Re: Question on File locking

On 13-Aug-2014 15:39 -0500, Vinay Gavankar wrote:

I think that using the timestamp (retrieved when writing to the data
queue), instead of the sequence number will work. I will have to use
an API to get UTC or something, otherwise if I use System Time,
wouldn't it go back when Daylight Saving time ends?

I believe the requirement to use GMT\UTC due to TIMEZONE issues is dependent upon how the system achieves the transition to the new time [either a reset or clock slowed] and if the timestamp has sufficient accuracy to guarantee uniqueness both in standard operation and when the clock is slowed to effect the transition. Seems ensuring UTC is probably the safest, because IIRC the implementation of the time change is hardware dependent; possibly until Power7?

For performance reasons previously discussed, obtaining a timestamp when the data is dequeued is probably a better choice.? Of course, the added benefit of having the timestamp of the actual I\O [versus an arbitrary but also chronologically\serially maintained timestamp] may outweigh the cost of obtaining the timestamp in the trigger program.