Fix thread-safety issue when writing addon data. (#2611)

Fix point count for addon data initialization.
Close #2610

io/EptReader.cpp

@@ -561,6 +561,7 @@ void EptReader::overlaps(const arbiter::Endpoint& ep,
     else
     {
         {
+            //ABELL we could probably use a local mutex to lock the target map.
             std::lock_guard<std::mutex> lock(m_mutex);
             target[key] = static_cast<uint64_t>(numPoints);
         }
@@ -595,16 +596,13 @@ PointViewSet EptReader::run(PointViewPtr view)
             // Read addon information after the native data, we'll possibly
             // overwrite attributes.
             for (const auto& addon : m_addons)
-            {
                 readAddon(*view, key, *addon, startId);
-            }
         });
 
         ++nodeId;
     }
 
     m_pool->await();
-
     log()->get(LogLevel::Debug) << "Done reading!" << std::endl;
 
     PointViewSet views;
@@ -716,7 +714,7 @@ void EptReader::process(PointView& dst, PointRef& pr, const uint64_t nodeId,
 void EptReader::readAddon(PointView& dst, const Key& key, const Addon& addon,
         const uint64_t pointId) const
 {
-    const uint64_t np(addon.points(key));
+    uint64_t np(addon.points(key));
     if (!np)
     {
         // If our addon has no points, then we are reading a superset of this
@@ -728,6 +726,10 @@ void EptReader::readAddon(PointView& dst, const Key& key, const Addon& addon,
         // for an EPT-read of the full dataset.  If the native EPT set already
         // contains Classification, then we should overwrite it with zeroes
         // where the addon leaves off.
+
+        std::lock_guard<std::mutex> lock(m_mutex);
+
+        np = m_overlaps.at(key);
         for (uint64_t id(pointId); id < pointId + np; ++id)
         {
             dst.setField(addon.id(), id, 0);
@@ -748,6 +750,7 @@ void EptReader::readAddon(PointView& dst, const Key& key, const Addon& addon,
         throwError("Invalid addon content length");
     }
 
+    std::lock_guard<std::mutex> lock(m_mutex);
     const char* pos(data.data());
     for (uint64_t id(pointId); id < pointId + np; ++id)
     {