Two-Point Meters
Several classes for transfer time measurement are derived from
TwoPointMeter:
+ The class
TimeMeter is implemented as base class and provides the methods
createTimeStamp(),
evaluateTimeStamp() and
deleteTimeStamp() for
an efficient memory management of time stamps (class
TimeStamp) using a so-called free
list. Whereby a time stamp contains the ID of the meter as well as a time value. Figure 1
depicts the principle of a transfer time meter.
Principle of a transfer time meter
+ The class
StdTimeMeter derived from
TimeMeter is a meter to determine the transfer
times between two or more ports and provides the following features. Upon constructor
call, no further parameters are required.
- The use of generic message filters and management in a respective data structure
-
attachFromPort() connects a meter to a port whose time measurement begins by
installing a filter of the type
GenMessageFilter, which uses the
setTimeStamp() method from
StdTimeMeter as a handler function.
-
attachToPort() connects a meter to a port whose time measurement ends by installing
a filter of the type
GenMessageFilter and uses the
readTimeStamp()
method from
StdTimeMeter as a handler function.
- Calling
setTimeStamp() causes a time stamp with the current system time to be
attached to the message that is just passing the port by calling the
Message method
addTimeStamp().
-
readTimeStamp() acquires the time stamp that belongs to the meter from the current
message using the method
getTimeStamp() from
Message, evaluates its transfer
time and removes it from the message (
removeTimeStamp()).
- Evaluation of transfer times with the help of a statistic of the type
SampleStatistic
+ The class
DistTimeMeter is derived from
StdTimeMeter and additionally provides a
distribution statistic. Therefore, the array size of measures as well as lower and upper limit
of the interarrival time that has to be captured during simulation are required upon construction.
+ The class
BoundaryTimeMeter is used to find the quantile for a given percentage. It
uses the a boundary statistic and thus provides two constructors, one
for
StdBoundaryStatistic and one for
JainBoundaryStatistic. Accordingly,
additionally to the percentage (e.g., 0.95) the expected number of samples is required upon
construction in case the
StdBoundaryStatictic is applied.
+ The class
MedianTimeMeter is used to determine the median of transfer time values
between two points in a simulation model.