Wachtdog event

No watchdog events, only watchdog actions. What kind of events would you like to use??

This might be an interesting integration. Do you mean something like: "if watchdog create a new log entry for module X with text ZZZZ, trigger a rule" ?

Yes exactly. With some conditions like severity, type and maybe more.
Would be a nice addition. In my case i want to be noticed(mail) when watchdog logs a PHP error.

I created a watchdog event.

You can trigger a rule on a watchdog log entry and then use the various arguments to do conditions. Available arguments are:
- Type (module)
- Message
- Severity
- Log User
- Referrer
- IP
- Link
- Time

With this event trigger you can somewhat integrate all kinds of modules that don't have a trigger. If they generate a watchdog log, you can use that to run a rule.

Here are the patches. Tested and working here. Please review and comment

Im not really sure how to create a condition with this. Should i use the rules conditions to compare the arguments?
Shouldnt there be a watchdog condition for the event?

Yes, use the rules conditions. You would pprobably need the PHP Filter module enables so you can evaluate PHP. Then, in the rules condition on a watchdog event you would find PHP variables for each of the watchdog components that you can compare. You can use a text comparison or a true/false condition based on PHP.

Once you have PHP Filter enabled, enter a condition and then in it you will find a helpful PHP variables tab. All the watchdog variables are listed there. You can then evaluate those in PHP. If you are wondering what they contain, you could create a system message action and display one with say

<? echo "Severity: " . $severity; ?> to see the contents.

Yep that seems to work. Though the $message variable doesnt seems to get run through t() correctly.
For example the watchdog notice for a new page shows: "@type: added %title.".

+1 for this feature. however let's just pass the log entry as whole to rules. Thus you you have to tell rules about it, but that's not hard: http://drupal.org/node/298639

Perhaps let's call it 'watchdog_entry' or so? Thus one could also add token support for it's entry. To get the message translated you'd have to call t() on the message using the variables in $log, see http://api.drupal.org/api/function/dblog_watchdog/6

@loop:
Rules has a recursion prevention, thus this should work for that case too. So you can remove this check.

ok

Totally agree about doing a type. I used the "comment" integration as my guide, so I can figure out how to do a data type quite easily, no problem.

On rules recursion: I know if you trigger a watchdog action from a rule, it will prevent recursion back into the same rule. But, during my test I found another possibility - if it triggered an *error* during the rule execution, and that error was reported by rules itself to the watchdog (ie npt a watchdog action, but a rules error notice), it went into an endless loop until PHP memory ran out. I can't remember exactly how I caused a rules error, but it did go into infinite loop. Let me see if I can re-create in case it is a problem.

@loop: I see, I didn't think of that error logging. However it would be nice if it would be possible to deal with rules error messages too.

Thus, what about moving

in rules_evaluate_rule_set() before the rules_log_evaluation_clear() call. I haven't overlooked something this should fix it thus the rules recurions prevents would prevent a loop. If that works, don't forget to add a comment to remind us of that later on.. :)