From 36786e898b00b8e6f8ad77b0965e8938c3493f86 Mon Sep 17 00:00:00 2001
From: Moritz Sallermann <m.sallermann@fz-juelich.de>
Date: Wed, 13 Nov 2019 11:07:16 +0100
Subject: [PATCH] API: Added a method Simulation_N_Shot. Works similar to
 Simulation_SingleShot but performs multiple iterations. Can reduce overhead
 of calling multiple singleshots in some applications.

---
 core/docs/c-api/Simulation.md    | 13 ++++++++
 core/include/Spirit/Simulation.h |  8 +++++
 core/python/spirit/simulation.py | 13 +++++++-
 core/src/Spirit/Simulation.cpp   | 53 +++++++++++++++++---------------
 4 files changed, 61 insertions(+), 26 deletions(-)

diff --git a/core/docs/c-api/Simulation.md b/core/docs/c-api/Simulation.md
index a0f91a1a3..8bf6f18b4 100644
--- a/core/docs/c-api/Simulation.md
+++ b/core/docs/c-api/Simulation.md
@@ -160,6 +160,19 @@ Otherwise, nothing will happen.
 
 
 
+### Simulation_N_Shot
+
+```C
+void Simulation_N_Shot(State *state, int N, int idx_image=-1, int idx_chain=-1);
+```
+
+N iterations of a Method
+
+If `singleshot=true` was passed to `Simulation_..._Start` before, this will perform N iterations.
+Otherwise, nothing will happen.
+
+
+
 ### Simulation_Stop
 
 ```C
diff --git a/core/include/Spirit/Simulation.h b/core/include/Spirit/Simulation.h
index e4e3280dc..0a8fa4a55 100644
--- a/core/include/Spirit/Simulation.h
+++ b/core/include/Spirit/Simulation.h
@@ -85,6 +85,14 @@ Otherwise, nothing will happen.
 */
 PREFIX void Simulation_SingleShot(State *state, int idx_image=-1, int idx_chain=-1) SUFFIX;
 
+/*
+N iterations of a Method
+
+If `singleshot=true` was passed to `Simulation_..._Start` before, this will perform N iterations.
+Otherwise, nothing will happen.
+*/
+PREFIX void Simulation_N_Shot(State *state, int N, int idx_image=-1, int idx_chain=-1) SUFFIX;
+
 // Stop a simulation running on an image or chain
 PREFIX void Simulation_Stop(State *state, int idx_image=-1, int idx_chain=-1) SUFFIX;
 
diff --git a/core/python/spirit/simulation.py b/core/python/spirit/simulation.py
index 3023b4cfd..73f53747c 100644
--- a/core/python/spirit/simulation.py
+++ b/core/python/spirit/simulation.py
@@ -173,7 +173,18 @@ def single_shot(p_state, idx_image=-1, idx_chain=-1):
     """
     spiritlib.wrap_function(_SingleShot, [ctypes.c_void_p(p_state),
                                          ctypes.c_int(idx_image), ctypes.c_int(idx_chain)])
-    # _SingleShot(ctypes.c_void_p(p_state), ctypes.c_int(idx_image), ctypes.c_int(idx_chain))
+
+_N_Shot          = _spirit.Simulation_N_Shot
+_N_Shot.argtypes = [ctypes.c_void_p, ctypes.c_int, ctypes.c_int, ctypes.c_int]
+_N_Shot.restype  = None
+def n_shot(p_state, N, idx_image=-1, idx_chain=-1):
+    """Perform a single iteration.
+
+    In order to use this, a single shot simulation must be running on the corresponding image or chain.
+    """
+    spiritlib.wrap_function(_N_Shot, [ctypes.c_void_p(p_state), ctypes.c_int(N),
+                                         ctypes.c_int(idx_image), ctypes.c_int(idx_chain)])
+
 
 _Stop           = _spirit.Simulation_Stop
 _Stop.argtypes  = [ctypes.c_void_p, ctypes.c_int, ctypes.c_int]
diff --git a/core/src/Spirit/Simulation.cpp b/core/src/Spirit/Simulation.cpp
index 45c922aba..0c1c142aa 100644
--- a/core/src/Spirit/Simulation.cpp
+++ b/core/src/Spirit/Simulation.cpp
@@ -385,8 +385,12 @@ catch( ... )
     spirit_handle_exception_api(idx_image, idx_chain);
 }
 
-
 void Simulation_SingleShot(State *state, int idx_image, int idx_chain) noexcept
+{
+    Simulation_N_Shot(state, 1, idx_image, idx_chain);
+}
+
+void Simulation_N_Shot(State *state, int N, int idx_image, int idx_chain) noexcept
 try
 {
     // Fetch correct indices and pointers for image and chain
@@ -415,34 +419,33 @@ try
     if( method->ContinueIterating() &&
         !method->Walltime_Expired(t_current - method->t_start) )
     {
-
         // Lock Systems
         method->Lock();
-
-        // Pre-iteration hook
-        method->Hook_Pre_Iteration();
-        // Do one single Iteration
-        method->Iteration();
-        // Post-iteration hook
-        method->Hook_Post_Iteration();
-
-        // Recalculate FPS
-        method->t_iterations.pop_front();
-        method->t_iterations.push_back(system_clock::now());
-
-        // Log Output every n_iterations_log steps
-        bool log = false;
-        if( method->n_iterations_log > 0 )
-            log = method->iteration > 0 && 0 == fmod(method->iteration, method->n_iterations_log);
-        if( log )
+        for(int i=0; i<N; i++)
         {
-            ++method->step;
-            method->Message_Step();
-            method->Save_Current(method->starttime, method->iteration, false, false);
+            // Pre-iteration hook
+            method->Hook_Pre_Iteration();
+            // Do one single Iteration
+            method->Iteration();
+            // Post-iteration hook
+            method->Hook_Post_Iteration();
+
+            // Recalculate FPS
+            method->t_iterations.pop_front();
+            method->t_iterations.push_back(system_clock::now());
+
+            // Log Output every n_iterations_log steps
+            bool log = false;
+            if( method->n_iterations_log > 0 )
+                log = method->iteration > 0 && 0 == fmod(method->iteration, method->n_iterations_log);
+            if( log )
+            {
+                ++method->step;
+                method->Message_Step();
+                method->Save_Current(method->starttime, method->iteration, false, false);
+            }
+            ++method->iteration;
         }
-
-        ++method->iteration;
-
         // Unlock systems
         method->Unlock();
     }