protected virtual Stream TryReadCacheFile(string uri, TimeSpan maxAge, string cacheFile)
{
return(HttpCacheUtility.TryReadCacheFile(uri, maxAge, cacheFile));
}
/// <summary>
/// Caching Get request.
/// </summary>
public async Task <T> GetAsync <T>(
HttpSourceCachedRequest request,
Func <HttpSourceResult, Task <T> > processAsync,
ILogger log,
CancellationToken token)
{
var cacheResult = HttpCacheUtility.InitializeHttpCacheResult(
HttpCacheDirectory,
_sourceUri,
request.CacheKey,
request.CacheContext);
return(await ConcurrencyUtilities.ExecuteWithFileLockedAsync(
cacheResult.CacheFile,
action : async lockedToken =>
{
cacheResult.Stream = TryReadCacheFile(request.Uri, cacheResult.MaxAge, cacheResult.CacheFile);
if (cacheResult.Stream != null)
{
log.LogInformation(string.Format(CultureInfo.InvariantCulture, " " + Strings.Http_RequestLog, "CACHE", request.Uri));
// Validate the content fetched from the cache.
try
{
request.EnsureValidContents?.Invoke(cacheResult.Stream);
cacheResult.Stream.Seek(0, SeekOrigin.Begin);
var httpSourceResult = new HttpSourceResult(
HttpSourceResultStatus.OpenedFromDisk,
cacheResult.CacheFile,
cacheResult.Stream);
return await processAsync(httpSourceResult);
}
catch (Exception e)
{
cacheResult.Stream.Dispose();
cacheResult.Stream = null;
string message = string.Format(CultureInfo.CurrentCulture, Strings.Log_InvalidCacheEntry, request.Uri)
+ Environment.NewLine
+ ExceptionUtilities.DisplayMessage(e);
log.LogWarning(message);
}
}
Func <HttpRequestMessage> requestFactory = () =>
{
var requestMessage = HttpRequestMessageFactory.Create(HttpMethod.Get, request.Uri, log);
foreach (var acceptHeaderValue in request.AcceptHeaderValues)
{
requestMessage.Headers.Accept.Add(acceptHeaderValue);
}
return requestMessage;
};
Func <Task <ThrottledResponse> > throttledResponseFactory = () => GetThrottledResponse(
requestFactory,
request.RequestTimeout,
request.DownloadTimeout,
request.MaxTries,
log,
lockedToken);
using (var throttledResponse = await throttledResponseFactory())
{
if (request.IgnoreNotFounds && throttledResponse.Response.StatusCode == HttpStatusCode.NotFound)
{
var httpSourceResult = new HttpSourceResult(HttpSourceResultStatus.NotFound);
return await processAsync(httpSourceResult);
}
if (throttledResponse.Response.StatusCode == HttpStatusCode.NoContent)
{
// Ignore reading and caching the empty stream.
var httpSourceResult = new HttpSourceResult(HttpSourceResultStatus.NoContent);
return await processAsync(httpSourceResult);
}
throttledResponse.Response.EnsureSuccessStatusCode();
if (!request.CacheContext.DirectDownload)
{
await HttpCacheUtility.CreateCacheFileAsync(
cacheResult,
throttledResponse.Response,
request.EnsureValidContents,
lockedToken);
using (var httpSourceResult = new HttpSourceResult(
HttpSourceResultStatus.OpenedFromDisk,
cacheResult.CacheFile,
cacheResult.Stream))
{
return await processAsync(httpSourceResult);
}
}
else
{
// Note that we do not execute the content validator on the response stream when skipping
// the cache. We cannot seek on the network stream and it is not valuable to download the
// content twice just to validate the first time (considering that the second download could
// be different from the first thus rendering the first validation meaningless).
using (var stream = await throttledResponse.Response.Content.ReadAsStreamAsync())
using (var httpSourceResult = new HttpSourceResult(
HttpSourceResultStatus.OpenedFromNetwork,
cacheFileName: null,
stream: stream))
{
return await processAsync(httpSourceResult);
}
}
}
},
token : token));
}
/// <summary>
/// Caching Get request.
/// </summary>
public async Task <HttpSourceResult> GetAsync(
HttpSourceCachedRequest request,
ILogger log,
CancellationToken token)
{
var result = HttpCacheUtility.InitializeHttpCacheResult(
HttpCacheDirectory,
_baseUri,
request.CacheKey,
request.CacheContext);
return(await ConcurrencyUtilities.ExecuteWithFileLockedAsync(
result.CacheFile,
action : async lockedToken =>
{
result.Stream = TryReadCacheFile(request.Uri, result.MaxAge, result.CacheFile);
if (result.Stream != null)
{
log.LogInformation(string.Format(CultureInfo.InvariantCulture, " " + Strings.Http_RequestLog, "CACHE", request.Uri));
// Validate the content fetched from the cache.
try
{
request.EnsureValidContents?.Invoke(result.Stream);
result.Stream.Seek(0, SeekOrigin.Begin);
return new HttpSourceResult(
HttpSourceResultStatus.OpenedFromDisk,
result.CacheFile,
result.Stream);
}
catch (Exception e)
{
result.Stream.Dispose();
result.Stream = null;
string message = string.Format(CultureInfo.CurrentCulture, Strings.Log_InvalidCacheEntry, request.Uri)
+ Environment.NewLine
+ ExceptionUtilities.DisplayMessage(e);
log.LogWarning(message);
}
}
Func <HttpRequestMessage> requestFactory = () =>
{
var requestMessage = HttpRequestMessageFactory.Create(HttpMethod.Get, request.Uri, log);
foreach (var acceptHeaderValue in request.AcceptHeaderValues)
{
requestMessage.Headers.Accept.Add(acceptHeaderValue);
}
return requestMessage;
};
Func <Task <ThrottledResponse> > throttledResponseFactory = () => GetThrottledResponse(
requestFactory,
request.RequestTimeout,
request.DownloadTimeout,
log,
lockedToken);
using (var throttledResponse = await throttledResponseFactory())
{
if (request.IgnoreNotFounds && throttledResponse.Response.StatusCode == HttpStatusCode.NotFound)
{
return new HttpSourceResult(HttpSourceResultStatus.NotFound);
}
if (throttledResponse.Response.StatusCode == HttpStatusCode.NoContent)
{
// Ignore reading and caching the empty stream.
return new HttpSourceResult(HttpSourceResultStatus.NoContent);
}
throttledResponse.Response.EnsureSuccessStatusCode();
await HttpCacheUtility.CreateCacheFileAsync(
result,
request.Uri,
throttledResponse.Response,
request.CacheContext,
request.EnsureValidContents,
lockedToken);
return new HttpSourceResult(
HttpSourceResultStatus.OpenedFromDisk,
result.CacheFile,
result.Stream);
}
},
token : token));
}
