Added the Lazarus_Linux_Console\LibraryBrowser demo

demos/Lazarus_Linux_Console/LibraryBrowser/uworkerthread.pas

@@ -0,0 +1,213 @@
+unit uworkerthread;
+
+{$mode objfpc}{$H+}
+
+interface
+
+uses
+  Classes, SysUtils, SyncObjs, Contnrs,
+  ucustommessage;
+
+const
+  WORKERTHREADMSG_QUIT = 1;
+
+type
+  TWorkerThread = class(TThread)
+    protected
+      FCritSect        : TCriticalSection;
+      FEvent           : TEvent;
+      FWaiting         : boolean;
+      FStop            : boolean;
+      FMsgQueue        : TObjectQueue;
+
+      function  Lock : boolean;
+      procedure Unlock;
+      function  CanContinue : boolean;
+      procedure ReadAllPendingMessages;
+      procedure ProcessValue(const aInfo : TMsgInfo); virtual;
+      function  ReadPendingMessage(var aMsgInfo : TMsgInfo) : boolean;
+      procedure StopThread;
+      procedure DestroyQueue;                      
+      procedure EnqueueMessage(const aMsgInfo : TMsgInfo); overload;  
+      procedure EnqueueMessage(aMsg: integer; aIntParam : integer = 0; const aStrParam : string = ''); overload;
+
+      procedure Execute; override;
+
+    public
+      constructor Create;
+      destructor  Destroy; override;
+      procedure   AfterConstruction; override;
+  end;
+
+implementation
+
+constructor TWorkerThread.Create;
+begin
+  FCritSect        := nil;
+  FWaiting         := False;
+  FStop            := False;
+  FEvent           := nil;
+  FMsgQueue        := nil;
+
+  inherited Create(True);
+
+  FreeOnTerminate := False;
+end;
+
+destructor TWorkerThread.Destroy;
+begin
+  if (FEvent    <> nil) then FreeAndNil(FEvent);
+  if (FCritSect <> nil) then FreeAndNil(FCritSect);
+
+  DestroyQueue;
+
+  inherited Destroy;
+end;
+
+procedure TWorkerThread.DestroyQueue;
+begin
+  if (FMsgQueue <> nil) then
+    begin
+      while (FMsgQueue.Count > 0) do
+        FMsgQueue.Pop.Free;
+
+      FreeAndNil(FMsgQueue);
+    end;
+end;
+
+procedure TWorkerThread.AfterConstruction;
+begin
+  inherited AfterConstruction;
+
+  FEvent    := TEvent.Create(nil, False, False, '');
+  FCritSect := TCriticalSection.Create;
+  FMsgQueue := TObjectQueue.Create;
+end;
+
+function TWorkerThread.Lock : boolean;
+begin
+  if (FCritSect <> nil) then
+    begin
+      FCritSect.Acquire;
+      Result := True;
+    end
+   else
+    Result := False;
+end;
+
+procedure TWorkerThread.Unlock;
+begin
+  if (FCritSect <> nil) then FCritSect.Release;
+end;
+
+procedure TWorkerThread.StopThread;
+begin
+  if Lock then
+    begin
+      FStop := True;
+      Unlock;
+    end;
+end;         
+
+procedure TWorkerThread.EnqueueMessage(aMsg, aIntParam : integer; const aStrParam : string);
+var
+  TempMsgInfo : TMsgInfo;
+begin
+  TempMsgInfo.Msg      := aMsg;
+  TempMsgInfo.StrParam := aStrParam;
+  TempMsgInfo.IntParam := aIntParam;
+  EnqueueMessage(TempMsgInfo);
+end;
+
+procedure TWorkerThread.EnqueueMessage(const aMsgInfo : TMsgInfo);
+begin
+  if Lock then
+    try
+      if (FMsgQueue <> nil) then
+        FMsgQueue.Push(TCustomMessage.Create(aMsgInfo));
+
+      if FWaiting then
+        begin
+          FWaiting := False;
+          FEvent.SetEvent;
+        end;
+    finally
+      Unlock;
+    end;
+end;
+
+function TWorkerThread.ReadPendingMessage(var aMsgInfo : TMsgInfo) : boolean;
+var
+  TempMessage : TCustomMessage;
+begin
+  Result := False;
+
+  if Lock then
+    try
+      FWaiting := False;
+
+      if (FMsgQueue <> nil) and (FMsgQueue.Count > 0) then
+        begin
+          TempMessage := TCustomMessage(FMsgQueue.Pop);
+          aMsgInfo    := TempMessage.Value;
+          Result      := True;
+          TempMessage.Free;
+        end;
+    finally
+      Unlock;
+    end;
+end;
+
+procedure TWorkerThread.ReadAllPendingMessages;
+var
+  TempInfo : TMsgInfo;
+begin
+  TempInfo.Msg      := 0;
+  TempInfo.StrParam := '';
+  TempInfo.IntParam := 0;
+
+  while ReadPendingMessage(TempInfo) do
+    case TempInfo.Msg of
+      WORKERTHREADMSG_QUIT :
+        begin
+          StopThread;
+          exit;
+        end;
+
+      else ProcessValue(TempInfo);
+    end;
+end;
+
+procedure TWorkerThread.ProcessValue(const aInfo : TMsgInfo);
+begin
+  //
+end;
+
+function TWorkerThread.CanContinue : boolean;
+begin
+  Result := False;
+
+  if Lock then
+    try
+      if not(Terminated) and not(FStop) then
+        begin
+          Result   := True;
+          FWaiting := True;
+          FEvent.ResetEvent;
+        end;
+    finally
+      Unlock;
+    end;
+end;
+
+procedure TWorkerThread.Execute;
+begin
+  while CanContinue do
+    begin
+      FEvent.WaitFor(INFINITE);
+      ReadAllPendingMessages;
+    end;
+end;
+
+end.
+