[SNMP4J] Unregister MO with context doesnt work

[Pentzlin, David [Contractor]]

Hi Frank,

Thank you. I can confirm it is working now.

Btw as I tried to fix it I found another little problem what gives me an annoying error in my IDE:

DefaultMOTable.java line 630:
MOMutableTableModel mmodel = (MOMutableTableModel)model; should be:
MOMutableTableModel<R> mmodel = (MOMutableTableModel)model; Or it will give a cast error in line 633

Best regards
Dave

-----Previous Message-----
Hi Dave,

Thank you for reporting this bug. It was actually caused by a bug (hole) in the corresponding JUnit test and therefore remained undiscovered until now.

The latest snapshot of SNMP4J-Agent should fix the issue.

The patch is:

Index: MOScopeComparator.java
===================================================================
--- MOScopeComparator.java    (revision 2722)
+++ MOScopeComparator.java    (working copy)
@@ -35,7 +35,7 @@
   * is checked. If it is unbounded (upper bound is <code>null</code), then
   * the scoped is deemed to be greater than the query. Otherwise, the upper bound
   * of the scope is compared with the lower bound of the query. Scope and query
- * are deemd to be equal if both bounds are equal and are both included.
+ * are deemed to be equal if both bounds are equal and both are included.
   * Otherwise the scope is deemed to be less than the query.
   *
   * @author Frank Fock
@@ -77,19 +77,31 @@
          result = -compareContextScope(o2, (MOContextScope) o1);
        }
        else {
-        result = o1.getLowerBound().compareTo(o2.getLowerBound());
-        if (result == 0) {
-          if ((!o1.isUpperIncluded()) ||
-              (!o2.isLowerIncluded())) {
-            return -1;
-          }
-        }
+        result = compareScope(o1, o2);
        }
      }
      return result;
    }

    private static int compareContextScope(MOScope scope, MOContextScope
scope2) {
+    if (scope == scope2) {
+      return 0;
+    }
+    int result = compareScope(scope, scope2);
+    if ((result == 0) && (scope instanceof MOContextScope)) {
+      OctetString c1 = ((MOContextScope)scope).getContext();
+      OctetString c2 = scope2.getContext();
+      if ((c1 != null) && (c2 != null)) {
+        result = c1.compareTo(c2);
+      }
+    }
+    return result;
+  }
+
+  private static int compareScope(MOScope scope, MOScope scope2) {
+    if ((scope == scope2) || scope.equals(scope2)) {
+      return 0;
+    }
      int result = 0;
      if (scope.getUpperBound() == null) {
        result = 1;
@@ -104,28 +116,19 @@
      else {
        result = scope.getUpperBound().compareTo(scope2.getUpperBound());
        if (result == 0) {
+        result += (scope.isUpperIncluded() ? -1 : 0);
+        result += (scope2.isUpperIncluded() ? 1 : 0);
          if (result == 0) {
-          result += (scope.isUpperIncluded() ? -1 : 0);
-          result += (scope2.isUpperIncluded() ? 1 : 0);
-        }
-        if (result == 0) {
            result =
scope.getUpperBound().compareTo(scope2.getLowerBound());
            if (result == 0) {
              if ((!scope.isUpperIncluded()) ||
-                    (!scope2.isLowerIncluded())) {
+                (!scope2.isLowerIncluded())) {
                return -1;
              }
            }
          }
        }
      }
-    if ((result == 0) && (scope instanceof MOContextScope)) {
-      OctetString c1 = ((MOContextScope)scope).getContext();
-      OctetString c2 = scope2.getContext();
-      if ((c1 != null) && (c2 != null)) {
-        result = c1.compareTo(c2);
-      }
-    }
      return result;
    }

Best regards,
Frank


Am 17.06.2014 16:44, schrieb Pentzlin, David [Contractor]:
> Maybe I should add:
> If a managedobject without context(null) will be unregistered the result of the comperator is:
> public int compare(MOScope o1, MOScope o2) {
>      if (o1==o2) {
>        return 0; // ensure identity is equal
>      }......
> Because the instance of the scope is the same (mo.getscope()).
>
> Register or unregister of a mo with context will always use a new instance of DefaultMOContextScope:
> new DefaultMOContextScope(context, mo.getScope());
>
> so o1==o2 in the comperator is false and the rest of the comperator will never result in 0 if the mo is the same.
> If you change the comperator to:
> public int compare(MOScope o1, MOScope o2) {
>      if (o1.equals(o2)) {
>        return 0; // ensure identity is equal
>      }.....
> It will work with the DefaultMOContextScope too (it will compare the content instead of the instance).
> Now registry.remove(key); will remove the mo from registry
>
> Is this the correct fix for this bug?
>
> Best regards
> Dave
>
> -----Previous Message-----
> Subject: [SNMP4J] Unregister MO with context doesnt work
>
> Unregister a managed object will call "public void unregister(ManagedObject mo, OctetString context)" (DefaultMOServer.java).
> This will remove the mo from registry (treemap) with "registry.remove(key);"
>
> The problem is the comperator from the treemap registry will call: "compareContextScope(MOScope scope, MOContextScope scope2)"
> In this function it will compare first the upperbound and if it is the same it will do:
> if (result == 0) {
>            result = 
> scope.getUpperBound().compareTo(scope2.getLowerBound());
>
> and this is always 1 so the result is always -1 or 1 even if it is exact the same scope. So it will never be removed from registry.
>
> If you unregister without context (context==null) the compare function:
> result = o1.getLowerBound().compareTo(o2.getLowerBound());
> will return 0 and it will be removed from registry.
>
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