I have a large and busy log file, once or twice a day a line will pop up looking something like one of these: 

2009-02-02 06:12:57,500 dates processed: 2009-01-31, 2009-01-29, 2009-
+01-30
2009-02-18 06:03:47,713 dates processed: 2009-02-16, 2009-02-17
2009-02-19 05:58:29,138 dates processed: 2009-02-18

[download]

I need to extract the all occurrences of the date pattern /\d{4}-\d{2}-\d{2}/ but only when the line also contains 'dates processed'. The trailing list of dates is of variable length but there will always be at least one.

Due to the log monitoring tool we have I need to grab this in a single regex. The log file is busy on a busy production server so some degree of efficiency is desired. Up until now even before optimising I have not got it to work, here are (some of) my attempts so far: 

@res =$_ =~/(\d{4}-\d\d-\d\d)/g
# gets them all but also from lines without 'dates processed'

@res = $_ =~/(\d{4}-\d\d-\d\d).*dates processed: (\d{4}-\d\d-\d\d,? ?)
+*/g
# only returns first of trailing list

@res = $_ =~/(\d{4}-\d\d-\d\d).*dates processed: ((\d{4}-\d\d-\d\d)*)/
# gets the right number of results but the final list all the same val
+ue!

[download]

Update

@res = $_ =~/(\d{4}-\d\d-\d\d).*dates processed: ((\d{4}-\d\d-\d\d,? ?
+)*)
# almost gets it but now have one too many results in the tail 
# due to the nested braces

[download]

Update 2

highlighted that the cunning part here is a single regex is needed, a few kind souls are missing this

</Updates>

Can any of the regex gurus out there give me a hint please

Thanks,
R.

Pereant, qui ante nos nostra dixerunt!

In reply to regex: extract multiple number of date patterns from certain lines by Random_Walk

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