Documentation
¶
Overview ¶
Package syncs contains additional sync types and functionality.
Index ¶
- func AssertLocked(m *sync.Mutex)
- func AssertRLocked(rw *sync.RWMutex)
- func AssertWLocked(rw *sync.RWMutex)
- func ClosedChan() <-chan struct{}
- func Watch(ctx context.Context, mu sync.Locker, tick, max time.Duration) chan time.Duration
- type AtomicValue
- type Map
- func (m *Map[K, V]) Clear()
- func (m *Map[K, V]) Delete(key K)
- func (m *Map[K, V]) Len() int
- func (m *Map[K, V]) Load(key K) (value V, loaded bool)
- func (m *Map[K, V]) LoadAndDelete(key K) (value V, loaded bool)
- func (m *Map[K, V]) LoadFunc(key K, f func(value V, loaded bool))
- func (m *Map[K, V]) LoadOrInit(key K, f func() V) (actual V, loaded bool)
- func (m *Map[K, V]) LoadOrStore(key K, value V) (actual V, loaded bool)
- func (m *Map[K, V]) Range(f func(key K, value V) bool)
- func (m *Map[K, V]) Store(key K, value V)
- type Semaphore
- type ShardedMap
- func (m *ShardedMap[K, V]) Contains(key K) bool
- func (m *ShardedMap[K, V]) Delete(key K) (shrunk bool)
- func (m *ShardedMap[K, V]) Get(key K) (value V)
- func (m *ShardedMap[K, V]) GetOk(key K) (value V, ok bool)
- func (m *ShardedMap[K, V]) Len() int
- func (m *ShardedMap[K, V]) Mutate(key K, mutator func(oldValue V, oldValueExisted bool) (newValue V, keep bool)) (sizeDelta int)
- func (m *ShardedMap[K, V]) Set(key K, value V) (grew bool)
- type WaitGroup
- type WaitGroupChan
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func AssertRLocked ¶
AssertRLocked panics if rw is not locked for reading or writing.
func AssertWLocked ¶
AssertWLocked panics if rw is not locked for writing.
func ClosedChan ¶
func ClosedChan() <-chan struct{}
ClosedChan returns a channel that's already closed.
func Watch ¶
Watch monitors mu for contention. On first call, and at every tick, Watch locks and unlocks mu. (Tick should be large to avoid adding contention to mu.) Max is the maximum length of time Watch will wait to acquire the lock. The time required to lock mu is sent on the returned channel. Watch exits when ctx is done, and closes the returned channel.
Types ¶
type AtomicValue ¶
type AtomicValue[T any] struct { // contains filtered or unexported fields }
AtomicValue is the generic version of atomic.Value.
func (*AtomicValue[T]) CompareAndSwap ¶
func (v *AtomicValue[T]) CompareAndSwap(oldV, newV T) (swapped bool)
CompareAndSwap executes the compare-and-swap operation for the Value.
func (*AtomicValue[T]) Load ¶
func (v *AtomicValue[T]) Load() T
Load returns the value set by the most recent Store. It returns the zero value for T if the value is empty.
func (*AtomicValue[T]) LoadOk ¶
func (v *AtomicValue[T]) LoadOk() (_ T, ok bool)
LoadOk is like Load but returns a boolean indicating whether the value was loaded.
func (*AtomicValue[T]) Store ¶
func (v *AtomicValue[T]) Store(x T)
Store sets the value of the Value to x.
func (*AtomicValue[T]) Swap ¶
func (v *AtomicValue[T]) Swap(x T) (old T)
Swap stores new into Value and returns the previous value. It returns the zero value for T if the value is empty.
type Map ¶
type Map[K comparable, V any] struct { // contains filtered or unexported fields }
Map is a Go map protected by a sync.RWMutex. It is preferred over sync.Map for maps with entries that change at a relatively high frequency. This must not be shallow copied.
func (*Map[K, V]) Delete ¶
func (m *Map[K, V]) Delete(key K)
Delete deletes the entry identified by key.
func (*Map[K, V]) LoadAndDelete ¶
LoadAndDelete returns the value for the given key if it exists. It ensures that the map is cleared of any entry for the key.
func (*Map[K, V]) LoadFunc ¶
LoadFunc calls f with the value for the provided key regardless of whether the entry exists or not. The lock is held for the duration of the call to f.
func (*Map[K, V]) LoadOrInit ¶
LoadOrInit returns the value for the given key if it exists otherwise f is called to construct the value to be set. The lock is held for the duration to prevent duplicate initialization.
func (*Map[K, V]) LoadOrStore ¶
LoadOrStore returns the value for the given key if it exists otherwise it stores value.
type Semaphore ¶
type Semaphore struct {
// contains filtered or unexported fields
}
Semaphore is a counting semaphore.
Use NewSemaphore to create one.
func NewSemaphore ¶
NewSemaphore returns a semaphore with resource count n.
func (Semaphore) Acquire ¶
func (s Semaphore) Acquire()
Acquire blocks until a resource is acquired.
func (Semaphore) AcquireContext ¶
AcquireContext reports whether the resource was acquired before the ctx was done.
func (Semaphore) TryAcquire ¶
TryAcquire reports, without blocking, whether the resource was acquired.
type ShardedMap ¶
type ShardedMap[K comparable, V any] struct { // contains filtered or unexported fields }
ShardedMap is a synchronized map[K]V, internally sharded by a user-defined K-sharding function.
The zero value is not safe for use; use NewShardedMap.
func NewShardedMap ¶
func NewShardedMap[K comparable, V any](shards int, shard func(K) int) *ShardedMap[K, V]
NewShardedMap returns a new ShardedMap with the given number of shards and sharding function.
The shard func must return a integer in the range [0, shards) purely deterministically based on the provided K.
func (*ShardedMap[K, V]) Contains ¶
func (m *ShardedMap[K, V]) Contains(key K) bool
Contains reports whether m contains key.
func (*ShardedMap[K, V]) Delete ¶
func (m *ShardedMap[K, V]) Delete(key K) (shrunk bool)
Delete removes key from m.
It reports whether the map size shrunk (that is, whether key was present in the map).
func (*ShardedMap[K, V]) Get ¶
func (m *ShardedMap[K, V]) Get(key K) (value V)
Get returns m[key] or the zero value of V if key is not present.
func (*ShardedMap[K, V]) GetOk ¶
func (m *ShardedMap[K, V]) GetOk(key K) (value V, ok bool)
GetOk returns m[key] and whether it was present.
func (*ShardedMap[K, V]) Len ¶
func (m *ShardedMap[K, V]) Len() int
Len returns the number of elements in m.
It does so by locking shards one at a time, so it's not particularly cheap, nor does it give a consistent snapshot of the map. It's mostly intended for metrics or testing.
func (*ShardedMap[K, V]) Mutate ¶
func (m *ShardedMap[K, V]) Mutate(key K, mutator func(oldValue V, oldValueExisted bool) (newValue V, keep bool)) (sizeDelta int)
Mutate atomically mutates m[k] by calling mutator.
The mutator function is called with the old value (or its zero value) and whether it existed in the map and it returns the new value and whether it should be set in the map (true) or deleted from the map (false).
It returns the change in size of the map as a result of the mutation, one of -1 (delete), 0 (change), or 1 (addition).
func (*ShardedMap[K, V]) Set ¶
func (m *ShardedMap[K, V]) Set(key K, value V) (grew bool)
Set sets m[key] = value.
present in m).
type WaitGroup ¶
WaitGroup is identical to sync.WaitGroup, but provides a Go method to start a goroutine.
type WaitGroupChan ¶
type WaitGroupChan struct {
// contains filtered or unexported fields
}
WaitGroupChan is like a sync.WaitGroup, but has a chan that closes on completion that you can wait on. (This, you can only use the value once) Also, its zero value is not usable. Use the constructor.
func NewWaitGroupChan ¶
func NewWaitGroupChan() *WaitGroupChan
NewWaitGroupChan returns a new single-use WaitGroupChan.
func (*WaitGroupChan) Add ¶
func (wg *WaitGroupChan) Add(delta int)
Add adds delta, which may be negative, to the WaitGroupChan counter. If the counter becomes zero, all goroutines blocked on Wait or the Done chan are released. If the counter goes negative, Add panics.
Note that calls with a positive delta that occur when the counter is zero must happen before a Wait. Calls with a negative delta, or calls with a positive delta that start when the counter is greater than zero, may happen at any time. Typically this means the calls to Add should execute before the statement creating the goroutine or other event to be waited for.
func (*WaitGroupChan) Decr ¶
func (wg *WaitGroupChan) Decr()
Decr decrements the WaitGroup counter by one.
(It is like sync.WaitGroup's Done method, but we don't use Done in this type, because it's ambiguous between Context.Done and WaitGroup.Done. So we use DoneChan and Decr instead.)
func (*WaitGroupChan) DoneChan ¶
func (wg *WaitGroupChan) DoneChan() <-chan struct{}
DoneChan returns a channel that's closed on completion.
func (*WaitGroupChan) Wait ¶
func (wg *WaitGroupChan) Wait()
Wait blocks until the WaitGroupChan counter is zero.
Source Files