[geos-commits] [SCM] GEOS branch master updated. 7ed0c824b76e2127a16597546e507900fe6816ef

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- Log -----------------------------------------------------------------
commit 7ed0c824b76e2127a16597546e507900fe6816ef
Author: Daniel Baston <dbaston at gmail.com>
Date:   Wed Nov 27 21:17:07 2019 -0500

    Avoid MonotoneChain self-compare in SimpleMCSweepLineIntersector
    
    This is a hotspot in validity profiling. This commit reduces the runtime
    of GEOSisValid from 3.7s to 2.0s for the 5,489 polygons in the
    HydroBASINS level 5 dataset, and from 610ms to 360ms for the individual
    polygon components of the boundary of Australia in the GADM country
    dataset.

diff --git a/NEWS b/NEWS
index c60ee6b..ba45097 100644
--- a/NEWS
+++ b/NEWS
@@ -2,10 +2,11 @@ Changes in 3.9.0
 2020-xx-xx
 
 - New things:
-  - 
+  -
 
 - Improvements:
   - Stack allocate segments in OverlapUnion (Paul Ramsey)
+  - Improve performance of GEOSisValid (Dan Baston)
 
 
 Changes in 3.8.0
diff --git a/src/geomgraph/index/SimpleMCSweepLineIntersector.cpp b/src/geomgraph/index/SimpleMCSweepLineIntersector.cpp
index b635ad7..f5749c9 100644
--- a/src/geomgraph/index/SimpleMCSweepLineIntersector.cpp
+++ b/src/geomgraph/index/SimpleMCSweepLineIntersector.cpp
@@ -143,6 +143,14 @@ SimpleMCSweepLineIntersector::processOverlaps(size_t start, size_t end,
         auto& ev1 = events[i];
         if(ev1->isInsert()) {
             MonotoneChain* mc1 = (MonotoneChain*) ev1->getObject();
+
+            if (mc1 == mc0) {
+                // Don't try to compute intersections between a MonotoneChain
+                // and itself. SegmentIntersector::addIntersections will just
+                // ignore them anyway.
+                continue;
+            }
+
             // don't compare edges in same group
             // null group indicates that edges should be compared
             if(ev0->edgeSet == nullptr || (ev0->edgeSet != ev1->edgeSet)) {

-----------------------------------------------------------------------

Summary of changes:
 NEWS                                                 | 3 ++-
 src/geomgraph/index/SimpleMCSweepLineIntersector.cpp | 8 ++++++++
 2 files changed, 10 insertions(+), 1 deletion(-)


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