[geos-commits] [SCM] GEOS branch 3.8 updated. c2a683d19b72d092f11f59e6063dfdf1cb739d9a

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- Log -----------------------------------------------------------------
commit c2a683d19b72d092f11f59e6063dfdf1cb739d9a
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.
    
    Fixes #1008

diff --git a/NEWS b/NEWS
index b32185d..440d266 100644
--- a/NEWS
+++ b/NEWS
@@ -7,7 +7,7 @@ Changes in 3.8.1
     (#1001, Dan Baston)
   - Avoid assertion failure with MSVC 2017 / 2019 (#1002, Dan Baston)
   - Remove whitespace from end of GEOSversion() output (azhi)
-
+  - Improve performance of GEOSisValid (#1008, Dan Baston)
 
 Changes in 3.8.0
 2019-10-10
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                                                 | 2 +-
 src/geomgraph/index/SimpleMCSweepLineIntersector.cpp | 8 ++++++++
 2 files changed, 9 insertions(+), 1 deletion(-)


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