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 (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;
var usedSize:DWord;
begin
usedSize:=GetUsedSize();
Result:=BufferSize-(usedSize+XRING_BUFFER_READ_POS_AND_WRITE_POS_Size);
end;

function TJsRingBuffer.PushData(Data:Pointer;Size:DWord):Bool;
begin
//  EnterCriticalSection(FCS);
Result:=PushData2(Data,Size);
//  LeaveCriticalSection(FCS);
end;

function TJsRingBuffer.PushData2(Data:Pointer;Size:DWord):Bool;
var freeSize,readPos,writePos,lenFromWritePosToBufferEnd,secondPartLen:DWord;
begin
freeSize:=GetFreeSize();
if (freeSize<Size) then begin//空闲数不足,无法写入
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(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 (writePos<readPos) then begin
CopyMemory(Pointer(Integer(BufferData)+writePos),Pointer(Integer(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
//  EnterCriticalSection(FCS);
Result:=CopyDataWithAddReadPosOption(Dest,DestSize,CopySize,False);
//  LeaveCriticalSection(FCS);
end;

function TJsRingBuffer.PopData(Dest:Pointer;DestSize,PopSize:DWord):Bool;
begin
//  EnterCriticalSection(FCS);
Result:=CopyDataWithAddReadPosOption(Dest,DestSize,popSize,True);
//  LeaveCriticalSection(FCS);
end;

function TJsRingBuffer.PopData(PopSize:DWord):Bool;
begin
//  EnterCriticalSection(FCS);
Result:=CopyDataWithAddReadPosOption(nil,0,PopSize,True);
//  LeaveCriticalSection(FCS);
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(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 (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(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) 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(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.