Changeset 870 for trunk/README.OS2

Timestamp:

May 26, 2011, 10:56:16 PM (14 years ago)

Author:

Dmitry A. Kuminov

Message:

README.OS2: Added some info about file watching and xWorkplace.

File:

• trunk/README.OS2 (modified) (1 diff)

trunk/README.OS2

@@ -414 +414 @@
 
 
+FILE WATCHING FUNCTION
+
+Qt supports a mechanism of notifying Qt applications about changes to the file
+system, such as creating files or directories, changing their attributes or
+deleting them, even if these changes are performed outside Qt applications. In
+particular, this is used in standard Qt open file dialogs where you can
+instantly observe changes made to the directory contents by third-party
+applications running in the background.
+
+In order to support this functionality on OS/2, Qt relies on the file watching
+mechanism provided by the Presentation Manager. This mechanism is a global
+system resource so that only one process may use it at a time. In a standard
+installation of OS/2 or eComStation this resource is exclusively used by the
+Workplace Shell and is not available to other applications. In order to overcome
+this limitation, a respective function was included to xWorkplace, the famous
+WPS extension (which lives inside the WPS process), starting with version 1.0.8.
+This function allows any number of other processes to receive notifications
+about file system changes and it gets utilized by Qt as well.
+
+If an earlier version of xWorkplace is installed on the user system, or if no
+xWorkplace extension is present at all, Qt uses its own method of detecting
+file system changes which is based on polling the directory contents in regular
+intervals. While this method works well for a small number of watched
+directories with just few files in them, it may significantly slow down the
+system if you work with a directory containing thousands of files.
+
+Therefore, is strongly recommended to install or upgrade to xWorkplace version
+1.0.8 or above to make sure that you will not suffer from the described problem.
+You will also need to make sure that the "Enable folder auto-refresh" check box
+located on the "Folder Views" page in the Workplace Shell settings notebook is
+turned on in order to enable the notification mechanism (note that you may need
+to reboot after changing its state).
+
+
+
 ENVIRONMENT VARIABLES