Only update paired sidesets once

refs #31025

Author: loganharbour

framework/include/mesh/MooseMesh.h

@@ -991,6 +991,11 @@ class MooseMesh : public MooseObject, public Restartable, public PerfGraphInterf
    */
   void detectPairedSidesets();
 
+  /**
+   * Whether or not detectedPairedSidesets() has been called.
+   */
+  bool hasDetectedPairedSidesets() const { return _paired_boundary.has_value(); }
+
   /**
    * This function attempts to return the paired boundary ids for the given component.  For example,
    * in a generated 2D mesh, passing 0 for the "x" component will return (3, 1).

framework/src/mesh/MooseMesh.C

@@ -2397,7 +2397,7 @@ MooseMesh::getPairedBoundaryMapping(unsigned int component) const
 
   mooseAssert(component < dimension(), "Requested dimension out of bounds");
 
-  if (!_paired_boundary)
+  if (!hasDetectedPairedSidesets())
     mooseError("MooseMesh::getPairedBoundaryMapping(): Paired boundaries not built; must call "
                "detectPairedSidesets() first");
 

framework/src/utils/PeriodicBCHelper.C

@@ -66,7 +66,8 @@ PeriodicBCHelper::setupPeriodicBoundaries(FEProblemBase & problem)
   mooseAssert(_periodic_boundaries.empty(), "Already set");
 
   // Setup paired sidesets to be able to call MooseMesh::getPairedBoundaryMapping()
-  problem.mesh().detectPairedSidesets();
+  if (!problem.mesh().hasDetectedPairedSidesets())
+    problem.mesh().detectPairedSidesets();
 
   if (_params.isParamValid("auto_direction"))
     setupAutoPeriodicBoundaries(problem.mesh());