/// <summary>
/// Reads the operation from the specified position in the log.
/// </summary>
/// <param name="resource">The parent <see cref="ITransactedResource" /> responsible for deserializing the operation.</param>
/// <param name="position">See the <see cref="ILogPosition" />.</param>
/// <returns>The <see cref="IOperation" /> read from the log.</returns>
public IOperation Read(ITransactedResource resource, ILogPosition position)
{
int cb;
long recEndPos;
string description;
IOperation operation;
using (TimedLock.Lock(this))
{
if (file == null)
{
throw new TransactionException(ClosedMsg);
}
file.Position = ((FileLogPosition)position).Position;
if (file.ReadInt32() != Magic)
{
throw new TransactionException(CorruptMsg);
}
cb = file.ReadInt32();
if (cb <= 0 || cb + file.Position > file.Length)
{
throw new TransactionException(CorruptMsg);
}
recEndPos = file.Position + cb;
description = file.ReadString32();
operation = resource.ReadOperation(file);
if (file.Position != recEndPos)
{
SysLog.LogWarning("ITransactedResource.ReadOperation() returned with an unexpected stream position.");
file.Position = recEndPos;
}
return(operation);
}
}
/// <summary>
/// Loads the cache index file.
/// </summary>
private void LoadIndex()
{
var indexPath = Path.Combine(settings.PhraseCacheFolder, IndexFileName);
try
{
if (!File.Exists(indexPath))
{
// No index exists yet, so create an empty one.
SaveIndex(false);
return;
}
using (var fs = new EnhancedFileStream(indexPath, FileMode.Open))
{
int count;
if (fs.ReadInt32() != Magic)
{
throw new SwitchException("[PhraseCache] cannot read index file [{0}] due to an invalid magic number. The existing cache will be purged.", indexPath);
}
count = fs.ReadInt32();
for (int i = 0; i < count; i++)
{
string text;
string voice;
string actualVoice;
PhraseType phraseType;
TtsEncoding encoding;
TtsSampleRate rate;
DateTime lastAccessUtc;
string path;
Phrase phrase;
phraseType = (PhraseType)Enum.Parse(typeof(PhraseType), fs.ReadString16());
text = fs.ReadString32();
voice = fs.ReadString16();
actualVoice = fs.ReadString16();
encoding = (TtsEncoding)Enum.Parse(typeof(TtsEncoding), fs.ReadString16());
rate = (TtsSampleRate)Enum.Parse(typeof(TtsSampleRate), fs.ReadString16());
lastAccessUtc = new DateTime(fs.ReadInt64());
path = fs.ReadString16();
phrase = new Phrase(phraseType, voice, encoding, rate, text)
{
Path = path,
ActualVoice = actualVoice,
LastAccessUtc = lastAccessUtc,
};
index[GetCacheKey(phrase)] = phrase;
}
}
}
catch (Exception e)
{
// We're going to handle all exceptions leaving the loaded phrase
// table empty. This will have the effect of starting the cache
// from scratch. Eventually, all of the existing files will be
// purged and the presumably bad index file will be overwritten.
index.Clear();
SysLog.LogException(e);
}
}