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/*
* include/framework/structure/BufferView.h
*
* Copyright (C) 2023 Douglas B. Rumbaugh <drumbaugh@psu.edu>
*
* Distributed under the Modified BSD License.
*
*/
#pragma once
#include <cstdlib>
#include <cassert>
#include <functional>
#include "psu-util/alignment.h"
#include "psu-ds/BloomFilter.h"
#include "framework/interface/Record.h"
namespace de {
typedef std::_Bind<void (*(void*, long unsigned int))(void*, long unsigned int)> ReleaseFunction;
template <RecordInterface R>
class BufferView {
public:
BufferView() = default;
/*
* the BufferView's lifetime is tightly linked to buffer versioning, and so
* copying and assignment are disabled.
*/
BufferView(const BufferView&) = delete;
BufferView &operator=(BufferView &) = delete;
BufferView(BufferView &&other)
: m_data(std::exchange(other.m_data, nullptr))
, m_release(std::move(other.m_release))
, m_head(std::exchange(other.m_head, 0))
, m_tail(std::exchange(other.m_tail, 0))
, m_cap(std::exchange(other.m_cap, 0))
, m_approx_ts_cnt(std::exchange(other.m_approx_ts_cnt, 0))
, m_tombstone_filter(std::exchange(other.m_tombstone_filter, nullptr)) {}
BufferView &operator=(BufferView &&other) = delete;
BufferView(Wrapped<R> *buffer, size_t cap, size_t head, size_t tail, size_t tombstone_cnt, psudb::BloomFilter<R> *filter,
ReleaseFunction release)
: m_data(buffer)
, m_release(release)
, m_head(head)
, m_tail(tail)
, m_cap(cap)
, m_approx_ts_cnt(tombstone_cnt)
, m_tombstone_filter(filter) {}
~BufferView() {
m_release();
}
bool check_tombstone(const R& rec) {
if (m_tombstone_filter && !m_tombstone_filter->lookup(rec)) return false;
for (size_t i=0; i<get_record_count(); i++) {
if (m_data[to_idx(i)].rec == rec && m_data[to_idx(i)].is_tombstone()) {
return true;
}
}
return false;
}
bool delete_record(const R& rec) {
for (size_t i=0; i<get_record_count(); i++) {
if (m_data[to_idx(i)].rec == rec) {
m_data[to_idx(i)].set_delete();
return true;
}
}
return false;
}
size_t get_record_count() {
return m_tail - m_head;
}
/*
* NOTE: This function returns an upper bound on the number
* of tombstones within the view. There may be less than
* this, due to synchronization issues during view creation.
*/
size_t get_tombstone_count() {
return m_approx_ts_cnt;
}
Wrapped<R> *get(size_t i) {
assert(i < get_record_count());
return m_data + to_idx(i);
}
void copy_to_buffer(psudb::byte *buffer) {
memcpy(buffer, (std::byte*) (m_data + m_head), get_record_count() * sizeof(Wrapped<R>));
}
private:
Wrapped<R>* m_data;
ReleaseFunction m_release;
size_t m_head;
size_t m_tail;
size_t m_cap;
size_t m_approx_ts_cnt;
psudb::BloomFilter<R> *m_tombstone_filter;
size_t to_idx(size_t i) {
return (m_head + i) % m_cap;
}
};
}
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