LevelDB-Go is port of LevelDB in Go language. LevelDB-Go often referred as native alternative for Go apps. Website has no examples and no documentation.
Should I learn it by reading source code? or there is another website with examples and docs?
Does library support concurrency?
I played around a little with leveldb Here is what I got so far. This should get you started.
package main
import (
"code.google.com/p/leveldb-go/leveldb/db"
"code.google.com/p/leveldb-go/leveldb/table"
"fmt"
"runtime"
)
type kv struct {
K []byte
V []byte
}
type kvs struct {
items map[int]kv
}
func (p *kv) PutKV(k []byte, v []byte) {
p.K = k
p.V = v
}
func (items *kvs) PutKVs() {
fmt.Println(items)
}
func (p *kv) GetKV() (key []byte, value []byte) {
key = p.K
value = p.V
return
}
func Check(e error) {
if e != nil {
_, file, line, _ := runtime.Caller(1)
}
}
func p(r []byte, e error) {
if e != nil {
return e
}
println(string(r))
}
const (
DBFILE = "/tmp/leveldb2.db"
)
var DBFS = db.DefaultFileSystem
func main() {
Connection, e := DBFS.Create(DBFILE)
Check(e)
w := table.NewWriter(Connection, nil)
defer w.Close()
e = w.Set([]byte("1"), []byte("red"), nil)
Check(e)
e = w.Set([]byte("2"), []byte("yellow"), nil)
Check(e)
e = w.Set([]byte("3"), []byte("blue"), nil)
Check(e)
e = w.Close()
Check(e)
w = nil
count()
fmt.Println("Printing # KV")
itemsKV := readByte()
fmt.Println(itemsKV[0])
fmt.Println(itemsKV[1])
fmt.Println(itemsKV[2])
println("Done Printing # KV")
Connection, e = DBFS.Create(DBFILE)
Check(e)
w = table.NewWriter(Connection, nil)
defer w.Close()
e = w.Set([]byte("4"), []byte("green"), nil)
Check(e)
e = w.Set([]byte("5"), []byte("white"), nil)
Check(e)
e = w.Set([]byte("6"), []byte("black"), nil)
Check(e)
e = w.Close()
Check(e)
}
func count() {
Connection, e := DBFS.Open(DBFILE)
Check(e)
b := []byte("0")
r := table.NewReader(Connection, nil)
println("\n\n###### Counting ###### ")
iter, n := r.Find(b, nil), 0
for iter.Next() {
n++
println("Count # ", n)
}
e = r.Close()
Check(e)
println("#####Total: ", n)
}
func read() map[int64]string {
Connection, e := DBFS.Open(DBFILE)
Check(e)
b := []byte("0")
r := table.NewReader(Connection, nil)
items := map[int64]string{}
iter, _ := r.Find(b, nil), 0
for iter.Next() {
k := iter.Key()
v := iter.Value()
items[int64(k[0])] = string(v)
}
e = r.Close()
Check(e)
return items
}
func readByte() map[int]kv {
Connection, e := DBFS.Open(DBFILE)
Check(e)
c := 0
b := []byte("0")
r := table.NewReader(Connection, nil)
//items := map[int64]kv{}
item := new(kv)
items := map[int]kv{}
iter, _ := r.Find(b, nil), 0
for iter.Next() {
k := iter.Key()
v := iter.Value()
item.PutKV(k, v)
items[c] = *item
c++
}
e = r.Close()
Check(e)
return items
}
func findOne(k []byte) []byte {
Connection, e := DBFS.Open(DBFILE)
Check(e)
b := []byte("0")
r := table.NewReader(Connection, nil)
iter, _ := r.Find(b, nil), 0
k = iter.Key()
v := iter.Value()
e = r.Close()
Check(e)
return v
}
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