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Aucb.568 fa.editor-p utcsrgv!utzoo!decvax!ucbvax!C70:editor-people Mon Mar 1 20:31:13 1982 interlocking >From ADMIN.MRC@SU-SCORE Mon Mar 1 20:12:19 1982 On TOPS-20, if you are interested in merely interlocking between cooperating processs, there are the ENQ% and DEQ% system calls. This lock and unlock a monitor resource independent of the file. The MM mailsystem uses this to great success. In addition, file clobberage due to that file being mapped during a system crash can be avoided by not allowing dribbling of updates from the swapper to the filesystem copy, then forcing the updates at graceful points (another feature that isn't in Tenex).

If you insist upon interlocking the file but allowing appends to it (as in a mail file), I don't know of any system offhand which allows this. On SAIL, a file is interlocked once you try to change it, and once that it done no changes (including appends) may be made by any other process. -- Mark -- -------

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