[Bro] deleting table entries

[François Pennaneach]

Hi,


I think this is the expected (at least, documented) behavior :

https://www.bro.org/sphinx/script-reference/statements.html#keyword-for

Currently, modifying a container’s membership while iterating over it 
may result in undefined behavior, so do not add or remove elements 
inside the loop.



François

Le 15/12/2016 à 22:32, Dk Jack a écrit :
> All,
> I performed on more experiment. If I iterate over table entries 
> without removing any entries
> while iterating then it iterates over all entries. However, if I 
> remove one or more entries
> during iteration, then the loop does not iterate over all the 
> elements. Some elements
> could be skipped. See the code and the result from my experiment below.
>
> Could one of the experts chime. Clearly, this is not a desired 
> behavior. Thanks.
>
> Dk.
>
>
> global test_table: table[count] of count = table();
>
> event bro_init()
> {
>   local c: count = 0;
>
>   while (c < 100) {
>     test_table[c] = c;
>     c += 1;
>   }
>
>   print fmt("test_table size: %d", |test_table|);
> }
>
> event bro_done()
> {
>   local lcount: count = 0;
>   for (c in test_table) {
>     ++lcount;
>   }
>
>   print fmt("Entries iterated: %d", lcount);
>   while (|test_table| > 0) {
>     lcount = 0;
>
>     print fmt("Table table size before deletion: %d", |test_table|);
>     for (c in test_table) {
>       delete test_table[c];
>       ++lcount;
>     }
>     print fmt("Entries deleted: %d", lcount);
>   }
>
>   print fmt("test_table size: %d", |test_table|);
> }
>
>
> test_table size: 100
> Entries iterated: 100
> Table table size before deletion: 100
> Entries deleted: 59
> Table table size before deletion: 41
> Entries deleted: 30
> Table table size before deletion: 11
> Entries deleted: 11
> test_table size: 0
>
> On Wed, Dec 14, 2016 at 1:30 PM, Dk Jack <dnj0496 at gmail.com 
> <mailto:dnj0496 at gmail.com>> wrote:
>
>     Hi,
>     Does bro scripting allow table entries to be deleted while
>     iterating over the entries of the table?
>     My test script below shows a weird behavior.
>
>     Is there a way to clear the entire contents of the table? I am
>     collecting sum-stats (epoch is 60s)
>     in a table during the epoch_result callback. Then in the
>     epoch_finished callback, I'd like to write
>     the summary results to a log. After that, I'd like to clear the
>     table so that its ready for the next
>     iteration. Iterating and deleting individual elements seems to
>     have a problem as shown in my
>     test script. Any help is appreciated. Thanks.
>
>     Dk.
>
>     global test_table: table[count] of count = table();
>
>     event bro_init()
>     {
>       local c: count = 0;
>
>       while (c < 100) {
>         test_table[c] = c;
>         c += 1;
>       }
>
>       print fmt("test_table size: %d", |test_table|);
>     }
>
>     event bro_done()
>     {
>       while (|test_table| > 0) {
>         print fmt("test_table size: %d", |test_table|);
>
>         # this loop should walk all entries in one go. But it doesn't
>         # because of the delete.
>         for (c in test_table) {
>           delete test_table[c];
>         }
>       }
>
>       print fmt("test_table size: %d", |test_table|);
>     }
>
>     #test_table size: 100
>     #test_table size: 100
>     #test_table size: 43
>     #test_table size: 14
>     #test_table size: 1
>     #test_table size: 0
>
>
>
>
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