MultiTask

FreePascal Multitask library

Very simple to use Queue based MultiTask library for FreePascal.

This library using https://github.com/tomas-raul/CriticalSection

Some properties :

• Simple
  
• FPC Windows/Linux compatible
  
• Add task on run - you can enqueue task anytime
  
• Priorities of task - you can add task priority - that's not thread priority, but place in the TaskQueue - tpFirst,tpHigh,tpNormal,tpLow,tpLast (default)
  
• Priorities can be globaly disabled
  
• Tasks is normal Threads
  
• UPDATE - Precompiler is done - as alfa prerelease, but i use it in production (for test)

Some properties (planed, in near future) :

• Pin Threads to cores
  
• EnqueueUnique - not finaly usable - UPDATE : Should run ok :D
• Before build method compilation - aplication which will build On_New_Work, and some methods directly
  

Initialization of library :

MultiTask := tMultiTask.Create;
MultiTask.On_Task_Run_Method:=@On_New_Work; // main method of set parameters to NORMAL methods/procedures
MultiTask.On_Before_Task_Method:=@__On_Before_Task_Method; // method BEFORE ANY Task is started - for logging and etc.
MultiTask.On_After_Task_Method:=@__On_After_Task_Method; // method AFTER ANY Task is done - for logging and etc.

Finalization :

MultiTask.Free;

Main Work :

...add tasks to queue possible here...
MultiTask.Start;
...add another tasks to queue possible here...
MultiTask.WaitFor;

Example of On_New_Work method : - or use Precompiler - which generate this method

procedure tmyObject.On_New_Work(const method_name: string; const task: tMultiTaskItem);
begin
case method_name of
'load_image' : Load_Image(task.I[1],task.S[2]);
'save_image' : Save_Image(task.I[1],task.S[2],tBGRABitmap(task.O[3]));
end;
end;

Enqueue task to queue :

for enqueue method :

procedure tMyObject.Load_Image(const id : integer; const fn: string);
var img : tBGRABitmap;
begin
img := tBGRABitmap.Create(fn);
MultiTask.Enqueue(tTaskMethod(@Save_Image),[id,fn,img],[tpHigh]); // enqueue Load_Image method with param ID and filename with HighPriority
end;

use this :

MultiTask.Enqueue(tTaskMethod(@Load_Image),[id,fn],[tpHigh]); // enqueue Load_Image method with param ID and filename with HighPriority

or simply use Precompiler which generate methods f.e.: Load_Image_MT(const id : integer; const fn: string); and other methods as unique or with priority

What is :

MultiTask - main class for automated running any task
Task - simple method or procedure, simply doing some work - as normal method or procedure

What to see :

Memory managment - When you enqeueue task with some objects as parameters, do not free this objects BEFORE task end - simple free this object near task end

Tested on :
Ubuntu 16.10 - (crosscompile from Windows, FPC 3.0.0, Lazarus 1.6.3, kernel 4.08,4.10.1, Ryzen 1800X,32Gb Ram, 256Gb NVMe ssd)
Ubuntu 17.04 - (crosscompile from Windows, FPC 3.0.0, Lazarus 1.6.3, kernel 4.08,4.10.1, Ryzen 1800X,32Gb Ram, 256Gb NVMe ssd)
Windows 8.1 - (partial test, compiled on Windows, FPC 3.0.0, Lazarus 1.6.3,i5-6500,16Gb Ran, 256Gb SSD)