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/* SPDX-License-Identifier: Apache-2.0 */
/*
* Copyright (C) 2014-2018 Intel Corporation
*
* This implementation is highly derived from ChromeOS:
* platform2/camera/hal/intel/ipu3/common/SharedItemPool.h
*/
#ifndef SHARED_ITEM_POOL_H
#define SHARED_ITEM_POOL_H
#include <memory>
#include <mutex>
#include <pthread.h>
#include <vector>
/**
* \class SharedItemPool
*
* Pool of ref counted items. This class creates a pool of items and manages
* the acquisition of them. When all references to this item have disappeared
* The item is returned to the pool.
*
* This class is thread safe, i.e. it can be called from multiple threads.
* When the element is recycled to the pool it can be reset via a client
* provided method.
*
*/
namespace libcamera {
template<class ItemType>
class SharedItemPool
{
public:
SharedItemPool(const char *name = "Unnamed");
~SharedItemPool();
/**
* Initializes the capacity of the pool. It allocates the objects.
* optionally it will take function to reset the item before recycling
* it to the pool.
* This method is thread safe.
*
* \param capacity[IN]: Number of items the pool will hold
* \param resetter[IN]: Function to reset the item before recycling to the
* pool.
* \return -ENOSYS if trying to initialize twice
* \return 0 If everything went ok.
*/
int init(int32_t capacity, void (*resetter)(ItemType *) = nullptr);
bool isFull();
/**
* Free the resources of the pool
*
* \return 0 on success
*/
int deInit();
/**
* Acquire an item from the pool.
* This method is thread safe. Access to the internal acquire/release
* methods are protected.
* BUT the thread-safety for the utilization of the item after it has been
* acquired is the user's responsibility.
* Be careful not to provide the same item to multiple threads that write
* into it.
*
* \param item[OUT] shared pointer to an item.
* \return 0 on success
*/
int acquireItem(std::shared_ptr<ItemType> &item);
/**
* Returns the number of currently available items
* It there would be issues acquiring the lock the method returns 0
* available items.
*
* \return item count
*/
size_t availableItems();
private:
int _releaseItem(ItemType *item);
class ItemDeleter
{
public:
ItemDeleter(SharedItemPool *pool)
: mPool(pool) {}
void operator()(ItemType *item) const
{
mPool->_releaseItem(item);
}
private:
SharedItemPool *mPool;
};
std::vector<ItemType *> available_; /* SharedItemPool doesn't have ownership */
ItemType *allocated_;
size_t capacity_;
ItemDeleter deleter_;
std::mutex mutex_; /* protects available_, allocated_, capacity_ */
const char *poolName_;
void (*resetter_)(ItemType *);
};
} /* namespace libcamera */
#endif /* SHARED_ITEM_POOL_H */
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