mtsatellite/interleaver/sqlite.go

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// Copyright 2014 by Sascha L. Teichmann
// Use of this source code is governed by the MIT license
// that can be found in the LICENSE file.
package main
import (
"database/sql"
"os"
"bitbucket.org/s_l_teichmann/mtredisalize/common"
_ "github.com/mattn/go-sqlite3"
)
const (
fetchSql = "SELECT pos, data FROM blocks"
)
type SQLiteBlockProducer struct {
db *sql.DB
rows *sql.Rows
splitter common.KeySplitter
}
func NewSQLiteBlockProducer(path string, splitter common.KeySplitter) (sbp *SQLiteBlockProducer, err error) {
// check if we can stat it -> exists.
if _, err = os.Stat(path); err != nil {
return
}
var db *sql.DB
if db, err = sql.Open("sqlite3", path); err != nil {
return
}
var rows *sql.Rows
if rows, err = db.Query(fetchSql); err != nil {
db.Close()
return
}
sbp = &SQLiteBlockProducer{
db: db,
rows: rows,
splitter: splitter}
return
}
func (sbp *SQLiteBlockProducer) Next() (block Block, err error) {
if sbp.rows == nil {
err = NoMoreBlocksErr
return
}
if sbp.rows.Next() {
var key int64
if err = sbp.rows.Scan(&key, &block.Data); err == nil {
block.Coord = sbp.splitter(key)
}
} else {
sbp.rows.Close()
sbp.rows = nil
err = NoMoreBlocksErr
}
return
}
func (sbp *SQLiteBlockProducer) Close() error {
if sbp.rows != nil {
sbp.rows.Close()
}
return sbp.db.Close()
}