I'm trying to quickstart with dynamic shared libraries in D, but I'm having a problem.
I'm building following code with dmd -shared ./testlib.d:
module testlib;
import std.c.stdio;
extern (C) export int hello(int a) {
printf("Number is %d", a);
return (a + 1);
}
It builds fine, and works. But when I'm trying to make use of following more D'ish source:
module testlib;
import std.stdio;
extern (C) export int hello(int a) {
writefln("Number is %d", a);
return (a + 1);
}
It fails with segmentation fault once I'm trying to call hello. What am I doing wrong?
I'm calling hello using Python:
import ctypes
testlib = ctypes.CDLL('testlib.dylib');
print (testlib.hello(10))
UPD1: Seems that I also cannot use Phobos functions like std.conv.to!(string).
UPD2: There is no such problem on Windows, everything seems to work fine. Mac OS X suffers from this.
UPD3: Possibly, this is connected with GC. I must somehow initialize GC, but core.memory.GC.enable() still fails with segmentation fault.
Solution is simple, yet brilliant:
static import core.runtime;
extern (C) export void init() { // to be called once after loading shared lib
core.runtime.Runtime.initialize();
}
extern (C) export void done() { // to be called before unloading shared lib
core.runtime.Runtime.terminate();
}
Possibly, there are ways in Linux and Mac OS X to call these functions automagically, but I'm satisfied with even this.
Related
I've always thought that using std::cout << something was thread safe.
For this little example
#include <iostream>
#include <thread>
void f()
{
std::cout << "Hello from f\n";
}
void g()
{
std::cout << "Hello from g\n";
}
int main()
{
std::thread t1(f);
std::thread t2(g);
t1.join();
t2.join();
}
my expectation was that the order of the two outputs would be undefined (and indeed that is what I observe in practice), but that the calls to operator<< are thread safe.
However, ThreadSanitizer, DRD and Helgrind all seem to give various errors regarding access to std::__1::ios_base::width(long) and std::__1::basic_ios<char, std::__1::char_traits >::fill()
On Compiler Explorer I don't see any errors.
On FreeBSD 13, ThreadSanitizer gives me 3 warnings, the two listed above plus the malloc/memcpy to the underlying i/o buffer.
Again in FreeBSD 13, DRD gives 4 errors, width() and fill() times two for the two threads.
Finally FreeBSD 13 Helgrind gives one known false positive related to TLS in thread creation, fill()and width() twice.
On Fedora 34
No errors with g++ 11.2.1 and ThreadSanitizer
DRD complains about malloc/memcpy in fwrite with g++ compiled exe
Helgrind also complains about fwrite and also for the construction of cout, again with the g++ compiled exe
clang++ 12 ThreadSanitizer complains about fill() and width()
DRD with the clang++ compiler exe complains about fill(), width(), fwrite and one other in start_thread
Helgrind with the clang++ exe complains about some TLS, fill(), width(), fwrite
macOS XCode clang++ ThreadSanitizer generates warnings as well (which will be libc++).
Looking at the libc++ and libstdc++ code I don't see anything at all that protects width(). So I don't understand why there are no complaints on compiler explorer.
I tried running with TSAN_OPTIONS=print_suppressions=1 and there was no more output (g++ Fedora ThreadSanitizer)
There does seem to be some consensus over the width() and fill() calls.
Looking more closely at the libstdc++ source I see that there is
(with some trimming and comments):
// ostream_insert.h
// __n is the length of the string pointed to by __s
template<typename _CharT, typename _Traits>
basic_ostream<_CharT, _Traits>&
__ostream_insert(basic_ostream<_CharT, _Traits>& __out,
const _CharT* __s, streamsize __n)
{
typedef basic_ostream<_CharT, _Traits> __ostream_type;
typedef typename __ostream_type::ios_base __ios_base;
typename __ostream_type::sentry __cerb(__out);
if (__cerb)
{
__try
{
const streamsize __w = __out.width();
if (__w > __n)
{
// snipped
// handle padding
}
else
__ostream_write(__out, __s, __n);
// why no hazard here?
__out.width(0);
}
__out is the stream object, global cout in this case. I don't see anything like locks or atomics.
Any suggestions as to how ThreadSanitizer/g++ is getting a "clean" output?
There is this somewhat cryptic comment
template<typename _CharT, typename _Traits>
basic_ostream<_CharT, _Traits>::sentry::
sentry(basic_ostream<_CharT, _Traits>& __os)
: _M_ok(false), _M_os(__os)
{
// XXX MT
if (__os.tie() && __os.good())
__os.tie()->flush();
The libc++ code looks similar. In iostream
template<class _CharT, class _Traits>
basic_ostream<_CharT, _Traits>&
__put_character_sequence(basic_ostream<_CharT, _Traits>& __os,
const _CharT* __str, size_t __len)
{
#ifndef _LIBCPP_NO_EXCEPTIONS
try
{
#endif // _LIBCPP_NO_EXCEPTIONS
typename basic_ostream<_CharT, _Traits>::sentry __s(__os);
if (__s)
{
typedef ostreambuf_iterator<_CharT, _Traits> _Ip;
if (__pad_and_output(_Ip(__os),
__str,
(__os.flags() & ios_base::adjustfield) == ios_base::left ?
__str + __len :
__str,
__str + __len,
__os,
__os.fill()).failed())
__os.setstate(ios_base::badbit | ios_base::failbit);
and in locale
template <class _CharT, class _OutputIterator>
_LIBCPP_HIDDEN
_OutputIterator
__pad_and_output(_OutputIterator __s,
const _CharT* __ob, const _CharT* __op, const _CharT* __oe,
ios_base& __iob, _CharT __fl)
{
streamsize __sz = __oe - __ob;
streamsize __ns = __iob.width();
if (__ns > __sz)
__ns -= __sz;
else
__ns = 0;
for (;__ob < __op; ++__ob, ++__s)
*__s = *__ob;
for (; __ns; --__ns, ++__s)
*__s = __fl;
for (; __ob < __oe; ++__ob, ++__s)
*__s = *__ob;
__iob.width(0);
return __s;
}
Again I see no thread protection, but also this time the tools detect a hazard.
Are these real issues? For plain calls to operator<< the value of width doesn't change, and is always 0.
libstdc++ does not produce the error while libc++ does.
iostream.objects.overview Concurrent access to a synchronized ([ios.members.static]) standard iostream object's formatted and unformatted input ([istream]) and output ([ostream]) functions or a standard C stream by multiple threads does not result in a data race ([intro.multithread]).
So this looks like a libc++ bug to me.
I got the answer from Jonathan Wakely. Makes me feel rather stupid.
The difference is that on Fedora, libstdc++.so contains an explicit instantiation of the iostream classes. libstdc++.so isn't instrumented for ThreadSanitizer so it cannot detect any hazards related to it.
I've the sample pass code from LLVM.org:
#include "llvm/Pass.h"
#include "llvm/IR/Function.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
namespace {
struct Hello : public FunctionPass {
static char ID;
Hello() : FunctionPass(ID) {}
bool runOnFunction(Function &F) override {
errs() << "Hello: ";
errs().write_escaped(F.getName()) << '\n';
return false;
}
}; // end of struct Hello
} // end of anonymous namespace
char Hello::ID = 0;
static RegisterPass<Hello> X("hello", "Hello World Pass",
false /* Only looks at CFG */,
false /* Analysis Pass */);
The project builds fine and creates a SkeletonPass.dll.
When I execute the command:
C:\Users\nlykkei\Projects\llvm-pass-tutorial\build>opt -load skeleton\Debug\SkeletonPass.dll -hello foo.bc
opt: Unknown command line argument '-hello'. Try: 'opt -help'
opt: Did you mean '-help'?
opt doesn't recognize -hello option, even thus everything works fine on Ubuntu 16.04.
In addition, if I execute:
clang -Xclang -load -Xclang skeleton\Debug\SkeletonPass.dll foo.bc
nothing is printed out on Visual Studio terminal (Native Tools Command Prompt x86). On Linux, the function names are printed nicely for the same bitcode file.
What can be the reason for my experience? I do exactly the same on Windows 10 as I do on Ubuntu, but very different results.
Plugins are special beasts on Windows, because the latter does not support proper dynamic linking, so, your pass simply does not register itself in the PassRegistry. So you'd either need to compile all the LLVM into .dll or link your pass statically into opt / clang.
I made my own interface, simplistic version looks like this:
#ifndef _FOO_IDL_
#define _FOO_IDL_
module FOO {
typedef unsigned long Bar;
interface FOOInterface {
void getBar(out FOO::Bar b);
};
};
#endif
After that I made "REDHAWK IDL Project", used that IDL, compiled, installed.
Then I made Redhawk component, added output port and used that interface on it, did code generation. During compilation I got error:
port_impl.h:26:29: error: expected ‘,’ or ‘...’ before ‘&&’ token
void getBar(FOO::Bar&& b);
It looks like code generator adds excessive ampersand. What could I do about it?
Thank you.
OK, I admit it, this is a unique case. When we build our application we are using make, so I've included my tests in a test folder under src. Then at the same level as our release folder we have created a unit-test folder that includes all of our source files and our test source files.
But my IDE is CLion, which uses CMake. In my CMakeLists.txt file, I have included:
enable_testing()
find_package(GTest REQUIRED)
include_directories(${GTEST_INCLUDE_DIRS})
add_executable(TestProject ${SOURCE_FILES})
target_link_libraries(TestProject ${GTEST_BOTH_LIBRARIES})
I am creating my first Test Fixture. Here is the code:
#include "OPProperties.h"
#include "gtest/gtest.h"
namespace {
// The fixture for testing class OPPropertiesTestTest.
class OPPropertiesTestTest : public ::testing::Test {
protected:
// You can remove any or all of the following functions if its body
// is empty.
OPPropertiesTestTest() {
// You can do set-up work for each test here.
}
virtual ~OPPropertiesTestTest() {
// You can do clean-up work that doesn't throw exceptions here.
}
// If the constructor and destructor are not enough for setting up
// and cleaning up each test, you can define the following methods:
virtual void SetUp() {
// Code here will be called immediately after the constructor (right
// before each test).
}
virtual void TearDown() {
// Code here will be called immediately after each test (right
// before the destructor).
}
// Objects declared here can be used by all tests in the test case for OPPropertiesTestTest.
};
TEST_F(OPPropertiesTestTest, ThisTestWillFail) {
EXPECT_EQ(0, 2);
}
} // namespace
int main(int argc, char **argv) {
::testing::InitGoogleTest(&argc, argv);
return RUN_ALL_TESTS();
}
Here is an image capture:
Notice the syntax checker errors in my TEST_F function. When I started to type TEST_F code completion is trying to find a Boost Test Function.
Can someone tell me what else I need to add to the CMakeLists.txt file or what I am not doing that GTest functions are not being recognized?
As πάντα ῥεῖ pointed out, I hadn't actually tried to build the code. When I did I first received a linker error for pthread, so we added the following line the the CMakeLists.txt file:
target_link_libraries(OnePrint pthread)
Then I tried again to build and received these errors:
/home/user/gtest-1.7.0/lib/.libs/libgtest.so: undefined reference to `pthread_key_create'
/home/user/gtest-1.7.0/lib/.libs/libgtest.so: undefined reference to `pthread_getspecific'
/home/user/gtest-1.7.0/lib/.libs/libgtest.so: undefined reference to `pthread_key_delete'
/home/user/gtest-1.7.0/lib/.libs/libgtest.so: undefined reference to `pthread_setspecific'
collect2: error: ld returned 1 exit status
So, I ran a search on these errors and found this question.
The answer that worked for me was here.
Till now I have learnt one thing, there's something wrong I'm doing with OpenCV, Qt has no role in the error
I'm trying to run two methods in different threads, but it gives me error:
[xcb] Unknown request in queue while dequeuing
[xcb] Most likely this is a multi-threaded client and XInitThreads has not been called
[xcb] Aborting, sorry about that.
Blurring_Images: ../../src/xcb_io.c:178: dequeue_pending_request: Assertion `!xcb_xlib_unknown_req_in_deq' failed.
The program has unexpectedly finished.
Here's my code:
void Dialog::blurImages(int b)
{
QtConcurrent::run(this,&Dialog::homogenour_blur,b);
QtConcurrent::run(this,&Dialog::gaussianBlur,b);
}
void Dialog::homogenour_blur(int b)
{
cv::blur(img,img1,cv::Size(b,b));
showImage("Homogenous Blur",img1);
}
void Dialog::gaussianBlur(int b)
{
cv::GaussianBlur(img,img2,cv::Size(b,b),b);
showImage("Gaussian Blur",img2);
}
whereas if i comment out one call(shown below), it runs fine
void Dialog::blurImages(int b)
{
QtConcurrent::run(this,&Dialog::homogenour_blur,b);
//QtConcurrent::run(this,&Dialog::gaussianBlur,b);
}
It's really annoying guys, please help !!
EDIT:
Instead of calling showImage(), I replaced it with the actial OpenCV call(see below):
void Dialog::homogenour_blur(int b)
{
cv::blur(img,img1,cv::Size(b,b));
//showImage("Homogenous Blur",img1);
cv::imshow("Homogenous Blur",img1);
}
void Dialog::gaussianBlur(int b)
{
cv::GaussianBlur(img,img2,cv::Size(b,b),b);
//showImage("Gaussian Blur",img2);
cv::imshow("Gaussian Blur",img2);
}
Now the error I get is:
Original Image: Fatal IO error 11 (Resource temporarily unavailable) on X server :0.
Original Image: Fatal IO error 0 (Success) on X server :0.
Fatal Error: Accessed global static 'KGlobalSettings *s_self()' after destruction. Defined at ../../kdeui/kernel/kglobalsettings.cpp:190
The program has unexpectedly finished.
To all concerned:
fix Jaydeep's problems
[xcb] Unknown request in queue while dequeuing
[xcb] Most likely this is a multi-threaded client and XInitThreads has not been called
[xcb] Aborting, sorry about that.
and
error: ‘XInitThreads’ was not declared in this scope
by linking X11, including xlib, and calling XInitThreads.
Example for including xlib and calling XInitThreads:
// main.cpp
#include <thread>
#include <X11/Xlib.h>
int main() {
XInitThreads();
// . . .
}
Example for linking:
g++ main.cpp -o my_program -std=c++0x -pthread -lX11 /* -pthread if you're on Linux */
Of course, don't forget to link the other files that may be necessary to your application
imshow() method seems not thread safe. if you use python, it can be solved like this:
self.img_lock = threading.Lock()
with self.img_lock:
cv2.imshow()
cv2.waitKey(1)