Merge pull request #754 from lbutler/getclosedlink-remove-recursion

Remove recursion in getclosedlink

ReleaseNotes2_3.md

@@ -47,4 +47,5 @@ This document describes the changes and updates that have been made in version 2
  - `EN_STATUS_REPORT` can now be used with `EN_getoption` and `EN_setoption` to get or set the type of status report that EPANET will generate (`EN_NO_REPORT`, `EN_NORMAL_REPORT` or `EN_FULL_REPORT`).  
  - A possible parser error that could result in a Trace Node ID in an input file not being recognized was fixed.
  - Additional API functions for enabling/disabling controls and rules were added.
+ - Updated the internal function `getclosedlink` in report.c to use a loop instead of recursion to prevent a stack overflow during the analysis of very large disconnections.
  

src/report.c

@@ -45,7 +45,7 @@ static void writeenergy(Project *);
 static int  writeresults(Project *);
 static int  disconnected(Project *);
 static void marknodes(Project *, int, int *, char *);
-static void getclosedlink(Project *, int, char *);
+static void getclosedlink(Project *, int, char *, int *);
 static void writelimits(Project *, int, int);
 static int  checklimits(Report *, double *, int, int);
 static char *fillstr(char *, char, int);
@@ -1287,7 +1287,7 @@ int disconnected(Project *pr)
                     clocktime(rpt->Atime, time->Htime));
             writeline(pr, pr->Msg);
         }
-        getclosedlink(pr, j, marked);
+        getclosedlink(pr, j, marked, nodelist);
     }
 
     // Free allocated memory
@@ -1350,11 +1350,12 @@ void marknodes(Project *pr, int m, int *nodelist, char *marked)
     }
 }
 
-void getclosedlink(Project *pr, int i, char *marked)
+void getclosedlink(Project *pr, int i, char *marked, int *stack)
 /*
 **----------------------------------------------------------------
 **   Input:   i = junction index
 **            marked[] = marks nodes already examined
+**            stack[] = stack to hold nodes to examine
 **   Output:  None.
 **   Purpose: Determines if a closed link connects to junction i.
 **----------------------------------------------------------------
@@ -1365,22 +1366,43 @@ void getclosedlink(Project *pr, int i, char *marked)
     int j, k;
     Padjlist alink;
 
+    int top = 0;
+
+    // Mark the current junction as examined and push onto stack
     marked[i] = 2;
-    for (alink = net->Adjlist[i]; alink != NULL; alink = alink->next)
+    stack[top] = i;
-    {
+
+    while (top >= 0) {
+        i = stack[top--];
+        alink = net->Adjlist[i];
+        
+        // Iterate through each link adjacent to the current node
+        while (alink != NULL) {
             k = alink->link;
             j = alink->node;
-        if (marked[j] == 2) continue;
+
-        if (marked[j] == 1)
+            // Skip nodes that have already been examined
-        {
+            if (marked[j] == 2) {
+                alink = alink->next;
+                continue;
+            }
+
+            // If a closed link is found, return and display a warning message
+            if (marked[j] == 1) {
                 sprintf(pr->Msg, WARN03c, net->Link[k].ID);
                 writeline(pr, pr->Msg);
                 return;
             }
-        else getclosedlink(pr, j, marked);
+
+            // Mark the node as examined and push it onto the stack
+            marked[j] = 2;
+            stack[++top] = j;
+            alink = alink->next;
         }
     }
 
+}
+
 void writelimits(Project *pr, int j1, int j2)
 /*
 **--------------------------------------------------------------