github.com/matrixorigin/matrixone@v0.7.0/pkg/txn/storage/memorystorage/memtable/table_iter.go (about)

     1  // Copyright 2022 Matrix Origin
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //      http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package memtable
    16  
    17  import (
    18  	"database/sql"
    19  	"errors"
    20  
    21  	"github.com/matrixorigin/matrixone/pkg/txn/storage/memorystorage/memorytable"
    22  	"github.com/tidwall/btree"
    23  )
    24  
    25  type TableIter[
    26  	K memorytable.Ordered[K],
    27  	V any,
    28  ] struct {
    29  	tx       *Transaction
    30  	iter     btree.GenericIter[*PhysicalRow[K, V]]
    31  	readTime Time
    32  }
    33  
    34  func (t *Table[K, V, R]) NewIter(tx *Transaction) *TableIter[K, V] {
    35  	iter := t.state.Load().rows.Copy().Iter()
    36  	ret := &TableIter[K, V]{
    37  		tx:       tx,
    38  		iter:     iter,
    39  		readTime: tx.Time,
    40  	}
    41  	return ret
    42  }
    43  
    44  func (t *TableIter[K, V]) Read() (key K, value V, err error) {
    45  	physicalRow := t.iter.Item()
    46  	if physicalRow == nil {
    47  		panic("impossible")
    48  	}
    49  	key = physicalRow.Key
    50  	value, err = physicalRow.Read(t.readTime, t.tx)
    51  	if err != nil {
    52  		return
    53  	}
    54  	return
    55  }
    56  
    57  func (t *TableIter[K, V]) Item() (row *PhysicalRow[K, V]) {
    58  	return t.iter.Item()
    59  }
    60  
    61  func (t *TableIter[K, V]) Next() bool {
    62  	for {
    63  		if ok := t.iter.Next(); !ok {
    64  			return false
    65  		}
    66  		// skip unreadable values
    67  		item := t.iter.Item()
    68  		_, err := item.Read(t.readTime, t.tx)
    69  		if errors.Is(err, sql.ErrNoRows) {
    70  			continue
    71  		}
    72  		return true
    73  	}
    74  }
    75  
    76  func (t *TableIter[K, V]) First() bool {
    77  	if ok := t.iter.First(); !ok {
    78  		return false
    79  	}
    80  	for {
    81  		// skip unreadable values
    82  		item := t.iter.Item()
    83  		_, err := item.Read(t.readTime, t.tx)
    84  		if errors.Is(err, sql.ErrNoRows) {
    85  			if ok := t.iter.Next(); !ok {
    86  				return false
    87  			}
    88  			continue
    89  		}
    90  		return true
    91  	}
    92  }
    93  
    94  func (t *TableIter[K, V]) Seek(key K) bool {
    95  	pivot := &PhysicalRow[K, V]{
    96  		Key: key,
    97  	}
    98  	if ok := t.iter.Seek(pivot); !ok {
    99  		return false
   100  	}
   101  	for {
   102  		// skip unreadable values
   103  		item := t.iter.Item()
   104  		_, err := item.Read(t.readTime, t.tx)
   105  		if errors.Is(err, sql.ErrNoRows) {
   106  			if ok := t.iter.Next(); !ok {
   107  				return false
   108  			}
   109  			continue
   110  		}
   111  		return true
   112  	}
   113  }
   114  
   115  func (t *TableIter[K, V]) Close() error {
   116  	t.iter.Release()
   117  	return nil
   118  }