public async Task Deserialize_DoesntAlterValue_WhenSerialized()
{
// Arrange
var content = "<b>some content</b>";
var formatter = GetFormatter();
var context = new DistributedCacheTagHelperFormattingContext
{
Html = new HtmlString(content)
};
var serialized = await formatter.SerializeAsync(context);
// Act
var deserialized = await formatter.DeserializeAsync(serialized);
// Assert
Assert.Equal(deserialized.ToString(), content);
}
/// <inheritdoc />
public Task <byte[]> SerializeAsync(DistributedCacheTagHelperFormattingContext context)
{
if (context == null)
{
throw new ArgumentNullException(nameof(context));
}
if (context.Html == null)
{
throw new ArgumentException(
Resources.FormatPropertyOfTypeCannotBeNull(
nameof(DistributedCacheTagHelperFormattingContext.Html),
typeof(DistributedCacheTagHelperFormattingContext).FullName));
}
var serialized = Encoding.UTF8.GetBytes(context.Html.ToString());
return(Task.FromResult(serialized));
}
public async Task <IHtmlContent> ProcessContentAsync(TagHelperOutput output, CacheContext cacheContext)
{
IHtmlContent content = null;
while (content == null)
{
Task <IHtmlContent> result;
// Is there any request already processing the value?
if (!_dynamicCacheTagHelperService.Workers.TryGetValue(CacheId, out result))
{
// There is a small race condition here between TryGetValue and TryAdd that might cause the
// content to be computed more than once. We don't care about this race as the probability of
// happening is very small and the impact is not critical.
var tcs = new TaskCompletionSource <IHtmlContent>();
_dynamicCacheTagHelperService.Workers.TryAdd(CacheId, tcs.Task);
try
{
var value = await _dynamicCacheService.GetCachedValueAsync(cacheContext);
if (value == null)
{
// The value is not cached, we need to render the tag helper output
var processedContent = await output.GetChildContentAsync();
var stringBuilder = new StringBuilder();
using (var writer = new StringWriter(stringBuilder))
{
processedContent.WriteTo(writer, HtmlEncoder);
}
var formattingContext = new DistributedCacheTagHelperFormattingContext
{
Html = new HtmlString(stringBuilder.ToString())
};
await _dynamicCacheService.SetCachedValueAsync(cacheContext, formattingContext.Html.ToString());
content = formattingContext.Html;
}
else
{
content = new HtmlString(value);
}
}
catch
{
content = null;
throw;
}
finally
{
// Remove the worker task before setting the result.
// If the result is null, other threads would potentially
// acquire it otherwise.
_dynamicCacheTagHelperService.Workers.TryRemove(CacheId, out result);
// Notify all other awaiters to render the content
tcs.TrySetResult(content);
}
}
else
{
content = await result;
}
}
return(content);
}
/// <inheritdoc />
public async Task <IHtmlContent> ProcessContentAsync(TagHelperOutput output, CacheTagKey key, DistributedCacheEntryOptions options)
{
IHtmlContent content = null;
while (content == null)
{
// Is there any request already processing the value?
if (!_workers.TryGetValue(key, out var result))
{
// There is a small race condition here between TryGetValue and TryAdd that might cause the
// content to be computed more than once. We don't care about this race as the probability of
// happening is very small and the impact is not critical.
var tcs = new TaskCompletionSource <IHtmlContent>(creationOptions: TaskCreationOptions.RunContinuationsAsynchronously);
_workers.TryAdd(key, tcs.Task);
try
{
var serializedKey = Encoding.UTF8.GetBytes(key.GenerateKey());
var storageKey = key.GenerateHashedKey();
var value = await _storage.GetAsync(storageKey);
if (value == null)
{
// The value is not cached, we need to render the tag helper output
var processedContent = await output.GetChildContentAsync();
var stringBuilder = new StringBuilder();
using (var writer = new StringWriter(stringBuilder))
{
processedContent.WriteTo(writer, _htmlEncoder);
}
var formattingContext = new DistributedCacheTagHelperFormattingContext
{
Html = new HtmlString(stringBuilder.ToString())
};
// Then cache the result
value = await _formatter.SerializeAsync(formattingContext);
var encodeValue = Encode(value, serializedKey);
await _storage.SetAsync(storageKey, encodeValue, options);
content = formattingContext.Html;
}
else
{
// The value was found in the storage, decode and ensure
// there is no cache key hash collision
byte[] decodedValue = Decode(value, serializedKey);
try
{
if (decodedValue != null)
{
content = await _formatter.DeserializeAsync(decodedValue);
}
}
catch (Exception e)
{
_logger.DistributedFormatterDeserializationException(storageKey, e);
}
finally
{
// If the deserialization fails the content is rendered
if (content == null)
{
content = await output.GetChildContentAsync();
}
}
}
}
catch
{
content = null;
throw;
}
finally
{
// Remove the worker task before setting the result.
// If the result is null, other threads would potentially
// acquire it otherwise.
_workers.TryRemove(key, out result);
// Notify all other awaiters to render the content
tcs.TrySetResult(content);
}
}
else
{
content = await result;
}
}
return(content);
}
public async Task <IHtmlContent> ProcessContentAsync(TagHelperOutput output, CacheContext cacheContext)
{
IHtmlContent content = null;
while (content == null)
{
Task <IHtmlContent> result;
// Is there any request already processing the value?
if (!_dynamicCacheTagHelperService.Workers.TryGetValue(CacheId, out result))
{
// There is a small race condition here between TryGetValue and TryAdd that might cause the
// content to be computed more than once. We don't care about this race as the probability of
// happening is very small and the impact is not critical.
var tcs = new TaskCompletionSource <IHtmlContent>();
_dynamicCacheTagHelperService.Workers.TryAdd(CacheId, tcs.Task);
try
{
var value = await _dynamicCacheService.GetCachedValueAsync(cacheContext);
if (value == null)
{
// The value is not cached, we need to render the tag helper output
var processedContent = await output.GetChildContentAsync();
using (var sb = StringBuilderPool.GetInstance())
{
using (var writer = new StringWriter(sb.Builder))
{
// Write the start of a cache debug block.
if (_cacheOptions.DebugMode)
{
// No need to optimize this code as it will be used for debugging purpose.
writer.WriteLine();
writer.WriteLine($"<!-- CACHE BLOCK: {cacheContext.CacheId} ({Guid.NewGuid()})");
writer.WriteLine($" VARY BY: {String.Join(", ", cacheContext.Contexts)}");
writer.WriteLine($" DEPENDENCIES: {String.Join(", ", cacheContext.Tags)}");
writer.WriteLine($" EXPIRES ON: {cacheContext.ExpiresOn}");
writer.WriteLine($" EXPIRES AFTER: {cacheContext.ExpiresAfter}");
writer.WriteLine($" EXPIRES SLIDING: {cacheContext.ExpiresSliding}");
writer.WriteLine("-->");
}
// Always write the content regardless of debug mode.
processedContent.WriteTo(writer, HtmlEncoder);
// Write the end of a cache debug block.
if (_cacheOptions.DebugMode)
{
writer.WriteLine();
writer.WriteLine($"<!-- END CACHE BLOCK: {cacheContext.CacheId} -->");
}
await writer.FlushAsync();
}
var html = sb.Builder.ToString();
var formattingContext = new DistributedCacheTagHelperFormattingContext
{
Html = new HtmlString(html)
};
await _dynamicCacheService.SetCachedValueAsync(cacheContext, html);
content = formattingContext.Html;
}
}
else
{
content = new HtmlString(value);
}
}
catch
{
content = null;
throw;
}
finally
{
// Remove the worker task before setting the result.
// If the result is null, other threads would potentially
// acquire it otherwise.
_dynamicCacheTagHelperService.Workers.TryRemove(CacheId, out result);
// Notify all other awaiters to render the content
tcs.TrySetResult(content);
}
}
else
{
content = await result;
}
}
return(content);
}