containers
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storage
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Replace containerStore.{RLock,Unlock} with {startReading,stopReading} 

This integrates ReloadIfChanges, and makes it clearer that the responsibility
for maintaining locking details is with the containerStore; we can change it
in a single place.

Should not change behavior.

Signed-off-by: Miloslav Trmač <mitr@redhat.com>
This commit is contained in:
Miloslav Trmač 2022-10-12 22:38:00 +02:00
parent 749be716f3
commit 243ec619f7
2 changed files with 62 additions and 54 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

36
containers.go
View File

@ -84,8 +84,12 @@ type rwContainerStore interface {
// - if the lock counter is corrupted
Unlock()
// Acquire a reader lock.
RLock()
// startReading makes sure the store is fresh, and locks it for reading.
// If this succeeds, the caller MUST call stopReading().
startReading() error
// stopReading releases locks obtained by startReading.
stopReading()
// Touch records, for others sharing the lock, that the caller was the
// last writer. It should only be called with the lock held.
@ -205,6 +209,30 @@ func (c *Container) MountOpts() []string {
}
}
// startReading makes sure the store is fresh, and locks it for reading.
// If this succeeds, the caller MUST call stopReading().
func (r *containerStore) startReading() error {
r.lockfile.RLock()
succeeded := false
defer func() {
if !succeeded {
r.lockfile.Unlock()
}
}()
if err := r.ReloadIfChanged(); err != nil {
return err
}
succeeded = true
return nil
}
// stopReading releases locks obtained by startReading.
func (r *containerStore) stopReading() {
r.lockfile.Unlock()
}
func (r *containerStore) Containers() ([]Container, error) {
containers := make([]Container, len(r.containers))
for i := range r.containers {
@ -642,10 +670,6 @@ func (r *containerStore) Lock() {
r.lockfile.Lock()
}
func (r *containerStore) RLock() {
r.lockfile.RLock()
}
func (r *containerStore) Unlock() {
r.lockfile.Unlock()
}

80
store.go
View File

@ -1664,11 +1664,10 @@ func (s *store) Metadata(id string) (string, error) {
if err != nil {
return "", err
}
cstore.RLock()
defer cstore.Unlock()
if err := cstore.ReloadIfChanged(); err != nil {
if err := cstore.startReading(); err != nil {
return "", err
}
defer cstore.stopReading()
if cstore.Exists(id) {
return cstore.Metadata(id)
}
@ -1933,11 +1932,10 @@ func (s *store) ContainerSize(id string) (int64, error) {
if err != nil {
return -1, err
}
rcstore.RLock()
defer rcstore.Unlock()
if err := rcstore.ReloadIfChanged(); err != nil {
if err := rcstore.startReading(); err != nil {
return -1, err
}
defer rcstore.stopReading()
// Read the container record.
container, err := rcstore.Get(id)
@ -1995,11 +1993,10 @@ func (s *store) ListContainerBigData(id string) ([]string, error) {
return nil, err
}
rcstore.RLock()
defer rcstore.Unlock()
if err := rcstore.ReloadIfChanged(); err != nil {
if err := rcstore.startReading(); err != nil {
return nil, err
}
defer rcstore.stopReading()
return rcstore.BigDataNames(id)
}
@ -2009,11 +2006,10 @@ func (s *store) ContainerBigDataSize(id, key string) (int64, error) {
if err != nil {
return -1, err
}
rcstore.RLock()
defer rcstore.Unlock()
if err := rcstore.ReloadIfChanged(); err != nil {
if err := rcstore.startReading(); err != nil {
return -1, err
}
defer rcstore.stopReading()
return rcstore.BigDataSize(id, key)
}
@ -2022,11 +2018,10 @@ func (s *store) ContainerBigDataDigest(id, key string) (digest.Digest, error) {
if err != nil {
return "", err
}
rcstore.RLock()
defer rcstore.Unlock()
if err := rcstore.ReloadIfChanged(); err != nil {
if err := rcstore.startReading(); err != nil {
return "", err
}
defer rcstore.stopReading()
return rcstore.BigDataDigest(id, key)
}
@ -2035,11 +2030,10 @@ func (s *store) ContainerBigData(id, key string) ([]byte, error) {
if err != nil {
return nil, err
}
rcstore.RLock()
defer rcstore.Unlock()
if err := rcstore.ReloadIfChanged(); err != nil {
if err := rcstore.startReading(); err != nil {
return nil, err
}
defer rcstore.stopReading()
return rcstore.BigData(id, key)
}
@ -2076,11 +2070,10 @@ func (s *store) Exists(id string) bool {
if err != nil {
return false
}
rcstore.RLock()
defer rcstore.Unlock()
if err := rcstore.ReloadIfChanged(); err != nil {
if err := rcstore.startReading(); err != nil {
return false
}
defer rcstore.stopReading()
if rcstore.Exists(id) {
return true
}
@ -2206,11 +2199,10 @@ func (s *store) Names(id string) ([]string, error) {
if err != nil {
return nil, err
}
rcstore.RLock()
defer rcstore.Unlock()
if err := rcstore.ReloadIfChanged(); err != nil {
if err := rcstore.startReading(); err != nil {
return nil, err
}
defer rcstore.stopReading()
if c, err := rcstore.Get(id); c != nil && err == nil {
return c.Names, nil
}
@ -2244,11 +2236,10 @@ func (s *store) Lookup(name string) (string, error) {
if err != nil {
return "", err
}
cstore.RLock()
defer cstore.Unlock()
if err := cstore.ReloadIfChanged(); err != nil {
if err := cstore.startReading(); err != nil {
return "", err
}
defer cstore.stopReading()
if c, err := cstore.Get(name); c != nil && err == nil {
return c.ID, nil
}
@ -2888,11 +2879,10 @@ func (s *store) ContainerParentOwners(id string) ([]int, []int, error) {
if err := rlstore.ReloadIfChanged(); err != nil {
return nil, nil, err
}
rcstore.RLock()
defer rcstore.Unlock()
if err := rcstore.ReloadIfChanged(); err != nil {
if err := rcstore.startReading(); err != nil {
return nil, nil, err
}
defer rcstore.stopReading()
container, err := rcstore.Get(id)
if err != nil {
return nil, nil, err
@ -2939,11 +2929,10 @@ func (s *store) Containers() ([]Container, error) {
return nil, err
}
rcstore.RLock()
defer rcstore.Unlock()
if err := rcstore.ReloadIfChanged(); err != nil {
if err := rcstore.startReading(); err != nil {
return nil, err
}
defer rcstore.stopReading()
return rcstore.Containers()
}
@ -3104,11 +3093,10 @@ func (s *store) Container(id string) (*Container, error) {
if err != nil {
return nil, err
}
rcstore.RLock()
defer rcstore.Unlock()
if err := rcstore.ReloadIfChanged(); err != nil {
if err := rcstore.startReading(); err != nil {
return nil, err
}
defer rcstore.stopReading()
return rcstore.Get(id)
}
@ -3118,11 +3106,10 @@ func (s *store) ContainerLayerID(id string) (string, error) {
if err != nil {
return "", err
}
rcstore.RLock()
defer rcstore.Unlock()
if err := rcstore.ReloadIfChanged(); err != nil {
if err := rcstore.startReading(); err != nil {
return "", err
}
defer rcstore.stopReading()
container, err := rcstore.Get(id)
if err != nil {
return "", err
@ -3139,11 +3126,10 @@ func (s *store) ContainerByLayer(id string) (*Container, error) {
if err != nil {
return nil, err
}
rcstore.RLock()
defer rcstore.Unlock()
if err := rcstore.ReloadIfChanged(); err != nil {
if err := rcstore.startReading(); err != nil {
return nil, err
}
defer rcstore.stopReading()
containerList, err := rcstore.Containers()
if err != nil {
return nil, err
@ -3162,11 +3148,10 @@ func (s *store) ContainerDirectory(id string) (string, error) {
if err != nil {
return "", err
}
rcstore.RLock()
defer rcstore.Unlock()
if err := rcstore.ReloadIfChanged(); err != nil {
if err := rcstore.startReading(); err != nil {
return "", err
}
defer rcstore.stopReading()
id, err = rcstore.Lookup(id)
if err != nil {
@ -3187,11 +3172,10 @@ func (s *store) ContainerRunDirectory(id string) (string, error) {
return "", err
}
rcstore.RLock()
defer rcstore.Unlock()
if err := rcstore.ReloadIfChanged(); err != nil {
if err := rcstore.startReading(); err != nil {
return "", err
}
defer rcstore.stopReading()
id, err = rcstore.Lookup(id)
if err != nil {