaseManager::ClearBackgroundActor()
 {

dom/indexedDB/IndexedDatabaseManager.h

@@ -131,6 +131,9 @@ public:
   static bool
   IsFileHandleEnabled();
 
+  static uint32_t
+  DataThreshold();
+
   void
   ClearBackgroundActor();