Stringbuf for concurrent writing And reading

[fuenfzig]

Hi all,

I want to use a single std::stringbuf for writing (by a std::ostream)
and for reading (by a std::istream), concurrently in two threads.
This came to my mind, because the code for reading should be as with any other istream and cannot be changed.

Now my problem is, that a do not get any data in the reading loop
std::ofstream tempfile("test.pdf",
std::ios_base::out | std::ios_base::trunc | std::ios_base::binary);
while (!is->eof()) {
is->read(buffer, bufferSize);
tempfile.write(buffer, is->gcount());
tempfile.flush;
}

The writing thread proceeds as expected and finally finishes writing.

Any hints? What are my misconceptions?

Thanks,
Christoph

[smartway]

How did you define 'is'?

[fuenfzig]

How did you define 'is'?

is is an istream* managed by a boost::shared_ptr

typedef boost::shared_ptr<std::istream> IStreamP;
IStreamP is = data->getIStream();

The istream is created with the same std::stringbuf used during writing (in a ostream of course!).
It seems that I do not get any content during reading or the read pointer is always at the end or ..

[fuenfzig]

Hi again,

let me put it differently. I just tested, that it does not depend on
multi-threading.
If I write to the stringbuf in a std:: ostream (or a std::iostream) and
then try to read
with a std::istream* is (or the same std::iostream* is), it does not
work either.
I immediatly get, (is->fail() == true) :-(
Also tried is->seekg(0); with the same result.

Does anybody have an example showing usage of stringbuf with
std:: ostream and std::istream?
Or can somebody give some details on the internals, when
(is->fail()==true) and (is->eof()==true) does occur?

Thanks very much,
Christoph