/// <summary>
/// Get an <see cref="IObservable{T}"/> for lines streamed from an HTTP GET request.
/// </summary>
/// <param name="request">
/// The <see cref="HttpRequest"/> to execute.
/// </param>
/// <param name="operationDescription">
/// A short description of the operation (used in error messages if the request fails).
/// </param>
/// <param name="bufferSize">
/// The buffer size to use when streaming data.
///
/// Default is 2048 bytes.
/// </param>
/// <returns>
/// The <see cref="IObservable{T}"/>.
/// </returns>
protected IObservable <string> ObserveLines(HttpRequest request, string operationDescription, int bufferSize = DefaultStreamingBufferSize)
{
if (request == null)
{
throw new ArgumentNullException(nameof(request));
}
if (String.IsNullOrWhiteSpace(operationDescription))
{
throw new ArgumentException("Argument cannot be null, empty, or entirely composed of whitespace: 'operationDescription'.", nameof(operationDescription));
}
return(Observable.Create <string>(async(subscriber, cancellationToken) =>
{
try
{
using (HttpResponseMessage responseMessage = await Http.GetStreamedAsync(request, cancellationToken).ConfigureAwait(false))
{
if (!responseMessage.IsSuccessStatusCode)
{
throw HttpRequestException <StatusV1> .Create(responseMessage.StatusCode,
await responseMessage.ReadContentAsStatusV1Async().ConfigureAwait(false)
);
}
MediaTypeHeaderValue contentTypeHeader = responseMessage.Content.Headers.ContentType;
if (contentTypeHeader == null)
{
throw new KubeClientException($"Unable to {operationDescription} (response is missing 'Content-Type' header).");
}
Encoding encoding =
!String.IsNullOrWhiteSpace(contentTypeHeader.CharSet)
? Encoding.GetEncoding(contentTypeHeader.CharSet)
: Encoding.UTF8;
Decoder decoder = encoding.GetDecoder();
using (Stream responseStream = await responseMessage.Content.ReadAsStreamAsync().ConfigureAwait(false))
{
StringBuilder lineBuilder = new StringBuilder();
byte[] buffer = new byte[bufferSize];
int bytesRead = await responseStream.ReadAsync(buffer, 0, buffer.Length, cancellationToken).ConfigureAwait(false);
while (bytesRead > 0)
{
// AF: Slightly inefficient because we wind up scanning the buffer twice.
char[] decodedCharacters = new char[decoder.GetCharCount(buffer, 0, bytesRead)];
int charactersDecoded = decoder.GetChars(buffer, 0, bytesRead, decodedCharacters, 0);
for (int charIndex = 0; charIndex < charactersDecoded; charIndex++)
{
const char CR = '\r';
const char LF = '\n';
char decodedCharacter = decodedCharacters[charIndex];
switch (decodedCharacter)
{
case CR:
{
if (charIndex < charactersDecoded - 1 && decodedCharacters[charIndex + 1] == LF)
{
charIndex++;
goto case LF;
}
break;
}
case LF:
{
string line = lineBuilder.ToString();
lineBuilder.Clear();
subscriber.OnNext(line);
break;
}
default:
{
lineBuilder.Append(decodedCharacter);
break;
}
}
}
bytesRead = await responseStream.ReadAsync(buffer, 0, buffer.Length, cancellationToken).ConfigureAwait(false);
}
// If stream doesn't end with a line-terminator sequence, publish trailing characters as the last line.
if (lineBuilder.Length > 0)
{
subscriber.OnNext(
lineBuilder.ToString()
);
}
}
}
}
catch (OperationCanceledException operationCanceled) when(operationCanceled.CancellationToken != cancellationToken)
{
if (!cancellationToken.IsCancellationRequested) // Don't bother publishing if subscriber has already disconnected.
{
subscriber.OnError(operationCanceled);
}
}
catch (HttpRequestException <StatusV1> requestError)
{
if (!cancellationToken.IsCancellationRequested)
{
subscriber.OnError(
new KubeClientException($"Unable to {operationDescription} (unexpected error while streaming from the Kubernetes API).", requestError)
);
}
}
catch (Exception exception)
{
if (!cancellationToken.IsCancellationRequested) // Don't bother publishing if subscriber has already disconnected.
{
subscriber.OnError(exception);
}
}
finally
{
if (!cancellationToken.IsCancellationRequested) // Don't bother publishing if subscriber has already disconnected.
{
subscriber.OnCompleted();
}
}
}));
}