progress_time: try to make this work when running parallel plyr jobs

[mike-lawrence]

Hadley doesn't think there will be any universal solution given the paucity of foreach's feedback, but possibly for macs using doMC and having users explicitly set the value of options('cores'), progress_time might be able to adjust its behaviour to accurately reflect the progress. Or possibly we just need to bug the foreach maintainers to have it provide appropriate feedback...

[russellpierce]

Another option you may want to consider (if you haven't already) is to use http://cran.r-project.org/web/packages/doRedis/index.html. It appears that it can store the number of 'jobs' completed allowing you to watch the intermediate states of the parallel process and it uses the %dopar% approach from foreach. Of course, that would require that the user install the backend, but it might be worth it from your standpoint because Redis is (supposedly) platform independent. Although, I will grant that at present setting up Redis appears non-trivial.