public IFile RegisterFile(IFile file)
{
cacheLock.EnterWriteLock();
try
{
var blockId = file.BlockId;
if (openedFiles.TryGetValue(blockId, out var fileWithRefCount))
{
var existingFile = Volatile.Read(ref fileWithRefCount.File);
if (existingFile != null)
{
throw new InvalidOperationException($"File with blockId = {file.BlockId} has already been registered");
}
}
fileWithRefCount = new FileWithRefCount
{
File = file,
RefCount = 1
};
openedFiles[blockId] = fileWithRefCount;
return(file);
}
finally
{
cacheLock.ExitWriteLock();
}
}
public IFile ReadFile(int blockId, Func <IFile> readFile)
{
cacheLock.EnterUpgradeableReadLock();
try
{
if (openedFiles.TryGetValue(blockId, out var fileWithRefCount))
{
var file = Volatile.Read(ref fileWithRefCount.File);
if (file != null)
{
Interlocked.Increment(ref fileWithRefCount.RefCount);
return(fileWithRefCount.File);
}
}
cacheLock.EnterWriteLock();
try
{
if (openedFiles.TryGetValue(blockId, out fileWithRefCount))
{
var file = Volatile.Read(ref fileWithRefCount.File);
if (file != null)
{
Interlocked.Increment(ref fileWithRefCount.RefCount);
return(fileWithRefCount.File);
}
}
fileWithRefCount = new FileWithRefCount
{
File = readFile(),
RefCount = 1
};
openedFiles.Add(blockId, fileWithRefCount);
return(fileWithRefCount.File);
}
finally
{
cacheLock.ExitWriteLock();
}
}
finally
{
cacheLock.ExitUpgradeableReadLock();
}
}
