From 9f26836b436d5d31428650216be7ae43abce0e41 Mon Sep 17 00:00:00 2001
From: Andrew Meadows <andrew@highfidelity.io>
Date: Wed, 13 Jul 2016 14:03:53 -0700
Subject: [PATCH] added basic CollisionGeometryCache container

---
 .../physics/src/CollisionGeometryCache.cpp    | 79 +++++++++++++++++++
 .../physics/src/CollisionGeometryCache.h      | 62 +++++++++++++++
 2 files changed, 141 insertions(+)
 create mode 100644 libraries/physics/src/CollisionGeometryCache.cpp
 create mode 100644 libraries/physics/src/CollisionGeometryCache.h

diff --git a/libraries/physics/src/CollisionGeometryCache.cpp b/libraries/physics/src/CollisionGeometryCache.cpp
new file mode 100644
index 0000000000..b474d44c32
--- /dev/null
+++ b/libraries/physics/src/CollisionGeometryCache.cpp
@@ -0,0 +1,79 @@
+//
+//  CollisionGeometryCache.cpp
+//  libraries/physcis/src
+//
+//  Created by Andrew Meadows 2016.07.13
+//  Copyright 2016 High Fidelity, Inc.
+//
+//  Distributed under the Apache License, Version 2.0.
+//  See the accompanying file LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html
+//
+
+#include <cassert>
+//#include <glm/gtx/norm.hpp>
+
+//#include "ShapeFactory.h"
+#include "CollisionGeometryCache.h"
+
+int foo = 0;
+
+GeometryPointer createGeometryFromShape(CollisionGeometryCache::Key key) {
+    return std::make_shared<int>(++foo);
+}
+
+CollisionGeometryCache::CollisionGeometryCache() {
+}
+
+CollisionGeometryCache::~CollisionGeometryCache() {
+    _geometryMap.clear();
+    _pendingGarbage.clear();
+}
+
+GeometryPointer CollisionGeometryCache::getGeometry(CollisionGeometryCache::Key key) {
+    if (!key) {
+        return GeometryPointer();
+    }
+    GeometryPointer geometry = 0;
+
+    CollisionGeometryMap::const_iterator itr = _geometryMap.find(key);
+    if (itr != _geometryMap.end()) {
+        // make geometry and add it to map
+        geometry = createGeometryFromShape(key);
+        if (geometry) {
+            _geometryMap.insert(std::make_pair(key, geometry));
+        }
+    }
+    return geometry;
+}
+
+bool CollisionGeometryCache::releaseGeometry(CollisionGeometryCache::Key key) {
+    if (!key) {
+        return false;
+    }
+    CollisionGeometryMap::const_iterator itr = _geometryMap.find(key);
+    if (itr != _geometryMap.end()) {
+        assert((*itr).second.use_count() != 1);
+        if ((*itr).second.use_count() == 2) {
+            // we hold all of the references inside the cache so we'll try to delete later
+            _pendingGarbage.push_back(key);
+        }
+        return true;
+    }
+    return false;
+}
+
+void CollisionGeometryCache::collectGarbage() {
+    int numShapes = _pendingGarbage.size();
+    for (int i = 0; i < numShapes; ++i) {
+        CollisionGeometryCache::Key key = _pendingGarbage[i];
+        CollisionGeometryMap::const_iterator itr = _geometryMap.find(key);
+        if (itr != _geometryMap.end()) {
+            if ((*itr).second.use_count() == 1) {
+                // we hold the only reference
+                _geometryMap.erase(itr);
+            }
+        }
+    }
+    _pendingGarbage.clear();
+}
+
diff --git a/libraries/physics/src/CollisionGeometryCache.h b/libraries/physics/src/CollisionGeometryCache.h
new file mode 100644
index 0000000000..f6a7a6f3e8
--- /dev/null
+++ b/libraries/physics/src/CollisionGeometryCache.h
@@ -0,0 +1,62 @@
+//
+//  CollisionGeometryCache.h
+//  libraries/physcis/src
+//
+//  Created by Andrew Meadows 2016.07.13
+//  Copyright 2016 High Fidelity, Inc.
+//
+//  Distributed under the Apache License, Version 2.0.
+//  See the accompanying file LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html
+//
+
+#ifndef hifi_CollisionGeometryCache
+#define hifi_CollisionGeometryCache
+
+#include <memory>
+#include <vector>
+#include <unordered_map>
+//#include <btBulletDynamicsCommon.h>
+//#include <LinearMath/btHashMap.h>
+
+class btCollisionShape;
+
+// BEGIN TEST HACK
+using GeometryPointer = std::shared_ptr<int>;
+// END TEST HACK
+
+namespace std {
+    template <>
+    struct hash<btCollisionShape*> {
+        std::size_t operator()(btCollisionShape* key) const {
+            return (hash<void*>()((void*)key));
+        }
+    };
+}
+
+class CollisionGeometryCache {
+public:
+	using Key = btCollisionShape const *;
+
+    CollisionGeometryCache();
+    ~CollisionGeometryCache();
+
+    /// \return pointer to geometry
+    GeometryPointer getGeometry(Key key);
+
+    /// \return true if geometry was found and released
+    bool releaseGeometry(Key key);
+
+    /// delete geometries that have zero references
+    void collectGarbage();
+
+    // validation methods
+    uint32_t getNumGeometries() const { return (uint32_t)_geometryMap.size(); }
+    bool hasGeometry(Key key) const { return _geometryMap.find(key) == _geometryMap.end(); }
+
+private:
+    using CollisionGeometryMap = std::unordered_map<Key, GeometryPointer>;
+    CollisionGeometryMap _geometryMap;
+    std::vector<Key> _pendingGarbage;
+};
+
+#endif // hifi_CollisionGeometryCache