pause_watch

PAUSE_WATCH

pauses a StopWatch watch

SYNOPSIS
subroutine pause_watch (watch, clock, err)

type (watchtype), intent(IN) :: watch

OR

type (watchtype), intent(IN) :: watch(:)

OR

type (watchgroup), intent(IN) :: watch

character(len=*), optional, intent(IN) :: clock

OR

character(len=*), optional, intent(IN) :: clock(:)

integer, optional, intent(OUT) :: err

DESCRIPTION
Pauses the specified clocks of the specified watches. This is useful when you want to temporarily stop the clocks to avoid timing a small segment of code, for example printed output or graphics, but do not know which watches or clocks are running. When pause_watch is called, the information about which of the clocks were running is maintained, so that a subsequent call to end_pause_watch will restart only those clocks that were running. Watches that are paused can not be started, stopped, reset, or paused again until they are resumed by end_pause_watch. However, they can be read and printed.

One or more watches must be specified. The argument watch can be a single variable of type watchtype (see stopwatch(3)) to pause one watch, an array of type watchtype to pause several watches, or a variable of type watchgroup (see stopwatch(3)) to pause the watches in a group.

The optional argument clock specifies which clocks to pause on the specified watch(es). If omitted, the current default clocks (see option_stopwatch(3)) are paused. If present, clock must be a character string containing 'cpu', 'user', 'sys', or 'wall', or an array of such character strings.

DIAGNOSTICS
If present, the optional intent OUT integer argument err returns a status code. The code is the sum of the values listed below.

An error message will be printed to a specified I/O unit (unit 6 by default) if print_errors is TRUE (default is TRUE). The error message contains more detail about the cause of the error than can be obtained from just the status code, so you should set print_errors to TRUE if you have trouble determining the cause of the error.

If abort_errors is TRUE (default is FALSE), the program will terminate on an error condition. Otherwise, the program will continue execution but the watch(es) will not be paused.

See option_stopwatch(3) for further information on print_errors, abort_errors and I/O units.

The relevant status codes and messages are:

0

No errors; execution successful.

1

Watch needs to be created. This error occurs if you attempt to pause a watch that has been destroyed. The watch must first be created again. See also the comment about watches that have never been created in the BUGS section.

2

Watch is in the wrong state for this operation. This occurs when you attempt to pause a watch that is currently paused.

4

Watch is in an unknown state. This occurs if StopWatch does not recognize the state (running, stopped, etc.) that the watch is in. This error should not occur, and indicates an internal bug in StopWatch .

8

Invalid clock type. This occurs if clock is present and one of the specified clocks is not supported by the implementation. See inquiry_stopwatch(3) to determine what clocks are available.

512

Failed to allocate required memory. When pause_watch is called with an array or group of watches, temporary memory is allocated. This error occurs if the Fortran allocate statement returns a nonzero status indicating that memory could not be allocated. Avoid memory leaks by always destroying watches and groups before recreating them, and destroying local variable watches and groups before returning from a subroutine.

1024

Error occurred while deallocating memory. This error occurs if the Fortran deallocate statement returns a nonzero status while deallocating temporary memory used for an array or group of watches. The watches are paused, but be aware that other problems could develop as a result of the deallocate error.

In addition to the run time diagnostics generated by StopWatch , the following problem may arise:

In Fortran 90, the character strings in an array constructor must all have the same length. Pad three letter clock names with a blank on the right to make a four character string, for example, 'cpu '.

EXAMPLES
type (watchtype) w1, w2(3)
type (watchgroup) g1
integer errcode

call pause_watch(w1)
call pause_watch(w2, err=errcode)
call pause_watch(g1, (/'cpu ', 'wall'/), errcode)

The first call pauses the default clocks on a single watch. The second call pauses the default clocks on three watches given as an array and returns a status code. The third call pauses the cpu and wall clocks on the watches in the group g1, and returns a status code.

BUGS
It cannot be determined whether or not a watch variable or watch group has been created (passed as an argument to create_watch or create_watchgroup). If a watch or watch group that has never been created is passed into pause_watch, it might generate a Fortran error due to passing a pointer with undefined association status to the Fortran intrinsic function associated. Some compilers will allow this as an extension to the Fortran 90 standard and recognize that the pointer is not associated, in which case the ``Watch needs to be created'' error message is generated.