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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#pragma once
#include "postinglistcounts.h"
#include <memory>
#include <cstdlib>
namespace search { class BitVector; }
namespace search::queryeval { class SearchIterator; }
namespace search::fef { class TermFieldMatchDataArray; }
namespace search::index {
class PostingListFileRandRead;
/**
* Class for owning a posting list in memory after having read it from
* posting list file, or referencing a chunk of memory containing the
* posting list (if the file was memory mapped).
*/
class PostingListHandle {
public:
using UP = std::unique_ptr<PostingListHandle>;
// Key portion
PostingListFileRandRead *_file; // File containing posting list
uint64_t _bitOffset; // posting list start relative to start of file
uint64_t _bitLength; // Length of posting list, in bits
// Value portion
uint32_t _firstSegment; // First segment for word
uint32_t _numSegments; // Number of segments
uint64_t _bitOffsetMem; // _mem relative to start of file
const void *_mem; // Memory backing posting list after read/mmap
void *_allocMem; // What to free after posting list
size_t _allocSize; // Size of allocated memory
PostingListHandle()
: _file(nullptr),
_bitOffset(0),
_bitLength(0),
_firstSegment(0),
_numSegments(0),
_bitOffsetMem(0),
_mem(nullptr),
_allocMem(nullptr),
_allocSize(0)
{ }
~PostingListHandle()
{
if (_allocMem != nullptr) {
free(_allocMem);
}
}
/**
* Create iterator for single word. Semantic lifetime of counts and
* handle must exceed lifetime of iterator.
*
* XXX: TODO: How to read next set of segments from disk if handle
* didn't cover the whole word, probably need access to higher level
* API above caches.
*/
std::unique_ptr<search::queryeval::SearchIterator>
createIterator(const PostingListCounts &counts,
const search::fef::TermFieldMatchDataArray &matchData,
bool useBitVector=false) const;
/**
* Drop value portion of handle.
*/
void drop() {
_firstSegment = 0;
_numSegments = 0;
_bitOffsetMem = 0;
_mem = nullptr;
if (_allocMem != nullptr) {
free(_allocMem);
_allocMem = nullptr;
}
_allocSize = 0;
}
};
}
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