/// <summary>
/// This is helper method to create a <see cref="ReadOnlyResettableAsyncLazy{T}"/> which will resolve host name or textual IP address into <see cref="IPAddress"/>.
/// The lazy can be resetted using <see cref="ReadOnlyResettableAsyncLazy{T}.Reset"/> method, if it is needed to resolve again (e.g. dns cache modification).
/// </summary>
/// <param name="addressOrHostName">The host name or textual IP address.</param>
/// <param name="addressSelector">The callback to select one address from potentially many addresses. Only used if this <paramref name="addressOrHostName"/> is host name.</param>
/// <param name="dnsResolve">The optional callback to perform DNS resolve. If <c>null</c>, then <paramref name="addressSelector"/> will get <c>null</c> as its argument.</param>
/// <returns>A new <see cref="ReadOnlyResettableAsyncLazy{T}"/> which will asynchronously </returns>
public static ReadOnlyResettableAsyncLazy <IPAddress> CreateAddressOrHostNameResolvingLazy(
String addressOrHostName,
Func <IPAddress[], IPAddress> addressSelector,
Func <String, Task <IPAddress[]> > dnsResolve = null
)
{
ReadOnlyResettableAsyncLazy <IPAddress> retVal;
if (IPAddress.TryParse(addressOrHostName, out var thisAddress))
{
retVal = new ReadOnlyResettableAsyncLazy <IPAddress>(() => thisAddress);
}
else
{
#if !NETSTANDARD1_3
if (dnsResolve == null)
{
dnsResolve = (host) =>
#if NET40
DnsEx
#else
Dns
#endif
.GetHostAddressesAsync(host);
}
#endif
retVal = new ReadOnlyResettableAsyncLazy <IPAddress>(async() =>
{
var allIPs = await(dnsResolve?.Invoke(addressOrHostName) ??
#if NET40
TaskEx
#else
Task
#endif
.FromResult <IPAddress[]>(null));
IPAddress resolvedAddress = null;
if ((allIPs?.Length ?? 0) > 1)
{
resolvedAddress = addressSelector?.Invoke(allIPs);
}
if (resolvedAddress == null)
{
resolvedAddress = allIPs.GetElementOrDefault(0);
}
return(resolvedAddress);
});
}
return(retVal);
}
public DataRowColumnSUKS(
DataColumnMetaData metadata,
Int32 thisStreamIndex,
ResizableArray <Byte> byteArray,
DataRowColumnSUKS[] allDataRowStreams
) : base(metadata, thisStreamIndex)
{
this.ByteArray = ArgumentValidator.ValidateNotNull(nameof(byteArray), byteArray);
this._totalBytesRead = 0;
this._byteCount = new ReadOnlyResettableAsyncLazy <Int32>(async() => await this.ReadByteCountAsync());
this._allStreams = ArgumentValidator.ValidateNotEmpty(nameof(allDataRowStreams), allDataRowStreams);
this._transitionFunc = async unused => await this.ReadByteCountAsync();
}
/// <summary>
/// Initializes a new instance of <see cref="DataColumnSUKS"/> with given parameters.
/// </summary>
/// <param name="metadata">The column <see cref="DataColumnMetaData"/>.</param>
/// <param name="columnIndex">The index of this column in <see cref="AsyncDataRow"/> it was obtained from.</param>
/// <param name="previousColumn">The previous <see cref="DataColumnSUKS"/> column of the <see cref="AsyncDataRow"/> this belongs to.</param>
/// <exception cref="ArgumentNullException">If <paramref name="metadata"/> is <c>null</c>, or if <paramref name="columnIndex"/> is greater than <c>0</c> but <paramref name="previousColumn"/> is <c>null</c>.</exception>
public DataColumnSUKS(
DataColumnMetaData metadata,
Int32 columnIndex,
AsyncDataColumn previousColumn
) : base(metadata, columnIndex)
{
if (columnIndex > 0)
{
ArgumentValidator.ValidateNotNull(nameof(previousColumn), previousColumn);
}
this._totalBytesRead = 0;
this._byteCount = new ReadOnlyResettableAsyncLazy <Int32>(async() =>
{
if (previousColumn != null)
{
await previousColumn.SkipBytesAsync(null);
}
return(await this.ReadByteCountAsync());
});
}
