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doc_test.go
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doc_test.go
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/*
* Copyright 2017 Dgraph Labs, Inc. and Contributors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package badger_test
import (
"fmt"
"io/ioutil"
"sync"
"github.com/dgraph-io/badger"
)
var d string = "doc"
func Example() {
opt := badger.DefaultOptions
dir, _ := ioutil.TempDir("", "badger")
opt.Dir = dir
opt.ValueDir = dir
kv, _ := badger.NewKV(&opt)
key := []byte("hello")
kv.Set(key, []byte("world"), 0x00)
fmt.Printf("SET %s world\n", key)
var item badger.KVItem
if err := kv.Get(key, &item); err != nil {
fmt.Printf("Error while getting key: %q", key)
return
}
var val []byte
err := item.Value(func(v []byte) {
val = make([]byte, len(v))
copy(val, v)
})
if err != nil {
fmt.Printf("Error while getting value for key: %q", key)
return
}
fmt.Printf("GET %s %s\n", key, val)
if err := kv.CompareAndSet(key, []byte("venus"), 100); err != nil {
fmt.Println("CAS counter mismatch")
} else {
if err = kv.Get(key, &item); err != nil {
fmt.Printf("Error while getting key: %q", key)
}
err := item.Value(func(v []byte) {
val = make([]byte, len(v))
copy(val, v)
})
if err != nil {
fmt.Printf("Error while getting value for key: %q", key)
return
}
fmt.Printf("Set to %s\n", val)
}
if err := kv.CompareAndSet(key, []byte("mars"), item.Counter()); err == nil {
fmt.Println("Set to mars")
} else {
fmt.Printf("Unsuccessful write. Got error: %v\n", err)
}
// Output:
// SET hello world
// GET hello world
// CAS counter mismatch
// Set to mars
}
// func ExampleNewIterator() {
// opt := DefaultOptions
// opt.Dir = "/tmp/badger"
// kv := NewKV(&opt)
// itrOpt := IteratorOptions{
// PrefetchSize: 1000,
// FetchValues: true,
// Reverse: false,
// }
// itr := kv.NewIterator(itrOpt)
// for itr.Rewind(); itr.Valid(); itr.Next() {
// item := itr.Item()
// item.Key()
// item.Value()
// }
// }
func ExampleKV_BatchSetAsync() {
opt := badger.DefaultOptions
dir, _ := ioutil.TempDir("", "badger")
opt.Dir = dir
opt.SyncWrites = true
opt.ValueDir = dir
kv, _ := badger.NewKV(&opt)
wg := new(sync.WaitGroup)
wb := make([]*badger.Entry, 0, 100)
wg.Add(1)
// Async writes would be useful if you want to write some key-value pairs without waiting
// for them to be complete and perform some cleanup when they are written.
// In Dgraph we keep on flushing posting lists periodically to badger. We do it an async
// manner and provide a callback to it which can do the cleanup when the writes are done.
f := func(err error) {
defer wg.Done()
if err != nil {
// At this point you can retry writing keys or send error over a channel to handle
// in some other goroutine.
fmt.Printf("Got error: %+v\n", err)
}
// Check for error in entries which could be non-nil if the user supplies a CasCounter.
for _, e := range wb {
if e.Error != nil {
fmt.Printf("Got error: %+v\n", e.Error)
}
}
// You can do cleanup now. Like deleting keys from cache.
fmt.Println("All async sets complete.")
}
for i := 0; i < 100; i++ {
k := []byte(fmt.Sprintf("%09d", i))
wb = append(wb, &badger.Entry{
Key: k,
Value: k,
})
}
kv.BatchSetAsync(wb, f)
fmt.Println("Finished writing keys to badger.")
wg.Wait()
// Output: Finished writing keys to badger.
// All async sets complete.
}