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glusterfsdb.go
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/
glusterfsdb.go
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//
// Copyright (c) 2014 The heketi Authors
//
// 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 glusterfs
import (
"encoding/gob"
"fmt"
"os"
"sync"
)
type GlusterFSDbOnDisk struct {
Nodes map[string]*NodeEntry
Volumes map[string]*VolumeEntry
}
type GlusterFSDB struct {
nodes map[string]*NodeEntry
volumes map[string]*VolumeEntry
dbfilename string
rwlock sync.RWMutex
}
func NewGlusterFSDB(dbfile string) *GlusterFSDB {
gfsdb := &GlusterFSDB{}
gfsdb.nodes = make(map[string]*NodeEntry)
gfsdb.volumes = make(map[string]*VolumeEntry)
gfsdb.dbfilename = dbfile
// Load db
if _, err := os.Stat(gfsdb.dbfilename); err == nil {
err := gfsdb.Load()
if err != nil {
fmt.Printf("Unable to load metadata: %s", err)
return nil
}
}
return gfsdb
}
func (g *GlusterFSDB) Writer(closure func() error) error {
g.rwlock.Lock()
defer g.rwlock.Unlock()
err := closure()
if err != nil {
return err
}
g.Commit()
return nil
}
func (g *GlusterFSDB) Reader(closure func() error) error {
g.rwlock.RLock()
defer g.rwlock.RUnlock()
return closure()
}
func (g *GlusterFSDB) Node(id string) *NodeEntry {
return g.nodes[id]
}
func (g *GlusterFSDB) Volume(id string) *VolumeEntry {
return g.volumes[id]
}
func (g *GlusterFSDB) Commit() error {
ondisk := &GlusterFSDbOnDisk{
Nodes: g.nodes,
Volumes: g.volumes,
}
fi, err := os.Create(g.dbfilename)
if err != nil {
return err
}
defer fi.Close()
encoder := gob.NewEncoder(fi)
err = encoder.Encode(&ondisk)
if err != nil {
return err
}
return nil
}
func (g *GlusterFSDB) Load() error {
ondisk := &GlusterFSDbOnDisk{}
fi, err := os.Open(g.dbfilename)
if err != nil {
return err
}
defer fi.Close()
decoder := gob.NewDecoder(fi)
err = decoder.Decode(&ondisk)
if err != nil {
return err
}
g.nodes = ondisk.Nodes
g.volumes = ondisk.Volumes
for _, node := range g.nodes {
node.Load(g)
}
for _, volume := range g.volumes {
volume.Load(g)
}
return nil
}
func (g *GlusterFSDB) Close() {
// Nothing to do since we commit on every change
}