buffer-metadata.hpp File Reference

Go to the source code of this file.

Description

Metadata for managing and accessing buffers.

The Lumiera Engine uses the Abstraction of an BufferProvider to handle various kinds of buffer organisation and access in a uniform way. Actually, buffers can be exposed and provided by several facilities, which might even be implemented through an external library. Thus the engine and the abstraction placed in between needs a common set of control data, to be able to expose the correct buffer for each request. Typically – and independent of the actual implementation – the following properties need to be tracked

• that overall storage size available within the buffer
• a pair of custom creator and destructor functions to use together with this buffer
• an additional client key to distinguish otherwise otherwise identical client requests These three distinctions are applied in sequence, thus forming a type tree with 3 levels. Only the first distinguishing level (the size) is mandatory. The others are provided, because some of the foreseeable buffer providers allow to re-access the data placed into the buffer, by assigning an internally managed ID to the buffer. The most prominent example is the frame cache, which obviously needs to keep track of the buffers after the render engine is finished, while the engine code just accesses yet another buffer to place the results of calculations.

These additional distinctions and properties are associated with the help of the BufferDescriptor, embedded into each BuffHandle. While the engine just uses these handles in the way of a pointer, the buffer descriptor acts as an additional tag attached to the buffer access, allowing to re-access a context within the buffer provider implementation.

See also

buffer-provider.hpp

BufferMetadata_test

BufferProviderProtocol_test

Definition in file buffer-metadata.hpp.

#include "lib/error.hpp"
#include "lib/symbol.hpp"
#include "lib/hash-value.h"
#include "lib/util-foreach.hpp"
#include "include/logging.h"
#include "steam/engine/type-handler.hpp"
#include "steam/engine/buffer-local-key.hpp"
#include "lib/nocopy.hpp"
#include <unordered_map>

Classes
class	BufferMetadata
	Registry for managing buffer metadata. More...
class	Entry
	A complete metadata Entry, based on a Key. More...
class	Key
	Description of a Buffer-"type". More...
class	Table
	(Hash)Table to store and manage buffer metadata. More...

Enumerations
enum	BufferState {   NIL,   FREE,   LOCKED,   EMITTED,   BLOCKED }
	Buffer states usable within BufferProvider and stored within the metadata. More...

Functions
template<typename VAL >
HashVal	chainedHash (HashVal accumulatedHash, VAL changedValue)
bool	nontrivial (TypeHandler const &toVerify)
bool	nontrivial (LocalKey const &toVerify)

Variables
const TypeHandler	RAW_BUFFER
const LocalKey	UNSPECIFIC

Namespaces
	steam
	Steam-Layer implementation namespace root.
	steam::engine
	Lumiera's render engine core and operational control.