From e0da6af91e49c68cd3e7cbb390aac432e6d283a6 Mon Sep 17 00:00:00 2001
From: John Tramm <john.tramm@gmail.com>
Date: Fri, 24 Jan 2020 02:31:00 +0000
Subject: [PATCH] added command line argument for event-based mode.

---
 examples/xml/pincell/settings.xml | 1 -
 openmc/executor.py                | 7 ++++++-
 src/initialize.cpp                | 3 +++
 src/output.cpp                    | 1 +
 4 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/examples/xml/pincell/settings.xml b/examples/xml/pincell/settings.xml
index 3cb3f043d8..5845898c8d 100644
--- a/examples/xml/pincell/settings.xml
+++ b/examples/xml/pincell/settings.xml
@@ -6,7 +6,6 @@
   <batches>100</batches>
   <inactive>10</inactive>
   <particles>1000</particles>
-  <event_based>true</event_based>
 
   <!-- The starting source is a uniform distribution over the entire pin
        cell. Note that since this is effectively a 2D model, the z coordinates
diff --git a/openmc/executor.py b/openmc/executor.py
index 8ad2bd8960..8e2979f019 100644
--- a/openmc/executor.py
+++ b/openmc/executor.py
@@ -154,7 +154,7 @@ def calculate_volumes(threads=None, output=True, cwd='.',
 
 def run(particles=None, threads=None, geometry_debug=False,
         restart_file=None, tracks=False, output=True, cwd='.',
-        openmc_exec='openmc', mpi_args=None):
+        openmc_exec='openmc', mpi_args=None, event_based=False):
     """Run an OpenMC simulation.
 
     Parameters
@@ -182,6 +182,8 @@ def run(particles=None, threads=None, geometry_debug=False,
     mpi_args : list of str, optional
         MPI execute command and any additional MPI arguments to pass,
         e.g. ['mpiexec', '-n', '8'].
+    event_based : bool, optional
+        Turns on event-based parallelism, instead of default history-based
 
     Raises
     ------
@@ -199,6 +201,9 @@ def run(particles=None, threads=None, geometry_debug=False,
 
     if geometry_debug:
         args.append('-g')
+    
+    if event_based:
+        args.append('-e')
 
     if isinstance(restart_file, str):
         args += ['-r', restart_file]
diff --git a/src/initialize.cpp b/src/initialize.cpp
index 166fddcf82..22479ae29d 100644
--- a/src/initialize.cpp
+++ b/src/initialize.cpp
@@ -134,6 +134,9 @@ parse_command_line(int argc, char* argv[])
       } else if (arg == "-n" || arg == "--particles") {
         i += 1;
         settings::n_particles = std::stoll(argv[i]);
+      
+      } else if (arg == "-e" || arg == "--event") {
+        settings::event_based = true;
 
       } else if (arg == "-r" || arg == "--restart") {
         i += 1;
diff --git a/src/output.cpp b/src/output.cpp
index edcb803915..95a08bb7bd 100644
--- a/src/output.cpp
+++ b/src/output.cpp
@@ -327,6 +327,7 @@ void print_usage()
       "                         or a particle restart file\n"
       "  -s, --threads          Number of OpenMP threads\n"
       "  -t, --track            Write tracks for all particles\n"
+      "  -e, --event            Run using event-based parallelism\n"
       "  -v, --version          Show version information\n"
       "  -h, --help             Show this message\n";
   }