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Tidying up.

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This commit is contained in:
David Williams 2015-03-08 23:48:55 +01:00
parent 72abcd8e9c
commit 99d0a226c8
2 changed files with 6 additions and 103 deletions
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21
include/PolyVox/PagedVolume.h
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@ -283,27 +283,6 @@ namespace PolyVox
private:
Chunk* getChunk(int32_t uChunkX, int32_t uChunkY, int32_t uChunkZ) const;
void purgeNullPtrsFromAllChunks(void) const;
// The chunk data is stored in the pair of maps below. This will often hold the same set of chunks but there are occasions
// when they can differ (more on that in a moment). The main store is the set of 'recently used chunks' which holds shared_ptr's
// to the chunk data. When memory is low chunks can be removed from this list and, assuming there are no more references to
// them, they will be deleted. However, it is also possible that a Sampler is pointing at a given chunk, and in this case the
// reference counting will ensure that the chunk survives until the sampler has finished with it.
//
// However, this leaves us open to a subtle bug. If a chunk is removed from the recently used set, continues to exist due to a
// sampler using it, and then the user tries to access it through the volume interface, then the volume will page the chunk
// back in (not knowing the sampler still has it). This would result in two chunks in memory with the same position is space.
// To avoid this, the 'all chunks' set tracks chunks with are used by the volume *and/or* the samplers. It holds weak pointers
// so does not cause chunks to persist.
//
// TODO: Do we really need maps here? It means we are storing the chunk positions in the map, but they are also stored in the
// chunks themselves (so they can be passed to the pager from the chunks destructor). Can we use a set here? What is a better approach?
/*typedef std::unordered_map<Vector3DInt32, std::weak_ptr< Chunk > > WeakPtrChunkMap;
mutable WeakPtrChunkMap m_pAllChunks;
typedef std::unordered_map<Vector3DInt32, std::shared_ptr< Chunk > > SharedPtrChunkMap;
mutable SharedPtrChunkMap m_pRecentlyUsedChunks;*/
mutable std::unordered_map<Vector3DInt32, std::unique_ptr< Chunk > > m_mapChunks;
mutable uint32_t m_uTimestamper = 0;

88
include/PolyVox/PagedVolume.inl
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@ -214,22 +214,11 @@ namespace PolyVox
template <typename VoxelType>
void PagedVolume<VoxelType>::flushAll()
{
// Clear this pointer so it doesn't hang on to any chunks.
// Clear this pointer as all chunks are about to be removed.
m_pLastAccessedChunk = nullptr;
/*for (auto chunk : m_mapChunks)
{
delete chunk.second;
}*/
// Erase all the most recently used chunks.
m_mapChunks.clear();
// Remove deleted chunks from the list of all loaded chunks.
//purgeNullPtrsFromAllChunks();
// If there are still some chunks left then this is a cause for concern. Perhaps samplers are holding on to them?
//POLYVOX_LOG_WARNING_IF(m_pAllChunks.size() > 0, "Chunks still exist after performing flushAll()! Perhaps you have samplers attached?");
}
////////////////////////////////////////////////////////////////////////////////
@ -238,7 +227,7 @@ namespace PolyVox
template <typename VoxelType>
void PagedVolume<VoxelType>::flush(Region regFlush)
{
// Clear this pointer so it doesn't hang on to any chunks.
// Clear this pointer in case the chunk it points at is flushed.
m_pLastAccessedChunk = nullptr;
// Convert the start and end positions into chunk space coordinates
@ -265,11 +254,6 @@ namespace PolyVox
}
}
}
m_pLastAccessedChunk = nullptr;
// We might now have so null pointers in the 'all chunks' list so clean them up.
purgeNullPtrsFromAllChunks();
}
template <typename VoxelType>
@ -287,9 +271,6 @@ namespace PolyVox
}
// The chunk was not the same as last time, but we can now hope it is in the set of most recently used chunks.
//std::shared_ptr<typename PagedVolume<VoxelType>::Chunk> pChunk = nullptr;
//typename SharedPtrChunkMap::iterator itChunk = m_pRecentlyUsedChunks.find(v3dChunkPos);
Chunk* pChunk = nullptr;
auto itChunk = m_mapChunks.find(v3dChunkPos);
@ -301,39 +282,16 @@ namespace PolyVox
POLYVOX_ASSERT(pChunk, "Recent chunk list shold never contain a null pointer.");
}
/*if (!pChunk)
{
// Although it's not in our recently use chunks, there's some (slim) chance that it
// exists in the list of all loaded chunks, because a sampler may be holding on to it.
typename WeakPtrChunkMap::iterator itWeakChunk = m_pAllChunks.find(v3dChunkPos);
if (itWeakChunk != m_pAllChunks.end())
{
// We've found an entry in the 'all chunks' list, but it can be null. This happens if a sampler was the
// last thing to be keeping it alive and then the sampler let it go. In this case we remove it from the
// list, and it will get added again soon when we page it in and fill it with valid data.
if (itWeakChunk->second.expired())
{
m_pAllChunks.erase(itWeakChunk);
}
else
{
// The chunk is valid. We know it's not in the recently used list (we checked earlier) so it should be added.
pChunk = std::shared_ptr< PagedVolume<VoxelType>::Chunk >(itWeakChunk->second);
m_pRecentlyUsedChunks.insert(std::make_pair(v3dChunkPos, pChunk));
}
}
}*/
// If we still haven't found the chunk then it's time to create a new one and page it in from disk.
if (!pChunk)
{
// The chunk was not found so we will create a new one.
//pChunk = std::make_shared< PagedVolume<VoxelType>::Chunk >(v3dChunkPos, m_uChunkSideLength, m_pPager);
pChunk = new PagedVolume<VoxelType>::Chunk(v3dChunkPos, m_uChunkSideLength, m_pPager);
pChunk->m_uChunkLastAccessed = ++m_uTimestamper; // Important, as we may soon delete the oldest chunk
m_mapChunks.insert(std::make_pair(v3dChunkPos, std::unique_ptr<Chunk>(pChunk)));
// As we are loading a new chunk we should try to ensure we don't go over our target memory usage.
bool erasedChunk = false;
while (m_mapChunks.size() + 1 > m_uChunkCountLimit) // +1 ready for new chunk we will add next.
while (m_mapChunks.size() > m_uChunkCountLimit)
{
// Find the least recently used chunk. Hopefully this isn't too slow.
auto itUnloadChunk = m_mapChunks.begin();
@ -346,25 +304,10 @@ namespace PolyVox
}
// Erase the least recently used chunk
//delete itUnloadChunk->second;
m_mapChunks.erase(itUnloadChunk);
erasedChunk = true;
}
// If we've deleted any chunks from the recently used list then this
// seems like a good place to purge the 'all chunks' list as well.
if (erasedChunk)
{
purgeNullPtrsFromAllChunks();
}
// Add our new chunk to the maps.
//m_pAllChunks.insert(std::make_pair(v3dChunkPos, pChunk));
//m_pRecentlyUsedChunks.insert(std::make_pair(v3dChunkPos, pChunk));
m_mapChunks.insert(std::make_pair(v3dChunkPos, std::unique_ptr<Chunk>(pChunk)));
}
pChunk->m_uChunkLastAccessed = ++m_uTimestamper;
m_pLastAccessedChunk = pChunk;
m_v3dLastAccessedChunkPos = v3dChunkPos;
@ -377,28 +320,9 @@ namespace PolyVox
template <typename VoxelType>
uint32_t PagedVolume<VoxelType>::calculateSizeInBytes(void)
{
// Purge null chunks so we know that all chunks are used.
purgeNullPtrsFromAllChunks();
// Note: We disregard the size of the other class members as they are likely to be very small compared to the size of the
// allocated voxel data. This also keeps the reported size as a power of two, which makes other memory calculations easier.
return PagedVolume<VoxelType>::Chunk::calculateSizeInBytes(m_uChunkSideLength) * m_mapChunks.size();
}
template <typename VoxelType>
void PagedVolume<VoxelType>::purgeNullPtrsFromAllChunks(void) const
{
/*for (auto chunkIter = m_pAllChunks.begin(); chunkIter != m_pAllChunks.end();)
{
if (chunkIter->second.expired())
{
chunkIter = m_pAllChunks.erase(chunkIter);
}
else
{
chunkIter++;
}
}*/
}
}