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:IF-EXISTS :SUPERSEDE
- To: Moon%SCRC-TENEX@MIT-MC.ARPA, CWH%SCRC-TENEX@MIT-MC.ARPA, Wholey@CMU-CS-C.ARPA, Fahlman@CMU-CS-C.ARPA
- Subject: :IF-EXISTS :SUPERSEDE
- From: "Bernard S. Greenberg" <BSG%SCRC-TENEX@MIT-MC.ARPA>
- Date: Tue, 6 Dec 83 10:30 EST
- Cc: Common-Lisp@SU-AI.ARPA, Bug-Lispm%SCRC-TENEX@MIT-MC.ARPA, ROM%SCRC-TENEX@MIT-MC.ARPA, file-protocol%SCRC-TENEX@MIT-MC.ARPA, jwalker%SCRC-TENEX@MIT-MC.ARPA
- In-reply-to: The message of 5 Dec 83 23:12-EST from David A. Moon <Moon at SCRC-TENEX>
Date: Monday, 5 December 1983, 23:12-EST
From: David A. Moon <Moon at SCRC-TENEX>
Argument #2:
Given the primitives available to the file server in versionated
operating systems, it is impossible to implement this as proposed
without a window between determining the version number and opening
it for superseding.
This argument is false. The Tops-20/Tenex Chaosnet file server has
no problem doing this without windows. During the time between opening
and closing, the old file is in an "open for reading" state that
prevents anyone else from superseding it or renaming it. Presumably other
versionated operating systems may have comparable primitives.
Could you detail the sequence of operations? The above is not sufficiently
clear. When do you open the second file? Under what name?