cache loaded NIF files to eliminate reloads

Created a NIF file caching mechanism to prevent the system from
reloading a NIF during a startup and cell changes.

apps/openmw/engine.cpp

@@ -277,6 +277,8 @@ std::string OMW::Engine::loadSettings (Settings::Manager & settings)
 
 void OMW::Engine::prepareEngine (Settings::Manager & settings)
 {
+    Nif::NIFFile::CacheLock cachelock;
+
     std::string renderSystem = settings.getString("render system", "Video");
     if (renderSystem == "")
     {

apps/openmw/mwworld/scene.cpp

@@ -172,6 +172,8 @@ namespace MWWorld
 
     void Scene::changeCell (int X, int Y, const ESM::Position& position, bool adjustPlayerPos)
     {
+        Nif::NIFFile::CacheLock cachelock;
+
         mRendering.preCellChange(mCurrentCell);
 
         // remove active

components/nif/nif_file.cpp

@@ -34,10 +34,159 @@
 #include "controller.hpp"
 
 #include <iostream>
+
+//TODO: when threading is needed, enable these
+//#include <boost/mutex.hpp>
+//#include <boost/thread/locks.hpp>
+
 using namespace std;
 using namespace Nif;
 using namespace Misc;
 
+class NIFFile::LoadedCache
+{
+    //TODO: enable this to make cache thread safe...
+    //typedef boost::mutex mutex;
+    
+    struct mutex
+    {
+        void lock () {};
+        void unlock () {}
+    };
+    
+    typedef boost::lock_guard <mutex> lock_guard;
+    typedef std::map < std::string, boost::weak_ptr <NIFFile> > loaded_map;
+    typedef std::vector < boost::shared_ptr <NIFFile> > locked_files;
+
+    static int sLockLevel;
+    static mutex sProtector;
+    static loaded_map sLoadedMap;
+    static locked_files sLockedFiles;
+
+public:
+
+    static ptr create (const std::string &name)
+    {
+        lock_guard _ (sProtector);
+
+        ptr result;
+
+        // lookup the resource
+        loaded_map::iterator i = sLoadedMap.find (name);
+
+        if (i == sLoadedMap.end ()) // it doesn't existing currently,
+        {                           // or hasn't in the very near past
+
+            // create it now, for smoother threading if needed, the
+            // loading should be performed outside of the sLoaderMap
+            // lock and an alternate mechanism should be used to
+            // synchronize threads competing to load the same resource
+            result = boost::make_shared <NIFFile> (name, psudo_private_modifier());
+
+            // if we are locking the cache add an extra reference
+            // to keep the file in memory
+            if (sLockLevel > 0)
+                sLockedFiles.push_back (result);
+
+            // stash a reference to the resource so that future
+            // calls can benefit
+            sLoadedMap [name] = boost::weak_ptr <NIFFile> (result);
+        }
+        else // it may (probably) still exists
+        {
+            // attempt to get the reference
+            result = i->second.lock ();
+
+            if (!result) // resource is in the process of being destroyed
+            {
+                // create a new instance, to replace the one that has
+                // begun the irreversible process of being destroyed
+                result = boost::make_shared <NIFFile> (name, psudo_private_modifier());
+
+                // respect the cache lock...
+                if (sLockLevel > 0)
+                    sLockedFiles.push_back (result);
+
+                // we potentially overwrite an expired pointer here
+                // but the other thread performing the delete on
+                // the previous copy of this resource will detect it
+                // and make sure not to erase the new reference
+                sLoadedMap [name] = boost::weak_ptr <NIFFile> (result);
+            }
+        }
+
+        // we made it!
+        return result;
+    }
+
+    static void release (NIFFile * file)
+    {
+        lock_guard _ (sProtector);
+
+        loaded_map::iterator i = sLoadedMap.find (file->filename);
+
+        // its got to be in here, it just might not be us...
+        assert (i != sLoadedMap.end ());
+
+        // if weak_ptr is still expired, this resource hasn't been recreated
+        // between the initiation of the final release due to destruction
+        // of the last shared pointer and this thread acquiring the lock on
+        // the loader map
+        if (i->second.expired ())
+            sLoadedMap.erase (i);
+    }
+
+    static void lockCache ()
+    {
+        lock_guard _ (sProtector);
+
+        sLockLevel++;
+    }
+
+    static void unlockCache ()
+    {
+        locked_files resetList;
+
+        {
+            lock_guard _ (sProtector);
+
+            if (--sLockLevel)
+                sLockedFiles.swap(resetList);
+        }
+
+        // this not necessary, but makes it clear that the
+        // deletion of the locked cache entries is being done
+        // outside the protection of sProtector
+        resetList.clear ();
+    }
+};
+
+int NIFFile::LoadedCache::sLockLevel = 0;
+NIFFile::LoadedCache::mutex NIFFile::LoadedCache::sProtector;
+NIFFile::LoadedCache::loaded_map NIFFile::LoadedCache::sLoadedMap;
+NIFFile::LoadedCache::locked_files NIFFile::LoadedCache::sLockedFiles;
+
+// these three calls are forwarded to the cache implementation...
+void NIFFile::lockCache ()     { LoadedCache::lockCache (); }
+void NIFFile::unlockCache ()   { LoadedCache::unlockCache (); }
+NIFFile::ptr NIFFile::create (const std::string &name) { return LoadedCache::create  (name); }
+
+/// Open a NIF stream. The name is used for error messages.
+NIFFile::NIFFile(const std::string &name, psudo_private_modifier)
+    : filename(name)
+{
+    inp = Ogre::ResourceGroupManager::getSingleton().openResource(name);
+    parse();
+}
+
+NIFFile::~NIFFile()
+{
+    LoadedCache::release (this);
+
+    for(std::size_t i=0; i<records.size(); i++)
+        delete records[i];
+}
+
 /* This file implements functions from the NIFFile class. It is also
    where we stash all the functions we couldn't add as inline
    definitions in the record types.

components/nif/nif_file.hpp

@@ -37,6 +37,11 @@
 #include <vector>
 #include <cassert>
 
+#include <boost/weak_ptr.hpp>
+#include <boost/shared_ptr.hpp>
+#include <boost/make_shared.hpp>
+#include <boost/detail/endian.hpp>
+
 #include <libs/platform/stdint.h>
 
 #include "record.hpp"
@@ -93,6 +98,14 @@ class NIFFile
         return u.f;
     }
 
+    class LoadedCache;
+    friend class LoadedCache;
+
+    // attempt to protect NIFFile from misuse...
+    struct psudo_private_modifier {}; // this dirty little trick should optimize out
+    NIFFile (NIFFile const &);
+    void operator = (NIFFile const &);
+
 public:
     /// Used for error handling
     void fail(const std::string &msg)
@@ -108,19 +121,21 @@ public:
                  << "File: "<<filename <<std::endl;
     }
 
+    typedef boost::shared_ptr <NIFFile> ptr;
+
     /// Open a NIF stream. The name is used for error messages.
-    NIFFile(const std::string &name)
-      : filename(name)
-    {
-        inp = Ogre::ResourceGroupManager::getSingleton().openResource(name);
-        parse();
-    }
+    NIFFile(const std::string &name, psudo_private_modifier);
+    ~NIFFile();
+
+    static ptr create (const std::string &name);
+    static void lockCache ();
+    static void unlockCache ();
 
-    ~NIFFile()
+    struct CacheLock
     {
-        for(std::size_t i=0; i<records.size(); i++)
-            delete records[i];
-    }
+        CacheLock () { lockCache (); }
+        ~CacheLock () { unlockCache (); }
+    };
 
     /// Get a given record
     Record *getRecord(size_t index)

components/nifbullet/bullet_nif_loader.cpp

@@ -82,7 +82,8 @@ void ManualBulletShapeLoader::loadResource(Ogre::Resource *resource)
     // of the early stages of development. Right now we WANT to catch
     // every error as early and intrusively as possible, as it's most
     // likely a sign of incomplete code rather than faulty input.
-    Nif::NIFFile nif(resourceName.substr(0, resourceName.length()-7));
+    Nif::NIFFile::ptr pnif (Nif::NIFFile::create (resourceName.substr(0, resourceName.length()-7)));
+    Nif::NIFFile & nif = *pnif.get ();
     if (nif.numRecords() < 1)
     {
         warn("Found no records in NIF.");

components/nifogre/ogre_nif_loader.cpp

@@ -252,7 +252,8 @@ void loadResource(Ogre::Resource *resource)
     Ogre::Skeleton *skel = dynamic_cast<Ogre::Skeleton*>(resource);
     OgreAssert(skel, "Attempting to load a skeleton into a non-skeleton resource!");
 
-    Nif::NIFFile nif(skel->getName());
+    Nif::NIFFile::ptr pnif(Nif::NIFFile::create (skel->getName()));
+    Nif::NIFFile & nif = *pnif.get ();
     const Nif::Node *node = dynamic_cast<const Nif::Node*>(nif.getRecord(0));
 
     std::vector<Nif::NiKeyframeController const*> ctrls;
@@ -956,8 +957,8 @@ public:
             return;
         }
 
-        Nif::NIFFile nif(mName);
-        Nif::Node const *node = dynamic_cast<Nif::Node const *>(nif.getRecord(0));
+        Nif::NIFFile::ptr nif = Nif::NIFFile::create (mName);
+        Nif::Node const *node = dynamic_cast<Nif::Node const *>(nif->getRecord(0));
         findTriShape(mesh, node);
     }
 
@@ -1054,7 +1055,8 @@ MeshPairList NIFLoader::load(std::string name, std::string skelName, const std::
         return meshiter->second;
 
     MeshPairList &meshes = sMeshPairMap[name+"@skel="+skelName];
-    Nif::NIFFile nif(name);
+    Nif::NIFFile::ptr pnif = Nif::NIFFile::create (name);
+    Nif::NIFFile &nif = *pnif.get ();
     if (nif.numRecords() < 1)
     {
         nif.warn("Found no records in NIF.");