Bug 1863035 - Remove unused watching functions in nsIWindowsRegKey. r…

…=win-reviewers,rkraesig

They were added in bug 292981 but this interface is not great,
as it is poll-based. Instead, we want a registry key change
notification of sorts.

Removing this simplifies upcoming patches.

Differential Revision: https://phabricator.services.mozilla.com/D192755

xpcom/ds/nsIWindowsRegKey.idl

@@ -304,33 +304,4 @@ interface nsIWindowsRegKey : nsISupports
    *        The data for the value to modify.
    */
   void writeBinaryValue(in AString name, in ACString data);
-
-  /**
-   * This method starts watching the key to see if any of its values have
-   * changed.  The key must have been opened with mode including ACCESS_NOTIFY.
-   * If recurse is true, then this key and any of its descendant keys are
-   * watched.  Otherwise, only this key is watched.
-   *
-   * @param recurse
-   *        Indicates whether or not to also watch child keys.
-   */
-  void startWatching(in boolean recurse);
-
-  /**
-   * This method stops any watching of the key initiated by a call to
-   * startWatching.  This method does nothing if the key is not being watched.
-   */
-  void stopWatching();
-
-  /**
-   * This method returns true if the key is being watched for changes (i.e.,
-   * if startWatching() was called).
-   */
-  boolean isWatching();
-
-  /**
-   * This method returns true if the key has changed and false otherwise.
-   * This method will always return false if startWatching was not called.
-   */
-  boolean hasChanged();
 };

xpcom/ds/nsWindowsRegKey.cpp

@@ -24,15 +24,12 @@ class nsWindowsRegKey final : public nsIWindowsRegKey {
   NS_DECL_ISUPPORTS
   NS_DECL_NSIWINDOWSREGKEY
 
-  nsWindowsRegKey()
-      : mKey(nullptr), mWatchEvent(nullptr), mWatchRecursive(FALSE) {}
+  nsWindowsRegKey() : mKey(nullptr) {}
 
  private:
   ~nsWindowsRegKey() { Close(); }
 
   HKEY mKey;
-  HANDLE mWatchEvent;
-  BOOL mWatchRecursive;
 };
 
 NS_IMPL_ISUPPORTS(nsWindowsRegKey, nsIWindowsRegKey)
@@ -45,17 +42,12 @@ nsWindowsRegKey::GetKey(HKEY* aKey) {
 
 NS_IMETHODIMP
 nsWindowsRegKey::SetKey(HKEY aKey) {
-  // We do not close the older aKey!
-  StopWatching();
-
   mKey = aKey;
   return NS_OK;
 }
 
 NS_IMETHODIMP
 nsWindowsRegKey::Close() {
-  StopWatching();
-
   if (mKey) {
     RegCloseKey(mKey);
     mKey = nullptr;
@@ -304,7 +296,7 @@ nsWindowsRegKey::ReadStringValue(const nsAString& aName, nsAString& aResult) {
     return NS_ERROR_OUT_OF_MEMORY;
   }
 
-  auto begin = aResult.BeginWriting();
+  auto* begin = aResult.BeginWriting();
 
   rv = RegQueryValueExW(mKey, flatName.get(), 0, &type, (LPBYTE)begin, &size);
 
@@ -390,7 +382,7 @@ nsWindowsRegKey::ReadBinaryValue(const nsAString& aName, nsACString& aResult) {
     return NS_ERROR_OUT_OF_MEMORY;
   }
 
-  auto begin = aResult.BeginWriting();
+  auto* begin = aResult.BeginWriting();
 
   rv = RegQueryValueExW(mKey, PromiseFlatString(aName).get(), 0, nullptr,
                         (LPBYTE)begin, &size);
@@ -448,65 +440,6 @@ nsWindowsRegKey::WriteBinaryValue(const nsAString& aName,
   return (rv == ERROR_SUCCESS) ? NS_OK : NS_ERROR_FAILURE;
 }
 
-NS_IMETHODIMP
-nsWindowsRegKey::StartWatching(bool aRecurse) {
-  if (NS_WARN_IF(!mKey)) {
-    return NS_ERROR_NOT_INITIALIZED;
-  }
-
-  if (mWatchEvent) {
-    return NS_OK;
-  }
-
-  mWatchEvent = CreateEventW(nullptr, TRUE, FALSE, nullptr);
-  if (!mWatchEvent) {
-    return NS_ERROR_OUT_OF_MEMORY;
-  }
-
-  DWORD filter = REG_NOTIFY_CHANGE_NAME | REG_NOTIFY_CHANGE_ATTRIBUTES |
-                 REG_NOTIFY_CHANGE_LAST_SET | REG_NOTIFY_CHANGE_SECURITY;
-
-  LONG rv = RegNotifyChangeKeyValue(mKey, aRecurse, filter, mWatchEvent, TRUE);
-  if (rv != ERROR_SUCCESS) {
-    StopWatching();
-    // On older versions of Windows, this call is not implemented, so simply
-    // return NS_OK in those cases and pretend that the watching is happening.
-    return (rv == ERROR_CALL_NOT_IMPLEMENTED) ? NS_OK : NS_ERROR_FAILURE;
-  }
-
-  mWatchRecursive = aRecurse;
-  return NS_OK;
-}
-
-NS_IMETHODIMP
-nsWindowsRegKey::StopWatching() {
-  if (mWatchEvent) {
-    CloseHandle(mWatchEvent);
-    mWatchEvent = nullptr;
-  }
-  return NS_OK;
-}
-
-NS_IMETHODIMP
-nsWindowsRegKey::HasChanged(bool* aResult) {
-  if (mWatchEvent && WaitForSingleObject(mWatchEvent, 0) == WAIT_OBJECT_0) {
-    // An event only gets signaled once, then it's done, so we have to set up
-    // another event to watch.
-    StopWatching();
-    StartWatching(mWatchRecursive);
-    *aResult = true;
-  } else {
-    *aResult = false;
-  }
-  return NS_OK;
-}
-
-NS_IMETHODIMP
-nsWindowsRegKey::IsWatching(bool* aResult) {
-  *aResult = (mWatchEvent != nullptr);
-  return NS_OK;
-}
-
 //-----------------------------------------------------------------------------
 
 void NS_NewWindowsRegKey(nsIWindowsRegKey** aResult) {

xpcom/tests/unit/test_windows_registry.js

@@ -31,8 +31,6 @@ function run_test() {
   //* check that creating/enumerating/deleting child keys works
   test_childkey_functions(testKey);
 
-  test_watching_functions(testKey);
-
   //* clean up
   cleanup_test_run(testKey, keyName);
 }
@@ -174,37 +172,6 @@ function test_childkey_functions(testKey) {
   strictEqual(testKey.hasChild(TESTDATA_CHILD_KEY), false);
 }
 
-function test_watching_functions(testKey) {
-  strictEqual(testKey.isWatching(), false);
-  strictEqual(testKey.hasChanged(), false);
-
-  testKey.startWatching(true);
-  strictEqual(testKey.isWatching(), true);
-
-  testKey.stopWatching();
-  strictEqual(testKey.isWatching(), false);
-
-  // Create a child key, and update a value
-  let childKey = testKey.createChild(
-    TESTDATA_CHILD_KEY,
-    nsIWindowsRegKey.ACCESS_ALL
-  );
-  childKey.writeIntValue(TESTDATA_INTNAME, TESTDATA_INTVALUE);
-
-  // Start a recursive watch, and update the child's value
-  testKey.startWatching(true);
-  strictEqual(testKey.isWatching(), true);
-
-  childKey.writeIntValue(TESTDATA_INTNAME, 0);
-  strictEqual(testKey.hasChanged(), true);
-  testKey.stopWatching();
-  strictEqual(testKey.isWatching(), false);
-
-  childKey.removeValue(TESTDATA_INTNAME);
-  childKey.close();
-  testKey.removeChild(TESTDATA_CHILD_KEY);
-}
-
 function cleanup_test_run(testKey, keyName) {
   info("Cleaning up test.");