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(*
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* Firebird Interface (fbintf). The fbintf components provide a set of
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* Pascal language bindings for the Firebird API.
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*
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* The contents of this file are subject to the Initial Developer's
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* Public License Version 1.0 (the "License"); you may not use this
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* file except in compliance with the License. You may obtain a copy
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* of the License here:
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*
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* http://www.firebirdsql.org/index.php?op=doc&id=idpl
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*
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* Software distributed under the License is distributed on an "AS
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* IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
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* implied. See the License for the specific language governing rights
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* and limitations under the License.
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*
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* The Initial Developer of the Original Code is Tony Whyman.
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*
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* The Original Code is (C) 2016 Tony Whyman, MWA Software
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* (http://www.mwasoftware.co.uk).
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*
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* All Rights Reserved.
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*
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* Contributor(s): ______________________________________.
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*
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*)
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unit FBActivityMonitor;
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{$IFDEF MSWINDOWS}
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{$DEFINE WINDOWS}
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{$ENDIF}
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{$IFDEF FPC}
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{$mode delphi}
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{$interfaces COM}
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{$ENDIF}
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interface
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uses
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Classes, SysUtils, IBExternals;
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{ $DEFINE DEBUGINTERFACES} {Define this to check that all interfaces are
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being destroyed.}
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type
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{ TMonitoredObject is an optional class used to journal all interface creatino
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and deletion as well as keeping a count of how many monitored interfaces
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exist at any one time. It is used at development to look for memory leaks
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due to interfaces not being discarded when no longer used.}
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{$IFDEF DEBUGINTERFACES}
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TMonitoredObject = class(TInterfacedObject)
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public
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constructor Create;
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destructor Destroy; override;
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end;
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{TFBInterfacedObject is used as the base class for interfaces objects and can
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be either a synonym for TInterfacedObject (default) or TMonitored object}
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TFBInterfacedObject = TMonitoredObject;
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{$ELSE}
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TFBInterfacedObject = TInterfacedObject;
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{$ENDIF}
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{ TInterfaceOwner }
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TInterfaceOwner = class(TFBInterfacedObject)
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private
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FInterfaces: array of TInterfacedObject;
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FInterfaceRefs: array of IUnknown;
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FRetainInterfaces: boolean;
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FMinInterfaces: integer;
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function GetCount: integer;
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procedure SetRetainInterfaces(AValue: boolean);
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protected
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procedure AddInterface(index: integer; obj: TInterfacedObject);
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function HasInterface(index: integer): boolean;
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procedure ReleaseInterfaces;
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public
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constructor Create(aInterfaces: integer=0);
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destructor Destroy; override;
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procedure AddObject(obj: TInterfacedObject);
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function GetInterface(index: integer): TInterfacedObject;
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procedure Remove(intf: TInterfacedObject);
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property InterfaceCount: integer read GetCount;
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property RetainInterfaces: boolean read FRetainInterfaces write SetRetainInterfaces;
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end;
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{The IActivityMonitor interface is provided by classes that receive activity
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reports.}
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IActivityMonitor = interface
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procedure AddObject(obj: TInterfacedObject);
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procedure Remove(intf: TInterfacedObject);
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procedure SignalActivity;
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end;
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{ TActivityReporter is a base class for objects that need to report their activity
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to an activity monitor, where activity is defined as use of a Firebird API call.
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Objects descending from this class always used the "Call" method as a wrapper
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for calls to the Firebird API. Each such call is then classed as activity
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and reported to one or more activity monitors.
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In practice, a transaction monitors statements, blobs and arrays. A Database
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monitors transactions and events. Transaction monitors use the ITransactionMonitor
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interface, implemented through the helper object TTransactionMonitor.
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}
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TActivityReporter = class(TInterfaceOwner)
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private
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FHasActivity: boolean;
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FMonitors: array of IActivityMonitor;
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function FindMonitor(aMonitor: IActivityMonitor): integer;
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protected
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function Call(ErrCode: ISC_STATUS; RaiseError: Boolean = true): ISC_STATUS;
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procedure AddMonitor(aMonitor: IActivityMonitor);
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procedure RemoveMonitor(aMonitor: IActivityMonitor);
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public
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constructor Create(aMonitor: IActivityMonitor;aInterfaces: integer=0);
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destructor Destroy; override;
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function HasActivity: boolean;
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procedure SignalActivity;
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end;
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{ TActivityHandler is a base class for classes that receive activity reports.}
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TActivityHandler = class(TInterfaceOwner,IActivityMonitor)
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private
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FHasActivity: boolean;
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public
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function HasActivity: boolean;
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procedure SignalActivity;
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end;
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implementation
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uses FB25ClientAPI;
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{ TActivityHandler }
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function TActivityHandler.HasActivity: boolean;
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begin
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Result := FHasActivity;
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FHasActivity := false;
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end;
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procedure TActivityHandler.SignalActivity;
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begin
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FHasActivity := true;
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end;
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{ TMonitoredObject }
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{$IFDEF DEBUGINTERFACES}
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var
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FObjectCount: integer;
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constructor TMonitoredObject.Create;
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begin
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inherited Create;
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Inc(FObjectCount);
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writeln('Creating ' + ClassName,', Obj Count = ',FObjectCount);
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end;
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destructor TMonitoredObject.Destroy;
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begin
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Dec(FObjectCount);
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writeln('Destroying ' + ClassName,' Obj Count = ',FObjectCount);
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inherited Destroy;
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end;
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{$ENDIF}
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{ TActivityReporter}
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function TActivityReporter.FindMonitor(aMonitor: IActivityMonitor): integer;
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var i: integer;
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begin
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Result := -1;
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for i := 0 to Length(FMonitors) - 1 do
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if FMonitors[i] = aMonitor then
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begin
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Result := i;
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Exit;
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end;
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end;
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function TActivityReporter.Call(ErrCode: ISC_STATUS; RaiseError: Boolean): ISC_STATUS;
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begin
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result := ErrCode;
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SignalActivity;
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if RaiseError and (ErrCode > 0) then
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Firebird25ClientAPI.IBDataBaseError;
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end;
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procedure TActivityReporter.AddMonitor(aMonitor: IActivityMonitor);
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var i: integer;
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begin
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if FindMonitor(aMonitor) = -1 then
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begin
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i := Length(FMonitors);
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Setlength(FMonitors,i+1);
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FMonitors[i] := aMonitor;
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aMonitor.AddObject(self);
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end;
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end;
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procedure TActivityReporter.RemoveMonitor(aMonitor: IActivityMonitor);
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var i,j: integer;
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begin
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i := FindMonitor(aMonitor);
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if i <> -1 then
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begin
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aMonitor.Remove(self);
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if Length(FMonitors) = 1 then
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SetLength(FMonitors,0)
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else
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begin
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for j := i + 1 to Length(FMonitors) - 1 do
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FMonitors[j-1] := FMonitors[j];
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SetLength(FMonitors,Length(FMonitors)-1);
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end;
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end;
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end;
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procedure TActivityReporter.SignalActivity;
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var i: integer;
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begin
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FHasActivity := true;
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for i := 0 to Length(FMonitors) - 1 do
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FMonitors[i].SignalActivity;
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end;
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constructor TActivityReporter.Create(aMonitor: IActivityMonitor;
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aInterfaces: integer);
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begin
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inherited Create(aInterfaces);
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if aMonitor <> nil then
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begin
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SetLength(FMonitors,1);
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FMonitors[0] := aMonitor;
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end;
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end;
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destructor TActivityReporter.Destroy;
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var i: integer;
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begin
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for i := 0 to Length(FMonitors) - 1 do
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FMonitors[i].Remove(self);
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inherited Destroy;
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end;
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function TActivityReporter.HasActivity: boolean;
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begin
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Result := FHasActivity;
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FHasActivity := false;
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end;
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{ TInterfaceOwner }
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constructor TInterfaceOwner.Create(aInterfaces: integer);
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begin
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inherited Create;
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FMinInterfaces := aInterfaces;
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SetLength(FInterfaces,aInterfaces);
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SetLength(FInterfaceRefs,aInterfaces);
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end;
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destructor TInterfaceOwner.Destroy;
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begin
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ReleaseInterfaces;
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inherited Destroy;
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end;
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procedure TInterfaceOwner.AddObject(obj: TInterfacedObject);
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var index: integer;
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begin
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index := Length(FInterfaces);
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SetLength(FInterfaces,index+1);
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SetLength(FInterfaceRefs,index+1);
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AddInterface(index,obj);
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end;
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function TInterfaceOwner.GetInterface(index: integer): TInterfacedObject;
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begin
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Result := FInterfaces[index];
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end;
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procedure TInterfaceOwner.SetRetainInterfaces(AValue: boolean);
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begin
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if FRetainInterfaces = AValue then Exit;
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FRetainInterfaces := AValue;
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if not FRetainInterfaces then
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ReleaseInterfaces;
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end;
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function TInterfaceOwner.GetCount: integer;
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begin
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Result := Length(FInterfaces);
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end;
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procedure TInterfaceOwner.AddInterface(index: integer; obj: TInterfacedObject);
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begin
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FInterfaces[index] := obj;
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if RetainInterfaces then
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FInterfaceRefs[index] := obj;
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end;
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function TInterfaceOwner.HasInterface(index: integer): boolean;
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begin
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Result := FInterfaces[index] <> nil;
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end;
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procedure TInterfaceOwner.Remove(intf: TInterfacedObject);
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var i, j: integer;
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begin
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for i := 0 to Length(FInterfaces) - 1 do
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if FInterfaces[i] = intf then
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begin
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if i < FMinInterfaces then
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begin
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FInterfaceRefs[i] := nil;
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FInterfaces[i] := nil;
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end
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else
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begin
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for j := i to Length(FInterfaces) - 2 do
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begin
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FInterfaceRefs[j] := FInterfaceRefs[j+1];
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FInterfaces[j] := FInterfaces[j+1];
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end;
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SetLength(FInterfaces,Length(FInterfaces)-1);
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SetLength(FInterfaceRefs,Length(FInterfaceRefs)-1);
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end;
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Exit;
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end;
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end;
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procedure TInterfaceOwner.ReleaseInterfaces;
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var i: integer;
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begin
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for i := 0 to Length(FInterfaces) - 1 do
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begin
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{$IFNDEF FPC}
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{With Delphi we need to explicitly null the object reference when it is
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going to be disposed of. This is because Delphi does not drop the reference
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count until after the containing object is released.}
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if (FInterfaces[i] <> nil) and (FInterfaces[i].RefCount <= 2) then
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FInterfaces[i] := nil;
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{$ENDIF}
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FInterfaceRefs[i] := nil;
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end;
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end;
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end.
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