SPUG: Does tie() do file-locking?
tim at consultix-inc.com
Wed Jun 14 11:49:28 CDT 2000
I'm teaching my "Intermediate Perl" class this week, and some questions
about file-locking have arisen. I could probably find the answers myself by
reading some source code, but I'd rather spend my time helping my students
on their lab assignments instead, so I thought I'd ask if anybody knows
1) Does the -i invocation option lock the files it processes?
(Seems like it should, but if it does, that's not documented!)
2) Does tie() do file-locking on its own? If not, how do
programmers protect the tied-file from disruptive accesses?
(such as that of a daemon program, or 500 "nobody UIDs" accessing
the same CGI program?)
3) When does the file tied to a hash get updated? Immediately
on changes to the hash? Not until UNIX flushes the buffer
holding the changes (via the next sync() )? Whenever the
writer of the *DB*_file module feels like doing it?
(Seems to me that file-locking should ideally be done on a
per-record basis by the *DB*_file module itself, but I'm
not finding any relevant documentation, so please clue me in
if you know!)
| Dr. Tim Maher, CEO, Consultix (206) 781-UNIX/8649; ask for FAX# |
| Email: tim at consultix-inc.com Web: http://www.consultix-inc.com |
| CLASSES; 6/12: Int. Perl 6/15: Pat. Matching 8/14: UNIX 8/21: Shell |
| DAMIAN CONWAY Seminars; Adv. OO Perl: 7/6, Parsing with Modules: 7/7 |
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