Bug 1526891 - Part 5: Allow calling NextGenLocalStorageEnabled on any thread in the parent process; r=asuth

Differential Revision: https://phabricator.services.mozilla.com/D20914

dom/localstorage/ActorsParent.cpp

@@ -182,10 +182,15 @@ const uint32_t kFlushTimeoutMs = 5000;
 
 const char kPrivateBrowsingObserverTopic[] = "last-pb-context-exited";
 
+const uint32_t kDefaultNextGen = false;
 const uint32_t kDefaultOriginLimitKB = 5 * 1024;
 const uint32_t kDefaultShadowWrites = true;
 const uint32_t kDefaultSnapshotPrefill = 4096;
 const uint32_t kDefaultClientValidation = true;
+/**
+ *
+ */
+const char kNextGenPref[] = "dom.storage.next_gen";
 /**
  * LocalStorage data limit as determined by summing up the lengths of all string
  * keys and values.  This is consistent with the legacy implementation and other
@@ -2718,6 +2723,7 @@ typedef nsClassHashtable<nsCStringHashKey, nsTArray<Observer*>>
 
 StaticAutoPtr<ObserverHashtable> gObservers;
 
+Atomic<bool> gNextGen(kDefaultNextGen);
 Atomic<uint32_t, Relaxed> gOriginLimitKB(kDefaultOriginLimitKB);
 Atomic<bool> gShadowWrites(kDefaultShadowWrites);
 Atomic<int32_t, Relaxed> gSnapshotPrefill(kDefaultSnapshotPrefill);
@@ -2940,6 +2946,11 @@ void InitializeLocalStorage() {
     NS_WARNING("Failed to initialize quota client!");
   }
 
+  if (NS_FAILED(Preferences::AddAtomicBoolVarCache(&gNextGen, kNextGenPref,
+                                                   kDefaultNextGen))) {
+    NS_WARNING("Unable to respond to next gen pref changes!");
+  }
+
   if (NS_FAILED(Preferences::AddAtomicUintVarCache(
           &gOriginLimitKB, kDefaultQuotaPref, kDefaultOriginLimitKB))) {
     NS_WARNING("Unable to respond to default quota pref changes!");
@@ -2959,6 +2970,8 @@ void InitializeLocalStorage() {
 #endif
 }
 
+bool GetCurrentNextGenPrefValue() { return gNextGen; }
+
 PBackgroundLSDatabaseParent* AllocPBackgroundLSDatabaseParent(
     const PrincipalInfo& aPrincipalInfo, const uint32_t& aPrivateBrowsingId,
     const uint64_t& aDatastoreId) {

dom/localstorage/ActorsParent.h

@@ -33,6 +33,8 @@ class Client;
 
 void InitializeLocalStorage();
 
+bool GetCurrentNextGenPrefValue();
+
 PBackgroundLSDatabaseParent* AllocPBackgroundLSDatabaseParent(
     const mozilla::ipc::PrincipalInfo& aPrincipalInfo,
     const uint32_t& aPrivateBrowsingId, const uint64_t& aDatastoreId);

dom/localstorage/LocalStorageCommon.cpp

@@ -6,6 +6,7 @@
 
 #include "LocalStorageCommon.h"
 
+#include "mozilla/dom/ContentChild.h"
 #include "mozilla/net/MozURL.h"
 
 namespace mozilla {
@@ -15,6 +16,7 @@ using namespace mozilla::net;
 
 namespace {
 
+StaticMutex gNextGenLocalStorageMutex;
 Atomic<int32_t> gNextGenLocalStorageEnabled(-1);
 
 }  // namespace
@@ -22,6 +24,17 @@ Atomic<int32_t> gNextGenLocalStorageEnabled(-1);
 const char16_t* kLocalStorageType = u"localStorage";
 
 bool NextGenLocalStorageEnabled() {
+  if (XRE_IsParentProcess()) {
+    StaticMutexAutoLock lock(gNextGenLocalStorageMutex);
+
+    if (gNextGenLocalStorageEnabled == -1) {
+      bool enabled = GetCurrentNextGenPrefValue();
+      gNextGenLocalStorageEnabled = enabled ? 1 : 0;
+    }
+
+    return !!gNextGenLocalStorageEnabled;
+  }
+
   MOZ_ASSERT(NS_IsMainThread());
 
   if (gNextGenLocalStorageEnabled == -1) {

dom/localstorage/LocalStorageCommon.h

@@ -220,8 +220,12 @@ class MOZ_STACK_CLASS LSNotifyInfo {
 };
 
 /**
- * Main-thread-only check of LSNG being enabled, the value is latched once
- * initialized so changing the preference during runtime has no effect.
+ * A check of LSNG being enabled, the value is latched once initialized so
+ * changing the preference during runtime has no effect.
+ * May be called on any thread in the parent process, but you should call
+ * CachedNextGenLocalStorageEnabled if you know that NextGenLocalStorageEnabled
+ * was already called because it is faster.
+ * May be called on the main thread only in a content process.
  */
 bool NextGenLocalStorageEnabled();
 

dom/quota/ActorsParent.cpp

@@ -2299,8 +2299,6 @@ nsresult QuotaManager::CreateRunnable::Init() {
     return rv;
   }
 
-  Unused << NextGenLocalStorageEnabled();
-
   return NS_OK;
 }
 
@@ -3237,7 +3235,7 @@ nsresult QuotaManager::Init(const nsAString& aBasePath) {
   mClients.AppendElement(asmjscache::CreateClient());
   mClients.AppendElement(cache::CreateQuotaClient());
   mClients.AppendElement(simpledb::CreateQuotaClient());
-  if (CachedNextGenLocalStorageEnabled()) {
+  if (NextGenLocalStorageEnabled()) {
     mClients.AppendElement(localstorage::CreateQuotaClient());
   } else {
     mClients.SetLength(Client::TypeMax());