104 lines
2.5 KiB
C
104 lines
2.5 KiB
C
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#pragma once
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#include <type_traits> // std::aligned_storage_t
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#include <cstring> // std::memcmp
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#include <cstdint>
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#include "libipc/def.h"
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#include "libipc/platform/detail.h"
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namespace ipc {
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using storage_id_t = std::int32_t;
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template <std::size_t DataSize, std::size_t AlignSize>
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struct id_type;
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template <std::size_t AlignSize>
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struct id_type<0, AlignSize> {
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uint_t<8> id_;
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id_type& operator=(storage_id_t val) {
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id_ = static_cast<uint_t<8>>(val);
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return (*this);
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}
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operator uint_t<8>() const {
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return id_;
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}
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};
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template <std::size_t DataSize, std::size_t AlignSize>
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struct id_type : id_type<0, AlignSize> {
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std::aligned_storage_t<DataSize, AlignSize> data_;
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};
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template <std::size_t DataSize = 0,
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std::size_t AlignSize = (ipc::detail::min)(DataSize, alignof(std::max_align_t))>
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class id_pool {
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static constexpr std::size_t limited_max_count() {
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return ipc::detail::min<std::size_t>(large_msg_cache, (std::numeric_limits<uint_t<8>>::max)());
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}
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public:
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enum : std::size_t {
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/* eliminate error: taking address of temporary */
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max_count = limited_max_count()
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};
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private:
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id_type<DataSize, AlignSize> next_[max_count];
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uint_t<8> cursor_ = 0;
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bool prepared_ = false;
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public:
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void prepare() {
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if (!prepared_ && this->invalid()) this->init();
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prepared_ = true;
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}
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void init() {
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for (storage_id_t i = 0; i < max_count;) {
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i = next_[i] = (i + 1);
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}
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}
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bool invalid() const {
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static id_pool inv;
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return std::memcmp(this, &inv, sizeof(id_pool)) == 0;
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}
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bool empty() const {
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return cursor_ == max_count;
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}
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storage_id_t acquire() {
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if (empty()) return -1;
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storage_id_t id = cursor_;
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cursor_ = next_[id]; // point to next
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return id;
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}
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bool release(storage_id_t id) {
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if (id < 0) return false;
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next_[id] = cursor_;
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cursor_ = static_cast<uint_t<8>>(id); // put it back
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return true;
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}
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void * at(storage_id_t id) { return &(next_[id].data_); }
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void const * at(storage_id_t id) const { return &(next_[id].data_); }
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};
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template <typename T>
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class obj_pool : public id_pool<sizeof(T), alignof(T)> {
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using base_t = id_pool<sizeof(T), alignof(T)>;
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public:
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T * at(storage_id_t id) { return reinterpret_cast<T *>(base_t::at(id)); }
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T const * at(storage_id_t id) const { return reinterpret_cast<T const *>(base_t::at(id)); }
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};
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} // namespace ipc
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