petsc-3.10.5 2019-03-28
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# PetscLogEventRegister

Registers an event name for logging operations in an application code.

### Synopsis

    #include "petscsys.h"
    PetscErrorCode  PetscLogEventRegister(const char name[],PetscClassId classid,PetscLogEvent *event)

Not Collective

### Input Parameter

| name | - The name associated with the event
| classid | - The classid associated to the class for this event, obtain either with PetscClassIdRegister() or use a predefined one such as KSP_CLASSID, SNES_CLASSID, the predefined ones are only available in C code

### Output Parameter

event -The event id for use with PetscLogEventBegin() and PetscLogEventEnd().

### Example of Usage

          PetscLogEvent USER_EVENT;
          PetscClassId classid;
          PetscLogDouble user_event_flops;
          PetscClassIdRegister("class name",&classid);
          PetscLogEventRegister("User event name",classid,&USER_EVENT);
          PetscLogEventBegin(USER_EVENT,0,0,0,0);
             [code segment to monitor]
             PetscLogFlops(user_event_flops);
          PetscLogEventEnd(USER_EVENT,0,0,0,0);

### Notes

PETSc automatically logs library events if the code has been configured with --with-log (which is the default) and -log_view or -log_all is specified. PetscLogEventRegister() is intended for logging user events to supplement this PETSc information.

PETSc can gather data for use with the utilities Jumpshot (part of the MPICH distribution). If PETSc has been compiled with flag -DPETSC_HAVE_MPE (MPE is an additional utility within MPICH), the user can employ another command line option, -log_mpe, to create a logfile, "mpe.log", which can be visualized Jumpshot.

The classid is associated with each event so that classes of events can be disabled simultaneously, such as all matrix events. The user can either use an existing classid, such as MAT_CLASSID, or create their own as shown in the example.

If an existing event with the same name exists, its event handle is returned instead of creating a new event.

### Keywords

log, event, register

### See Also

PetscLogEventBegin(), PetscLogEventEnd(), PetscLogFlops(),
PetscLogEventActivate(), PetscLogEventDeactivate(), PetscClassIdRegister()

### Level

intermediate

### Location

src/sys/logging/plog.c

### Examples

src/sys/classes/random/examples/tutorials/ex1.c.html
src/sys/logging/examples/tutorials/ex1f.F90.html
src/sys/examples/tutorials/ex3.c.html
src/sys/examples/tutorials/ex3f.F.html
src/vec/vec/examples/tutorials/ex5.c.html
src/vec/vec/examples/tutorials/ex10.c.html
src/vec/vec/examples/tutorials/ex15.c.html
src/ksp/ksp/examples/tutorials/ex9.c.html
src/snes/examples/tutorials/ex12.c.html
src/snes/examples/tutorials/ex62.c.html
src/snes/examples/tutorials/ex77.c.html
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