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C++

/**
*
* \section COPYRIGHT
*
* Copyright 2013-2021 Software Radio Systems Limited
*
* By using this file, you agree to the terms and conditions set
* forth in the LICENSE file which can be found at the top level of
* the distribution.
*
*/
#ifndef SRSRAN_MEMBLOCK_CACHE_H
#define SRSRAN_MEMBLOCK_CACHE_H
#include <mutex>
namespace srsran {
/// Stores provided mem blocks in a stack in an non-owning manner. Not thread-safe
class memblock_cache
{
struct node {
node* prev;
explicit node(node* prev_) : prev(prev_) {}
};
public:
constexpr static size_t min_memblock_size() { return sizeof(node); }
memblock_cache() = default;
memblock_cache(const memblock_cache&) = delete;
memblock_cache(memblock_cache&& other) noexcept : head(other.head) { other.head = nullptr; }
memblock_cache& operator=(const memblock_cache&) = delete;
memblock_cache& operator=(memblock_cache&& other) noexcept
{
head = other.head;
other.head = nullptr;
return *this;
}
void push(void* block) noexcept
{
// printf("head: %ld\n", (long)head);
node* next = ::new (block) node(head);
head = next;
count++;
}
uint8_t* try_pop() noexcept
{
if (is_empty()) {
return nullptr;
}
node* last_head = head;
head = head->prev;
count--;
return (uint8_t*)last_head;
}
bool is_empty() const { return head == nullptr; }
size_t size() const { return count; }
void clear() { head = nullptr; }
private:
node* head = nullptr;
size_t count = 0;
};
/// memblock stack that mutexes pushing/popping
class mutexed_memblock_cache
{
public:
mutexed_memblock_cache() = default;
mutexed_memblock_cache(const mutexed_memblock_cache&) = delete;
mutexed_memblock_cache(mutexed_memblock_cache&& other) noexcept
{
std::unique_lock<std::mutex> lk1(other.mutex, std::defer_lock);
std::unique_lock<std::mutex> lk2(mutex, std::defer_lock);
std::lock(lk1, lk2);
stack = std::move(other.stack);
}
mutexed_memblock_cache& operator=(const mutexed_memblock_cache&) = delete;
mutexed_memblock_cache& operator=(mutexed_memblock_cache&& other) noexcept
{
std::unique_lock<std::mutex> lk1(other.mutex, std::defer_lock);
std::unique_lock<std::mutex> lk2(mutex, std::defer_lock);
std::lock(lk1, lk2);
stack = std::move(other.stack);
return *this;
}
void push(void* block) noexcept
{
std::lock_guard<std::mutex> lock(mutex);
stack.push(block);
}
uint8_t* try_pop() noexcept
{
std::lock_guard<std::mutex> lock(mutex);
uint8_t* block = stack.try_pop();
return block;
}
template <size_t N>
size_t try_pop(std::array<void*, N>& result) noexcept
{
std::lock_guard<std::mutex> lock(mutex);
size_t i = 0;
for (; i < N; ++i) {
result[i] = stack.try_pop();
if (result[i] == nullptr) {
break;
}
}
return i;
}
bool is_empty() const noexcept { return stack.is_empty(); }
size_t size() const noexcept
{
std::lock_guard<std::mutex> lock(mutex);
return stack.size();
}
void clear()
{
std::lock_guard<std::mutex> lock(mutex);
stack.clear();
}
private:
memblock_cache stack;
mutable std::mutex mutex;
};
} // namespace srsran
#endif // SRSRAN_MEMBLOCK_CACHE_H