/
DiskTopicPersistentStore.go
87 lines (74 loc) · 2.16 KB
/
DiskTopicPersistentStore.go
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package disklog
import (
"encoding/json"
"io/ioutil"
"log"
"os"
"path"
"sync"
)
const TOPIC_STORE_NAME = "topic-store"
type DiskTopicPersistentStore struct {
Term int64
VotedFor string
lock sync.Mutex
path string
}
func NewDiskTopicPersistentStore(dirpath string) *DiskTopicPersistentStore {
store := &DiskTopicPersistentStore{path: path.Join(dirpath, TOPIC_STORE_NAME)}
return store
}
func (store *DiskTopicPersistentStore) SetTerm(term int64, votedFor string) (err error) {
log.Printf("DISKLOG - Saving Store with term %v, voted for: %v\n", term, votedFor)
store.lock.Lock()
defer store.lock.Unlock()
file, err := os.Create(store.path)
defer file.Close()
if err != nil {
log.Printf("DISKLOG-Error creating topic store information at path %v: %v\n", store.path, err)
return err
}
store.Term = term
store.VotedFor = votedFor
data, err := json.Marshal(store)
if err != nil {
log.Printf("Error creating json for path %v: %v\n", store.path, err)
return err
}
_, err = file.Write(data)
if err != nil {
log.Printf("DISKLOG-Error writing topic store information at path %v: %v\n", store.path, err)
return err
}
return nil
}
// Load reads the given topic information from persistent storage
func (store *DiskTopicPersistentStore) Load() (term int64, votedFor string, err error) {
store.lock.Lock()
defer store.lock.Unlock()
file, err := os.Open(store.path)
defer file.Close()
if err != nil {
if os.IsNotExist(err) {
log.Printf("No topic store found at path %v\n", store.path)
return 0, "", nil
} else {
log.Printf("DISKLOG-Error reading topic store information at path %v: %v\n", store.path, err)
return 0, "", err
}
}
// It's a short file - so just read the lot.
data, err := ioutil.ReadAll(file)
if err != nil {
log.Printf("DISKLOG-Error reading topic store information at path %v: %v\n", store.path, err)
log.Printf("Will default to 0 term and no vote.")
return 0, "", nil
}
err = json.Unmarshal(data, store)
if err != nil {
log.Printf("Error reading json for path %v: %v\n", store.path, err)
log.Printf("Will default to 0 term and no vote.")
return 0, "", nil
}
return store.Term, store.VotedFor, nil
}