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unit VirtualThread;
// Version 1.1.17
// The contents of this file are subject to the Mozilla Public License
// Version 1.1 (the "License"); you may not use this file except
// in compliance with the License. You may obtain a copy of the
// License at
//
// http://www.mozilla.org/MPL/
//
// Software distributed under the License is distributed on an
// " AS IS" basis, WITHOUT WARRANTY OF ANY KIND, either expressed or
// implied. See the License for the specific language governing rights
// and limitations under the License.
//
//
// Alternatively, the contents of this file may be used under
// the terms of the GNU General Public License Version 2 or later
// (the "GPL"), in which case the provisions of the GPL are applicable
// instead of those above. If you wish to allow use of your version of
// this file only under the terms of the GPL and not to allow others to
// use your version of this file under the MPL, indicate your decision
// by deleting the provisions above and replace them with the notice and
// other provisions required by the GPL. If you do not delete the provisions
// above, a recipient may use your version of this file under either the
// MPL or the GPL.
//
// The initial developer of this code is Jim Kueneman <jimdk@mindspring.com>
//
//----------------------------------------------------------------------------
interface
uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, VirtualUtilities;
type
TVirtualThread = class
private
FHandle: THandle;
FThreadID: THandle;
FStub: pointer;
FTerminated: Boolean;
FSuspended: Boolean;
FFinished: Boolean;
FEvent: THandle;
FCriticalSectionInitialized: Boolean;
FCriticalSection: TRTLCriticalSection;
FRefCount: Integer;
function GetPriority: TThreadPriority;
procedure SetPriority(const Value: TThreadPriority);
procedure SetSuspended(const Value: Boolean);
procedure ExecuteStub; stdcall;
function GetTriggerEvent: THandle;
function GetLock: TRTLCriticalSection;
protected
procedure Execute; virtual; abstract;
property CriticalSectionInitialized: Boolean read FCriticalSectionInitialized write FCriticalSectionInitialized;
property Event: THandle read FEvent write FEvent;
property Stub: pointer read FStub write FStub;
property Terminated: Boolean read FTerminated;
public
constructor Create(CreateSuspended: Boolean);
destructor Destroy; override;
procedure AddRef;
procedure Release;
procedure Resume;
procedure SetTriggerEvent;
procedure Terminate;
property Finished: Boolean read FFinished;
property Handle: THandle read FHandle;
property Lock: TRTLCriticalSection read GetLock;
property Priority: TThreadPriority read GetPriority write SetPriority;
property RefCount: Integer read FRefCount write FRefCount;
property Suspended: Boolean read FSuspended write SetSuspended;
property ThreadID: THandle read FThreadID;
property TriggerEvent: THandle read GetTriggerEvent;
end;
implementation
{ TVirtualThread }
procedure TVirtualThread.AddRef;
begin
InterlockedIncrement(FRefCount);
end;
constructor TVirtualThread.Create(CreateSuspended: Boolean);
var
Flags: DWORD;
begin
IsMultiThread := True;
Stub := CreateStub(Self, @TVirtualThread.ExecuteStub);
Flags := 0;
if CreateSuspended then
begin
Flags := CREATE_SUSPENDED;
FSuspended := True
end;
FHandle := CreateThread(nil, 0, Stub, nil, Flags, FThreadID);
end;
destructor TVirtualThread.Destroy;
begin
DisposeStub(Stub);
if Handle <> 0 then
CloseHandle(Handle);
if Event <> 0 then
CloseHandle(Event);
if CriticalSectionInitialized then
DeleteCriticalSection(FCriticalSection);
inherited;
end;
procedure TVirtualThread.ExecuteStub;
// Called in the context of the thread
begin
try
try
Execute
except
end
finally
FFinished := True;
ExitThread(0);
end
end;
function TVirtualThread.GetLock: TRTLCriticalSection;
begin
if not CriticalSectionInitialized then
InitializeCriticalSection(FCriticalSection);
Result := FCriticalSection
end;
function TVirtualThread.GetPriority: TThreadPriority;
var
P: Integer;
begin
Result := tpNormal;
P := GetThreadPriority(FHandle);
case P of
THREAD_PRIORITY_IDLE: Result := tpIdle;
THREAD_PRIORITY_LOWEST: Result := tpLowest;
THREAD_PRIORITY_BELOW_NORMAL: Result := tpLower;
THREAD_PRIORITY_NORMAL: Result := tpNormal;
THREAD_PRIORITY_HIGHEST: Result := tpHigher;
THREAD_PRIORITY_ABOVE_NORMAL: Result := tpHighest;
THREAD_PRIORITY_TIME_CRITICAL: Result := tpTimeCritical;
end
end;
function TVirtualThread.GetTriggerEvent: THandle;
begin
if Event = 0 then
Event := CreateEvent(nil, True, False, nil);
Result := Event;
end;
procedure TVirtualThread.Release;
begin
InterlockedDecrement(FRefCount);
end;
procedure TVirtualThread.Resume;
begin
Suspended := False
end;
procedure TVirtualThread.SetPriority(const Value: TThreadPriority);
begin
begin
case Value of
tpIdle : SetThreadPriority(Handle, THREAD_PRIORITY_IDLE);
tpLowest : SetThreadPriority(Handle, THREAD_PRIORITY_LOWEST);
tpLower : SetThreadPriority(Handle, THREAD_PRIORITY_BELOW_NORMAL);
tpNormal : SetThreadPriority(Handle, THREAD_PRIORITY_NORMAL);
tpHigher : SetThreadPriority(Handle, THREAD_PRIORITY_HIGHEST);
tpHighest : SetThreadPriority(Handle, THREAD_PRIORITY_ABOVE_NORMAL);
tpTimeCritical: SetThreadPriority (Handle, THREAD_PRIORITY_TIME_CRITICAL);
end
end;
end;
procedure TVirtualThread.SetSuspended(const Value: Boolean);
begin
if FSuspended <> Value then
begin
if Handle <> 0 then
begin
if Value then
SuspendThread(FHandle)
else
ResumeThread(FHandle);
FSuspended := Value;
end
end
end;
procedure TVirtualThread.SetTriggerEvent;
begin
SetEvent(TriggerEvent);
end;
procedure TVirtualThread.Terminate;
begin
FTerminated := True
end;
end.
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