//Main Operations
//Create Operation
public FileMetadata create(string filename, int numberOfDataServers, int readQuorum, int writeQuorum)
{
LogPrint("Create Operation");
LogPrint("\t Filename: " + filename + " Number of Data Servers: " + numberOfDataServers +
" ReadQuorum: " + readQuorum + " Write Quorum: " + writeQuorum);
if (!_isMaster)
{
FileMetadata fileToReturn = _metadataMasterActualProxy.create(filename, numberOfDataServers, readQuorum, writeQuorum);
LogPrint("Sucessfull!");
return fileToReturn;
}
lock (this)
{
//Verification if the file with this filename already exists, if it does, returns that file
if (_filesMetadata.ContainsKey(filename))
{
return _filesMetadata[filename];
}
//Associates this filename with a unique filename for local DataServer storage
string associatedFilename = generateFilenameForDataServers();
_dataServersAssociatedFilenames.Add(filename, associatedFilename);
//Creates an association between filename and a list with data servers to fill in
_localFilesDataServers.Add(associatedFilename, new List<string>());
//Association between dataServers and local filenames for the filename asked
List<Tuple<string, string>> dataServersLocalFilenames = new List<Tuple<string, string>>();
//Computation about who will have filename asked to create and store it in the dataServersLocalFilenames list
Dictionary<string, int> sortedDataServersNumberOfFiles = _dataServersNumberOfFiles.OrderBy(x => x.Value).ToDictionary(p => p.Key, q => q.Value);
int counter = 0;
foreach (string dataServerName in sortedDataServersNumberOfFiles.Keys)
{
_dataServersProxys[dataServerName].createFilename(associatedFilename);
_dataServersNumberOfFiles[dataServerName] = _dataServersNumberOfFiles[dataServerName] + 1;
_localFilesDataServers[associatedFilename].Add(dataServerName);
dataServersLocalFilenames.Add(new Tuple<string, string>(_dataServersURLS[dataServerName], associatedFilename));
if (++counter == numberOfDataServers)
break;
}
// If there are missing DataServers to associate to this file, it creates a task for it (which include the number of DataServers missing to associate to this file)
// and it will be executed when appropriate
if (counter < numberOfDataServers)
{
_filesWithMissingDataServers.Add(filename, numberOfDataServers - counter);
}
FileMetadata newFileMetadata = new FileMetadata(filename, numberOfDataServers, readQuorum, writeQuorum, dataServersLocalFilenames);
_filesMetadata.Add(filename, newFileMetadata);
//Update replicas
if (_isMaster)
updateMetadataServerReplicas();
LogPrint("Sucessfull!");
return newFileMetadata;
}
}
private void saveFileMetadata(FileMetadata fileMetadata)
{
_filesInfo[_registerPosition] = new Tuple<FileMetadata, PADI_FS_Library.File>(fileMetadata,null);
if (++_registerPosition == numberOfRegisters)
_registerPosition = 0;
}
