Hello,
This looks promising. Can you explain the similarities and differences with MPI ? Several people have asked about MPI in Free Pascal. Maybe this is an answer for them. Michael. On Mon, 5 Apr 2010, Werner Van Belle wrote:
Hello, After the couple of questions I had about reference counting and cmpxchg, I can finally share what we have been working on, this would be the eternal gratitude part. A freepascal implementation of active objects. http://werner.yellowcouch.org/Papers/activeobjects/index.html From the abstract: Active objects seperates various tasks through means of a message queue whereby the queue will activate the underlying task whenever a new message comes in. Using this abstraction it becomes possible to have time speration between threads (they will not influence each others execution/not wait for each other), space separation (different tasks will not write into each others data space), scheduling independence (we can run multiple tasks with one, two or more processes), syntactical separation (each task is declared in its own source file) and finally lockfree programming, which thus also leads to a noticable lack of deadlock and race-conditions The library consists of a precompiler and a runtime. Originally, both were written in C++. Recently I modified the compiler to generate pascal code. In general, to write an active object description one writes a littl file: active DemoSender { integer tosend = 20; DemoReceiver recv; message startSending(DemoReceiver vrecv, integer nr); }; active DemoReceiver { message printNumber(integer nr); }; This can then be compiled to a forward include, an interface include and an implementation include.- aoc demo2.ao demo2.pas --pascal This generates - demo2_ifc.inc: contains the most important part of the interface section. It can be included in other interface sections. - demo2_imp.inc: contains all the function, constructor and producedure implementations. Can be included in -guess what- an implementation section. - demo2_fwd.inc: if you need them, you get a collection of forward declarations. Can also be included in an interface section. Of course, the messages startSending and printNumber must be implemented. This is done in the file demo2.pas program demo2; {$MODE OBJFPC}{$H+} uses cthreads, sysutils, active_objects; {$include demo2_fwd.inc} {$include demo2_ifc.inc} {$include demo2_imp.inc} Function ActiveDemoSender.startSending(vrecv: DemoReceiver; nr: Integer): ElementResult; Var i : integer; Begin WriteLn(-14); tosend:= nr; for i := 0 to tosend-1 do vrecv.printNumber(i); deactivate; Result:= Done; WriteLn(-15); End; Function ActiveDemoReceiver.printNumber(nr: Integer): elementResult; Begin WriteLn(nr); if nr = 20 then deactivate; Result:= Done; End; An then of course, in the end, we want to start these two task after allocating them- Var sender : DemoSender; recv : DemoReceiver; begin sender:= DemoSender.Create; recv:= DemoReceiver.Create; WriteLn('Loaded Objects. Press enter...'); Readln(); sender.startSending(recv,100); sleep(100); End. So, obviously a very quick example. If you are interested, it is probably best to read the article mentioned above and to download both the C++ version (it contains the compiler) and the fpc version (which contains the runtime) from ftp://ftp.yellowcouch.org/flow/ With kind regards, -- http://werner.yellowcouch.org/
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