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go-asink
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Surround sqlite3 transactions with a lock to handle concurrency

This commit is contained in:
Aaron Lindsay 2013-03-10 23:13:30 -04:00
parent 1ddbcb3636
commit 11bcf164c6
2 changed files with 38 additions and 13 deletions
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13
client/asink.go
View File

@ -5,7 +5,6 @@ import (
"asink/util"
"bytes"
"code.google.com/p/goconf/conf"
"database/sql"
"encoding/json"
"errors"
"flag"
@ -23,7 +22,7 @@ type AsinkGlobals struct {
syncDir string
cacheDir string
tmpDir string
db *sql.DB
db *AsinkDB
storage Storage
server string
port int
@ -91,13 +90,13 @@ func main() {
for {
event := <-fileUpdates
ProcessEvent(globals, event)
go ProcessEvent(globals, event)
}
}
func ProcessEvent(globals AsinkGlobals, event *asink.Event) {
//add to database
err := DatabaseAddEvent(globals.db, event)
err := globals.db.DatabaseAddEvent(event)
if err != nil {
panic(err)
}
@ -129,7 +128,7 @@ func ProcessEvent(globals AsinkGlobals, event *asink.Event) {
event.Status |= asink.CACHED
//update database
err = DatabaseUpdateEvent(globals.db, event)
err = globals.db.DatabaseUpdateEvent(event)
if err != nil {
panic(err)
}
@ -142,7 +141,7 @@ func ProcessEvent(globals AsinkGlobals, event *asink.Event) {
event.Status |= asink.UPLOADED
//update database again
err = DatabaseUpdateEvent(globals.db, event)
err = globals.db.DatabaseUpdateEvent(event)
if err != nil {
panic(err)
}
@ -156,7 +155,7 @@ func ProcessEvent(globals AsinkGlobals, event *asink.Event) {
}
event.Status |= asink.ON_SERVER
err = DatabaseUpdateEvent(globals.db, event)
err = globals.db.DatabaseUpdateEvent(event)
if err != nil {
panic(err) //TODO probably, definitely, none of these should panic
}

38
client/database.go
View File

@ -7,9 +7,15 @@ import (
"errors"
_ "github.com/mattn/go-sqlite3"
"strconv"
"sync"
)
func GetAndInitDB(config *conf.ConfigFile) (*sql.DB, error) {
type AsinkDB struct {
db *sql.DB
lock sync.Mutex
}
func GetAndInitDB(config *conf.ConfigFile) (*AsinkDB, error) {
dbLocation, err := config.GetString("local", "dblocation")
if err != nil {
return nil, errors.New("Error: database location not specified in config file.")
@ -41,14 +47,25 @@ func GetAndInitDB(config *conf.ConfigFile) (*sql.DB, error) {
return nil, err
}
return db, nil
ret := new(AsinkDB)
ret.db = db
return ret, nil
}
func DatabaseAddEvent(db *sql.DB, e *asink.Event) error {
tx, err := db.Begin()
func (adb *AsinkDB) DatabaseAddEvent(e *asink.Event) (err error) {
adb.lock.Lock()
tx, err := adb.db.Begin()
if err != nil {
return err
}
//make sure the transaction gets rolled back on error, and the database gets unlocked
defer func() {
if err != nil {
tx.Rollback()
}
adb.lock.Unlock()
}()
result, err := tx.Exec("INSERT INTO events (id, type, status, path, hash, timestamp, permissions) VALUES (?,?,?,?,?,?,?);", e.Id, e.Type, e.Status, e.Path, e.Hash, e.Timestamp, e.Permissions)
if err != nil {
return err
@ -67,15 +84,24 @@ func DatabaseAddEvent(db *sql.DB, e *asink.Event) error {
return nil
}
func DatabaseUpdateEvent(db *sql.DB, e *asink.Event) error {
func (adb *AsinkDB) DatabaseUpdateEvent(e *asink.Event) (err error) {
if !e.InDB {
return errors.New("Attempting to update an event in the database which hasn't been previously added.")
}
tx, err := db.Begin()
adb.lock.Lock()
tx, err := adb.db.Begin()
if err != nil {
return err
}
//make sure the transaction gets rolled back on error, and the database gets unlocked
defer func() {
if err != nil {
tx.Rollback()
}
adb.lock.Unlock()
}()
result, err := tx.Exec("UPDATE events SET id=?, type=?, status=?, path=?, hash=?, timestamp=?, permissions=? WHERE localid=?;", e.Id, e.Type, e.Status, e.Path, e.Hash, e.Timestamp, e.Permissions, e.LocalId)
if err != nil {
return err