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/*
* include/framework/scheduling/Version.h
*
* Copyright (C) 2023-2024 Douglas B. Rumbaugh <drumbaugh@psu.edu>
*
* Distributed under the Modified BSD License.
*
*/
#pragma once
#include <mutex>
#include "framework/structure/BufferView.h"
#include "framework/structure/ExtensionStructure.h"
#include "framework/structure/MutableBuffer.h"
namespace de {
template <ShardInterface ShardType, QueryInterface<ShardType> QueryType>
class Version {
private:
typedef typename ShardType::RECORD RecordType;
typedef MutableBuffer<RecordType> BufferType;
typedef ExtensionStructure<ShardType, QueryType> StructureType;
typedef BufferView<RecordType> BufferViewType;
public:
Version(size_t vid = 0)
: m_buffer(nullptr), m_structure(nullptr), m_id(vid), m_buffer_head(0),
m_pending_buffer_head(-1) {}
Version(size_t number, std::unique_ptr<StructureType> structure, BufferType *buff,
size_t head)
: m_buffer(buff), m_structure(std::move(structure)), m_id(number),
m_buffer_head(head), m_pending_buffer_head(-1) {}
~Version() = default;
/*
* Versions are *not* copyable or movable. Only one can exist, and all users
* of it work with pointers
*/
Version(const Version &) = delete;
Version(Version &&) = delete;
Version &operator=(const Version &) = delete;
Version &operator=(Version &&) = delete;
size_t get_id() const { return m_id; }
void set_id(size_t id) { m_id = id;}
const StructureType *get_structure() const { return m_structure.get(); }
StructureType *get_mutable_structure() { return m_structure.get(); }
bool set_structure(std::unique_ptr<StructureType> new_struct) {
if (m_structure) {
return false;
}
m_structure = std::move(new_struct);
return true;
}
BufferViewType get_buffer() const {
return m_buffer->get_buffer_view(m_buffer_head);
}
/*
* Returns a new Version object that is a copy of this one. The new object
* will also contain a copy of the m_structure, rather than a reference to
* the same one. The epoch number of the new epoch will be set to the
* provided argument.
*/
Version *clone(size_t number) {
auto version = new Version(number);
version->m_buffer = m_buffer;
version->m_buffer_head = m_buffer_head;
if (m_structure) {
version->m_structure = std::unique_ptr(m_structure->copy());
}
return version;
}
bool advance_buffer_head(size_t new_head) {
m_buffer_head = new_head;
return m_buffer->advance_head(new_head);
}
void merge_changes_from(Version *old, size_t version_id) {
/*
* for a maint reconstruction, the buffer head may have advanced
* during the reconstruction; we don't need to adjust the buffer
* for maintenance reconstructions, so we can simply "catch" the
* internal head index up to the current version.
*/
if (old->m_buffer_head > m_buffer_head) {
m_buffer_head = old->m_buffer_head;
}
// FIXME: we should also ensure that we don't clobber anything
// in the event that multiple concurrent reconstructions affect
// the same levels. As it stands, two reconstructions *could* share
// source shards, resulting in some records being lost or duplicated.
//
// For the moment, I'm being careful to avoid this within the
// scheduling policy itself, and only forwarding changes to this
// version.
/* using INVALID_VERSION disables shard reconcilliation */
if (version_id == 0) {
return;
}
/* add any shards newer than version_id to this version */
auto old_structure = old->get_structure();
m_structure->merge_structure(old_structure, version_id);
}
void update_shard_version(size_t version) {
m_structure->update_shard_version(version);
}
private:
BufferType *m_buffer;
std::unique_ptr<StructureType> m_structure;
size_t m_id;
size_t m_buffer_head;
ssize_t m_pending_buffer_head;
};
} // namespace de
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