github.com/weaviate/weaviate@v1.24.6/adapters/repos/db/lsmkv/cursor_memtable_collection.go (about)

     1  //                           _       _
     2  // __      _____  __ ___   ___  __ _| |_ ___
     3  // \ \ /\ / / _ \/ _` \ \ / / |/ _` | __/ _ \
     4  //  \ V  V /  __/ (_| |\ V /| | (_| | ||  __/
     5  //   \_/\_/ \___|\__,_| \_/ |_|\__,_|\__\___|
     6  //
     7  //  Copyright © 2016 - 2024 Weaviate B.V. All rights reserved.
     8  //
     9  //  CONTACT: hello@weaviate.io
    10  //
    11  
    12  package lsmkv
    13  
    14  import (
    15  	"bytes"
    16  
    17  	"github.com/weaviate/weaviate/entities/lsmkv"
    18  )
    19  
    20  type memtableCursorCollection struct {
    21  	data    []*binarySearchNodeMulti
    22  	current int
    23  	lock    func()
    24  	unlock  func()
    25  }
    26  
    27  func (m *Memtable) newCollectionCursor() innerCursorCollection {
    28  	// This cursor is a really primitive approach, it actually requires
    29  	// flattening the entire memtable - even if the cursor were to point to the
    30  	// very last element. However, given that the memtable will on average be
    31  	// only half it's max capacity and even that is relatively small, we might
    32  	// get away with the full-flattening and a linear search. Let's not optimize
    33  	// prematurely.
    34  
    35  	m.RLock()
    36  	defer m.RUnlock()
    37  
    38  	data := m.keyMulti.flattenInOrder()
    39  
    40  	return &memtableCursorCollection{
    41  		data:   data,
    42  		lock:   m.RLock,
    43  		unlock: m.RUnlock,
    44  	}
    45  }
    46  
    47  func (c *memtableCursorCollection) first() ([]byte, []value, error) {
    48  	c.lock()
    49  	defer c.unlock()
    50  
    51  	if len(c.data) == 0 {
    52  		return nil, nil, lsmkv.NotFound
    53  	}
    54  
    55  	c.current = 0
    56  
    57  	// there is no key-level tombstone, only individual values can have
    58  	// tombstones
    59  	return c.data[c.current].key, c.data[c.current].values, nil
    60  }
    61  
    62  func (c *memtableCursorCollection) seek(key []byte) ([]byte, []value, error) {
    63  	c.lock()
    64  	defer c.unlock()
    65  
    66  	pos := c.posLargerThanEqual(key)
    67  	if pos == -1 {
    68  		return nil, nil, lsmkv.NotFound
    69  	}
    70  
    71  	c.current = pos
    72  	// there is no key-level tombstone, only individual values can have
    73  	// tombstones
    74  	return c.data[pos].key, c.data[pos].values, nil
    75  }
    76  
    77  func (c *memtableCursorCollection) posLargerThanEqual(key []byte) int {
    78  	for i, node := range c.data {
    79  		if bytes.Compare(node.key, key) >= 0 {
    80  			return i
    81  		}
    82  	}
    83  
    84  	return -1
    85  }
    86  
    87  func (c *memtableCursorCollection) next() ([]byte, []value, error) {
    88  	c.lock()
    89  	defer c.unlock()
    90  
    91  	c.current++
    92  	if c.current >= len(c.data) {
    93  		return nil, nil, lsmkv.NotFound
    94  	}
    95  
    96  	// there is no key-level tombstone, only individual values can have
    97  	// tombstones
    98  	return c.data[c.current].key, c.data[c.current].values, nil
    99  }