From 07d7c997998470335aebc1373249892186636550 Mon Sep 17 00:00:00 2001
From: Stefan Vigerske <svigerske@gams.com>
Date: Sat, 14 Dec 2024 14:16:28 +0100
Subject: [PATCH] stop gracefully on SIGINT in scalable problem examples

---
 examples/ScalableProblems/RegisteredTNLP.hpp | 26 ++++++++++++++++++++
 examples/ScalableProblems/solve_problem.cpp  |  5 ++++
 2 files changed, 31 insertions(+)

diff --git a/examples/ScalableProblems/RegisteredTNLP.hpp b/examples/ScalableProblems/RegisteredTNLP.hpp
index be1efb910..c0fa321ee 100644
--- a/examples/ScalableProblems/RegisteredTNLP.hpp
+++ b/examples/ScalableProblems/RegisteredTNLP.hpp
@@ -15,6 +15,10 @@ using namespace Ipopt;
 class RegisteredTNLP: public TNLP
 {
 public:
+   RegisteredTNLP()
+   : interrupted_(false)
+   { }
+
    /** Initialize internal parameters.
     *
     *  @return false, if N has an invalid value
@@ -22,6 +26,28 @@ class RegisteredTNLP: public TNLP
    virtual bool InitializeProblem(
       Index N  /**< determines problems size */
    ) = 0;
+
+   bool intermediate_callback(
+      AlgorithmMode              /*mode*/,
+      Index                      /*iter*/,
+      Number                     /*obj_value*/,
+      Number                     /*inf_pr*/,
+      Number                     /*inf_du*/,
+      Number                     /*mu*/,
+      Number                     /*d_norm*/,
+      Number                     /*regularization_size*/,
+      Number                     /*alpha_du*/,
+      Number                     /*alpha_pr*/,
+      Index                      /*ls_trials*/,
+      const IpoptData*           /*ip_data*/,
+      IpoptCalculatedQuantities* /*ip_cq*/
+   )
+   {
+      /* returning false makes Ipopt stop */
+      return !interrupted_;
+   }
+
+   bool interrupted_;
 };
 
 class RegisteredTNLPs
diff --git a/examples/ScalableProblems/solve_problem.cpp b/examples/ScalableProblems/solve_problem.cpp
index 5257b5c46..06005fd5f 100644
--- a/examples/ScalableProblems/solve_problem.cpp
+++ b/examples/ScalableProblems/solve_problem.cpp
@@ -5,6 +5,7 @@
 // Authors:  Andreas Waechter            IBM    2004-11-05
 
 #include "IpIpoptApplication.hpp"
+#include "IpUtils.hpp"
 #include "RegisteredTNLP.hpp"
 
 #include <cstdio>
@@ -202,7 +203,11 @@ int main(
    app->Options()->SetNumericValue("max_wall_time", runtime);
 #endif
 
+   Ipopt::RegisterInterruptHandler(NULL, &tnlp->interrupted_);
+
    status = app->OptimizeTNLP(GetRawPtr(tnlp));
 
+   Ipopt::UnregisterInterruptHandler();
+
    return (int) status;
 }