if shared lock, still need to wait for exclusive lock to release

This commit is contained in:
chrislu 2023-09-23 12:08:23 -07:00
parent 9ba4639a27
commit 0414b68a4f

View file

@ -18,7 +18,8 @@ type LockTable[T comparable] struct {
type LockEntry struct {
mu sync.Mutex
waiters []*ActiveLock // ordered waiters that are blocked by exclusive locks
activeLockOwnerCount int32
activeSharedLockOwnerCount int32
activeExclusiveLockOwnerCount int32
lockType LockType
cond *sync.Cond
}
@ -34,6 +35,7 @@ type ActiveLock struct {
ID int64
isDeleted bool
intention string // for debugging
lockType LockType
}
func NewLockTable[T comparable]() *LockTable[T] {
@ -42,9 +44,9 @@ func NewLockTable[T comparable]() *LockTable[T] {
}
}
func (lt *LockTable[T]) NewActiveLock(intention string) *ActiveLock {
func (lt *LockTable[T]) NewActiveLock(intention string, lockType LockType) *ActiveLock {
id := atomic.AddInt64(&lt.lockIdSeq, 1)
l := &ActiveLock{ID: id, intention: intention}
l := &ActiveLock{ID: id, intention: intention, lockType: lockType}
return l
}
@ -65,7 +67,7 @@ func (lt *LockTable[T]) AcquireLock(intention string, key T, lockType LockType)
entry.mu.Lock()
if len(entry.waiters) > 0 || lockType == ExclusiveLock {
if glog.V(4) {
fmt.Printf("ActiveLock %d %s wait for %+v type=%v with waiters %d active %d.\n", lock.ID, lock.intention, key, lockType, len(entry.waiters), entry.activeLockOwnerCount)
fmt.Printf("ActiveLock %d %s wait for %+v type=%v with waiters %d active r%d w%d.\n", lock.ID, lock.intention, key, lockType, len(entry.waiters), entry.activeSharedLockOwnerCount, entry.activeExclusiveLockOwnerCount)
if len(entry.waiters) > 0 {
for _, waiter := range entry.waiters {
fmt.Printf(" %d", waiter.ID)
@ -75,11 +77,11 @@ func (lt *LockTable[T]) AcquireLock(intention string, key T, lockType LockType)
}
entry.waiters = append(entry.waiters, lock)
if lockType == ExclusiveLock {
for !lock.isDeleted && ((len(entry.waiters) > 0 && lock.ID != entry.waiters[0].ID) || entry.activeLockOwnerCount > 0) {
for !lock.isDeleted && ((len(entry.waiters) > 0 && lock.ID != entry.waiters[0].ID) || entry.activeExclusiveLockOwnerCount > 0 || entry.activeSharedLockOwnerCount > 0) {
entry.cond.Wait()
}
} else {
for !lock.isDeleted && (len(entry.waiters) > 0 && lock.ID != entry.waiters[0].ID) {
for !lock.isDeleted && (len(entry.waiters) > 0 && lock.ID != entry.waiters[0].ID) || entry.activeExclusiveLockOwnerCount > 0 {
entry.cond.Wait()
}
}
@ -93,7 +95,7 @@ func (lt *LockTable[T]) AcquireLock(intention string, key T, lockType LockType)
// Otherwise, grant the lock
entry.lockType = lockType
if glog.V(4) {
fmt.Printf("ActiveLock %d %s locked %+v type=%v with waiters %d active %d.\n", lock.ID, lock.intention, key, lockType, len(entry.waiters), entry.activeLockOwnerCount)
fmt.Printf("ActiveLock %d %s locked %+v type=%v with waiters %d active r%d w%d.\n", lock.ID, lock.intention, key, lockType, len(entry.waiters), entry.activeSharedLockOwnerCount, entry.activeExclusiveLockOwnerCount)
if len(entry.waiters) > 0 {
for _, waiter := range entry.waiters {
fmt.Printf(" %d", waiter.ID)
@ -101,7 +103,11 @@ func (lt *LockTable[T]) AcquireLock(intention string, key T, lockType LockType)
fmt.Printf("\n")
}
}
entry.activeLockOwnerCount++
if lock.lockType == ExclusiveLock {
entry.activeExclusiveLockOwnerCount++
} else {
entry.activeSharedLockOwnerCount++
}
entry.mu.Unlock()
return lock
@ -134,7 +140,7 @@ func (lt *LockTable[T]) ReleaseLock(key T, lock *ActiveLock) {
}
if glog.V(4) {
fmt.Printf("ActiveLock %d %s unlocked %+v type=%v with waiters %d active %d.\n", lock.ID, lock.intention, key, entry.lockType, len(entry.waiters), entry.activeLockOwnerCount)
fmt.Printf("ActiveLock %d %s unlocked %+v type=%v with waiters %d active r%d w%d.\n", lock.ID, lock.intention, key, entry.lockType, len(entry.waiters), entry.activeSharedLockOwnerCount, entry.activeExclusiveLockOwnerCount)
if len(entry.waiters) > 0 {
for _, waiter := range entry.waiters {
fmt.Printf(" %d", waiter.ID)
@ -142,7 +148,11 @@ func (lt *LockTable[T]) ReleaseLock(key T, lock *ActiveLock) {
fmt.Printf("\n")
}
}
entry.activeLockOwnerCount--
if lock.lockType == ExclusiveLock {
entry.activeExclusiveLockOwnerCount--
} else {
entry.activeSharedLockOwnerCount--
}
// Notify the next waiter
entry.cond.Broadcast()