public static void WriteBlock(this FileStream fileStream, Block block)
{
if (fileStream.Length < block.ThisPos)
{
fileStream.SetLength(block.ThisPos);
}
fileStream.Seek(block.ThisPos, SeekOrigin.Begin);
Consts.formatter.Serialize(fileStream, block);
BlockCache.TryRemoveFloatingBlock(block); // 如果是new Block()，需要在此时从floating列表移除
BlockCache.AddSunkBlock(block); // 如果是new Block()，需要在此时加入sunk字典
}
/// <summary>
/// 创建初始状态的数据库文件。
/// </summary>
/// <param name="fullname">数据库文件据对路径。</param>
/// <param name="config">数据库配置信息。</param>
private void CreateDB(string fullname, DBConfig config)
{
FileInfo fileInfo = new FileInfo(fullname);
Directory.CreateDirectory(fileInfo.DirectoryName);
using (FileStream fs = new FileStream(fullname, FileMode.CreateNew, FileAccess.Write, FileShare.None, Consts.pageSize))
{
PageHeaderBlock page = new PageHeaderBlock()
{
OccupiedBytes = Consts.pageSize, AvailableBytes = 0,
};
fs.WriteBlock(page);
DBHeaderBlock dbHeader = new DBHeaderBlock()
{
MaxLevelOfSkipList = config.MaxLevelOfSkipList, ProbabilityOfSkipList = config.ProbabilityOfSkipList, MaxSunkCountInMemory = config.MaxSunkCountInMemory, LockTimeout = config.LockTimeout, ThisPos = fs.Position
};
fs.WriteBlock(dbHeader);
TableBlock tableHead = new TableBlock()
{
ThisPos = fs.Position,
};
fs.WriteBlock(tableHead);
byte[] leftSpace = new byte[Consts.pageSize - fs.Length];
fs.Write(leftSpace, 0, leftSpace.Length);
BlockCache.TryRemoveFloatingBlock(page);
BlockCache.TryRemoveFloatingBlock(dbHeader);
BlockCache.TryRemoveFloatingBlock(tableHead);
BlockCache.TryRemoveSunkBlock(page);
BlockCache.TryRemoveSunkBlock(dbHeader);
BlockCache.TryRemoveSunkBlock(tableHead);
}
}
/// <summary>
/// 系统启动时初始化各项常量。
/// </summary>
static Consts()
{
{
PropertyInfo[] properties = typeof(Table).GetProperties();
foreach (var property in properties)
{
TableIndexAttribute attr = property.GetCustomAttribute <TableIndexAttribute>();
if (attr != null && property.PropertyType == typeof(ObjectId))
{
Consts.TableIdString = property.Name;
break;
}
}
}
{
PageHeaderBlock page = new PageHeaderBlock();
using (MemoryStream ms = new MemoryStream())
{
formatter.Serialize(ms, page);
if (ms.Length > Consts.pageSize / 10)
{
throw new Exception("Page header block takes too much space!");
}
Consts.pageHeaderBlockLength = (Int16)ms.Length;
Consts.maxAvailableSpaceInPage = (Int16)(Consts.pageSize - ms.Length);
Consts.minOccupiedBytes = (Int16)(Consts.pageSize - Consts.maxAvailableSpaceInPage);
}
BlockCache.TryRemoveFloatingBlock(page);
}
{
PageHeaderBlock page = new PageHeaderBlock();
DBHeaderBlock dbHeader = new DBHeaderBlock();
TableBlock tableHead = new TableBlock();
Int16 usedSpaceInFirstPage;
using (MemoryStream ms = new MemoryStream())
{
formatter.Serialize(ms, page);
dbHeader.ThisPos = ms.Length;
formatter.Serialize(ms, dbHeader);
tableHead.ThisPos = ms.Length;
Consts.dbHeaderBlockLength = (Int16)(ms.Length - Consts.pageHeaderBlockLength);
formatter.Serialize(ms, tableHead);
Consts.tableBlockLength = (Int16)(ms.Length - tableHead.ThisPos);
usedSpaceInFirstPage = (Int16)ms.Length;
}
if (usedSpaceInFirstPage > Consts.pageSize)
{
throw new Exception("First page is full!");
}
BlockCache.TryRemoveFloatingBlock(page);
BlockCache.TryRemoveFloatingBlock(dbHeader);
BlockCache.TryRemoveFloatingBlock(tableHead);
}
{
IndexBlock block = new IndexBlock();
int length = block.ToBytes().Length;
if (length > Consts.pageSize / 10)
{
throw new Exception("index block takes too much space!");
}
Consts.indexBlockLength = (Int16)length;
BlockCache.TryRemoveFloatingBlock(block);
}
{
SkipListNodeBlock block = new SkipListNodeBlock();
int length = block.ToBytes().Length;
if (length > Consts.pageSize / 10)
{
throw new Exception("index block takes too much space!");
}
Consts.skipListNodeBlockLength = (Int16)length;
BlockCache.TryRemoveFloatingBlock(block);
}
{
PageHeaderBlock page = new PageHeaderBlock();
DataBlock dataBlock = new DataBlock();
dataBlock.Data = new byte[0];
Int16 minValue;
using (MemoryStream ms = new MemoryStream())
{
formatter.Serialize(ms, page);
long pos = ms.Length;
formatter.Serialize(ms, dataBlock);
Consts.dataBlockLength = (Int16)(ms.Length - pos);
if (ms.Length > Consts.pageSize / 10)
{
throw new Exception("data block's metadata takes too much space!");
}
minValue = (Int16)ms.Length;
}
Consts.maxDataBytes = (Int16)(Consts.pageSize - minValue);
BlockCache.TryRemoveFloatingBlock(page);
BlockCache.TryRemoveFloatingBlock(dataBlock);
}
}
