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#pragma once
#include "coding/file_reader.hpp"
#include "coding/file_writer.hpp"
#include "base/base.hpp"
#include "base/logging.hpp"
#include "base/exception.hpp"
#include "std/algorithm.hpp"
#include "std/cstdlib.hpp"
#include "std/functional.hpp"
#include "std/queue.hpp"
#include "std/unique_ptr.hpp"
#include "std/string.hpp"
#include "std/utility.hpp"
#include "std/vector.hpp"
template <typename LessT>
struct Sorter
{
LessT m_Less;
Sorter(LessT lessF) : m_Less(lessF) {}
template <typename IterT> void operator() (IterT beg, IterT end) const
{
sort(beg, end, m_Less);
}
};
template <
typename T, // Item type.
class OutputSinkT = FileWriter, // Sink to output into result file.
typename LessT = less<T>, // Item comparator.
template <typename LessT1> class SorterT = Sorter // Item sorter.
>
class FileSorter
{
public:
FileSorter(size_t bufferBytes,
string const & tmpFileName,
OutputSinkT & outputSink,
LessT fLess = LessT()) :
m_TmpFileName(tmpFileName),
m_BufferCapacity(max(size_t(16), bufferBytes / sizeof(T))),
m_OutputSink(outputSink),
m_ItemCount(0),
m_Less(fLess)
{
m_Buffer.reserve(m_BufferCapacity);
m_pTmpWriter.reset(new FileWriter(tmpFileName));
}
void Add(T const & item)
{
if (m_Buffer.size() == m_BufferCapacity)
FlushToTmpFile();
m_Buffer.push_back(item);
++m_ItemCount;
}
void SortAndFinish()
{
ASSERT(m_pTmpWriter.get(), ());
FlushToTmpFile();
// Write output.
{
m_pTmpWriter.reset();
FileReader reader(m_TmpFileName);
ItemIndexPairGreater fGreater(m_Less);
PriorityQueueType q(fGreater);
for (uint32_t i = 0; i < m_ItemCount; i += m_BufferCapacity)
Push(q, i, reader);
while (!q.empty())
{
m_OutputSink(q.top().first);
uint32_t const i = q.top().second + 1;
q.pop();
if (i % m_BufferCapacity != 0 && i < m_ItemCount)
Push(q, i, reader);
}
}
FileWriter::DeleteFileX(m_TmpFileName);
}
~FileSorter()
{
if (m_pTmpWriter.get())
{
try
{
SortAndFinish();
}
catch(RootException const & e)
{
LOG(LERROR, (e.Msg()));
}
catch(std::exception const & e)
{
LOG(LERROR, (e.what()));
}
}
}
private:
struct ItemIndexPairGreater
{
explicit ItemIndexPairGreater(LessT fLess) : m_Less(fLess) {}
inline bool operator() (pair<T, uint32_t> const & a, pair<T, uint32_t> const & b) const
{
return m_Less(b.first, a.first);
}
LessT m_Less;
};
typedef priority_queue<pair<T, uint32_t>, vector<pair<T, uint32_t> >, ItemIndexPairGreater>
PriorityQueueType;
void FlushToTmpFile()
{
if (m_Buffer.empty())
return;
SorterT<LessT> sorter(m_Less);
sorter(m_Buffer.begin(), m_Buffer.end());
m_pTmpWriter->Write(&m_Buffer[0], m_Buffer.size() * sizeof(T));
m_Buffer.clear();
}
void Push(PriorityQueueType & q, uint32_t i, FileReader const & reader)
{
T item;
reader.Read(static_cast<uint64_t>(i) * sizeof(T), &item, sizeof(T));
q.push(pair<T, uint32_t>(item, i));
}
string const m_TmpFileName;
size_t const m_BufferCapacity;
OutputSinkT & m_OutputSink;
unique_ptr<FileWriter> m_pTmpWriter;
vector<T> m_Buffer;
uint32_t m_ItemCount;
LessT m_Less;
};
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