mirror of https://github.com/poanetwork/quorum.git
108 lines
2.3 KiB
Markdown
108 lines
2.3 KiB
Markdown
This is an implementation of the [LevelDB key/value database](http:code.google.com/p/leveldb) in the [Go programming language](http:golang.org).
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[](https://travis-ci.org/syndtr/goleveldb)
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Installation
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-----------
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go get github.com/syndtr/goleveldb/leveldb
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Requirements
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-----------
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* Need at least `go1.5` or newer.
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Usage
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-----------
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Create or open a database:
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```go
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// The returned DB instance is safe for concurrent use. Which mean that all
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// DB's methods may be called concurrently from multiple goroutine.
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db, err := leveldb.OpenFile("path/to/db", nil)
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...
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defer db.Close()
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...
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```
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Read or modify the database content:
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```go
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// Remember that the contents of the returned slice should not be modified.
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data, err := db.Get([]byte("key"), nil)
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...
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err = db.Put([]byte("key"), []byte("value"), nil)
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...
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err = db.Delete([]byte("key"), nil)
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...
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```
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Iterate over database content:
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```go
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iter := db.NewIterator(nil, nil)
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for iter.Next() {
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// Remember that the contents of the returned slice should not be modified, and
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// only valid until the next call to Next.
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key := iter.Key()
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value := iter.Value()
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...
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}
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iter.Release()
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err = iter.Error()
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...
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```
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Seek-then-Iterate:
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```go
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iter := db.NewIterator(nil, nil)
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for ok := iter.Seek(key); ok; ok = iter.Next() {
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// Use key/value.
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...
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}
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iter.Release()
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err = iter.Error()
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...
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```
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Iterate over subset of database content:
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```go
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iter := db.NewIterator(&util.Range{Start: []byte("foo"), Limit: []byte("xoo")}, nil)
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for iter.Next() {
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// Use key/value.
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...
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}
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iter.Release()
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err = iter.Error()
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...
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```
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Iterate over subset of database content with a particular prefix:
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```go
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iter := db.NewIterator(util.BytesPrefix([]byte("foo-")), nil)
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for iter.Next() {
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// Use key/value.
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...
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}
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iter.Release()
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err = iter.Error()
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...
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```
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Batch writes:
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```go
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batch := new(leveldb.Batch)
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batch.Put([]byte("foo"), []byte("value"))
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batch.Put([]byte("bar"), []byte("another value"))
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batch.Delete([]byte("baz"))
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err = db.Write(batch, nil)
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...
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```
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Use bloom filter:
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```go
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o := &opt.Options{
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Filter: filter.NewBloomFilter(10),
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}
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db, err := leveldb.OpenFile("path/to/db", o)
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...
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defer db.Close()
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...
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```
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Documentation
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-----------
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You can read package documentation [here](http:godoc.org/github.com/syndtr/goleveldb).
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