Add discontinuity-controller state to DDE integrators

The shared autonomous-discontinuity controller reads is_disco_step and disco_checkpoint, but DDEIntegrator did not carry either field. Initialize the state from the runtime time value, reset it during reinit!, and cover discontinuity-enabled and unitful public solver paths.

Co-Authored-By: Chris Rackauckas <accounts@chrisrackauckas.com>

Author: ChrisRackauckas

lib/DelayDiffEq/src/integrators/interface.jl

@@ -510,6 +510,8 @@ function DiffEqBase.reinit!(
     integrator.iter = 0
     integrator.success_iter = 0
     integrator.derivative_discontinuity = false
+    integrator.is_disco_step = false
+    integrator.disco_checkpoint = zero(integrator.t)
 
     # full re-initialize the controller in timestepping
     OrdinaryDiffEqCore.reinit_controller!(integrator, integrator.controller_cache)

lib/DelayDiffEq/src/integrators/type.jl

@@ -100,6 +100,8 @@ mutable struct DDEIntegrator{
     fsalfirst::FSALType
     fsallast::FSALType
     initializealg::IA
+    is_disco_step::Bool
+    disco_checkpoint::tType
     # SDE/RODE noise fields: populated for SDDEProblem, Nothing for DDEProblem.
     W::WType
     P::PType

lib/DelayDiffEq/src/solve.jl

@@ -455,6 +455,8 @@ function SciMLBase.__init(
     success_iter = 0
     erracc = QT(1)
     dtacc = tType(1)
+    is_disco_step = false
+    disco_checkpoint = zero(t0)
 
     fsalfirst, fsallast = OrdinaryDiffEqCore.get_fsalfirstlast(cache, rate_prototype)
     OrdinaryDiffEqCore.set_EEst!(controller_cache, EEst)
@@ -525,6 +527,7 @@ function SciMLBase.__init(
         differential_vars,
         controller_cache,
         ode_integrator, fsalfirst, fsallast, initializealg,
+        is_disco_step, disco_checkpoint,
         W, P, sqdt, nothing,
     )
 

lib/DelayDiffEq/test/interface/discontinuities.jl

@@ -1,6 +1,7 @@
 using DelayDiffEq, DDEProblemLibrary
 using OrdinaryDiffEqLowOrderRK
 using OrdinaryDiffEqTsit5
+using OrdinaryDiffEqCore: PIController
 using SciMLBase: ReturnCode
 using Test
 
@@ -62,6 +63,25 @@ end
     end
 end
 
+@testset "autonomous discontinuity controller state" begin
+    alg = BS3()
+    controller = PIController(alg; discontinuity_detection = true)
+    integrator = init(prob, MethodOfSteps(alg); controller = controller, dt = 0.01)
+
+    @test !integrator.is_disco_step
+    @test iszero(integrator.disco_checkpoint)
+    @test typeof(integrator.disco_checkpoint) === typeof(integrator.t)
+
+    sol = solve!(integrator)
+    @test sol.retcode == ReturnCode.Success
+
+    integrator.is_disco_step = true
+    integrator.disco_checkpoint = integrator.t
+    reinit!(integrator)
+    @test !integrator.is_disco_step
+    @test iszero(integrator.disco_checkpoint)
+end
+
 # additional discontinuities
 @testset "DDE with discontinuities" begin
     integrator = init(

lib/DelayDiffEq/test/interface/units.jl

@@ -29,6 +29,16 @@ const probs = Dict(
         fpsolve = NLFunctional(; max_iter = 100)
     )
 
+    integrator = init(prob, alg)
+    @test typeof(integrator.disco_checkpoint) === typeof(integrator.t)
+    @test iszero(integrator.disco_checkpoint)
+
+    integrator.is_disco_step = true
+    integrator.disco_checkpoint = oneunit(integrator.t)
+    reinit!(integrator)
+    @test !integrator.is_disco_step
+    @test iszero(integrator.disco_checkpoint)
+
     # default
     sol1 = solve(prob, alg)