github.com/KinWaiYuen/client-go/v2@v2.5.4/txnkv/transaction/batch_getter.go (about)

     1  // Copyright 2021 TiKV Authors
     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  // NOTE: The code in this file is based on code from the
    16  // TiDB project, licensed under the Apache License v 2.0
    17  //
    18  // https://github.com/pingcap/tidb/tree/cc5e161ac06827589c4966674597c137cc9e809c/store/tikv/tests/snapshot_test.go
    19  //
    20  
    21  // Copyright 2016 PingCAP, Inc.
    22  //
    23  // Licensed under the Apache License, Version 2.0 (the "License");
    24  // you may not use this file except in compliance with the License.
    25  // You may obtain a copy of the License at
    26  //
    27  //     http://www.apache.org/licenses/LICENSE-2.0
    28  //
    29  // Unless required by applicable law or agreed to in writing, software
    30  // distributed under the License is distributed on an "AS IS" BASIS,
    31  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    32  // See the License for the specific language governing permissions and
    33  // limitations under the License.
    34  
    35  package transaction
    36  
    37  import (
    38  	"context"
    39  
    40  	tikverr "github.com/KinWaiYuen/client-go/v2/error"
    41  	"github.com/KinWaiYuen/client-go/v2/internal/unionstore"
    42  	"github.com/pingcap/errors"
    43  )
    44  
    45  // BatchBufferGetter is the interface for BatchGet.
    46  type BatchBufferGetter interface {
    47  	Len() int
    48  	unionstore.Getter
    49  }
    50  
    51  // BatchGetter is the interface for BatchGet.
    52  type BatchGetter interface {
    53  	// BatchGet gets a batch of values.
    54  	BatchGet(ctx context.Context, keys [][]byte) (map[string][]byte, error)
    55  }
    56  
    57  // BufferBatchGetter is the type for BatchGet with MemBuffer.
    58  type BufferBatchGetter struct {
    59  	buffer   BatchBufferGetter
    60  	snapshot BatchGetter
    61  }
    62  
    63  // NewBufferBatchGetter creates a new BufferBatchGetter.
    64  func NewBufferBatchGetter(buffer BatchBufferGetter, snapshot BatchGetter) *BufferBatchGetter {
    65  	return &BufferBatchGetter{buffer: buffer, snapshot: snapshot}
    66  }
    67  
    68  // BatchGet gets a batch of values.
    69  func (b *BufferBatchGetter) BatchGet(ctx context.Context, keys [][]byte) (map[string][]byte, error) {
    70  	if b.buffer.Len() == 0 {
    71  		return b.snapshot.BatchGet(ctx, keys)
    72  	}
    73  	bufferValues := make([][]byte, len(keys))
    74  	shrinkKeys := make([][]byte, 0, len(keys))
    75  	for i, key := range keys {
    76  		val, err := b.buffer.Get(key)
    77  		if err == nil {
    78  			bufferValues[i] = val
    79  			continue
    80  		}
    81  		if !tikverr.IsErrNotFound(err) {
    82  			return nil, errors.Trace(err)
    83  		}
    84  		shrinkKeys = append(shrinkKeys, key)
    85  	}
    86  	storageValues, err := b.snapshot.BatchGet(ctx, shrinkKeys)
    87  	if err != nil {
    88  		return nil, errors.Trace(err)
    89  	}
    90  	for i, key := range keys {
    91  		if len(bufferValues[i]) == 0 {
    92  			continue
    93  		}
    94  		storageValues[string(key)] = bufferValues[i]
    95  	}
    96  	return storageValues, nil
    97  }