Fix: deadlock on sync all

bitcask/bitcask.go

@@ -71,18 +71,23 @@ func (db *DB) Meta() models.Metadata {
  return m
 }
 
+func (db *DB) allStores() map[string]database.Filer {
+ var stores = make(map[string]database.Filer)
+ for n, s := range db.store {
+ stores[n] = s
+ }
+ return stores
+}
+
 // AllStores returns a map of the names of all bitcask datastores and the corresponding Filers.
 func (db *DB) AllStores() map[string]database.Filer {
  if err := db.init(); err != nil {
  panic(err)
  }
  db.mu.RLock()
- defer db.mu.RUnlock()
- var stores = make(map[string]database.Filer)
- for n, s := range db.store {
- stores[n] = s
- }
- return stores
+ ast := db.allStores()
+ db.mu.RUnlock()
+ return ast
 }
 
 func (db *DB) _init() error {
@@ -504,7 +509,7 @@ func (db *DB) CloseAll() error {
  return err
 }
 func (db *DB) addAllStoresToMeta() {
- storeMap := db.AllStores()
+ storeMap := db.allStores()
  storeNames := make([]string, len(storeMap))
  for name := range storeMap {
  storeNames = append(storeNames, name)
@@ -513,6 +518,7 @@ func (db *DB) addAllStoresToMeta() {
 }
 
 // SyncAll syncs all pogreb datastores.
+// TODO: investigate locking here, right now if we try to hold a lock during a backup we'll hang :^)
 func (db *DB) SyncAll() error {
  db.addAllStoresToMeta()
  var errs = make([]error, 0)

go.mod

@@ -23,6 +23,7 @@ require (
 )
 
 retract (
+ v0.4.3 // deadlock
  v0.4.0 // broken metadata system
  v0.3.0 // doesn't pass go vet
 )

pogreb/pogreb.go

@@ -175,25 +175,37 @@ func (db *DB) Meta() models.Metadata {
  return m
 }
 
-func (db *DB) UpdateMetrics() {
- db.mu.RLock()
- defer db.mu.RUnlock()
+func (db *DB) updateMetrics() {
  for _, s := range db.store {
- s.metrics = s.DB.Metrics()
+ if s != nil && s.DB != nil {
+ s.metrics = s.DB.Metrics()
+ }
  }
 }
 
-// AllStores returns a map of the names of all pogreb datastores and the corresponding Filers.
-func (db *DB) AllStores() map[string]database.Filer {
+func (db *DB) UpdateMetrics() {
  db.mu.RLock()
- defer db.mu.RUnlock()
+ db.updateMetrics()
+ db.mu.RUnlock()
+}
+
+func (db *DB) allStores() map[string]database.Filer {
  var stores = make(map[string]database.Filer)
  for n, s := range db.store {
  stores[n] = s
  }
  return stores
 }
 
+// AllStores returns a map of the names of all pogreb datastores and the corresponding Filers.
+func (db *DB) AllStores() map[string]database.Filer {
+
+ db.mu.RLock()
+ ast := db.allStores()
+ db.mu.RUnlock()
+ return ast
+}
+
 // FIXME: not returning the error is probably pretty irresponsible.
 
 // OpenDB will either open an existing set of pogreb datastores at the given directory, or it will create a new one.
@@ -522,21 +534,19 @@ func (db *DB) CloseAll() error {
 }
 
 func (db *DB) allMetrics() map[string]*pogreb.Metrics {
- db.UpdateMetrics()
+ db.updateMetrics()
  allmet := make(map[string]*pogreb.Metrics, len(db.store))
- db.mu.RLock()
  for name, store := range db.store {
  if store == nil || store.Backend().(*pogreb.DB) == nil {
  continue
  }
  allmet[name] = store.metrics
  }
- db.mu.RUnlock()
  return allmet
 }
 
 func (db *DB) addAllStoresToMeta() {
- storeMap := db.AllStores()
+ storeMap := db.allStores()
  storeNames := make([]string, len(storeMap))
  for name := range storeMap {
  storeNames = append(storeNames, name)
@@ -550,6 +560,7 @@ func (db *DB) syncMetaValues() {
 }
 
 // SyncAll syncs all pogreb datastores.
+// TODO: investigate locking here, right now if we try to hold a lock during a backup we'll hang :^)
 func (db *DB) SyncAll() error {
  db.syncMetaValues()
  var errs = make([]error, 0)