10 Feb
2021
10 Feb
'21
1:06 a.m.
On 2/9/21 12:31 PM, John Cowan wrote:
From BTSJ 57:6:
The file system maintains no locks visible to the user, nor is there
any restriction on the number of users who may have a file open for
reading or writing. Although it is possible for the contents of a file
to become scrambled when two users write on it simultaneously, in
practice difficulties do not arise.We take the view that locks are
neither necessary nor sufficient, in our environment, to prevent
interference between users of the same file. They are unnecessary
because we are not faced with large, single-file databases maintained
by independent processes. They are insufficient because locks in the
ordinary sense, whereby one user is prevented from writing on a file
that another user is reading, cannot prevent confusion when, for
example, both users are editing a file with an editor that makes a copy
of the file being edited.
"In our environment" is doing some pretty heavy lifting there.
--
``The lyf so short, the craft so long to lerne.'' - Chaucer
``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU chet(a)case.edu http://tiswww.cwru.edu/~chet/