I have a custom class that uses boost mutexes and locks like this (only relevant parts):
template<class T> class FFTBuf
{
public:
FFTBuf();
[...]
void lock();
void unlock();
private:
T *_dst;
int _siglen;
int _processed_sums;
int _expected_sums;
int _assigned_sources;
bool _written;
boost::recursive_mutex _mut;
boost::unique_lock<boost::recursive_mutex> _lock;
};
template<class T> FFTBuf<T>::FFTBuf() : _dst(NULL), _siglen(0),
_expected_sums(1), _processed_sums(0), _assigned_sources(0),
_written(false), _lock(_mut, boost::defer_lock_t())
{
}
template<class T> void FFTBuf<T>::lock()
{
std::cerr << "Locking" << std::endl;
_lock.lock();
std::cerr << "Locked" << std::endl;
}
template<class T> void FFTBuf<T>::unlock()
{
std::cerr << "Unlocking" << std::endl;
_lock.unlock();
}
If I try to lock more than once the object from the same thread, I get an exception (lock_error):
#include "fft_buf.hpp"
int main( void ) {
FFTBuf<int> b( 256 );
b.lock();
b.lock();
b.unlock();
b.unlock();
return 0;
}
This is the output:
sb@dex $ ./src/test
Locking
Locked
Locking
terminate called after throwing an instance of 'boost::lock_error'
what(): boost::lock_error
zsh: abort ./src/test
Why is this happening? Am I understanding some concept incorrectly?
