commit 14dd07742afef46baf5b597b09a3d7e431a55f7a Author: George Kadianakis <desnacked@riseup.net> Date: Wed Apr 13 14:37:21 2016 +0300 prop224: Time periods now start at 12:00UTC and last 24 hours. --- proposals/224-rend-spec-ng.txt | 31 +++++++++++++++++++------------ 1 file changed, 19 insertions(+), 12 deletions(-) diff --git a/proposals/224-rend-spec-ng.txt b/proposals/224-rend-spec-ng.txt index a3fb40b..e270f1d 100644 --- a/proposals/224-rend-spec-ng.txt +++ b/proposals/224-rend-spec-ng.txt @@ -609,18 +609,25 @@ Status: Draft The length of a "time period" is controlled by the consensus parameter 'hsdir-interval', and is a number of minutes between 30 and - 14400 (10 days). The default time period length is 1500 (one day plus - one hour). - - Time periods start with the Unix epoch (Jan 1, 1970), and are - computed by taking the number of whole minutes since the epoch and - dividing by the time period. So if the current time is 2013-11-12 - 13:44:32 UTC, making the seconds since the epoch 1384281872, the - number of minutes since the epoch is 23071364. If the current time - period length is 1500 (the default), then the current time period - number is 15380. It began 15380*1500*60 seconds after the epoch at - 2013-11-11 20:00:00 UTC, and will end at (15380+1)*1500*60 seconds - after the epoch at 2013-11-12 21:00:00 UTC. + 14400 (10 days). The default time period length is 1440 (one day). + + Time periods start at the Unix epoch (Jan 1, 1970), and are computed by + taking the number of minutes since the epoch and dividing by the time + period. However, we want our time periods to start at 12:00UTC every day, so + we subtract a "rotation time offset" of 12*60 minutes from the number of + minutes since the epoch, before dividing by the time period (effectively + making "our" epoch start at Jan 1, 1970 12:00UTC). + + Example: If the current time is 2016-04-13 11:15:01 UTC, making the seconds + since the epoch 1460546101, and the number of minutes since the epoch + 24342435. We then subtract the "rotation time offset" of 12*60 minutes from + the minutes since the epoch, to get 24341715. If the current time period + length is 1440 minutes, by doing the division we see that we are currently + in time period number 16903. + + Specifically, time period #16903 began 16903*1440*60 + (12*60*60) seconds + after the epoch at 2016-04-12 12:00 UTC, and ended at (16904+1)*1500*60 + + (12*60*60) seconds after the epoch at 2016-04-13 12:00 UTC. 2.2.2. Overlapping time periods to avoid thundering herds [TIME-OVERLAP]