Use memcpy to create navmesh key

Implementation with memcpy is ~13 times faster.

components/detournavigator/navmeshtilescache.cpp

@@ -9,42 +9,32 @@ namespace DetourNavigator
 {
     namespace
     {
-        inline std::string makeNavMeshKey(const RecastMesh& recastMesh,
+        inline std::vector<unsigned char> makeNavMeshKey(const RecastMesh& recastMesh,
             const std::vector<OffMeshConnection>& offMeshConnections)
         {
-            std::string result;
+            const std::size_t indicesSize = recastMesh.getIndices().size() * sizeof(int);
-            result.reserve(
+            const std::size_t verticesSize = recastMesh.getVertices().size() * sizeof(float);
-                recastMesh.getIndices().size() * sizeof(int)
+            const std::size_t areaTypesSize = recastMesh.getAreaTypes().size() * sizeof(AreaType);
-                + recastMesh.getVertices().size() * sizeof(float)
+            const std::size_t waterSize = recastMesh.getWater().size() * sizeof(RecastMesh::Water);
-                + recastMesh.getAreaTypes().size() * sizeof(AreaType)
+            const std::size_t offMeshConnectionsSize = offMeshConnections.size() * sizeof(OffMeshConnection);
-                + recastMesh.getWater().size() * sizeof(RecastMesh::Water)
+
-                + offMeshConnections.size() * sizeof(OffMeshConnection)
+            std::vector<unsigned char> result(indicesSize + verticesSize + areaTypesSize + waterSize + offMeshConnectionsSize);
-            );
+            unsigned char* dst = result.data();
-            std::copy(
+
-                reinterpret_cast<const char*>(recastMesh.getIndices().data()),
+            std::memcpy(dst, recastMesh.getIndices().data(), indicesSize);
-                reinterpret_cast<const char*>(recastMesh.getIndices().data() + recastMesh.getIndices().size()),
+            dst += indicesSize;
-                std::back_inserter(result)
+
-            );
+            std::memcpy(dst, recastMesh.getVertices().data(), verticesSize);
-            std::copy(
+            dst += verticesSize;
-                reinterpret_cast<const char*>(recastMesh.getVertices().data()),
+
-                reinterpret_cast<const char*>(recastMesh.getVertices().data() + recastMesh.getVertices().size()),
+            std::memcpy(dst, recastMesh.getAreaTypes().data(), areaTypesSize);
-                std::back_inserter(result)
+            dst += areaTypesSize;
-            );
+
-            std::copy(
+            std::memcpy(dst, recastMesh.getWater().data(), waterSize);
-                reinterpret_cast<const char*>(recastMesh.getAreaTypes().data()),
+            dst += waterSize;
-                reinterpret_cast<const char*>(recastMesh.getAreaTypes().data() + recastMesh.getAreaTypes().size()),
+
-                std::back_inserter(result)
+            std::memcpy(dst, offMeshConnections.data(), offMeshConnectionsSize);
-            );
+
-            std::copy(
-                reinterpret_cast<const char*>(recastMesh.getWater().data()),
-                reinterpret_cast<const char*>(recastMesh.getWater().data() + recastMesh.getWater().size()),
-                std::back_inserter(result)
-            );
-            std::copy(
-                reinterpret_cast<const char*>(offMeshConnections.data()),
-                reinterpret_cast<const char*>(offMeshConnections.data() + offMeshConnections.size()),
-                std::back_inserter(result)
-            );
             return result;
         }
     }
@@ -189,8 +179,8 @@ namespace DetourNavigator
     {
         struct CompareBytes
         {
-            const char* mRhsIt;
+            const unsigned char* mRhsIt;
-            const char* mRhsEnd;
+            const unsigned char* const mRhsEnd;
 
             template <class T>
             int operator ()(const std::vector<T>& lhs)
@@ -225,7 +215,7 @@ namespace DetourNavigator
         };
     }
 
-    int NavMeshTilesCache::RecastMeshKeyView::compare(const std::string& other) const
+    int NavMeshTilesCache::RecastMeshKeyView::compare(const std::vector<unsigned char>& other) const
     {
         CompareBytes compareBytes {other.data(), other.data() + other.size()};
 

components/detournavigator/navmeshtilescache.hpp

@@ -11,6 +11,8 @@
 #include <list>
 #include <mutex>
 #include <cassert>
+#include <cstring>
+#include <vector>
 
 namespace osg
 {
@@ -33,10 +35,10 @@ namespace DetourNavigator
             std::atomic<std::int64_t> mUseCount;
             osg::Vec3f mAgentHalfExtents;
             TilePosition mChangedTile;
-            std::string mNavMeshKey;
+            std::vector<unsigned char> mNavMeshKey;
             NavMeshData mNavMeshData;
 
-            Item(const osg::Vec3f& agentHalfExtents, const TilePosition& changedTile, std::string navMeshKey)
+            Item(const osg::Vec3f& agentHalfExtents, const TilePosition& changedTile, std::vector<unsigned char>&& navMeshKey)
                 : mUseCount(0)
                 , mAgentHalfExtents(agentHalfExtents)
                 , mChangedTile(changedTile)
@@ -120,19 +122,32 @@ namespace DetourNavigator
 
             virtual ~KeyView() = default;
 
-            KeyView(const std::string& value)
+            KeyView(const std::vector<unsigned char>& value)
                 : mValue(&value) {}
 
-            const std::string& getValue() const
+            const std::vector<unsigned char>& getValue() const
             {
                 assert(mValue);
                 return *mValue;
             }
 
-            virtual int compare(const std::string& other) const
+            virtual int compare(const std::vector<unsigned char>& other) const
             {
                 assert(mValue);
-                return mValue->compare(other);
+
+                const auto valueSize = mValue->size();
+                const auto otherSize = other.size();
+
+                if (const auto result = std::memcmp(mValue->data(), other.data(), std::min(valueSize, otherSize)))
+                    return result;
+
+                if (valueSize < otherSize)
+                    return -1;
+
+                if (valueSize > otherSize)
+                    return 1;
+
+                return 0;
             }
 
             virtual bool isLess(const KeyView& other) const
@@ -147,7 +162,7 @@ namespace DetourNavigator
             }
 
         private:
-            const std::string* mValue = nullptr;
+            const std::vector<unsigned char>* mValue = nullptr;
         };
 
         class RecastMeshKeyView : public KeyView
@@ -156,7 +171,7 @@ namespace DetourNavigator
             RecastMeshKeyView(const RecastMesh& recastMesh, const std::vector<OffMeshConnection>& offMeshConnections)
                 : mRecastMesh(recastMesh), mOffMeshConnections(offMeshConnections) {}
 
-            int compare(const std::string& other) const override;
+            int compare(const std::vector<unsigned char>& other) const override;
 
             bool isLess(const KeyView& other) const override
             {