github.com/linapex/ethereum-go-chinese@v0.0.0-20190316121929-f8b7a73c3fa1/swarm/storage/database.go (about)

     1  
     2  //<developer>
     3  //    <name>linapex 曹一峰</name>
     4  //    <email>linapex@163.com</email>
     5  //    <wx>superexc</wx>
     6  //    <qqgroup>128148617</qqgroup>
     7  //    <url>https://jsq.ink</url>
     8  //    <role>pku engineer</role>
     9  //    <date>2019-03-16 19:16:44</date>
    10  //</624450118451466240>
    11  
    12  
    13  package storage
    14  
    15  //这是以太坊ethdb/数据库早期状态的克隆
    16  //不需要排队/缓存
    17  
    18  import (
    19  	"github.com/ethereum/go-ethereum/metrics"
    20  	"github.com/syndtr/goleveldb/leveldb"
    21  	"github.com/syndtr/goleveldb/leveldb/iterator"
    22  	"github.com/syndtr/goleveldb/leveldb/opt"
    23  )
    24  
    25  const openFileLimit = 128
    26  
    27  type LDBDatabase struct {
    28  	db *leveldb.DB
    29  }
    30  
    31  func NewLDBDatabase(file string) (*LDBDatabase, error) {
    32  //打开数据库
    33  	db, err := leveldb.OpenFile(file, &opt.Options{OpenFilesCacheCapacity: openFileLimit})
    34  	if err != nil {
    35  		return nil, err
    36  	}
    37  
    38  	database := &LDBDatabase{db: db}
    39  
    40  	return database, nil
    41  }
    42  
    43  func (db *LDBDatabase) Put(key []byte, value []byte) error {
    44  	metrics.GetOrRegisterCounter("ldbdatabase.put", nil).Inc(1)
    45  
    46  	return db.db.Put(key, value, nil)
    47  }
    48  
    49  func (db *LDBDatabase) Get(key []byte) ([]byte, error) {
    50  	metrics.GetOrRegisterCounter("ldbdatabase.get", nil).Inc(1)
    51  
    52  	dat, err := db.db.Get(key, nil)
    53  	if err != nil {
    54  		return nil, err
    55  	}
    56  	return dat, nil
    57  }
    58  
    59  func (db *LDBDatabase) Delete(key []byte) error {
    60  	return db.db.Delete(key, nil)
    61  }
    62  
    63  func (db *LDBDatabase) NewIterator() iterator.Iterator {
    64  	metrics.GetOrRegisterCounter("ldbdatabase.newiterator", nil).Inc(1)
    65  
    66  	return db.db.NewIterator(nil, nil)
    67  }
    68  
    69  func (db *LDBDatabase) Write(batch *leveldb.Batch) error {
    70  	metrics.GetOrRegisterCounter("ldbdatabase.write", nil).Inc(1)
    71  
    72  	return db.db.Write(batch, nil)
    73  }
    74  
    75  func (db *LDBDatabase) Close() {
    76  //关闭LevelDB数据库
    77  	db.db.Close()
    78  }
    79