e955c94ed3
Listing the "Blender Foundation" as copyright holder implied the Blender Foundation holds copyright to files which may include work from many developers. While keeping copyright on headers makes sense for isolated libraries, Blender's own code may be refactored or moved between files in a way that makes the per file copyright holders less meaningful. Copyright references to the "Blender Foundation" have been replaced with "Blender Authors", with the exception of `./extern/` since these this contains libraries which are more isolated, any changed to license headers there can be handled on a case-by-case basis. Some directories in `./intern/` have also been excluded: - `./intern/cycles/` it's own `AUTHORS` file is planned. - `./intern/opensubdiv/`. An "AUTHORS" file has been added, using the chromium projects authors file as a template. Design task: #110784 Ref !110783.
88 lines
2.6 KiB
C++
88 lines
2.6 KiB
C++
/* SPDX-FileCopyrightText: 2023 Blender Authors
|
|
*
|
|
* SPDX-License-Identifier: GPL-2.0-or-later */
|
|
|
|
#pragma once
|
|
|
|
#include "BLI_cache_mutex.hh"
|
|
|
|
namespace blender {
|
|
|
|
/**
|
|
* A `SharedCache` is meant to share lazily computed data between equivalent objects. It allows
|
|
* saving unnecessary computation by making a calculated value accessible from any object that
|
|
* shares the cache. Unlike `CacheMutex`, the cached data is embedded inside of this object.
|
|
*
|
|
* When data is copied (copy-on-write before changing a mesh, for example), the cache is shared,
|
|
* allowing its calculation on either the source or original to make the result available on both
|
|
* objects. As soon as either object is changed in a way that invalidates the cache, the data is
|
|
* "un-shared", and they will no-longer influence each other.
|
|
*
|
|
* One important use case is a typical CoW update loop of a persistent geometry data-block in
|
|
* `Main`. Even if bounds are only calculated on the evaluated *copied* geometry, if nothing
|
|
* changes them, they only need to be calculated on the first evaluation, because the same
|
|
* evaluated bounds are also accessible from the original geometry.
|
|
*
|
|
* The cache is implemented with a shared pointer, so it is relatively cheap, but to avoid
|
|
* unnecessary overhead it should only be used for relatively expensive computations.
|
|
*/
|
|
template<typename T> class SharedCache {
|
|
struct CacheData {
|
|
CacheMutex mutex;
|
|
T data;
|
|
};
|
|
std::shared_ptr<CacheData> cache_;
|
|
|
|
public:
|
|
SharedCache()
|
|
{
|
|
/* The cache should be allocated to trigger sharing of the cached data as early as possible. */
|
|
cache_ = std::make_shared<CacheData>();
|
|
}
|
|
|
|
/** Tag the data for recomputation and stop sharing the cache with other objects. */
|
|
void tag_dirty()
|
|
{
|
|
if (cache_.unique()) {
|
|
cache_->mutex.tag_dirty();
|
|
}
|
|
else {
|
|
cache_ = std::make_shared<CacheData>();
|
|
}
|
|
}
|
|
|
|
/**
|
|
* If the cache is dirty, trigger its computation with the provided function which should set
|
|
* the proper data.
|
|
*/
|
|
void ensure(FunctionRef<void(T &data)> compute_cache)
|
|
{
|
|
cache_->mutex.ensure([&]() { compute_cache(this->cache_->data); });
|
|
}
|
|
|
|
/** Retrieve the cached data. */
|
|
const T &data() const
|
|
{
|
|
BLI_assert(cache_->mutex.is_cached());
|
|
return cache_->data;
|
|
}
|
|
|
|
/**
|
|
* Return true if the cache currently does not exist or has been invalidated.
|
|
*/
|
|
bool is_dirty() const
|
|
{
|
|
return cache_->mutex.is_dirty();
|
|
}
|
|
|
|
/**
|
|
* Return true if the cache exists and is valid.
|
|
*/
|
|
bool is_cached() const
|
|
{
|
|
return cache_->mutex.is_cached();
|
|
}
|
|
};
|
|
|
|
} // namespace blender
|