/// <summary>
/// Mutates a value in-place with optimistic locking transaction semantics via a specified transformation
/// function. The transformation is retried as many times as necessary to win the optimistic locking race.
/// </summary>
/// <typeparam name="TKey">The type of key stored by the dictionary.</typeparam>
/// <typeparam name="TValue">The type of value stored by the dictionary.</typeparam>
/// <typeparam name="TArg">The type of argument passed to the <paramref name="transformer"/>.</typeparam>
/// <param name="location">
/// The variable or field to be changed, which may be accessed by multiple threads.
/// </param>
/// <param name="transformer">
/// A function that mutates the value. This function should be side-effect free, as it may run multiple times
/// when races occur with other threads.</param>
/// <param name="transformerArgument">The argument to pass to <paramref name="transformer"/>.</param>
/// <returns>
/// <see langword="true"/> if the location's value is changed by applying the result of the
/// <paramref name="transformer"/> function; otherwise, <see langword="false"/> if the location's value remained
/// the same because the last invocation of <paramref name="transformer"/> returned the existing value.
/// </returns>
public static bool Update <TKey, TValue, TArg>(ref ImmutableSegmentedDictionary <TKey, TValue> location, Func <ImmutableSegmentedDictionary <TKey, TValue>, TArg, ImmutableSegmentedDictionary <TKey, TValue> > transformer, TArg transformerArgument)
where TKey : notnull
{
if (transformer is null)
{
throw new ArgumentNullException(nameof(transformer));
}
var oldValue = ImmutableSegmentedDictionary <TKey, TValue> .PrivateInterlocked.VolatileRead(in location);
while (true)
{
var newValue = transformer(oldValue, transformerArgument);
if (oldValue == newValue)
{
// No change was actually required.
return(false);
}
var interlockedResult = InterlockedCompareExchange(ref location, newValue, oldValue);
if (oldValue == interlockedResult)
{
return(true);
}
oldValue = interlockedResult; // we already have a volatile read that we can reuse for the next loop
}
}
/// <inheritdoc cref="ImmutableInterlocked.GetOrAdd{TKey, TValue}(ref ImmutableDictionary{TKey, TValue}, TKey, Func{TKey, TValue})"/>
public static TValue GetOrAdd <TKey, TValue>(
ref ImmutableSegmentedDictionary <TKey, TValue> location,
TKey key,
Func <TKey, TValue> valueFactory
) where TKey : notnull
{
if (valueFactory is null)
{
throw new ArgumentNullException(nameof(valueFactory));
}
var map = ImmutableSegmentedDictionary <TKey, TValue> .PrivateInterlocked.VolatileRead(
in location
);
if (map.IsDefault)
{
throw new ArgumentNullException(nameof(location));
}
if (map.TryGetValue(key, out var value))
{
return(value);
}
value = valueFactory(key);
return(GetOrAdd(ref location, key, value));
}
/// <inheritdoc cref="ImmutableInterlocked.TryUpdate{TKey, TValue}(ref ImmutableDictionary{TKey, TValue}, TKey, TValue, TValue)"/>
public static bool TryUpdate <TKey, TValue>(ref ImmutableSegmentedDictionary <TKey, TValue> location, TKey key, TValue newValue, TValue comparisonValue)
where TKey : notnull
{
var valueComparer = EqualityComparer <TValue> .Default;
var priorCollection = ImmutableSegmentedDictionary <TKey, TValue> .PrivateInterlocked.VolatileRead(in location);
while (true)
{
if (priorCollection.IsDefault)
{
throw new ArgumentNullException(nameof(location));
}
if (!priorCollection.TryGetValue(key, out var priorValue) || !valueComparer.Equals(priorValue, comparisonValue))
{
// The key isn't in the dictionary, or its current value doesn't match what the caller expected.
return(false);
}
var updatedCollection = priorCollection.SetItem(key, newValue);
var interlockedResult = InterlockedCompareExchange(ref location, updatedCollection, priorCollection);
if (priorCollection == interlockedResult)
{
return(true);
}
priorCollection = interlockedResult; // we already have a volatile read that we can reuse for the next loop
}
}
/// <inheritdoc cref="ImmutableInterlocked.TryRemove{TKey, TValue}(ref ImmutableDictionary{TKey, TValue}, TKey, out TValue)"/>
public static bool TryRemove <TKey, TValue>(ref ImmutableSegmentedDictionary <TKey, TValue> location, TKey key, [MaybeNullWhen(false)] out TValue value)
where TKey : notnull
{
var priorCollection = ImmutableSegmentedDictionary <TKey, TValue> .PrivateInterlocked.VolatileRead(in location);
while (true)
{
if (priorCollection.IsDefault)
{
throw new ArgumentNullException(nameof(location));
}
if (!priorCollection.TryGetValue(key, out value))
{
return(false);
}
var updatedCollection = priorCollection.Remove(key);
var interlockedResult = InterlockedCompareExchange(ref location, updatedCollection, priorCollection);
if (priorCollection == interlockedResult)
{
return(true);
}
priorCollection = interlockedResult; // we already have a volatile read that we can reuse for the next loop
}
}
/// <inheritdoc cref="ImmutableInterlocked.GetOrAdd{TKey, TValue}(ref ImmutableDictionary{TKey, TValue}, TKey, TValue)"/>
public static TValue GetOrAdd <TKey, TValue>(ref ImmutableSegmentedDictionary <TKey, TValue> location, TKey key, TValue value)
where TKey : notnull
{
var priorCollection = ImmutableSegmentedDictionary <TKey, TValue> .PrivateInterlocked.VolatileRead(in location);
while (true)
{
if (priorCollection.IsDefault)
{
throw new ArgumentNullException(nameof(location));
}
if (priorCollection.TryGetValue(key, out var oldValue))
{
return(oldValue);
}
var updatedCollection = priorCollection.Add(key, value);
var interlockedResult = InterlockedCompareExchange(ref location, updatedCollection, priorCollection);
if (priorCollection == interlockedResult)
{
// We won the race-condition and have updated the collection.
// Return the value that is in the collection (as of the Interlocked operation).
return(value);
}
priorCollection = interlockedResult; // we already have a volatile read that we can reuse for the next loop
}
}
internal KeyCollection(
ImmutableSegmentedDictionary <TKey, TValue> .Builder dictionary
)
{
Debug.Assert(dictionary is not null);
_dictionary = dictionary !;
}
/// <summary>
/// Assigns a field or variable containing an immutable dictionary to the specified value and returns the
/// previous value.
/// </summary>
/// <typeparam name="TKey">The type of key stored by the dictionary.</typeparam>
/// <typeparam name="TValue">The type of value stored by the dictionary.</typeparam>
/// <param name="location">The field or local variable to change.</param>
/// <param name="value">The new value to assign.</param>
/// <returns>The prior value at the specified <paramref name="location"/>.</returns>
public static ImmutableSegmentedDictionary <TKey, TValue> InterlockedExchange <TKey, TValue>(
ref ImmutableSegmentedDictionary <TKey, TValue> location,
ImmutableSegmentedDictionary <TKey, TValue> value
) where TKey : notnull
{
return(ImmutableSegmentedDictionary <
TKey,
TValue
> .PrivateInterlocked.InterlockedExchange(ref location, value));
}
/// <inheritdoc cref="ImmutableInterlocked.AddOrUpdate{TKey, TValue}(ref ImmutableDictionary{TKey, TValue}, TKey, Func{TKey, TValue}, Func{TKey, TValue, TValue})"/>
public static TValue AddOrUpdate <TKey, TValue>(
ref ImmutableSegmentedDictionary <TKey, TValue> location,
TKey key,
Func <TKey, TValue> addValueFactory,
Func <TKey, TValue, TValue> updateValueFactory
) where TKey : notnull
{
if (addValueFactory is null)
{
throw new ArgumentNullException(nameof(addValueFactory));
}
if (updateValueFactory is null)
{
throw new ArgumentNullException(nameof(updateValueFactory));
}
TValue newValue;
var priorCollection = ImmutableSegmentedDictionary <
TKey,
TValue
> .PrivateInterlocked.VolatileRead(in location);
while (true)
{
if (priorCollection.IsDefault)
{
throw new ArgumentNullException(nameof(location));
}
if (priorCollection.TryGetValue(key, out var oldValue))
{
newValue = updateValueFactory(key, oldValue);
}
else
{
newValue = addValueFactory(key);
}
var updatedCollection = priorCollection.SetItem(key, newValue);
var interlockedResult = InterlockedCompareExchange(
ref location,
updatedCollection,
priorCollection
);
if (priorCollection == interlockedResult)
{
// We won the race-condition and have updated the collection.
// Return the value that is in the collection (as of the Interlocked operation).
return(newValue);
}
priorCollection = interlockedResult; // we already have a volatile read that we can reuse for the next loop
}
}
/// <summary>
/// Assigns a field or variable containing an immutable dictionary to the specified value if it is has not yet
/// been initialized.
/// </summary>
/// <typeparam name="TKey">The type of key stored by the dictionary.</typeparam>
/// <typeparam name="TValue">The type of value stored by the dictionary.</typeparam>
/// <param name="location">The field or local variable to change.</param>
/// <param name="value">The new value to assign.</param>
/// <returns><see langword="true"/> if the field was assigned the specified value; otherwise,
/// <see langword="false"/> if it was previously initialized.</returns>
public static bool InterlockedInitialize <TKey, TValue>(
ref ImmutableSegmentedDictionary <TKey, TValue> location,
ImmutableSegmentedDictionary <TKey, TValue> value
) where TKey : notnull
{
return(InterlockedCompareExchange(
ref location,
value,
default(ImmutableSegmentedDictionary <TKey, TValue>)
).IsDefault);
}
public static ImmutableSegmentedDictionary <TKey, TValue> ToImmutableSegmentedDictionary <
TKey,
TValue
>(this ImmutableSegmentedDictionary <TKey, TValue> .Builder builder) where TKey : notnull
{
if (builder is null)
{
throw new ArgumentNullException(nameof(builder));
}
return(builder.ToImmutable());
}
public static bool TryAdd <T>(
this ImmutableSegmentedDictionary <T, VoidResult> .Builder dictionary,
T value)
where T : notnull
{
#if NETCOREAPP
return(dictionary.TryAdd(value, default));
#else
if (dictionary.ContainsKey(value))
{
return(false);
}
dictionary[value] = default;
return(true);
#endif
}
internal Enumerator(
ImmutableSegmentedDictionary <TKey, TValue> .Enumerator enumerator
)
{
_enumerator = enumerator;
}
internal ValueCollection(ImmutableSegmentedDictionary <TKey, TValue> dictionary)
{
_dictionary = dictionary;
}
internal Builder(ImmutableSegmentedDictionary <TKey, TValue> dictionary)
{
_dictionary = dictionary;
}
