1 files changed, 95 insertions, 0 deletions
diff --git a/xpcom/glue/nsCategoryCache.h b/xpcom/glue/nsCategoryCache.h
new file mode 100644
index 000000000..023aa7a75
--- /dev/null
+++ b/xpcom/glue/nsCategoryCache.h
@@ -0,0 +1,95 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsCategoryCache_h_
+#define nsCategoryCache_h_
+
+#include "mozilla/Attributes.h"
+
+#include "nsICategoryManager.h"
+#include "nsIObserver.h"
+#include "nsISimpleEnumerator.h"
+#include "nsISupportsPrimitives.h"
+
+#include "nsServiceManagerUtils.h"
+
+#include "nsAutoPtr.h"
+#include "nsCOMArray.h"
+#include "nsInterfaceHashtable.h"
+
+#include "nsXPCOM.h"
+
+class nsCategoryObserver final : public nsIObserver
+{
+  ~nsCategoryObserver();
+
+public:
+  explicit nsCategoryObserver(const char* aCategory);
+
+  void ListenerDied();
+  nsInterfaceHashtable<nsCStringHashKey, nsISupports>& GetHash()
+  {
+    return mHash;
+  }
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIOBSERVER
+private:
+  void RemoveObservers();
+
+  nsInterfaceHashtable<nsCStringHashKey, nsISupports> mHash;
+  nsCString mCategory;
+  bool mObserversRemoved;
+};
+
+/**
+ * This is a helper class that caches services that are registered in a certain
+ * category. The intended usage is that a service stores a variable of type
+ * nsCategoryCache<nsIFoo> in a member variable, where nsIFoo is the interface
+ * that these services should implement. The constructor of this class should
+ * then get the name of the category.
+ */
+template<class T>
+class nsCategoryCache final
+{
+public:
+  explicit nsCategoryCache(const char* aCategory)
+    : mCategoryName(aCategory)
+  {
+  }
+  ~nsCategoryCache()
+  {
+    if (mObserver) {
+      mObserver->ListenerDied();
+    }
+  }
+
+  void GetEntries(nsCOMArray<T>& aResult)
+  {
+    // Lazy initialization, so that services in this category can't
+    // cause reentrant getService (bug 386376)
+    if (!mObserver) {
+      mObserver = new nsCategoryObserver(mCategoryName.get());
+    }
+
+    for (auto iter = mObserver->GetHash().Iter(); !iter.Done(); iter.Next()) {
+      nsISupports* entry = iter.UserData();
+      nsCOMPtr<T> service = do_QueryInterface(entry);
+      if (service) {
+        aResult.AppendElement(service.forget());
+      }
+    }
+  }
+
+private:
+  // Not to be implemented
+  nsCategoryCache(const nsCategoryCache<T>&);
+
+  nsCString mCategoryName;
+  RefPtr<nsCategoryObserver> mObserver;
+};
+
+#endif