Delphi版 环形无锁缓冲(二)

{*******************************************************}{                                                       }{       环形无锁缓冲Delphi版                            }{         2016.04.13 By  Lance                          }{        联系方式QQ:286922468                           }{                                                       }{*******************************************************}{  本源码受原作者节制，你可以任意复制、修改、使用，如发现  BUG请报告给我们。为了倡导开源，你的一切修改版本，我们  希望也能开源。  警告：使用本项目源码产生的一切后果由使用者自行负责。  注：TJsRingBuffer 基于寰子博客中C++源码，版权归原作者所有  寰子博客原文 http://blog.csdn.net/xocoder/article/details/7880769 2016.04.13    基于寰子博客中C++源码,实现环形无锁缓冲 2017.10.23    增加动态扩容功能    兼容Delphi XE 10.1}unit JsRingBuffer;{.$DEFINE DeBugLog}//仅适用于一个线程写,一个线程读的情况(不适用于多个线程写或多个线程读)interfaceuses Windows;const RingBuffer_ReadPos_And_WritePos_Size=2;type  TJsRingBuffer=class  private    BufferData:Pointer;    BufferSize,DefaultSize,FWritePosition,FReadPosition:DWord;    function CopyDataWithAddReadPosOption(Dest:Pointer;DestSize,CopySize:DWord;AddReadPos:Bool):Bool;    function PushData2(Data:Pointer;Size:DWord):Bool;    procedure AddRingSize;//自动扩展缓冲区大小  protected  public    function GetUsedSize:DWord;//数据的大小    function GetRingSize:DWord;//缓冲区总大小    function GetFreeSize:DWord;//空闲大小    function PopData(Dest:Pointer;DestSize,PopSize:DWord):Bool; overload;//读出数据    function PopData(PopSize:DWord):Bool; overload;//丢弃数据    function PushData(Data:Pointer;Size:DWord):Bool;//插入数据    function CopyData(Dest:Pointer;DestSize,CopySize:DWord):Bool;//只读方式复制数据(不会移动读指针)    function ClearData:Bool;//清空所有数据    procedure RestoreDefaultSize;//将缓冲区还原到默认大小,释放一部份内存  public    constructor Create(const Size:DWord);    destructor Destroy; override;  end;implementationconstructor TJsRingBuffer.Create(const Size:DWord);begin  inherited Create;  BufferSize:=(Size+RingBuffer_ReadPos_And_WritePos_Size);  FWritePosition:=1;  FReadPosition:=0;  BufferData:=nil;  GetMem(BufferData,BufferSize);  ZeroMemory(BufferData,BufferSize);  DefaultSize:=BufferSize;end;destructor TJsRingBuffer.Destroy;begin  FreeMem(BufferData);  inherited Destroy;end;function TJsRingBuffer.GetRingSize:DWord;begin  Result:=BufferSize;end;function TJsRingBuffer.GetUsedSize:DWord;var ReadPos,WritePos:DWord;begin  ReadPos:=FReadPosition;  WritePos:=FWritePosition;  if WritePos>ReadPos then begin    Result:=WritePos-ReadPos-1;    Exit;  end else if (WritePos<ReadPos) then begin    Result:=(BufferSize-ReadPos-1)+FWritePosition;    Exit;  end else begin    {$IFDEF DeBugLog}    OutputDebugString(PChar('error:write pos equal read pos'));    {$ENDIF}    Result:=0;  end;end;function TJsRingBuffer.GetFreeSize:DWord;begin  Result:=BufferSize-(GetUsedSize+RingBuffer_ReadPos_And_WritePos_Size);end;function TJsRingBuffer.ClearData:Bool;begin  Result:=PopData(GetUsedSize);end;procedure TJsRingBuffer.RestoreDefaultSize;begin  if BufferSize=DefaultSize then Exit;  BufferSize:=DefaultSize;  ReallocMem(BufferData,BufferSize);  FWritePosition:=1;  FReadPosition:=0;end;procedure TJsRingBuffer.AddRingSize;var  OldData:Pointer;  i:Integer;begin  i:=GetUsedSize;  GetMem(OldData,i);  CopyDataWithAddReadPosOption(OldData,i,i,True);//取出缓冲区的数据  //增加一倍容量  BufferSize:=BufferSize*2;  ReallocMem(BufferData,BufferSize);//重新分配内存  //重置开始位置  FWritePosition:=1;  FReadPosition:=0;  PushData2(OldData,i);//把旧数据重新插入  FreeMem(OldData);  {$IFDEF DeBugLog}  OutputDebugString(PChar('发生一次写入溢出,已自动扩大缓冲区'));  {$ENDIF}end;function TJsRingBuffer.PushData(Data:Pointer;Size:DWord):Bool;begin  while GetFreeSize<Size do AddRingSize;//空闲数不足,无法写入,溢出,增加自动一倍缓冲区大小(写速比读速快时,会出现这种情况)  Result:=PushData2(Data,Size);end;function TJsRingBuffer.PushData2(Data:Pointer;Size:DWord):Bool;var ReadPos,WritePos,lenFromWritePosToBufferEnd,SecondPartLen:DWord;begin//  if (GetFreeSize<Size) then begin//    //写入溢出,这种情况不可能出现//    Result:=False;//    Exit;//  end;  ReadPos:=FReadPosition;  WritePos:=FWritePosition;  if (WritePos>ReadPos) then begin//写入在未读数据后面,初始化时,写入点为1,读取点为0    lenFromWritePosToBufferEnd:=BufferSize-WritePos;    if (Size<=lenFromWritePosToBufferEnd) then begin//写入的数据,未跨环      CopyMemory(Pointer(PAnsiChar(BufferData)+FWritePosition),Pointer(Data),Size);      Inc(FWritePosition,Size);      //若写完数据后,新写入点刚好是在环最尾,就把写入点定位到环头      if (FWritePosition=BufferSize) then FWritePosition:=0//      else if (FWritePosition>BufferSize) then begin//        //若写完数据后,新写入点比环还大,出错处理//        //这里不可能发生   Size<=lenFromWritePosToBufferEnd时,不可能出现这种情况//        {$IFDEF DeBugLog}//        OutputDebugString(PChar('wirtepos cannot bigger than Size'));//        {$ENDIF}//        Result:=False;//        Exit;//      end      ;      Result:=True;      Exit;    end else begin      // 先拷贝前一部分到缓冲区尾部      CopyMemory(Pointer(PAnsiChar(BufferData)+FWritePosition),Pointer(Data),lenFromWritePosToBufferEnd);      SecondPartLen:=Size-lenFromWritePosToBufferEnd;      // 拷贝后一部分到缓冲区前部      CopyMemory(Pointer(PAnsiChar(BufferData)),Pointer(PAnsiChar(Data)+lenFromWritePosToBufferEnd),SecondPartLen);      FWritePosition:=SecondPartLen;      Result:=True;      Exit;    end;  end else if (WritePos<ReadPos) then begin    CopyMemory(Pointer(PAnsiChar(BufferData)+WritePos),Pointer(Data),Size);    Inc(FWritePosition,Size);    Result:=True;    Exit;  end else begin    {$IFDEF DeBugLog}    OutputDebugString(PChar('error:write pos equal read pos'));    {$ENDIF}    Result:=False;    Exit;  end;end;function TJsRingBuffer.CopyData(Dest:Pointer;DestSize,CopySize:DWord):Bool;begin  Result:=CopyDataWithAddReadPosOption(Dest,DestSize,CopySize,False);end;function TJsRingBuffer.PopData(Dest:Pointer;DestSize,PopSize:DWord):Bool;begin  Result:=CopyDataWithAddReadPosOption(Dest,DestSize,popSize,True);end;function TJsRingBuffer.PopData(PopSize:DWord):Bool;begin  Result:=CopyDataWithAddReadPosOption(nil,0,PopSize,True);end;function TJsRingBuffer.CopyDataWithAddReadPosOption(Dest:Pointer;DestSize,CopySize:DWord;AddReadPos:Bool):Bool;var UsedSize,WritePos,ReadPos,LenFromReadPosToBufferEnd,SecondPartLen:DWord;begin  UsedSize:=GetUsedSize();  if (UsedSize<CopySize) then begin    {$IFDEF DeBugLog}    OutputDebugString(PChar('Data is not enought to copy'));    {$ENDIF}    Result:=False;    Exit;  end;  if (Dest<>nil) then begin    if (DestSize<CopySize) then begin      {$IFDEF DeBugLog}      OutputDebugString(PChar('Dest buffer Size is smaller than copy Size'));      {$ENDIF}      Result:=False;      Exit;    end;  end;  WritePos:=FWritePosition;  ReadPos:=FReadPosition;  if (WritePos>ReadPos) then begin//要读取得数据,未跨环    if (Dest<>nil) then begin      CopyMemory(Pointer(Dest),Pointer(PAnsiChar(BufferData)+ReadPos+1),CopySize);      {$IFDEF DeBugLog}      //读出数据后,清理无用的数据      if addReadPos then ZeroMemory(Pointer(PAnsiChar(BufferData)+ReadPos+1),CopySize);      {$ENDIF}    end;    if addReadPos then Inc(FReadPosition,CopySize);    Result:=True;    Exit;  end else if (WritePos<ReadPos) then begin//要读取的数据,跨环    LenFromReadPosToBufferEnd:=BufferSize-ReadPos-1;    if (CopySize<=LenFromReadPosToBufferEnd) then begin      if (Dest<>nil) then begin        CopyMemory(Pointer(Dest),Pointer(PAnsiChar(BufferData)+ReadPos+1),CopySize);        {$IFDEF DeBugLog}        //读出数据后,清理无用的数据        if addReadPos then ZeroMemory(Pointer(PAnsiChar(BufferData)+ReadPos+1),CopySize);        {$ENDIF}      end;      if addReadPos then begin        inc(FReadPosition,CopySize);        if not(FReadPosition<BufferSize) then begin          {$IFDEF DeBugLog}          OutputDebugString(PChar('FReadPosition => BufferSize'));          {$ENDIF}          Result:=False;          Exit;        end;      end;      Result:=True;      Exit;    end else begin      SecondPartLen:=CopySize-LenFromReadPosToBufferEnd;      if Dest<>nil then begin        CopyMemory(Pointer(Dest),Pointer(PAnsiChar(BufferData)+ReadPos+1),LenFromReadPosToBufferEnd);        CopyMemory(Pointer(PAnsiChar(Dest)+LenFromReadPosToBufferEnd),Pointer(BufferData),SecondPartLen);      end;      if addReadPos then FReadPosition:=SecondPartLen-1;      Result:=True;      Exit;    end;  end else begin    {$IFDEF DeBugLog}    OutputDebugString(PChar('error:write pos equal read pos'));    {$ENDIF}    Result:=False;    Exit;  end;end;end.