Does anything survive an uncaught exception?

Question

If I am running some Apex code that generates an uncaught exception, everything is rolled back automatically - changes to records, sent emails, future tasks, etc.

Is there anything that does not get rolled back?

The reason I am asking is because I wish to provide an audit log of operations (even unsuccessful ones). Obviously there is the debug log, but that only appears if enabled, doesn't handle managed packages very well, and no longer appears for Sites guest users unless you jump through hoops (which isn't always possible).

Answer 1

You might be knowing that we can handle different kind of exceptions using a try catch statement. With that you can collect different logs in a custom object.

// Set save point
Savepoint sp = Database.setSavepoint();

// custom object used for logging
Logging__c objLogging = new Logging__c();
try{
     //Your code here

     objLogging.description = 'inside try statement';
} catch (ListException e) {
     //Optional catch of a specific exception type
     //Specific exception handling code here

     objLogging.description += 'List exception: ' + e.getMessage();
} catch (Exception e) {
     //Generic exception handling code here

     objLogging.description += 'generic exception: ' + e.getMessage();
} finally {
     //optional finally block
     //code to run whether there is an exception or not

     // Rolling back to previous state!
     Database.rollback(sp);
     // log the error into custom object
     insert/update objLogging;
}

Additionally you may want to use Database.rollback for having a more controlled rollback mechanism.

Answer 2

The short answer to your question is that uncaught exceptions can't be logged. It is a best practice to wrap your code in try/catch blocks. You can even wrap large sections of code in a try and even nest try/catch blocks within an existing try block.

Developerforce has a very comprehensive article on exception handling