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Description

The wait function accepts one or more parameters as described below, and waits (i.e. suspends execution of the program) until signalled to return, or until a timeout period expires.

Parameters

• The first parameter is an expression of integral type, which specifies the timeout period in milliseconds. If the value of the first parameter is zero then the wait function doesn't actually wait, instead it just checks whether it has been signaled to return. If the value of the first argument is equal to the built-in contant maxword then the timout interval is infinite, and the wait function will wait indefinitely until signalled to return.
• The other parameters, if supplied, are expressions of integral type, which specify handles to synchronization objects. The wait function will wait until one of the synchronization objects signals it to return, or until the timeout interval expires. The wait function returns the handle to the synchronization object that signaled it, or zero if the timeout period expires before it was signalled to return.

The authoritative source of information about synchronization objects is the Microsoft Developers Network (MSDN). You can access the MSDN on the Microsoft website at msdn.microsoft.com.

Example

For example, the following procedure was taken from the WinServS sample program and uses the wait function to stop running when requested to do so. ProgramState is a global variable used as a flag to signal when the program is stopping (i.e. being shut down) to prevent recursive calls to the ServerShutDown procedure. The ServerShutDown procedure shuts down the program.

 procedure CheckForStopServiceEvent;
 const
  WAIT_INTERVAL=0;
 begin
  if (ProgramState<>Stopping) and (StopServiceEvent<>0) then
   begin
    //LogMessage('Calling wait');
    if wait(WAIT_INTERVAL, StopServiceEvent)=StopServiceEvent then
     begin
      ProgramState := Stopping;
      ServerShutDown;
     end;
   end
 end;

Portability

Operating Systems: All
Standard Pascal: No

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