private FetchCacheEntry ( |
||
fetchEntry | ||
Результат | void |
// // Private methods // // // This method may be invoked as part of the request submission but before issuing a live request // private void CheckRetrieveBeforeSubmit() { GlobalLog.Assert(_ProtocolStatus == CacheValidationStatus.Continue, "CheckRetrieveBeforeSubmit()|Unexpected _ProtocolStatus = {0}", _ProtocolStatus); try { while (true) { RequestCacheEntry cacheEntry; if (_Validator.CacheStream != null && _Validator.CacheStream != Stream.Null) { // Reset to Initial state _Validator.CacheStream.Close(); _Validator.CacheStream = Stream.Null; } if (_Validator.StrictCacheErrors) { _Validator.CacheStream = _RequestCache.Retrieve(_Validator.CacheKey, out cacheEntry); } else { Stream stream; _RequestCache.TryRetrieve(_Validator.CacheKey, out cacheEntry, out stream); _Validator.CacheStream = stream; } if (cacheEntry == null) { cacheEntry = new RequestCacheEntry(); cacheEntry.IsPrivateEntry = _RequestCache.IsPrivateCache; _Validator.FetchCacheEntry(cacheEntry); } if (_Validator.CacheStream == null) { // If entry does not have a stream an empty stream wrapper must be returned. // A null or Stream.Null value stands for non existent cache entry. _Validator.CacheStream = Stream.Null; } ValidateFreshness(cacheEntry); _ProtocolStatus = ValidateCache(); // This will tell us what to do next switch (_ProtocolStatus) { case CacheValidationStatus.ReturnCachedResponse: if (_Validator.CacheStream == null || _Validator.CacheStream == Stream.Null) { if (Logging.On) { Logging.PrintError(Logging.RequestCache, SR.GetString(SR.net_log_cache_no_cache_entry, "ValidateCache()")); } _ProtocolStatus = CacheValidationStatus.Fail; _ProtocolException = new InvalidOperationException(SR.GetString(SR.net_cache_no_stream, _Validator.CacheKey)); break; } // Final decision is made, check on a range response from cache Stream stream = _Validator.CacheStream; // The entry can now be replaced as we are not going for cache entry metadata-only update _RequestCache.UnlockEntry(_Validator.CacheStream); if (_Validator.CacheStreamOffset != 0L || _Validator.CacheStreamLength != _Validator.CacheEntry.StreamSize) { stream = new RangeStream(stream, _Validator.CacheStreamOffset, _Validator.CacheStreamLength); if (Logging.On) { Logging.PrintInfo(Logging.RequestCache, SR.GetString(SR.net_log_cache_returned_range_cache, "ValidateCache()", _Validator.CacheStreamOffset, _Validator.CacheStreamLength)); } } _ResponseStream = stream; _ResponseStreamLength = _Validator.CacheStreamLength; break; case CacheValidationStatus.Continue: // copy a cache stream ref _ResponseStream = _Validator.CacheStream; break; case CacheValidationStatus.RetryResponseFromCache: // loop thought cache retrieve continue; case CacheValidationStatus.DoNotTakeFromCache: case CacheValidationStatus.DoNotUseCache: break; case CacheValidationStatus.Fail: _ProtocolException = new InvalidOperationException(SR.GetString(SR.net_cache_validator_fail, "ValidateCache")); break; default: _ProtocolStatus = CacheValidationStatus.Fail; _ProtocolException = new InvalidOperationException(SR.GetString(SR.net_cache_validator_result, "ValidateCache", _Validator.ValidationStatus.ToString())); if (Logging.On) { Logging.PrintError(Logging.RequestCache, SR.GetString(SR.net_log_cache_unexpected_status, "ValidateCache()", _Validator.ValidationStatus.ToString())); } break; } break; } } catch (Exception e) { _ProtocolStatus = CacheValidationStatus.Fail; _ProtocolException = e; if (e is ThreadAbortException || e is StackOverflowException || e is OutOfMemoryException) { throw; } if (Logging.On) { Logging.PrintError(Logging.RequestCache, SR.GetString(SR.net_log_cache_object_and_exception, "CacheProtocol#" + this.GetHashCode().ToString(NumberFormatInfo.InvariantInfo), (e is WebException? e.Message: e.ToString()))); } } finally { // This is to release cache entry on error if (_ResponseStream == null && _Validator.CacheStream != null && _Validator.CacheStream != Stream.Null) { _Validator.CacheStream.Close(); _Validator.CacheStream = Stream.Null; } } }