Class ScyllaQueue<T>.SynchronizedScyllaQueue

Thread-safe wrapper around a ScyllaQueue<T> that serializes all operations through a single lock object.

Inheritance

object

ScyllaQueue<T>.SynchronizedScyllaQueue

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 ScyllaQueue<T>.SynchronizedScyllaQueue : IScyllaCollection<T>, IScyllaCollection

Remarks

Obtain an instance via AsSynchronized(object) or through the fluent builder's Synchronized(object) method. Do not construct this class directly in production code.

Capabilities and IsFixedCapacity are cached at wrapper creation time so that those properties can be read without acquiring the lock on every call.

Compound atomicity: Individual operations are atomic with respect to each other, but a check-then-act sequence (e.g. check IsEmpty then call TryDequeue(out T)) is still subject to a TOCTOU race. Use SyncRoot to hold the lock across the combined operation:

lock (wrapper.SyncRoot)
{
    if (!wrapper.IsEmpty)
        wrapper.TryDequeue(out var item);
}

Multiple ScyllaQueue<T>.SynchronizedScyllaQueue instances can share the same syncRoot object (passed to AsSynchronized(object)) to coordinate atomic operations across two wrappers.

Constructors

SynchronizedScyllaQueue(ScyllaQueue<T>, object)

Initializes a new ScyllaQueue<T>.SynchronizedScyllaQueue that wraps the given queue and serializes all operations through the specified lock object.

Declaration

public SynchronizedScyllaQueue(ScyllaQueue<T> inner, object syncRoot)

Parameters

Type	Name	Description
ScyllaQueue<T>	inner	The unsynchronized queue to wrap. Must not be `null`.
object	syncRoot	The lock object to use for all synchronized operations. When `null`, a new private `object` is allocated and owned by this wrapper. Passing a shared object allows compound atomic operations to be coordinated across multiple synchronized collections.

Exceptions

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

Properties

Capabilities

Gets the capability flags supported by the wrapped queue.

Declaration

public ScyllaCollectionCapabilities Capabilities { get; }

Property Value

Type	Description
ScyllaCollectionCapabilities	The same ScyllaCollectionCapabilities flags reported by the inner ScyllaQueue<T>. This value is cached at construction and does not require the lock.

Capacity

Gets the current capacity of the backing circular buffer.

Declaration

public int Capacity { get; }

Property Value

Type	Description
int	The number of elements the internal buffer can currently hold without growing. In fixed-capacity mode this is the permanent maximum.

Remarks

This property acquires the internal lock on every read.

Count

Gets the number of elements currently in the queue.

Declaration

public int Count { get; }

Property Value

Type	Description
int	A non-negative integer representing the current element count. Returns `0` when the queue is empty.

Remarks

This property acquires the internal lock on every read.

IsEmpty

Gets a value indicating whether the queue contains no elements.

Declaration

public bool IsEmpty { get; }

Property Value

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

Remarks

This property acquires the internal lock on every read.

IsFixedCapacity

Gets a value indicating whether this queue operates in fixed-capacity mode.

Declaration

public bool IsFixedCapacity { get; }

Property Value

Type	Description
bool	`true` if the queue was constructed with `fixedCapacity: true` and will never grow; `false` if the buffer grows automatically when full.

Remarks

This value is cached at wrapper creation time and is read without acquiring the lock.

IsFull

Gets a value indicating whether the queue is at full capacity.

Declaration

public bool IsFull { get; }

Property Value

Type	Description
bool	`true` when Count equals Capacity. This is only a meaningful stopping condition when IsFixedCapacity is `true`; in auto-growing mode the queue will expand on the next enqueue.

Remarks

This property acquires the internal lock on every read.

SyncRoot

Gets the lock object used to serialize all operations on this wrapper.

Declaration

public object SyncRoot { get; }

Property Value

Type	Description
object	A non-null object that can be used with `lock` to perform compound atomic operations that span multiple individual method calls. This is the same object used internally by every synchronized method on this wrapper.

ThreadSafety

Gets the thread-safety level of this wrapper.

Declaration

public ScyllaCollectionThreadSafety ThreadSafety { get; }

Property Value

Type	Description
ScyllaCollectionThreadSafety	Always Synchronized, indicating that all operations are protected by an internal lock.

Methods

Clear()

Removes all elements from the queue and resets it to an empty state.

Declaration

public void Clear()

Remarks

For reference types, internal slots are cleared to default to release object references. This operation acquires the internal lock.

Contains(T, IEqualityComparer<T>)

Determines whether the queue contains the specified item using a linear search.

Declaration

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

Parameters

Type	Name	Description
T	item	The item to locate in the queue.
IEqualityComparer<T>	comparer	Optional equality comparer to use when comparing elements. When `null`, Default is used.

Returns

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

Remarks

This is an O(n) operation. This operation acquires the internal lock.

CopyTo(Span<T>)

Copies elements from the queue into the provided span in FIFO order (oldest element first).

Declaration

public int CopyTo(Span<T> destination)

Parameters

Type	Name	Description
Span<T>	destination	The caller-owned span to copy elements into. If smaller than Count, only the first `destination.Length` elements are copied.

Returns

Type	Description
int	The number of elements copied, which is `min(Count, destination.Length)`. Returns `0` if the queue is empty or the destination is zero-length.

Remarks

This operation acquires the internal lock and produces a consistent snapshot.

CopyTo(T[], int)

Copies elements from the queue into the provided array starting at the specified index, in FIFO order (oldest element first).

Declaration

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

Parameters

Type	Name	Description
T[]	destination	The array to copy elements 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 copied. Returns `0` if the queue is empty or there is no available space at `destinationIndex`.

Remarks

This operation acquires the internal lock and produces a consistent snapshot.

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 queue. Equivalent to TryEnqueue(T); provided for polymorphic IScyllaCollection<T> usage.

Declaration

public bool TryAdd(T item)

Parameters

Type	Name	Description
T	item	The item to enqueue.

Returns

Type	Description
bool	`true` if the item was added successfully; `false` if the queue is in fixed-capacity mode and is currently full.

Remarks

This operation acquires the internal lock.

TryDequeue(out T)

Attempts to remove and return the oldest (front) element from the queue.

Declaration

public bool TryDequeue(out T item)

Parameters

Type	Name	Description
T	item	When this method returns `true`, contains the dequeued front element. When `false`, contains `default(T)`.

Returns

Type	Description
bool	`true` if an element was dequeued; `false` if the queue is empty.

Remarks

This operation acquires the internal lock.

TryEnqueue(T)

Attempts to add an item to the back of the queue.

Declaration

public bool TryEnqueue(T item)

Parameters

Type	Name	Description
T	item	The item to enqueue.

Returns

Type	Description
bool	`true` if the item was enqueued; `false` if the queue is in fixed-capacity mode and is currently full.

Remarks

This operation acquires the internal lock.

TryPeek(out T)

Attempts to inspect the front element without removing it. Equivalent to TryPeekFront(out T); provided for polymorphic IScyllaCollection<T> usage.

Declaration

public bool TryPeek(out T item)

Parameters

Type	Name	Description
T	item	When this method returns `true`, contains the front element. When `false`, contains `default(T)`.

Returns

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

Remarks

This operation acquires the internal lock.

TryPeekFront(out T)

Attempts to inspect the oldest (front) element without removing it from the queue.

Declaration

public bool TryPeekFront(out T item)

Parameters

Type	Name	Description
T	item	When this method returns `true`, contains the front element. When `false`, contains `default(T)`.

Returns

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

Remarks

This operation acquires the internal lock.

TryRemove(out T)

Attempts to remove the front element from the queue. Equivalent to TryDequeue(out T); provided for polymorphic IScyllaCollection<T> usage.

Declaration

public bool TryRemove(out T item)

Parameters

Type	Name	Description
T	item	When this method returns `true`, contains the dequeued front element. When `false`, contains `default(T)`.

Returns

Type	Description
bool	`true` if an element was dequeued; `false` if the queue is empty.

Remarks

This operation acquires the internal lock.

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)