blob: c1549b32f9396bd860dcd6525ed0b02a9e40b173 (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
|
// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#pragma once
#include <vector>
namespace search {
/*
* Provide priority queue semantics for a set of posting readers.
*/
template <class Reader>
class PostingPriorityQueue
{
protected:
class Ref
{
Reader *_ref;
public:
Ref(Reader *ref)
: _ref(ref)
{
}
bool operator<(const Ref &rhs) const { return *_ref < *rhs._ref; }
Reader *get() const noexcept { return _ref; }
};
using Vector = std::vector<Ref>;
Vector _vec;
uint32_t _heap_limit;
uint32_t _merge_chunk;
public:
PostingPriorityQueue()
: _vec(),
_heap_limit(0u),
_merge_chunk(0u)
{
}
bool empty() const { return _vec.empty(); }
void clear() { _vec.clear(); }
void initialAdd(Reader *it) { _vec.push_back(Ref(it)); }
/*
* Sort vector after a set of initial add operations, so lowest()
* and adjust() can be used. Skip sort if _vec.size() < heap_limit
* since merging with few elements don't use heap.
*/
void setup(uint32_t heap_limit);
/*
* Return lowest value. Assumes vector is sorted.
*/
Reader *lowest() const { return _vec.front().get(); }
/*
* The vector might no longer be sorted since the first element has changed
* value. Perform adjustments to make vector sorted again.
*/
void adjust();
};
}
|
