//Read Operation
public string read(int fileRegister, string semantics, int stringRegister)
{
//Read variables restore
_readResponses = 0;
_readFilesResponses = new List<PADI_FS_Library.File>();
// Variables for retry (monotonic)
Boolean _success = false;
int _retry = 3;
LogPrint("Read Operation");
LogPrint("\tFile Register: " + fileRegister + " Semantics: " + semantics + " String Register: " + stringRegister);
FileMetadata fileMetadataToRead;
//if the file register to read is null (that is, if that file does not exists in the client) sends an exception
if (_filesInfo[fileRegister] != null)
{
fileMetadataToRead = _filesInfo[fileRegister].Item1;
}
else throw new Exception("Registo na posicao " + fileRegister + " nao existe");
//if data servers with this file is smaller than the read quorum do REOPEN
while (_filesInfo[fileRegister].Item1.FileDataServersLocations.Count < _filesInfo[fileRegister].Item1.ReadQuorum)
{
FileMetadata fileMetadataToReopen = null;
Tuple<string, MetadataServerInterface> aliveMetadataServerMaster = isAnyoneAlive();
while (aliveMetadataServerMaster == null)
aliveMetadataServerMaster = isAnyoneAlive();
//Someone (MetadataServer) is alive (no matter who - it wont be null)
if (aliveMetadataServerMaster != null) //just to check xD
{
MetadataServerInterface aliveMetadataServerMasterInterface = aliveMetadataServerMaster.Item2;
fileMetadataToReopen = aliveMetadataServerMasterInterface.open(_filesInfo[fileRegister].Item1.Filename);
_filesInfo[fileRegister] = new Tuple<FileMetadata, PADI_FS_Library.File>(fileMetadataToReopen, _filesInfo[fileRegister].Item2);
}
}
fileMetadataToRead = _filesInfo[fileRegister].Item1;
while (_retry > 0)
{
//Call every Data Server that contains the file
foreach (Tuple<string, string> fileDataServerLocation in fileMetadataToRead.FileDataServersLocations)
{
DataServerInterface dataServerProxy = (DataServerInterface)Activator.GetObject(
typeof(DataServerInterface),
fileDataServerLocation.Item1);
// Alternative 2: asynchronous call with callback
// Create delegate to remote method
RemoteAsyncGetFileDelegate RemoteDel = new RemoteAsyncGetFileDelegate(dataServerProxy.read);
// Create delegate to local callback
AsyncCallback RemoteCallback = new AsyncCallback(this.GetFileRemoteAsyncCallBack);
// Call remote method
IAsyncResult RemAr = RemoteDel.BeginInvoke(fileDataServerLocation.Item2, semantics, RemoteCallback, null);
}
//Waits for a quorum of Read Responses
while (_readResponses < fileMetadataToRead.ReadQuorum)
{
continue;
}
//After getting a quorum decides what to save (the most recent version of the files obtained)
int counter = 0;
int version = -1;
PADI_FS_Library.File fileToSave = null;
foreach (PADI_FS_Library.File fileRead in _readFilesResponses)
{
if (counter == fileMetadataToRead.ReadQuorum)
break;
if (fileRead.VersionNumber >= version)
{
version = fileRead.VersionNumber;
fileToSave = fileRead;
}
counter++;
}
//fileToSave = null problem (maybe because someone deleted the file in the exact moment this client was going to read it, etc)
if (fileToSave == null)
{
LogPrint("Not Sucessfull!");
throw new FileDoesntExistException(_filesInfo[fileRegister].Item1.Filename);
}
else
{
//Array registers update - monotonic and default
if (semantics.Equals("monotonic"))
{
if (_filesInfo[fileRegister].Item2 == null || fileToSave.VersionNumber >= _filesInfo[fileRegister].Item2.VersionNumber)
{
_filesInfo[fileRegister] = new Tuple<FileMetadata, PADI_FS_Library.File>(_filesInfo[fileRegister].Item1, fileToSave);
_stringRegister[stringRegister] = fileToSave.FileContents;
_success = true;
_retry = 0;
}
else _retry--;
}
else if (semantics.Equals("default"))
{
_filesInfo[fileRegister] = new Tuple<FileMetadata, PADI_FS_Library.File>(_filesInfo[fileRegister].Item1, fileToSave);
_stringRegister[stringRegister] = fileToSave.FileContents;
_success = true;
_retry = 0;
}
else throw new Exception("Unknown Semantics");
}
if(!_success)
LogPrint("Version too old, retrying...");
}
if (!_success)
return ("Unable to fetch a recent version. Aborting");
LogPrint("File Read Contents: " + _stringRegister[stringRegister]);
LogPrint("Sucessful!");
return "" + _filesInfo[fileRegister].Item2.FileContents + " || " + "Version: " + _filesInfo[fileRegister].Item2.VersionNumber;
}
// Copy Operation
public string copy(int sourceFileRegister, string semantics, int destinFileRegister, byte[] salt)
{
string saltString = System.Text.Encoding.Default.GetString(salt);
LogPrint("Copy Operation");
LogPrint("\t Source File Register: " + sourceFileRegister + " Destination File Register: " + destinFileRegister +
" Semantics: " + semantics + " Salt: " + saltString);
//Read variables restore
_readResponses = 0;
_readFilesResponses = new List<PADI_FS_Library.File>();
// Variables for retry (monotonic)
Boolean _success = false;
int _retry = 3;
FileMetadata fileMetadataToRead;
string contentToWrite;
PADI_FS_Library.File fileToSave = null;
//if the file register to read is null (that is, if that file does not exists in the client) sends an exception
if (_filesInfo[sourceFileRegister] != null)
{
fileMetadataToRead = _filesInfo[sourceFileRegister].Item1;
}
else throw new Exception("Registo na posicao " + sourceFileRegister + " nao existe");
//if data servers with this file is smaller than the read quorum do REOPEN
while (_filesInfo[sourceFileRegister].Item1.FileDataServersLocations.Count < _filesInfo[sourceFileRegister].Item1.ReadQuorum)
{
LogPrint("\t!!!REOPEN FILE!!!");
FileMetadata fileMetadataToReopen = null;
Tuple<string, MetadataServerInterface> aliveMetadataServerMaster = isAnyoneAlive();
while (aliveMetadataServerMaster == null)
aliveMetadataServerMaster = isAnyoneAlive();
//Someone (MetadataServer) is alive (no matter who - it wont be null)
if (aliveMetadataServerMaster != null) //just to check xD
{
MetadataServerInterface aliveMetadataServerMasterInterface = aliveMetadataServerMaster.Item2;
fileMetadataToReopen = aliveMetadataServerMasterInterface.open(_filesInfo[sourceFileRegister].Item1.Filename);
_filesInfo[sourceFileRegister] = new Tuple<FileMetadata, PADI_FS_Library.File>(fileMetadataToReopen, _filesInfo[sourceFileRegister].Item2);
}
}
fileMetadataToRead = _filesInfo[sourceFileRegister].Item1;
while (_retry > 0)
{
//Call every Data Server that contains the file
foreach (Tuple<string, string> fileDataServerLocation in fileMetadataToRead.FileDataServersLocations)
{
DataServerInterface dataServerProxy = (DataServerInterface)Activator.GetObject(
typeof(DataServerInterface),
fileDataServerLocation.Item1);
// Alternative 2: asynchronous call with callback
// Create delegate to remote method
RemoteAsyncGetFileDelegate RemoteDel = new RemoteAsyncGetFileDelegate(dataServerProxy.read);
// Create delegate to local callback
AsyncCallback RemoteCallback = new AsyncCallback(this.GetFileRemoteAsyncCallBack);
// Call remote method
IAsyncResult RemAr = RemoteDel.BeginInvoke(fileDataServerLocation.Item2, semantics, RemoteCallback, null);
}
//Waits for a quorum of Read Responses
while (_readResponses < fileMetadataToRead.ReadQuorum)
{
continue;
}
//After getting a quorum decides what to save (the most recent version of the files obtained)
int counter = 0;
int version = -1;
foreach (PADI_FS_Library.File fileRead in _readFilesResponses)
{
if (counter == fileMetadataToRead.ReadQuorum)
break;
if (fileRead.VersionNumber >= version)
{
version = fileRead.VersionNumber;
fileToSave = fileRead;
}
counter++;
}
//fileToSave = null problem (maybe because someone deleted the file in the exact moment this client was going to read it, etc)
if (fileToSave == null)
{
LogPrint("Not Sucessfull!");
throw new FileDoesntExistException(_filesInfo[sourceFileRegister].Item1.Filename);
}
else
{
//Array registers update - monotonic and default
if (semantics.Equals("monotonic"))
{
if (_filesInfo[sourceFileRegister].Item2 == null || fileToSave.VersionNumber >= _filesInfo[sourceFileRegister].Item2.VersionNumber)
{
_filesInfo[sourceFileRegister] = new Tuple<FileMetadata, PADI_FS_Library.File>(_filesInfo[sourceFileRegister].Item1, fileToSave);
_success = true;
_retry = 0;
}
else _retry--;
}
else if (semantics.Equals("default"))
{
_filesInfo[sourceFileRegister] = new Tuple<FileMetadata, PADI_FS_Library.File>(_filesInfo[sourceFileRegister].Item1, fileToSave);
_success = true;
_retry = 0;
}
else throw new Exception("Unknown Semantics");
}
if (!_success)
LogPrint("Version too old, retrying...");
}
if (!_success)
return ("Unable to fetch a recent version. Aborting");
contentToWrite = fileToSave.FileContents + saltString;
//Write variables restore
_writeResponses = 0;
_writeOperationSucedded = true;
PADI_FS_Library.File fileToWrite = _filesInfo[destinFileRegister].Item2;
//if the file register to write is null (that is, if that file does not exists in the client) then
//the version number used to write will be 0, otherwise it will be the version number of the existing file plus one
int versionNumberToWrite = 1;
FileMetadata fileMetadataToWrite;
if (fileToWrite != null)
versionNumberToWrite = fileToWrite.VersionNumber + 1;
fileMetadataToWrite = _filesInfo[destinFileRegister].Item1;
//if data servers with this file is smaller than the write quorum do REOPEN
while (_filesInfo[destinFileRegister].Item1.FileDataServersLocations.Count < _filesInfo[destinFileRegister].Item1.WriteQuorum)
{
FileMetadata fileMetadataToReopen = null;
Tuple<string, MetadataServerInterface> aliveMetadataServerMaster = isAnyoneAlive();
while (aliveMetadataServerMaster == null)
aliveMetadataServerMaster = isAnyoneAlive();
//Someone (MetadataServer) is alive (no matter who - it wont be null)
if (aliveMetadataServerMaster != null) //just to check xD
{
MetadataServerInterface aliveMetadataServerMasterInterface = aliveMetadataServerMaster.Item2;
fileMetadataToReopen = aliveMetadataServerMasterInterface.open(_filesInfo[destinFileRegister].Item1.Filename);
_filesInfo[destinFileRegister] = new Tuple<FileMetadata, PADI_FS_Library.File>(fileMetadataToReopen, _filesInfo[destinFileRegister].Item2);
}
}
fileMetadataToWrite = _filesInfo[destinFileRegister].Item1;
//Call every Data Server that contains the file
foreach (Tuple<string, string> fileDataServerLocation in fileMetadataToWrite.FileDataServersLocations)
{
DataServerInterface dataServerProxy = (DataServerInterface)Activator.GetObject(
typeof(DataServerInterface),
fileDataServerLocation.Item1);
// Alternative 2: asynchronous call with callback
// Create delegate to remote method
RemoteAsyncWriteFileDelegate RemoteDel = new RemoteAsyncWriteFileDelegate(dataServerProxy.write);
// Create delegate to local callback
AsyncCallback RemoteCallback = new AsyncCallback(this.WriteFileRemoteAsyncCallBack);
// Call remote method
IAsyncResult RemAr = RemoteDel.BeginInvoke(fileDataServerLocation.Item2, versionNumberToWrite, contentToWrite, RemoteCallback, null);
}
//Waits for a quorum of Write Responses
while (_writeResponses < fileMetadataToWrite.WriteQuorum) //ESTA A HAVER PROBLEMAS AQUI ???
{
continue;
}
if (_writeOperationSucedded == false)
{
LogPrint("Not Sucessfull!");
throw new FileDoesntExistException(_filesInfo[destinFileRegister].Item1.Filename);
}
//Updates local registers (not really necessary because before any write the client has to make a read)
//Info: They arent updated if file didnt exist before
if (fileToWrite == null)
{
PADI_FS_Library.File newFile = new PADI_FS_Library.File(fileMetadataToWrite.Filename, contentToWrite, versionNumberToWrite);
_filesInfo[destinFileRegister] = new Tuple<FileMetadata, PADI_FS_Library.File>(fileMetadataToWrite, newFile);
}
else
{
_filesInfo[destinFileRegister].Item2.VersionNumber = versionNumberToWrite;
_filesInfo[destinFileRegister].Item2.FileContents = contentToWrite;
}
LogPrint("Sucessful!");
return contentToWrite;
}