Delphi版 环形无锁缓冲

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{       环形无锁缓冲Delphi版                            }
{         2016.04.13 By  Lance                          }
{        联系方式QQ:286922468                           }
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{
  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
}
unit JsRingBuffer;
{.$DEFINE DeBugLog}
interface
uses Windows;
const XRING_BUFFER_READ_POS_AND_WRITE_POS_Size=2;
type
  TJsRingBuffer=class
  private
    //    FCS:TRTLCriticalSection;
    BufferData:array of Byte;
    BufferSize,FWritePosition,FReadPosition:DWord;
    function CopyDataWithAddReadPosOption(Dest:Pointer;DestSize,CopySize:DWord;AddReadPos:Bool):Bool;
    function PushData2(Data:Pointer;Size:DWord):Bool;
    function GetFreeSize():DWord;
  protected
  public
    function GetUsedSize():DWord;
    function PopData(Dest:Pointer;DestSize,PopSize:DWord):Bool; overload;
    function PopData(PopSize:DWord):Bool; overload;
    function PushData(Data:Pointer;Size:DWord):Bool;
    function CopyData(Dest:Pointer;DestSize,CopySize:DWord):Bool;
  public
    constructor Create(const Size:DWord);
    destructor Destroy; override;
  end;
implementation

constructor TJsRingBuffer.Create(const Size:DWord);
begin
  inherited Create;
  //  InitializeCriticalSection(FCS);
  BufferSize:=(Size+XRING_BUFFER_READ_POS_AND_WRITE_POS_Size);
  FWritePosition:=1;
  FReadPosition:=0;
  BufferData:=nil;
  SetLength(BufferData,BufferSize);
  //  ZeroMemory(BufferData,BufferSize);
end;

destructor TJsRingBuffer.Destroy;
begin
  SetLength(BufferData,0);
  //  DeleteCriticalSection(FCS);
  inherited Destroy;
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 (writePosreadPos) 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(Integer(BufferData)+FWritePosition),Pointer(Integer(Data)),Size);
      Inc(FWritePosition,Size);
      if (FWritePosition=BufferSize) then begin
        //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
        FWritePosition:=0
      end else if (FWritePosition>BufferSize) then begin
        //若写完数据后,新写入点比环还大,出错处理
        //这里应该不可能发生吧?   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(Integer(BufferData)+FWritePosition),Pointer(Integer(Data)),lenFromWritePosToBufferEnd);
      secondPartLen:=Size-lenFromWritePosToBufferEnd;
      // 拷贝后一部分到缓冲区前部
      CopyMemory(Pointer(Integer(BufferData)),Pointer(Integer(Data)+lenFromWritePosToBufferEnd),secondPartLen);
      FWritePosition:=secondPartLen;
      Result:=True;
      Exit;
    end;
  end else if (writePosnil) then begin
    if (DestSizereadPos) then begin//要读取得数据,未跨环
    if (Dest<>nil) then begin
      CopyMemory(Pointer(Integer(Dest)),Pointer(Integer(BufferData)+readPos+1),CopySize);
      {$IFDEF DeBugLog}
      //读出数据后,清理无用的数据
      if (addReadPos) then ZeroMemory(Pointer(Integer(BufferData)+readPos+1),CopySize);
      {$ENDIF}
    end;
    if (addReadPos) then Inc(FReadPosition,CopySize);
    Result:=True;
    Exit;
  end else if (writePosnil) then begin
        CopyMemory(Pointer(Integer(Dest)),Pointer(Integer(BufferData)+readPos+1),CopySize);
        {$IFDEF DeBugLog}
        //读出数据后,清理无用的数据
        if (addReadPos) then ZeroMemory(Pointer(Integer(BufferData)+readPos+1),CopySize);
        {$ENDIF}
      end;
      if (addReadPos) then begin
        inc(FReadPosition,CopySize);
        if not(FReadPosition BufferSize'));
          {$ENDIF}
          Result:=False;
          Exit;
        end;
      end;
      Result:=True;
      Exit;
    end else begin
      secondPartLen:=CopySize-lenFromReadPosToBufferEnd;
      if (Dest<>nil) then begin
        CopyMemory(Pointer(Integer(Dest)),Pointer(Integer(BufferData)+readPos+1),lenFromReadPosToBufferEnd);
        CopyMemory(Pointer(Integer(Dest)+lenFromReadPosToBufferEnd),Pointer(Integer(BufferData)),secondPartLen);
      end;
      if (addReadPos) then FReadPosition:=secondPartLen-1;
      Result:=True;
      Exit;
    end;
  end else begin
    {$IFDEF DeBugLog}
    OutputDebugString(PChar('error:write pos equal read pos'));
    {$ENDIF}
    Result:=False;
    Exit;
  end;
end;
end.