Changeset 870

May 26, 2011, 8:56:16 PM (9 years ago)
Dmitry A. Kuminov

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

1 edited


  • trunk/README.OS2

    r830 r870  
     418Qt supports a mechanism of notifying Qt applications about changes to the file
     419system, such as creating files or directories, changing their attributes or
     420deleting them, even if these changes are performed outside Qt applications. In
     421particular, this is used in standard Qt open file dialogs where you can
     422instantly observe changes made to the directory contents by third-party
     423applications running in the background.
     425In order to support this functionality on OS/2, Qt relies on the file watching
     426mechanism provided by the Presentation Manager. This mechanism is a global
     427system resource so that only one process may use it at a time. In a standard
     428installation of OS/2 or eComStation this resource is exclusively used by the
     429Workplace Shell and is not available to other applications. In order to overcome
     430this limitation, a respective function was included to xWorkplace, the famous
     431WPS extension (which lives inside the WPS process), starting with version 1.0.8.
     432This function allows any number of other processes to receive notifications
     433about file system changes and it gets utilized by Qt as well.
     435If an earlier version of xWorkplace is installed on the user system, or if no
     436xWorkplace extension is present at all, Qt uses its own method of detecting
     437file system changes which is based on polling the directory contents in regular
     438intervals. While this method works well for a small number of watched
     439directories with just few files in them, it may significantly slow down the
     440system if you work with a directory containing thousands of files.
     442Therefore, is strongly recommended to install or upgrade to xWorkplace version
     4431.0.8 or above to make sure that you will not suffer from the described problem.
     444You will also need to make sure that the "Enable folder auto-refresh" check box
     445located on the "Folder Views" page in the Workplace Shell settings notebook is
     446turned on in order to enable the notification mechanism (note that you may need
     447to reboot after changing its state).
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