interval_set: optimize intersect_of for identical spans

Optimize comparisons for identical spans of intervals. When this patch is combined with the previous map insert optimization, a benchmark using 400000 identical intervals shows a 7 times performance improvement in comparison to without the patches. Signed-off-by: Zac Medico <[email protected]>
amincheloh · Aug 30, 2017 · b6a0356 · b6a0356
1 parent 32bc043
commit b6a0356
Showing 1 changed file with 11 additions and 0 deletions.
diff --git a/src/include/interval_set.h b/src/include/interval_set.h
@@ -471,6 +471,17 @@ class interval_set {
         { pa++;  continue; }
       if (pb->first + pb->second <= pa->first) 
         { pb++;  continue; }
+
+      if (*pa == *pb) {
+        do {
+          mi = m.insert(mi, *pa);
+          _size += pa->second;
+          ++pa;
+          ++pb;
+        } while (pa != a.m.end() && pb != b.m.end() && *pa == *pb);
+        continue;
+      }
+
       T start = MAX(pa->first, pb->first);
       T en = MIN(pa->first+pa->second, pb->first+pb->second);
       assert(en > start);