internal static SharedFile LoadFile(string filePath, SharedFileMetaData metaData, byte[] blockAvailable, SharedFileState state, SynchronizationContext syncCxt)
{
//check if file already shared
lock (_sharedFiles)
{
SharedFile sharedFile;
if (_sharedFiles.ContainsKey(metaData.FileID))
{
sharedFile = _sharedFiles[metaData.FileID];
}
else
{
if (state == SharedFileState.Advertisement)
{
sharedFile = new SharedFile(null, metaData, new byte[metaData.BlockHash.Length], 0, syncCxt);
_sharedFiles.Add(metaData.FileID, sharedFile);
sharedFile._state = SharedFileState.Advertisement;
}
else
{
int availableBlocksCount = 0;
for (int i = 0; i < blockAvailable.Length; i++)
{
if (blockAvailable[i] == FILE_BLOCK_AVAILABLE)
{
availableBlocksCount++;
}
}
FileStream fS;
if (blockAvailable.Length == availableBlocksCount)
{
fS = new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.Read);
}
else
{
fS = new FileStream(filePath, FileMode.Open, FileAccess.ReadWrite);
}
sharedFile = new SharedFile(fS, metaData, blockAvailable, availableBlocksCount, syncCxt);
_sharedFiles.Add(metaData.FileID, sharedFile);
sharedFile._state = SharedFileState.Paused;
if (state != SharedFileState.Paused)
{
sharedFile.Start();
}
}
}
return(sharedFile);
}
}
private SharedFile(FileStream fS, SharedFileMetaData metaData, byte[] blockAvailable, int availableBlocksCount, SynchronizationContext syncCxt)
{
_fileStream = fS;
_metaData = metaData;
_blockAvailable = blockAvailable;
_availableBlocksCount = availableBlocksCount;
_syncCxt = syncCxt;
_isComplete = (_blockAvailable.Length == _availableBlocksCount);
}
internal static SharedFile PrepareDownloadFile(SharedFileMetaData metaData, SynchronizationContext syncCxt)
{
//check if file already exists
lock (_sharedFiles)
{
SharedFile sharedFile;
if (_sharedFiles.ContainsKey(metaData.FileID))
{
sharedFile = _sharedFiles[metaData.FileID];
}
else
{
sharedFile = new SharedFile(null, metaData, new byte[metaData.BlockHash.Length], 0, syncCxt);
_sharedFiles.Add(metaData.FileID, sharedFile);
}
return(sharedFile);
}
}
internal static SharedFile ShareFile(string filePath, string hashAlgo, SynchronizationContext syncCxt)
{
FileStream fS = new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.Read);
HashAlgorithm hash = HashAlgorithm.Create(hashAlgo);
int hashSize = hash.HashSize / 8;
//calculate block size
int blockSize;
{
int totalBlocksPossible = BUFFER_SIZE / hashSize;
blockSize = Convert.ToInt32(fS.Length / totalBlocksPossible);
if (blockSize < FILE_BLOCK_MINIMUM_SIZE)
{
blockSize = FILE_BLOCK_MINIMUM_SIZE;
}
else
{
//align to 16 bytes
int remainder = blockSize % 16;
if (remainder > 0)
{
blockSize = blockSize - remainder + 16;
}
}
}
//compute block hashes and file info hash
int totalBlocks = Convert.ToInt32(Math.Ceiling(Convert.ToDouble((double)fS.Length / blockSize)));
byte[][] blockHash = new byte[totalBlocks][];
byte[] blockAvailable = new byte[totalBlocks];
//init
for (int i = 0; i < totalBlocks; i++)
{
long offset = i * blockSize;
long length = blockSize;
if ((offset + length) > fS.Length)
{
length = fS.Length - offset;
}
blockHash[i] = hash.ComputeHash(new OffsetStream(fS, offset, length));
blockAvailable[i] = FILE_BLOCK_AVAILABLE;
}
//get file meta data
SharedFileMetaData metaData = new SharedFileMetaData(Path.GetFileName(fS.Name), WebUtilities.GetContentType(fS.Name), File.GetLastWriteTimeUtc(fS.Name), fS.Length, blockSize, hashAlgo, blockHash);
//check if file already shared
lock (_sharedFiles)
{
SharedFile sharedFile;
if (_sharedFiles.ContainsKey(metaData.FileID))
{
sharedFile = _sharedFiles[metaData.FileID];
if (sharedFile._isComplete)
{
//close the file and do nothing
fS.Dispose();
}
else
{
//since the current shared file is incomplete and we are adding a complete shared file copy
//stop current download process
sharedFile.Pause();
sharedFile._fileStream.Dispose();
//update the current object with new file data
sharedFile._fileStream = fS;
sharedFile._blockAvailable = blockAvailable;
sharedFile._availableBlocksCount = blockAvailable.Length;
sharedFile._isComplete = true;
//start sharing new file
sharedFile.StartSharing();
}
}
else
{
sharedFile = new SharedFile(fS, metaData, blockAvailable, blockAvailable.Length, syncCxt);
sharedFile.StartSharing();
_sharedFiles.Add(metaData.FileID, sharedFile);
}
return(sharedFile);
}
}
