Merge pull request #4637 from SciML/as/fmi-fixes

refactor: avoid repeatedly instantiating FMUs during initialization

Author: AayushSabharwal

ext/MTKFMIExt.jl

@@ -93,13 +93,16 @@ with the name `namespace__variable`.
   FMU. For CoSimulation FMUs whose states/outputs are used in algebraic equations of the
   system, this needs to be an algorithm that will solve for the new algebraic variables.
   For example, `OrdinaryDiffEqCore.BrownFullBasicInit()`.
+- `stop_time`: The `stopTime` for the FMU, as defined in the FMI spec. By default, this will
+  be set to `tspan[2]` when the `ODEProblem` is solved. An explicit value will overwrite this.
 - `type`: Either `:ME` or `:CS` depending on whether `fmu` is a Model Exchange or
   CoSimulation FMU respectively.
 - `name`: The name of the system.
 """
 function MTK.FMIComponent(
         ::Val{Ver}; fmu = nothing, tolerance = 1.0e-6,
-        communication_step_size = nothing, reinitializealg = nothing, type, name
+        communication_step_size = nothing, reinitializealg = nothing,
+        stop_time = nothing, type, name
     ) where {Ver}
     if Ver != 2 && Ver != 3
         throw(ArgumentError("FMI Version must be `2` or `3`"))
@@ -264,9 +267,9 @@ function MTK.FMIComponent(
         append!(observed, der_observed)
     elseif type == :CS
         _functor = if Ver == 2
-            FMI2CSFunctor(state_value_references, output_value_references, Base.Ref{FMI.fmi2Real}(NaN))
+            FMI2CSFunctor(state_value_references, output_value_references, Base.Ref{FMI.fmi2Real}(something(stop_time, NaN)))
         else
-            FMI3CSFunctor(state_value_references, output_value_references, Base.Ref{FMI.fmi3Float64}(NaN))
+            FMI3CSFunctor(state_value_references, output_value_references, Base.Ref{FMI.fmi3Float64}(something(stop_time, NaN)))
         end
         @parameters (functor::(typeof(_functor)))(..)[1:(length(__mtk_internal_u) + length(__mtk_internal_o))] = _functor
         # for co-simulation, we need to ensure the output buffer is solved for
@@ -567,6 +570,19 @@ function get_instance_CS!(wrapper::FMI2InstanceWrapper, states, inputs, params,
             )
         end
         @statuscheck FMI.fmi2ExitInitializationMode(wrapper.instance)
+    else
+        if !isempty(states)
+            @statuscheck FMI.fmi2SetReal(
+                wrapper.instance, wrapper.state_value_references,
+                Csize_t(length(wrapper.state_value_references)), states
+            )
+        end
+        if !isempty(inputs)
+            @statuscheck FMI.fmi2SetReal(
+                wrapper.instance, wrapper.input_value_references,
+                Csize_t(length(inputs)), inputs
+            )
+        end
     end
     return wrapper.instance
 end
@@ -729,6 +745,17 @@ function get_instance_CS!(wrapper::FMI3InstanceWrapper, states, inputs, params,
             )
         end
         @statuscheck FMI.fmi3ExitInitializationMode(wrapper.instance)
+    else
+        if !isempty(inputs)
+            @statuscheck FMI.fmi3SetFloat64(
+                wrapper.instance, wrapper.input_value_references, inputs
+            )
+        end
+        if !isempty(states)
+            @statuscheck FMI.fmi3SetFloat64(
+                wrapper.instance, wrapper.state_value_references, states
+            )
+        end
     end
     return wrapper.instance
 end
@@ -850,9 +877,6 @@ function (fn::FMI2CSFunctor)(wrapper::FMI2InstanceWrapper, states, inputs, param
     states = states isa SubArray ? copy(states) : states
     inputs = inputs isa SubArray ? copy(inputs) : inputs
     params = params isa SubArray ? copy(params) : params
-    if wrapper.instance !== nothing
-        reset_instance!(wrapper)
-    end
     instance = get_instance_CS!(wrapper, states, inputs, params, t, fn.t_end[])
     if isempty(fn.output_value_references)
         return eltype(states)[]
@@ -887,7 +911,9 @@ function fmiCSInitialize!(m, o, ctx::FMI2CSFunctor, integrator)
     params = o.params
     t = o.t
     wrapper = o.wrapper
-    ctx.t_end[] = integrator.sol.prob.tspan[2]
+    if isnan(ctx.t_end[])
+        ctx.t_end[] = integrator.sol.prob.tspan[2]
+    end
     if wrapper.instance !== nothing
         reset_instance!(wrapper)
     end
@@ -993,7 +1019,9 @@ function fmiCSInitialize!(m, o, ctx::FMI3CSFunctor, integrator)
     params = o.params
     t = o.t
     wrapper = o.wrapper
-    ctx.t_end[] = integrator.sol.prob.tspan[2]
+    if isnan(ctx.t_end[])
+        ctx.t_end[] = integrator.sol.prob.tspan[2]
+    end
     if wrapper.instance !== nothing
         reset_instance!(wrapper)
     end