repeat

A node can be automatically repeated in a number of different ways. All nodes can be repeated based on the following (where <variable> is the name of the variable that will be generated for each iteration):

• a sequence of integer values

repeat integer <variable> <start> <end> [<delta>]
  # <start>, <end>, and <delta> are integer values
  # if <delta> is not provided, the default value is '1'

• a sequence of enumerated (string) values

repeat enumerated <variable> <value-1> [<value-2> [... <value-N>]]
  # <value-X> are string values

• a sequence of string values

repeat string <variable> <string-1> [<string-2> [... <string-N>]]
  # <string-X> are string values
  # the iteration will follow the order of the list, and not the alphabetical order of the string values

• a sequence of dates, determined by [begin, end] and a delta

repeat date <variable> <begin> <end> [<delta>]
  # <begin> and <end> are given as YYYYMMDD
  # <delta> is given as an integer number of days
  # if <delta> is not provided, the default value is '1'
  # date arithmetic is used when evaluating trigger/complete expressions

• a sequence of dates, determined by an arbitrary list of dates

repeat datelist <variable> <date-1> [<date-2> [... <date-N>]]
  # <date-X> are given as YYYYMMDD
  # date arithmetic is used when evaluating trigger/complete expressions
  # the iteration will follow the order of the list, and not the chronological order of the dates

• a sequence of time instants, determined by [begin, end] and a delta

repeat datetime <variable> <begin> <end> [<delta>]
  # <begin> and <end> are given as YYYYMMDDTHHMMSS
  # <delta> is given as a duration in the format HH:MM:SS
  # if <delta> is not provided, the default value is '24:00:00'
  # seconds-based arithmetic is used when evaluating trigger/complete expressions

• a sequence of time instants, determined by an arbitrary list of time instants

repeat datetimelist <variable> <instant-1> [<instant-2> [... <instant-N>]]
  # <instant-X> are given as YYYYMMDDTHHMMSS
  # seconds-based arithmetic is used when evaluating trigger/complete expressions
  # the iteration will follow the order of the list, and not the chronological order of the time instants

repeat day [<delta>]
  # only for suites
  # <delta> is given as an integer number of days
  # if <delta> is not provided, the default value is '1'

Important

The day repeats, available only for suites, are tied to the clock used by the suite.

A hybrid clock must be used in order to stop the iteration; a suite using a real-time clock cannot be stopped by means of end time.

Note

Completing a node, with force complete, will only force the current running job to complete. This means that, if the repetition is not finished, the next value of the iteration is used to immediately continue with the next job, provided any children of the repeated node are also complete.

Tip

The common practice at ECMWF is to use the repeat date when designing a suite. This approach is considered superior (compared to using the repeat day on the suite), as it allows to easily adjust the date the suite is running.

Warning

When a repeat is associated to a family/suite, this repeat will only continue iterating (and thus automatically re-queue all children) if all the children are complete.

Care must be taken when designing a Suite that uses a repeat on a family/suite and the children have triggers or attributes that can prevent them from completing (e.g. a cron attribute will immediately re-queue the node once it finishes, preventing the iteration of the repeat from moving forward).

Generated variables

Each kind of repeat attribute type defines a set of generated variables, which can be used in the generation of job scripts and included in trigger and complete expressions.

The value of these variables is automatically updated when the node associated with the repeat attribute completes and the node is re-queued – except, of course, when the iteration reaches the end.

The set of generated variables depends on the type of repeat, but in general includes the current value of the iteration, and for date and datetime repeats, components of the date/time instant. The following table specifies the generated variables for each repeat type:

Table 7 Generated variables for each repeat type

Repeat Type	Variable Name, and Value
integer	<variable>, the current integer value of the loop.
string	<variable>, the current string value (the item from the list for this iteration).
enumerated	<variable>, the current string value (the item from the list for this iteration).
date, datelist	<variable>, the current date value, formatted as YYYYMMDD. <variable>_YYYY, the Year component of the current date (four digits, YYYY). <variable>_MM, the Month component of the current date (two digits, MM). <variable>_DD, the Day component of the current date (two digits, DD). <variable>_DOW, the Day of week of the current date. <variable>_JULIAN, the Julian day corresponding to the current date.
datetime, datetimelist	<variable>, the current time instant value, formatted as YYYYMMDDThhmmss. <variable>_DATE, the Date of the current time instant, formatted as YYYYMMDD. <variable>_YYYY, the Year component of the current time instant (four digits, YYYY). <variable>_MM, the Month component of the current time instant (two digits, MM). <variable>_DD, the Day component of the current time instant (two digits, DD). <variable>_DOW, the Day of week of the current time instant. <variable>_TIME, the Time of the current time instant, formatted as hhmmss. <variable>_HOURS, the Hour component of the current time instant (two digits, hh). <variable>_MINUTES, the Minute component of the current time instant (two digits, mm). <variable>_SECONDS, the Seconds component of the current time instant (two digits, ss). <variable>_JULIAN, the Julian day corresponding to the date of the current time instant.

When used in trigger or complete expressions, for integer arithmetic, the interpretation of the variables value depends on the repeat type – see the following table for details.

Table 8 Interpretation of repeat variable’s value in trigger/complete expressions for integer arithmetic

Repeat Type	Variable Interpretation
integer	The value of <variable> is interpreted as the current integer value of the loop.
string	The value of <variable> is interpreted as the current index in the list (0-based).
enumerated	The value of <variable> is interpreted as the current enumeration value converted to integer, if convertible; otherwise, the value is the current index in the list (0-based).
date, datelist	The value of <variable> is interpreted as the current date integer value, formatted as YYYYMMDD. This value will be subject to date arithmetic (e.g 20090101 - 1 == 20081231).
datetime, datetimelist	The value of <variable> is interpreted as the current time instant value, as integer seconds since 19700101T000000. Integer arithmetic applies (e.g. adding 86400 advances the value by one day).

Used in combination with relative time

Relative time attributes can be used in combination with a repeat, and will automatically reset when the repeat loops. This allows to easily delay the starting of a task for a certain amount of time after the previous iteration completes.

Important

When using a relative time attribute, e.g. time +02:00, below a repeat attribute, then this time is considered relative to the repeat iteration value.

The following example shows how to delay the starting of task a by 1 minute after the previous iteration completes, using a repeat integer. When task a and task b complete, the repeat is incremented, and any relative time attributes are reset. In this case, effectively delaying the starting of task a by 1 minute.

suite s
  family f
    repeat integer YEAR 1993 2017
    time +00:01    # when the repeat loops delay starting task a, for 1 minute
    task a
    task b
      trigger a  == complete
    endfamily
endsuite

See also:

Command line interface (CLI)	add, alter
Python API	ecflow.Node.add_repeat, ecflow.Repeat, ecflow.RepeatDate, ecflow.RepeatDateList, ecflow.RepeatDateTime, ecflow.RepeatDateTimeList, ecflow.RepeatEnumerated, ecflow.RepeatInteger, ecflow.RepeatDay
Definition file grammar	repeat
Glossary	repeat