/// <summary>
/// Lazily convert the reliable state enumerable into a queryable <see cref="Entity{TKey, TValue}"/> enumerable.
/// /// </summary>
/// <param name="source">Reliable state enumerable.</param>
/// <param name="partitionId">Partition id.</param>
/// <param name="cancellationToken">Cancellation token.</param>
/// <returns>The</returns>
private static IAsyncEnumerable <Entity <TKey, TValue> > AsEntity <TKey, TValue>(this IAsyncEnumerable <KeyValuePair <TKey, TValue> > source, Guid partitionId, CancellationToken cancellationToken)
{
return(source.SelectAsync(kvp => new Entity <TKey, TValue>
{
PartitionId = partitionId,
Key = kvp.Key,
Value = kvp.Value,
// TODO: only set the ETag if the query selects this object.
Etag = CRC64.ToCRC64(JsonConvert.SerializeObject(kvp.Value)).ToString(),
}));
}
private static async Task <HttpStatusCode> ExecuteUpdateAsync(ITransaction tx, IReliableState dictionary, EntityOperation <JToken, JToken> operation)
{
// Get type information.
Type keyType = dictionary.GetKeyType();
Type valueType = dictionary.GetValueType();
var key = operation.Key.ToObject(keyType);
var value = operation.Value.ToObject(valueType);
Type dictionaryType = typeof(IReliableDictionary <,>).MakeGenericType(keyType, valueType);
// Read the existing value.
MethodInfo tryGetMethod = dictionaryType.GetMethod("TryGetValueAsync", new[] { typeof(ITransaction), keyType, typeof(LockMode) });
var tryGetTask = (Task)tryGetMethod.Invoke(dictionary, new[] { tx, key, LockMode.Update });
await tryGetTask.ConfigureAwait(false);
var tryGetResult = tryGetTask.GetPropertyValue <object>("Result");
// Only update the value if it exists.
if (!tryGetResult.GetPropertyValue <bool>("HasValue"))
{
throw new QueryException(HttpStatusCode.NotFound, "Key not found.");
}
// Validate the ETag.
var currentValue = tryGetResult.GetPropertyValue <object>("Value");
var currentEtag = CRC64.ToCRC64(JsonConvert.SerializeObject(currentValue)).ToString();
if (currentEtag != operation.Etag)
{
throw new QueryException(HttpStatusCode.PreconditionFailed, "The value has changed on the server.");
}
// Update in reliable dictionary.
MethodInfo setMethod = dictionaryType.GetMethod("SetAsync", new[] { typeof(ITransaction), keyType, valueType });
await((Task)setMethod.Invoke(dictionary, new[] { tx, key, value })).ConfigureAwait(false);
return(HttpStatusCode.OK);
}