1 files changed, 162 insertions, 0 deletions
diff --git a/xpcom/components/nsCategoryCache.cpp b/xpcom/components/nsCategoryCache.cpp
new file mode 100644
index 0000000000..35f555fa51
--- /dev/null
+++ b/xpcom/components/nsCategoryCache.cpp
@@ -0,0 +1,162 @@
+/* -*- 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/. */
+
+#include "nsIObserverService.h"
+#include "mozilla/Services.h"
+#include "mozilla/SimpleEnumerator.h"
+
+#include "nsICategoryManager.h"
+#include "nsISupportsPrimitives.h"
+
+#include "nsXPCOMCID.h"
+
+#include "nsCategoryCache.h"
+
+using mozilla::SimpleEnumerator;
+
+nsCategoryObserver::nsCategoryObserver(const nsACString& aCategory)
+    : mCategory(aCategory),
+      mCallback(nullptr),
+      mClosure(nullptr),
+      mObserversRemoved(false) {
+  MOZ_ASSERT(NS_IsMainThread());
+  // First, enumerate the currently existing entries
+  nsCOMPtr<nsICategoryManager> catMan =
+      do_GetService(NS_CATEGORYMANAGER_CONTRACTID);
+  if (!catMan) {
+    return;
+  }
+
+  nsCOMPtr<nsISimpleEnumerator> enumerator;
+  nsresult rv =
+      catMan->EnumerateCategory(aCategory, getter_AddRefs(enumerator));
+  if (NS_FAILED(rv)) {
+    return;
+  }
+
+  for (auto& categoryEntry : SimpleEnumerator<nsICategoryEntry>(enumerator)) {
+    nsAutoCString entryValue;
+    categoryEntry->GetValue(entryValue);
+
+    if (nsCOMPtr<nsISupports> service = do_GetService(entryValue.get())) {
+      nsAutoCString entryName;
+      categoryEntry->GetEntry(entryName);
+
+      mHash.InsertOrUpdate(entryName, service);
+    }
+  }
+
+  // Now, listen for changes
+  nsCOMPtr<nsIObserverService> serv = mozilla::services::GetObserverService();
+  if (serv) {
+    serv->AddObserver(this, NS_XPCOM_SHUTDOWN_OBSERVER_ID, false);
+    serv->AddObserver(this, NS_XPCOM_CATEGORY_ENTRY_ADDED_OBSERVER_ID, false);
+    serv->AddObserver(this, NS_XPCOM_CATEGORY_ENTRY_REMOVED_OBSERVER_ID, false);
+    serv->AddObserver(this, NS_XPCOM_CATEGORY_CLEARED_OBSERVER_ID, false);
+  }
+}
+
+nsCategoryObserver::~nsCategoryObserver() = default;
+
+NS_IMPL_ISUPPORTS(nsCategoryObserver, nsIObserver)
+
+void nsCategoryObserver::ListenerDied() {
+  MOZ_ASSERT(NS_IsMainThread());
+  RemoveObservers();
+  mCallback = nullptr;
+  mClosure = nullptr;
+}
+
+void nsCategoryObserver::SetListener(void(aCallback)(void*), void* aClosure) {
+  MOZ_ASSERT(NS_IsMainThread());
+  mCallback = aCallback;
+  mClosure = aClosure;
+}
+
+void nsCategoryObserver::RemoveObservers() {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (mObserversRemoved) {
+    return;
+  }
+
+  if (mCallback) {
+    mCallback(mClosure);
+  }
+
+  mObserversRemoved = true;
+  nsCOMPtr<nsIObserverService> obsSvc = mozilla::services::GetObserverService();
+  if (obsSvc) {
+    obsSvc->RemoveObserver(this, NS_XPCOM_SHUTDOWN_OBSERVER_ID);
+    obsSvc->RemoveObserver(this, NS_XPCOM_CATEGORY_ENTRY_ADDED_OBSERVER_ID);
+    obsSvc->RemoveObserver(this, NS_XPCOM_CATEGORY_ENTRY_REMOVED_OBSERVER_ID);
+    obsSvc->RemoveObserver(this, NS_XPCOM_CATEGORY_CLEARED_OBSERVER_ID);
+  }
+}
+
+NS_IMETHODIMP
+nsCategoryObserver::Observe(nsISupports* aSubject, const char* aTopic,
+                            const char16_t* aData) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (strcmp(aTopic, NS_XPCOM_SHUTDOWN_OBSERVER_ID) == 0) {
+    mHash.Clear();
+    RemoveObservers();
+
+    return NS_OK;
+  }
+
+  if (!aData ||
+      !nsDependentString(aData).Equals(NS_ConvertASCIItoUTF16(mCategory))) {
+    return NS_OK;
+  }
+
+  nsAutoCString str;
+  nsCOMPtr<nsISupportsCString> strWrapper(do_QueryInterface(aSubject));
+  if (strWrapper) {
+    strWrapper->GetData(str);
+  }
+
+  if (strcmp(aTopic, NS_XPCOM_CATEGORY_ENTRY_ADDED_OBSERVER_ID) == 0) {
+    // We may get an add notification even when we already have an entry. This
+    // is due to the notification happening asynchronously, so if the entry gets
+    // added and an nsCategoryObserver gets instantiated before events get
+    // processed, we'd get the notification for an existing entry.
+    // Do nothing in that case.
+    if (mHash.GetWeak(str)) {
+      return NS_OK;
+    }
+
+    nsCOMPtr<nsICategoryManager> catMan =
+        do_GetService(NS_CATEGORYMANAGER_CONTRACTID);
+    if (!catMan) {
+      return NS_OK;
+    }
+
+    nsCString entryValue;
+    catMan->GetCategoryEntry(mCategory, str, entryValue);
+
+    nsCOMPtr<nsISupports> service = do_GetService(entryValue.get());
+
+    if (service) {
+      mHash.InsertOrUpdate(str, service);
+    }
+    if (mCallback) {
+      mCallback(mClosure);
+    }
+  } else if (strcmp(aTopic, NS_XPCOM_CATEGORY_ENTRY_REMOVED_OBSERVER_ID) == 0) {
+    mHash.Remove(str);
+    if (mCallback) {
+      mCallback(mClosure);
+    }
+  } else if (strcmp(aTopic, NS_XPCOM_CATEGORY_CLEARED_OBSERVER_ID) == 0) {
+    mHash.Clear();
+    if (mCallback) {
+      mCallback(mClosure);
+    }
+  }
+  return NS_OK;
+}