public static IList <AllocatedSpace> Alloc(this FileDBContext db, long length, AllocPageTypes type)
{
// 由于一页能用的空间很有限，所以可能需要从多个页上获取空间。
IList <AllocatedSpace> result = new List <AllocatedSpace>();
FileStream fs = db.fileStream;
long allocated = 0;
while (allocated < length)
{
Int16 partLength = (length - allocated >= Consts.maxAvailableSpaceInPage) ? Consts.maxAvailableSpaceInPage : (Int16)(length - allocated);
// 找出一个可用空间充足的指定类型的页。
PageHeaderBlock page = PickPage(db, partLength, type);
if (!db.transaction.affectedPages.ContainsKey(page.ThisPos))// 加入缓存备用。
{
db.transaction.affectedPages.Add(page.ThisPos, page);
}
AllocatedSpace item = new AllocatedSpace(page.ThisPos + Consts.pageSize - page.AvailableBytes - partLength, (Int16)length);
result.Add(item);
allocated += partLength;
}
return(result);
}
/// <summary>
/// 申请一个空白页或新页。
/// </summary>
/// <param name="db"></param>
/// <returns></returns>
private static PageHeaderBlock AllocEmptyPageOrNewPage(this FileDBContext db)
{
PageHeaderBlock page;
FileStream fs = db.fileStream;
DBHeaderBlock dbHeader = db.headerBlock;
long emptyPagePos = dbHeader.FirstEmptyPagePos;
if (emptyPagePos != 0)// 存在空白页，则使用此空白页。
{
PageHeaderBlock emptyPage = fs.ReadBlock <PageHeaderBlock>(emptyPagePos);
// 从链表中去掉此空白页。
dbHeader.FirstEmptyPagePos = emptyPage.NextPagePos;
emptyPage.NextPagePos = 0;
page = emptyPage;
}
else// 没有空白页，则拓展数据库文件，增加一个页的长度。
{
PageHeaderBlock newPage = new PageHeaderBlock();
newPage.ThisPos = fs.Length;
newPage.OccupiedBytes = (Int16)(Consts.pageSize - Consts.maxAvailableSpaceInPage);
newPage.AvailableBytes = Consts.maxAvailableSpaceInPage;
fs.SetLength(fs.Length + Consts.pageSize);
page = newPage;
}
return(page);
}
private static void SortPage(AllocPageTypes type, PageHeaderBlock page, FileStream fs, Transaction ts, Blocks.DBHeaderBlock dbHeader)
{
long headPos = dbHeader.GetPosOfFirstPage(type);
if (headPos == 0)// 一个页也没有。
{
dbHeader.SetPosOfFirstPage(type, page.ThisPos);
}
else
{
PageHeaderBlock head = GetPageHeaderBlock(fs, ts, headPos);
if (page.AvailableBytes >= head.AvailableBytes)// 与第一个页进行比较。
{
page.NextPagePos = head.ThisPos;
dbHeader.SetPosOfFirstPage(type, page.ThisPos);
}
else// 与后续的页进行比较。
{
PageHeaderBlock current = head;
while (current.NextPagePos != 0)
{
PageHeaderBlock next = GetPageHeaderBlock(fs, ts, current.NextPagePos);
if (page.AvailableBytes >= next.AvailableBytes)
{
if (next.ThisPos != current.NextPagePos)
{
throw new Exception(string.Format("this should not happen."));
}
page.NextPagePos = current.NextPagePos; // next.ThisPos;
current.NextPagePos = page.ThisPos;
break;
}
else
{
current = next;
}
}
if (current.NextPagePos == 0)
{
current.NextPagePos = page.ThisPos;
}
if (!ts.affectedPages.ContainsKey(current.ThisPos))
{
ts.affectedPages.Add(current.ThisPos, current);
}
}
}
}
private static PageHeaderBlock PickPage(this FileDBContext db, Int16 allocatingLength, AllocPageTypes type)
{
PageHeaderBlock page;
FileStream fs = db.fileStream;
Transaction ts = db.transaction;
DBHeaderBlock dbHeader = db.headerBlock;
// 找到第一个给定类型的页的位置。
long pagePos = dbHeader.GetPosOfFirstPage(type);
if (pagePos == 0)// 尚无给定类型的页。
{
page = db.AllocEmptyPageOrNewPage();
page.AvailableBytes -= allocatingLength;
page.OccupiedBytes += allocatingLength;
dbHeader.SetPosOfFirstPage(type, page.ThisPos);
}
else
{
// 最前面的table页的可用空间是最大的（这需要在后续操作中进行排序）
PageHeaderBlock firstTablePage = GetTablePage(fs, ts, pagePos);
if (firstTablePage.AvailableBytes >= allocatingLength)// 此页的空间足够用。
{
// 把此页从Page链表中移除。
dbHeader.SetPosOfFirstPage(type, firstTablePage.NextPagePos);
firstTablePage.NextPagePos = 0;
page = firstTablePage;
}
else// 此页的空间不够用，还是要申请一个新页。
{
page = db.AllocEmptyPageOrNewPage();
}
page.AvailableBytes -= allocatingLength;
page.OccupiedBytes += allocatingLength;
// 对申请的类型的页的链表进行排序。呼应上面的排序需求。
SortPage(type, page, fs, ts, dbHeader);
}
return(page);
}
//static readonly Brush pageHeaderBrush = new LinearGradientBrush(new Rectangle(0, 0, Consts.pageHeaderBlockLength, bmpHeight), Color.Silver, Color.GreenYellow, 90);
private static void DrawPageHeaders(FileStream fs, long pageCount, Bitmap[] bmps)
{
for (int i = 0; i < pageCount; i++)
{
long pos = i * Consts.pageSize;
PageHeaderBlock page = fs.ReadBlock <PageHeaderBlock>(pos);
long index = pos / Consts.pageSize;
Bitmap bmp = bmps[index];
Graphics g = Graphics.FromImage(bmp);
int startPos = (int)(page.ThisPos - Consts.pageSize * index);
int length = page.ToBytes().Length;
Brush brush = new LinearGradientBrush(new Point(startPos, 0), new Point(startPos + length, 0), Color.YellowGreen, Color.GreenYellow);
g.FillRectangle(brush, startPos, 1, length, bmpHeight - 1);
g.DrawRectangle(boundPen, startPos, 1, length, bmpHeight - 1);
g.Dispose();
}
}
/// <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>
/// 打印数据库文件里所有表的所有主键的skip list和所有类型的页链表。
/// </summary>
/// <param name="db"></param>
/// <returns></returns>
public static string Print(this FileDBContext db)
{
StringBuilder builder = new StringBuilder();
builder.AppendLine(db.Fullname);
FileStream fs = db.GetFileStream();
//PageHeaderBlock firstPage = fs.ReadBlock<PageHeaderBlock>(0);
DBHeaderBlock dbHeader = db.GetDBHeaderBlock();// fs.ReadBlock<DBHeaderBlock>(fs.Position);
PrintSkipLists(db, builder, fs);
builder.AppendLine();
builder.AppendLine("Page Info.:");
for (long i = 0; i < fs.Length; i += Consts.pageSize)
{
PageHeaderBlock pageInfo = fs.ReadBlock <PageHeaderBlock>(i);
string str = Print(pageInfo);
builder.AppendLine(str);
}
builder.AppendLine();
builder.AppendLine();
builder.AppendLine("table pages:");
long tablePos = dbHeader.FirstTablePagePos;
while (tablePos != 0)
{
PageHeaderBlock pageInfo = fs.ReadBlock <PageHeaderBlock>(tablePos);
builder.Append(string.Format(" {0}[{1}] ->", pageInfo.ThisPos, pageInfo.ThisPos / Consts.pageSize));
tablePos = pageInfo.NextPagePos;
}
builder.AppendLine();
builder.AppendLine();
builder.AppendLine("index pages:");
long indexPos = dbHeader.FirstIndexPagePos;
while (indexPos != 0)
{
PageHeaderBlock pageInfo = fs.ReadBlock <PageHeaderBlock>(indexPos);
builder.Append(string.Format(" {0}[{1}] ->", pageInfo.ThisPos, pageInfo.ThisPos / Consts.pageSize));
indexPos = pageInfo.NextPagePos;
}
builder.AppendLine();
builder.AppendLine();
builder.AppendLine("skip list node pages:");
long skiplistnodePos = dbHeader.FirstSkipListNodePagePos;
while (skiplistnodePos != 0)
{
PageHeaderBlock pageInfo = fs.ReadBlock <PageHeaderBlock>(skiplistnodePos);
builder.Append(string.Format(" {0}[{1}] ->", pageInfo.ThisPos, pageInfo.ThisPos / Consts.pageSize));
skiplistnodePos = pageInfo.NextPagePos;
}
builder.AppendLine();
builder.AppendLine();
builder.AppendLine("data block pages:");
long dataBlockPos = dbHeader.FirstDataPagePos;
while (dataBlockPos != 0)
{
PageHeaderBlock pageInfo = fs.ReadBlock <PageHeaderBlock>(dataBlockPos);
builder.Append(string.Format(" {0}[{1}] ->", pageInfo.ThisPos, pageInfo.ThisPos / Consts.pageSize));
dataBlockPos = pageInfo.NextPagePos;
}
builder.AppendLine();
builder.AppendLine();
builder.AppendLine("empty pages:");
long emptyPos = dbHeader.FirstEmptyPagePos;
while (emptyPos != 0)
{
PageHeaderBlock pageInfo = fs.ReadBlock <PageHeaderBlock>(emptyPos);
builder.Append(string.Format(" {0}[{1}] ->", pageInfo.ThisPos, pageInfo.ThisPos / Consts.pageSize));
emptyPos = pageInfo.NextPagePos;
}
builder.AppendLine();
return(builder.ToString());
}
static string Print(PageHeaderBlock pageHeaderBlock)
{
return(string.Format("Pos: {0}, available: {1}, Occupied: {2}",
pageHeaderBlock.ThisPos, pageHeaderBlock.AvailableBytes, pageHeaderBlock.OccupiedBytes));
}
/// <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);
}
}
