Router optimise doesn't work with regex grouping.

[iain-buclaw-sociomantic]

Now that the number of rules has grown to a big enough size to trigger router_optimise to walk through all patterns. I've noticed that some aggregations have stopped, where a rule like so exists.

aggregate
    (foo|bar)\.(.+)
  # ...
  ;

What happens is that a bar group is created, and all rules that match bar go into it. But when a metric foo comes in, it never hits the rule.

[grobian]

Ok, it's a matter of removing the optimiser code, or making it deal with simple expressions only. (I guess its heuristics still work out well for a pattern like '.*foo.*bar.*')

[iain-buclaw-sociomantic]

Yes. Although that's not to say that being aware of regex groups is not a bad thing, where in the above example, two groups are created with the same rules inside.

However for simplicity, something like the following works well enough.

/* strip off chars that won't belong to a block */
int ingroup = 0;
while (
                p > rwalk->pattern &&
                ingroup > 0 ||
                (*p < 'a' || *p > 'z') &&
                (*p < 'A' || *p > 'Z') &&
                *p != '_'
          ) {
        if (*p == ')')
                ingroup++;
        else if (*p == '(' && ingroup > 0)
                ingroup--;
        p--;
}

So a pattern like foo\.(bar|baz) will go inside a group for foo

[grobian]

That works too. The code was originally setup to be very rule-of-thumb-like (WorkingForUs(tm)) and quite naive, but worked wonders back then. Perhaps skipping the complex part would be smartest thing to do here indeed.