protected override async Task <HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
{
HttpResponseMessage response = null;
CacheEnabledRequestMessage cacheRequest = request as CacheEnabledRequestMessage;
if (cacheRequest != null && cacheRequest.CacheOptions.UseFileCache)
{
Uri uri = request.RequestUri;
using (var uriLock = new UriLock(uri, cancellationToken))
{
cancellationToken.ThrowIfCancellationRequested();
// check cache
Stream stream = null;
if (_fileCache.TryGet(uri, out stream))
{
DataTraceSources.Verbose("[HttpClient] Cached Length: {0}", "" + stream.Length);
response = new CacheResponse(stream);
}
else
{
// get the item and add it to the cache
DataTraceSources.Verbose("[HttpClient] GET {0}", uri.AbsoluteUri);
response = await base.SendAsync(request, cancellationToken);
if (response.IsSuccessStatusCode)
{
DataTraceSources.Verbose("[HttpClient] Caching {0}");
_fileCache.Add(uri, cacheRequest.CacheOptions.MaxCacheLife, await response.Content.ReadAsStreamAsync());
}
}
}
}
if (response == null)
{
// skip cache
DataTraceSources.Verbose("[HttpClient] GET {0}", request.RequestUri.AbsoluteUri);
response = await base.SendAsync(request, cancellationToken);
}
return(response);
}
private async Task <JObject> GetFileInternal(Uri uri, TimeSpan cacheTime, bool cacheInGraph = true, bool cloneJson = true)
{
if (uri == null)
{
throw new ArgumentNullException("uri");
}
if (cacheTime == null)
{
throw new ArgumentNullException("cacheTime");
}
bool cache = cacheTime.TotalSeconds > 0;
// request the root document
Uri fixedUri = Utility.GetUriWithoutHash(uri);
Stream stream = null;
JObject result = null;
JObject clonedResult = null; // the copy we give the caller
try
{
using (var uriLock = new UriLock(fixedUri))
{
if (!cache || !_fileCache.TryGet(fixedUri, out stream))
{
// the stream was not in the cache or we are skipping the cache
int tries = 0;
// try up to 5 times to be a little more robust
while (stream == null && tries < 5)
{
tries++;
try
{
HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Get, fixedUri.AbsoluteUri);
DataTraceSources.Verbose("[HttpClient] GET {0}", fixedUri.AbsoluteUri);
var response = await _httpClient.SendAsync(request);
Debug.Assert(response.StatusCode == HttpStatusCode.OK, "Received non-OK status code response from " + request.RequestUri.ToString());
if (response.StatusCode == HttpStatusCode.OK)
{
stream = await response.Content.ReadAsStreamAsync();
if (stream != null)
{
if (cache)
{
DataTraceSources.Verbose("[HttpClient] Caching {0}");
_fileCache.Add(fixedUri, _lifeSpan, stream);
}
DataTraceSources.Verbose("[HttpClient] 200 OK Length: {0}", "" + stream.Length);
result = await StreamToJson(stream);
}
}
else
{
DataTraceSources.Verbose("[HttpClient] FAILED {0}", "" + (int)response.StatusCode);
result = new JObject();
result.Add("HttpStatusCode", (int)response.StatusCode);
}
}
catch (HttpRequestException ex)
{
Debug.Fail("WebRequest failed: " + ex.ToString());
DataTraceSources.Verbose("[HttpClient] FAILED {0}", ex.ToString());
// request error
result = new JObject();
result.Add("HttpRequestException", ex.ToString());
}
}
}
else
{
// the stream was in the cache
DataTraceSources.Verbose("[HttpClient] Cached Length: {0}", "" + stream.Length);
result = await StreamToJson(stream);
}
}
}
finally
{
if (stream != null)
{
stream.Dispose();
}
}
if (result != null)
{
// this must be called before the entity cache thread starts using it
if (cloneJson)
{
clonedResult = result.DeepClone() as JObject;
}
else
{
// in some scenarios we can skip cloning, such as when we are throwing away the result
clonedResult = result;
}
if (cacheInGraph)
{
// this call is only blocking if the cache is overloaded
_entityCache.Add(result, fixedUri);
}
}
return(clonedResult);
}
