Class ScyllaDeque<T>.SynchronizedScyllaDeque

Thread-safe decorator that wraps a ScyllaDeque<T> and serializes all operations through a single lock statement, making every individual operation atomic.

Inheritance

object

ScyllaDeque<T>.SynchronizedScyllaDeque

Implements

IScyllaCollection<T>

IScyllaCollection

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.ReferenceEquals(object, object)

object.ToString()

Namespace: Scylla.Core.Structures

Assembly: ScyllaCore.dll

Syntax

public sealed class ScyllaDeque<T>.SynchronizedScyllaDeque : IScyllaCollection<T>, IScyllaCollection

Remarks

Obtain an instance by calling AsSynchronized(object) on an existing deque, or by configuring the fluent ScyllaDeque<T>.Builder with Synchronized(object). Both return an IScyllaCollection<T> whose ThreadSafety property reports Synchronized.

Compound operations: while each individual operation is atomic, multi-step sequences such as peek-then-remove are not atomic as a unit unless the caller holds the lock for the entire sequence:

lock (syncedDeque.SyncRoot)
{
    if (syncedDeque.TryPeekFront(out var item))
        syncedDeque.TryPopFront(out _);
}

The IsFixedCapacity and Capabilities properties are cached at construction time and are safe to read without acquiring the lock.

Constructors

SynchronizedScyllaDeque(ScyllaDeque<T>, object)

Initializes a new synchronized wrapper around the specified ScyllaDeque<T>.

Declaration

public SynchronizedScyllaDeque(ScyllaDeque<T> inner, object syncRoot)

Parameters

Type	Name	Description
ScyllaDeque<T>	inner	The deque to wrap. Must not be `null`. The wrapper holds a direct reference to this instance; the caller must not continue to access `inner` unsynchronized after wrapping it.
object	syncRoot	The lock object to use for synchronization. If `null`, a new private object is created and owned by this wrapper. Supply a shared `syncRoot` to coordinate locking across multiple synchronized collections.

Exceptions

Type	Condition
ArgumentNullException	Thrown when `inner` is `null`.

Properties

Capabilities

Gets the capability flags of the wrapped deque. This value is cached at construction time and is safe to read without acquiring the lock.

Declaration

public ScyllaCollectionCapabilities Capabilities { get; }

Property Value

Type	Description
ScyllaCollectionCapabilities	The same ScyllaCollectionCapabilities bitmask reported by the inner deque. Includes HasCapacity, SupportsPeek, SupportsCopyTo, and SupportsContains.

Capacity

Gets the current capacity of the backing circular buffer. Acquires the internal lock to read a consistent value from the inner deque.

Declaration

public int Capacity { get; }

Property Value

Type	Description
int	The number of elements the backing buffer can hold before it would need to grow. For a fixed-capacity deque this value never changes after construction.

Count

Gets the number of elements currently stored in the deque. Acquires the internal lock to read a consistent value.

Declaration

public int Count { get; }

Property Value

Type	Description
int	A non-negative integer in the range `[0, Capacity]`.

IsEmpty

Gets a value indicating whether the deque contains no elements. Acquires the internal lock to read a consistent value.

Declaration

public bool IsEmpty { get; }

Property Value

Type	Description
bool	`true` when Count is `0`; otherwise `false`.

IsFixedCapacity

Gets a value indicating whether the inner deque was created with a fixed capacity. This property is safe to read without acquiring the lock because it is cached at construction.

Declaration

public bool IsFixedCapacity { get; }

Property Value

Type	Description
bool	`true` if the deque will not grow beyond its initial capacity; `false` if the deque grows automatically when full.

IsFull

Gets a value indicating whether the deque is currently full. Acquires the internal lock to read a consistent value.

Declaration

public bool IsFull { get; }

Property Value

Type	Description
bool	`true` when Count equals Capacity. Only meaningful for fixed-capacity deques; auto-growing deques are never permanently full.

SyncRoot

Gets the synchronization root object used to coordinate all operations on this wrapper. Callers can lock on this object to make multi-step compound operations atomic.

Declaration

public object SyncRoot { get; }

Property Value

Type	Description
object	A non-`null` object that is the same instance used internally for every `lock` statement inside this wrapper.

ThreadSafety

Gets the thread-safety level of this wrapper, which is always Synchronized.

Declaration

public ScyllaCollectionThreadSafety ThreadSafety { get; }

Property Value

Type	Description
ScyllaCollectionThreadSafety	Synchronized

Methods

Clear()

Removes all elements from the deque. For reference-type elements, clears the backing array slots to release managed references. Acquires the internal lock.

Declaration

public void Clear()

Contains(T, IEqualityComparer<T>)

Determines whether the deque contains the specified item using a linear scan (O(n)). Acquires the internal lock before delegating to the inner deque.

Declaration

public bool Contains(T item, IEqualityComparer<T> comparer = null)

Parameters

Type	Name	Description
T	item	The item to locate.
IEqualityComparer<T>	comparer	Optional equality comparer. If `null`, Default is used.

Returns

Type	Description
bool	`true` if the item is found; otherwise `false`.

CopyTo(Span<T>)

Copies elements from the deque into the provided span in front-to-back order. Acquires the internal lock so the snapshot is consistent.

Declaration

public int CopyTo(Span<T> destination)

Parameters

Type	Name	Description
Span<T>	destination	The span to copy into. At most `min(Count, destination.Length)` elements are written.

Returns

Type	Description
int	The number of elements actually copied.

CopyTo(T[], int)

Copies elements from the deque into the provided array starting at the specified index, in front-to-back order. Acquires the internal lock so the snapshot is consistent.

Declaration

public int CopyTo(T[] destination, int destinationIndex)

Parameters

Type	Name	Description
T[]	destination	The array to copy into. Must not be `null`.
int	destinationIndex	The zero-based index in `destination` at which copying begins. Must be in the range `[0, destination.Length]`.

Returns

Type	Description
int	The number of elements actually copied.

Exceptions

Type	Condition
ArgumentNullException	Thrown when `destination` is `null`.
ArgumentOutOfRangeException	Thrown when `destinationIndex` is negative or greater than `destination.Length`.

TryAdd(T)

Attempts to add an item to the back of the deque (FIFO convention). Acquires the internal lock before delegating to the inner deque's TryPushBack(T).

Declaration

public bool TryAdd(T item)

Parameters

Type	Name	Description
T	item	The item to push onto the back of the deque.

Returns

Type	Description
bool	`true` if the item was added; `false` if the deque is fixed-capacity and full.

TryPeek(out T)

Attempts to inspect the front element without removing it. Acquires the internal lock before delegating to the inner deque's TryPeekFront(out T).

Declaration

public bool TryPeek(out T item)

Parameters

Type	Name	Description
T	item	When this method returns `true`, the current front element; otherwise `default`.

Returns

Type	Description
bool	`true` if an element was available; `false` if the deque is empty.

TryPeekBack(out T)

Attempts to inspect the back element without removing it. Acquires the internal lock before delegating to the inner deque.

Declaration

public bool TryPeekBack(out T item)

Parameters

Type	Name	Description
T	item	When this method returns `true`, the current back element; otherwise `default`.

Returns

Type	Description
bool	`true` if an element was available; `false` if the deque is empty.

TryPeekFront(out T)

Attempts to inspect the front element without removing it. Acquires the internal lock before delegating to the inner deque.

Declaration

public bool TryPeekFront(out T item)

Parameters

Type	Name	Description
T	item	When this method returns `true`, the current front element; otherwise `default`.

Returns

Type	Description
bool	`true` if an element was available; `false` if the deque is empty.

TryPopBack(out T)

Attempts to remove and return the back element of the deque. Acquires the internal lock before delegating to the inner deque.

Declaration

public bool TryPopBack(out T item)

Parameters

Type	Name	Description
T	item	When this method returns `true`, the removed back element; otherwise `default`.

Returns

Type	Description
bool	`true` if an element was removed; `false` if the deque is empty.

TryPopFront(out T)

Attempts to remove and return the front element of the deque. Acquires the internal lock before delegating to the inner deque.

Declaration

public bool TryPopFront(out T item)

Parameters

Type	Name	Description
T	item	When this method returns `true`, the removed front element; otherwise `default`.

Returns

Type	Description
bool	`true` if an element was removed; `false` if the deque is empty.

TryPushBack(T)

Attempts to push an item onto the back of the deque. Acquires the internal lock before delegating to the inner deque.

Declaration

public bool TryPushBack(T item)

Parameters

Type	Name	Description
T	item	The item to place at the back of the deque.

Returns

Type	Description
bool	`true` if the item was added; `false` if the deque is fixed-capacity and full.

TryPushFront(T)

Attempts to push an item onto the front of the deque. Acquires the internal lock before delegating to the inner deque.

Declaration

public bool TryPushFront(T item)

Parameters

Type	Name	Description
T	item	The item to place at the front of the deque.

Returns

Type	Description
bool	`true` if the item was added; `false` if the deque is fixed-capacity and full.

TryRemove(out T)

Attempts to remove and return the front element of the deque (FIFO convention). Acquires the internal lock before delegating to the inner deque's TryPopFront(out T).

Declaration

public bool TryRemove(out T item)

Parameters

Type	Name	Description
T	item	When this method returns `true`, the removed front element; otherwise `default`.

Returns

Type	Description
bool	`true` if an element was removed; `false` if the deque is empty.

Implements

IScyllaCollection<T>

IScyllaCollection

Extension Methods

FileExtensions.SaveSecureToFileAsync<T>(T, string, string, CancellationToken)

FileExtensions.SaveSecureToFile<T>(T, string, string)

FileExtensions.SaveToFileAsync<T>(T, string, CancellationToken)

FileExtensions.SaveToFile<T>(T, string)

FileExtensions.SaveToFile<T>(T, string, SerializationSettings)