[fpc-devel] StdOut capture for FPC RTL
jonas.maebe at elis.ugent.be
Thu Nov 25 11:44:09 CET 2010
On 25 Nov 2010, at 11:16, Anton Kavalenka wrote:
> ?? 25.11.2010 12:01, Jonas Maebe ???????(??):
>> On 25 Nov 2010, at 10:52, Anton Kavalenka wrote:
>>> Due to incompatibility of RTL between FPC and Delphi my capturing
>>> tricks not work.
>>> BTW what the real reason to make these files as threadvar?
>> To prevent multiple threads writing to stdin/stdout/sterr at the
>> same time from corrupting each other's data (all of these text
>> files use an internal buffer, even when the output is immediately
>> flushed afterwards).
> Is not the better way to use something like this:
> // do something nasty with the buffer
It's obviously better for Delphi compatibility and for what you want
to do, but in general I'd say that's simply a different way. It's also
worse in other ways: performance (not just locking/unlocking, which
doesn't matter that much since stdio is never that fast, but mainly
creating the mutexes when the threads are started), backwards
compatibility with existing FPC code, resources required (mutexes
require more than threadvars).
I can't imagine that any of that matters much to you though, since it
does not help you solve your problem. I can't immediately think of a
way to make this programmatically changeable at run time either.
> There is NO other runtimes on this planet instead FPC RTL which take
> care of per-thread buffer of output.
That would very much surprise me.
> It is programmers duty to lock/flush buffer in multithreaded
I don't think it's a programmer's duty to define a global lock that
they manually acquire/release whenever they use writeln() to print
something to stdout in a multi-threaded program using writeln(). Just
like the heap manager, ioresult, and the widestring manager are also
thread-safe by default. In general, I think that all "global" system
unit functionality is thread safe by default. The only part of the
standard RTL that isn't, is afaik the crt unit.
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