/
db.go
146 lines (113 loc) · 2.9 KB
/
db.go
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package db
import (
"bytes"
"os"
"time"
"github.com/dgraph-io/badger"
humanize "github.com/dustin/go-humanize"
. "github.com/dvsekhvalnov/k-ray/log"
)
type Operation func(txn *badger.Txn) error
type Lookup func(start, end, current []byte, count int) []byte
type DB struct {
db *badger.DB
}
func (db *DB) Update(ops ...Operation) error {
return db.db.Update(func(txn *badger.Txn) error {
for _, op := range ops {
err := op(txn)
if err != nil {
return err
}
}
return nil
})
}
func (db *DB) Close() {
Log.Println("Closing db.")
db.db.Close()
}
func Open(dir string) (*DB, error) {
Log.Println("Opening database at:", dir)
startInstant := time.Now()
if _, err := os.Stat(dir); os.IsNotExist(err) {
Log.Printf("Didn't find data dir:'%v'. Creating.\n", dir)
err = os.MkdirAll(dir, 0755)
if err != nil {
panic(err)
}
}
opts := badger.DefaultOptions
opts.Dir = dir
opts.ValueDir = dir
db, err := badger.Open(opts)
if err != nil {
Log.Println("Unable to open embedded database at path:", dir, "error:", err)
return nil, err
}
duration := humanize.RelTime(startInstant, time.Now(), "", "")
Log.Println("Succesully opened database at:", dir, " in:", duration)
return &DB{db}, nil
}
func keyRangeScan(txn *badger.Txn,
reverse bool,
skip int,
start, end []byte,
prefix, ref Lookup,
paginate func(keyIndex int, key []byte)) [][]byte {
opts := badger.DefaultIteratorOptions
opts.PrefetchValues = false
opts.Reverse = reverse
it := txn.NewIterator(opts)
result := make([][]byte, 0)
keyIdx := 0
for it.Seek(start); it.Valid(); it.Next() {
item := it.Item()
key := item.Key()
partitial := prefix(start, end, key, keyIdx)
//scan till the end, reverse (< and >)
if reverse {
if bytes.Compare(partitial, end) <= 0 {
break
}
} else {
if bytes.Compare(partitial, end) >= 0 {
break
}
}
//skip number of rows to support paging
if keyIdx >= skip {
result = append(result, CopyBytes(ref(start, end, key, keyIdx)))
}
//let caller chance to paginate or do whatever
paginate(keyIdx, key)
keyIdx++
}
return result
}
func fetchAll(txn *badger.Txn, refs [][]byte, limit int, key func(ref []byte) []byte, value func(blob []byte)) {
for i := 0; i < len(refs) && i < limit; i++ {
if item, err := txn.Get(key(refs[i])); err == nil {
if blob, err := item.Value(); err == nil {
value(blob)
}
}
}
}
func paginate(search *SearchRequest, result *SearchResponse) func(keyIndex int, key []byte) {
var limit int = search.Paging.Limit
var startPage int = search.Page
var pages []int = search.Paging.Pages
return func(keyIndex int, key []byte) {
if keyIndex%limit == 0 {
page := (keyIndex / limit) + 1
//advance page number if we not scanning (using offset)
if len(search.Offset) > 0 {
page = page + startPage - 1
}
if len(pages) == 0 || Contains(pages, page) {
result.AddOffset(page, CopyBytes(key))
}
}
}
}