On Wed, 10 Mar 2021 15:38:27 GMT, Alexey Ivanov <aiva...@openjdk.org> wrote:
> [JDK-8153732](https://bugs.openjdk.java.net/browse/JDK-8153732) implemented > polling for remote printers. > That bug description also mentions watching the registry for changes and > links to the article which describes the method yet it does so in terms of > WMI. Using WMI is not necessary to watch for the registry updates. > > It is possible to replace polling mechanism with registry change > notifications. If the registry at `HKCU\Printers\Connections` is updated, > refresh the list of print services. > > It works perfectly well in my own testing with sharing a Generic / Text Only > printer from another laptop. The notification comes as soon as the printer is > installed, it results in a new key created under `Connections`. If a remote > printer is removed, the notification is also triggered as the key > corresponding to that printer is removed from the registry. > > I updated the steps in the manual test: `RemotePrinterStatusRefresh.java`. src/java.desktop/windows/native/libawt/windows/WPrinterJob.cpp line 258: > 256: > REG_NOTIFY_CHANGE_NAME, > 257: NULL, > 258: FALSE); [`RegNotifyChangeKeyValue`](https://docs.microsoft.com/en-us/windows/win32/api/winreg/nf-winreg-regnotifychangekeyvalue) notifies the caller about changes to the attributes or contents of a specified registry key. • `hKey`: A handle to `HKEY_CURRENT_USER\Printers\Connections` key which is opened above. • `bWatchSubtree = TRUE`: The function reports changes in the specified key and its subkeys. • `dwNotifyFilter = REG_NOTIFY_CHANGE_NAME`: Notify the caller if a subkey is added or deleted. • `hEvent = NULL`: If `fAsynchronous` is FALSE, `hEvent` is ignored. • `fAsynchronous = FALSE`: The function does not return until a change has occurred. When a new remote printer is added, a new key is created under `HKCU\Printers\Connections`; when an existing remote printer is removed, the key below `Connections` is removed; no values are added or removed in `Connections` key, thus `REG_NOTIFY_CHANGE_LAST_SET` filter is not needed. ------------- PR: https://git.openjdk.java.net/jdk/pull/2915
