github.com/insionng/yougam@v0.0.0-20170714101924-2bc18d833463/libraries/pingcap/tidb/store/localstore/goleveldb/goleveldb.go (about)

     1  // Copyright 2015 PingCAP, Inc.
     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  // See the License for the specific language governing permissions and
    12  // limitations under the License.
    13  
    14  package goleveldb
    15  
    16  import (
    17  	"sync"
    18  
    19  	"github.com/insionng/yougam/libraries/juju/errors"
    20  	"github.com/insionng/yougam/libraries/pingcap/tidb/store/localstore/engine"
    21  	"github.com/insionng/yougam/libraries/syndtr/goleveldb/leveldb"
    22  	"github.com/insionng/yougam/libraries/syndtr/goleveldb/leveldb/opt"
    23  	"github.com/insionng/yougam/libraries/syndtr/goleveldb/leveldb/storage"
    24  	"github.com/insionng/yougam/libraries/syndtr/goleveldb/leveldb/util"
    25  )
    26  
    27  var (
    28  	_ engine.DB    = (*db)(nil)
    29  	_ engine.Batch = (*leveldb.Batch)(nil)
    30  )
    31  
    32  var (
    33  	p = sync.Pool{
    34  		New: func() interface{} {
    35  			return &leveldb.Batch{}
    36  		},
    37  	}
    38  )
    39  
    40  type db struct {
    41  	*leveldb.DB
    42  }
    43  
    44  func (d *db) Get(key []byte) ([]byte, error) {
    45  	v, err := d.DB.Get(key, nil)
    46  	if err == leveldb.ErrNotFound {
    47  		return nil, errors.Trace(engine.ErrNotFound)
    48  	}
    49  	return v, err
    50  }
    51  
    52  func (d *db) NewBatch() engine.Batch {
    53  	b := p.Get().(*leveldb.Batch)
    54  	return b
    55  }
    56  
    57  func (d *db) Seek(startKey []byte) ([]byte, []byte, error) {
    58  	iter := d.DB.NewIterator(&util.Range{Start: startKey}, nil)
    59  	defer iter.Release()
    60  	if ok := iter.First(); !ok {
    61  		return nil, nil, errors.Trace(engine.ErrNotFound)
    62  	}
    63  	return iter.Key(), iter.Value(), nil
    64  }
    65  
    66  func (d *db) SeekReverse(key []byte) ([]byte, []byte, error) {
    67  	iter := d.DB.NewIterator(&util.Range{}, nil)
    68  	defer iter.Release()
    69  	if len(key) == 0 {
    70  		if ok := iter.Last(); !ok {
    71  			return nil, nil, engine.ErrNotFound
    72  		}
    73  		return iter.Key(), iter.Value(), nil
    74  	}
    75  	iter.Seek(key)
    76  	if ok := iter.Prev(); !ok {
    77  		return nil, nil, engine.ErrNotFound
    78  	}
    79  	return iter.Key(), iter.Value(), nil
    80  }
    81  
    82  func (d *db) Commit(b engine.Batch) error {
    83  	batch, ok := b.(*leveldb.Batch)
    84  	if !ok {
    85  		return errors.Errorf("invalid batch type %T", b)
    86  	}
    87  	err := d.DB.Write(batch, nil)
    88  	batch.Reset()
    89  	p.Put(batch)
    90  	return err
    91  }
    92  
    93  func (d *db) Close() error {
    94  	return d.DB.Close()
    95  }
    96  
    97  // Driver implements engine Driver.
    98  type Driver struct {
    99  }
   100  
   101  // Open opens or creates a local storage database for the given path.
   102  func (driver Driver) Open(path string) (engine.DB, error) {
   103  	d, err := leveldb.OpenFile(path, &opt.Options{BlockCacheCapacity: 600 * 1024 * 1024})
   104  
   105  	return &db{d}, err
   106  }
   107  
   108  // MemoryDriver implements engine Driver
   109  type MemoryDriver struct {
   110  }
   111  
   112  // Open opens a memory storage database.
   113  func (driver MemoryDriver) Open(path string) (engine.DB, error) {
   114  	d, err := leveldb.Open(storage.NewMemStorage(), nil)
   115  	return &db{d}, err
   116  }