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RingFile.pas
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RingFile.pas
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unit RingFile;
interface
uses
typex, systemx, sharedobject, QueueStream, helpers_stream, numbers, sysutils, signals, stringx, tickcount, betterobject;
type
TRingFile = class(TSharedObject)
private
FSize: int64;
function GetDataAvailable: int64;
function GetSpaceAvailable: int64;
procedure SetSize(const Value: int64);
function GetfileName: string;
procedure SetFileNAme(const Value: string);
protected
FWritePtr: int64;
FReadPtr: int64;
OpenAllSignals: boolean;
FSTream: TAdaptiveQueuedFileStream;
procedure MovePtr(ptr: PInt64; by: int64);
public
evEmpty, evData: TSignal;
constructor Create;override;
destructor Destroy;override;
procedure Detach;override;
property FileName: string read GetfileName write SetFileNAme;
function PutData(const p: PByte; const l: ni): ni;
function GetData(const p: PByte; const l: ni): ni;
function GuaranteePutData(const p: PByte; const l: ni): ni;
function GuaranteeGetData(const p: pbyte; const l: ni; iTimeOut: ni = 16000): ni;
property SpaceAvailable: int64 read GetSpaceAvailable;
property DataAvailable: int64 read GetDataAvailable;
property Size: int64 read FSize write SetSize;
function DebugString: string;
end;
implementation
{ TRingFile }
constructor TRingFile.Create;
begin
inherited;
evEmpty := TSignal.create;
signal(evEmpty, true);
evData := TSignal.create;
FSize := 1000*MILLION;
end;
function TRingFile.DebugString: string;
begin
result := 'sz='+commaize(size)+' w='+commaize(FWritePtr)+' r='+commaize(FReadptr)+' '+FileNAme;
end;
destructor TRingFile.Destroy;
begin
inherited;
end;
procedure TRingFile.Detach;
begin
OpenAllSignals := true;
signal(evData,true);
signal(evEmpty,true);
FStream.free;
FStream := nil;
inherited;
end;
function TRingFile.GetData(const p: PByte;const l: ni): ni;
var
icanGet: int64;
begin
Lock;
try
icanGet := FWritePtr - FReadPtr;
if iCanGet < 0 then begin
iCanGet := Fsize - FReadPtr;
end;
iCanGet := lesserof(l, iCanGet);
FStream.Seek(FReadPtr, 0);
result := Stream_Guaranteeread(FStream, p, iCanGet);
moveptr(@FReadPtr, result);
Signal(evEmpty, (DataAvailable=0) or OpenAllSignals);
Signal(evDAta, (DataAvailable>0) or OpenAllSignals);
finally
Unlock;
end;
end;
function TRingFile.GetDataAvailable: int64;
begin
result := FWritePtr - FReadPtr;
if result < 0 then
result := result + FSize;
end;
function TRingFile.GetfileName: string;
begin
result := '';
if FStream = nil then
exit;
result := FStream.FileNAme;
end;
function TRingFile.GetSpaceAvailable: int64;
begin
result := FSize - DataAvailable;
end;
function TRingFile.GuaranteeGetData(const p: pbyte; const l: ni; iTimeOut: ni = 16000): ni;
var
tm: ticker;
begin
result := GetData(p, l);
tm := GetTicker;
while result < l do begin
if WaitForSignal(evData, 1000) then begin
result := result + GetData(@p[result], l-result);
tm := GetTicker;
end else
if GetTimeSince(tm) > iTimeOut then begin
raise ECritical.create('Ring File timeout');
end;
end;
end;
function TRingFile.GuaranteePutData(const p: PByte; const l: ni): ni;
begin
result := PutData(p, l);
if result < l then
result := result + PutData(@p[result], l-result);
end;
procedure TRingFile.MovePtr(ptr: PInt64; by: int64);
begin
inc(Ptr^, by);
while Ptr^ >= FSize do
dec(Ptr^, size);
while ptr^ < 0 do
inc(ptr^, size);
end;
function TRingFile.PutData(const p: PByte; const l: ni): ni;
var
icanPut: int64;
begin
Lock;
try
//determine how many we can put in this iteration
//iCanPut is the number of bytes until wrap around
//aaaaaaaa bbbbbbbb cccccccc dddddddd
//[--++--] [+---++] [++--++] [------]
//[ r w ] [ w r ] [ w r ] [ & ]
//[012345] [012345] [012345] [012345]
icanPut := (FReadPtr-FWritePtr)-1; //iCanPut = (a:(2-4)=-2 b:4-1=3 c: (4-2)=2 d: 2-2=0) - 1 = a:-3 b:3 c:1 d: -1
if iCanPut < 0 then begin
iCanPut := Fsize - FWritePtr; //iCanPut = a: 3, 3, 1,5
end;
iCanput := lesserof(l, iCanPut);
Stream_Grow(FStream, FWritePtr);
FStream.Seek(FWritePtr, 0);
result := Stream_GuaranteeWrite(FStream, p, iCanPut);
moveptr(@FWritePtr, result);
Signal(evData, (DataAVailable>0) or OpenAllSignals);
finally
unlock;
end;
end;
procedure TRingFile.SetFileNAme(const Value: string);
begin
if FStream <> nil then begin
FStream.free;
FStream := nil;
end;
FStream := TAdaptiveQueuedFileStream.Create(value, fmOpenREadWrite+fmShareExclusive);
end;
procedure TRingFile.SetSize(const Value: int64);
begin
if DataAvailable > 0 then
raise ECritical.Create('Cannot set size of '+self.ClassName+' when ' +inttostr(DataAvailable)+' bytes are in the buffer. Buffer must be empty.');
FSize := Value;
end;
end.