Improve performance of isEqual() by skipping Comparator Factory

[willemstuursma]

For our case, a lot of time during test evaluation is spent on the comparison of different values through the assertEquals() assertion. See for example the performance trace of a test run:

This PR will change PHPUnit to do a quick strict comparison check before doing an equality check. This check is very cheap, and is the most common case during test runs. If the expected and the actual value are not identical, the existing code path is followed and the Comparator library is used.

Performance of tests with this patch:

Time: 56.02 seconds, Memory: 261.00Mb

OK, but incomplete, skipped, or risky tests!
Tests: 4488, Assertions: 10734, Incomplete: 2, Skipped: 22.

Performance with base PHPUnit (4.3.1)

Time: 1.21 minutes, Memory: 261.00Mb

OK, but incomplete, skipped, or risky tests!
Tests: 4488, Assertions: 10734, Incomplete: 2, Skipped: 22.

Performance improvement is about 25-30%.

[willemstuursma]

Thanks, that was quick!

[sebastianbergmann]

Thank you for the idea. I changed the patch after the merge, though. Next step should be figuring out a solution for #1474.

[willemstuursma]

Any chances of this landing in the 4.3 branch too?

[sebastianbergmann]

No. This is too big of a change for a branch that is in "bugfix only" mode. This will go into PHPUnit 4.5.

[willemstuursma]

I've thought a bit about #1474. I see that is uses a singleton for the Comparator\Factory class. Most of the overhead is in constructing this object. So if it uses a singleton, we do not need the changes from this PR anymore, lost of time will already be saved by not instanciating the Factory for every comparison.