Reopen #390: Update callback (#440)

* add `UpdateCallback`

* fix typo

* apply formatter

* remove update bool

* adapt docstring

* implement suggestions

* remove redundant comment

src/TrixiParticles.jl

@@ -46,7 +46,7 @@ export InitialCondition
 export WeaklyCompressibleSPHSystem, EntropicallyDampedSPHSystem, TotalLagrangianSPHSystem,
        BoundarySPHSystem, DEMSystem, BoundaryDEMSystem
 export InfoCallback, SolutionSavingCallback, DensityReinitializationCallback,
-       PostprocessCallback, StepsizeCallback
+       PostprocessCallback, StepsizeCallback, UpdateCallback
 export ContinuityDensity, SummationDensity
 export PenaltyForceGanzenmueller
 export SchoenbergCubicSplineKernel, SchoenbergQuarticSplineKernel,

src/callbacks/callbacks.jl

@@ -31,3 +31,4 @@ include("solution_saving.jl")
 include("density_reinit.jl")
 include("post_process.jl")
 include("stepsize.jl")
+include("update.jl")

src/callbacks/update.jl

@@ -0,0 +1,130 @@
+struct UpdateCallback{I}
+    interval::I
+end
+
+"""
+    UpdateCallback(; interval::Integer, dt=0.0)
+
+Callback to update quantities either at the end of every `interval` time steps or
+in intervals of `dt` in terms of integration time by adding additional `tstops`
+(note that this may change the solution).
+
+# Keywords
+- `interval=1`: Update quantities at the end of every `interval` time steps.
+- `dt`: Update quantities in regular intervals of `dt` in terms of integration time
+        by adding additional `tstops` (note that this may change the solution).
+"""
+function UpdateCallback(; interval::Integer=-1, dt=0.0)
+    if dt > 0 && interval !== -1
+        throw(ArgumentError("Setting both interval and dt is not supported!"))
+    end
+
+    # Update in intervals in terms of simulation time
+    if dt > 0
+        interval = Float64(dt)
+
+        # Update every time step (default)
+    elseif interval == -1
+        interval = 1
+    end
+
+    update_callback! = UpdateCallback(interval)
+
+    if dt > 0
+        # Add a `tstop` every `dt`, and save the final solution.
+        return PeriodicCallback(update_callback!, dt,
+                                initialize=initial_update!,
+                                save_positions=(false, false))
+    else
+        # The first one is the `condition`, the second the `affect!`
+        return DiscreteCallback(update_callback!, update_callback!,
+                                initialize=initial_update!,
+                                save_positions=(false, false))
+    end
+end
+
+# `initialize`
+function initial_update!(cb, u, t, integrator)
+    # The `UpdateCallback` is either `cb.affect!` (with `DiscreteCallback`)
+    # or `cb.affect!.affect!` (with `PeriodicCallback`).
+    # Let recursive dispatch handle this.
+
+    initial_update!(cb.affect!, u, t, integrator)
+end
+
+initial_update!(cb::UpdateCallback, u, t, integrator) = cb(integrator)
+
+# `condition`
+function (update_callback!::UpdateCallback)(u, t, integrator)
+    (; interval) = update_callback!
+
+    return condition_integrator_interval(integrator, interval)
+end
+
+# `affect!`
+function (update_callback!::UpdateCallback)(integrator)
+    t = integrator.t
+    semi = integrator.p
+    v_ode, u_ode = integrator.u.x
+
+    # Update quantities that are stored in the systems. These quantities (e.g. pressure)
+    # still have the values from the last stage of the previous step if not updated here.
+    update_systems_and_nhs(v_ode, u_ode, semi, t)
+
+    # Other updates might be added here later (e.g. Transport Velocity Formulation).
+    # @trixi_timeit timer() "update open boundary" foreach_system(semi) do system
+    #     update_open_boundary_eachstep!(system, v_ode, u_ode, semi, t)
+    # end
+    #
+    # @trixi_timeit timer() "update TVF" foreach_system(semi) do system
+    #     update_transport_velocity_eachstep!(system, v_ode, u_ode, semi, t)
+    # end
+
+    # Tell OrdinaryDiffEq that `u` has been modified
+    u_modified!(integrator, true)
+
+    return integrator
+end
+
+function Base.show(io::IO, cb::DiscreteCallback{<:Any, <:UpdateCallback})
+    @nospecialize cb # reduce precompilation time
+    print(io, "UpdateCallback(interval=", cb.affect!.interval, ")")
+end
+
+function Base.show(io::IO,
+                   cb::DiscreteCallback{<:Any,
+                                        <:PeriodicCallbackAffect{<:UpdateCallback}})
+    @nospecialize cb # reduce precompilation time
+    print(io, "UpdateCallback(dt=", cb.affect!.affect!.interval, ")")
+end
+
+function Base.show(io::IO, ::MIME"text/plain",
+                   cb::DiscreteCallback{<:Any, <:UpdateCallback})
+    @nospecialize cb # reduce precompilation time
+
+    if get(io, :compact, false)
+        show(io, cb)
+    else
+        update_cb = cb.affect!
+        setup = [
+            "interval" => update_cb.interval,
+        ]
+        summary_box(io, "UpdateCallback", setup)
+    end
+end
+
+function Base.show(io::IO, ::MIME"text/plain",
+                   cb::DiscreteCallback{<:Any,
+                                        <:PeriodicCallbackAffect{<:UpdateCallback}})
+    @nospecialize cb # reduce precompilation time
+
+    if get(io, :compact, false)
+        show(io, cb)
+    else
+        update_cb = cb.affect!.affect!
+        setup = [
+            "dt" => update_cb.interval,
+        ]
+        summary_box(io, "UpdateCallback", setup)
+    end
+end

test/callbacks/callbacks.jl

@@ -2,5 +2,6 @@
     include("info.jl")
     include("stepsize.jl")
     include("postprocess.jl")
+    include("update.jl")
     include("solution_saving.jl")
 end

test/callbacks/update.jl

@@ -0,0 +1,48 @@
+@testset verbose=true "UpdateCallback" begin
+    @testset verbose=true "show" begin
+        # Default
+        callback0 = UpdateCallback()
+
+        show_compact = "UpdateCallback(interval=1)"
+        @test repr(callback0) == show_compact
+
+        show_box = """
+        ┌──────────────────────────────────────────────────────────────────────────────────────────────────┐
+        │ UpdateCallback                                                                                   │
+        │ ══════════════                                                                                   │
+        │ interval: ……………………………………………………… 1                                                                │
+        └──────────────────────────────────────────────────────────────────────────────────────────────────┘"""
+        @test repr("text/plain", callback0) == show_box
+
+        callback1 = UpdateCallback(interval=11)
+
+        show_compact = "UpdateCallback(interval=11)"
+        @test repr(callback1) == show_compact
+
+        show_box = """
+        ┌──────────────────────────────────────────────────────────────────────────────────────────────────┐
+        │ UpdateCallback                                                                                   │
+        │ ══════════════                                                                                   │
+        │ interval: ……………………………………………………… 11                                                               │
+        └──────────────────────────────────────────────────────────────────────────────────────────────────┘"""
+        @test repr("text/plain", callback1) == show_box
+
+        callback2 = UpdateCallback(dt=1.2)
+
+        show_compact = "UpdateCallback(dt=1.2)"
+        @test repr(callback2) == show_compact
+
+        show_box = """
+        ┌──────────────────────────────────────────────────────────────────────────────────────────────────┐
+        │ UpdateCallback                                                                                   │
+        │ ══════════════                                                                                   │
+        │ dt: ……………………………………………………………………… 1.2                                                              │
+        └──────────────────────────────────────────────────────────────────────────────────────────────────┘"""
+        @test repr("text/plain", callback2) == show_box
+    end
+
+    @testset "Illegal Input" begin
+        error_str = "Setting both interval and dt is not supported!"
+        @test_throws ArgumentError(error_str) UpdateCallback(dt=0.1, interval=1)
+    end
+end