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#ifndef __RCPP_PARALLEL_COMMON__
#define __RCPP_PARALLEL_COMMON__
#include <cerrno>
#include <cstddef>
#include <cstdlib>
namespace RcppParallel {
template <typename T, typename U>
inline int resolveValue(const char* envvar,
T requestedValue,
U defaultValue)
{
// if the requested value is non-zero and not the default, we can use it
if (requestedValue != defaultValue && requestedValue > 0)
return requestedValue;
// otherwise, try reading the default from associated envvar
// if the environment variable is unset, use the default
const char* var = getenv(envvar);
if (var == NULL)
return defaultValue;
// try to convert the string to a number
// if an error occurs during conversion, just use default
errno = 0;
char* end;
long value = strtol(var, &end, 10);
// check for conversion failure
if (end == var || *end != '\0' || errno == ERANGE)
return defaultValue;
// okay, return the parsed environment variable value
return value;
}
// Work executed within a background thread. We implement dynamic
// dispatch using vtables so we can have a stable type to cast
// to from the void* passed to the worker thread (required because
// the tinythreads interface allows to pass only a void* to the
// thread main rather than a generic type / template)
struct Worker
{
// construct and destruct (delete virtually)
Worker() {}
virtual ~Worker() {}
// dispatch work over a range of values
virtual void operator()(std::size_t begin, std::size_t end) = 0;
// disable copying and assignment
private:
Worker(const Worker&);
void operator=(const Worker&);
};
// Tag type used for disambiguating splitting constructors
struct Split {};
} // namespace RcppParallel
#endif // __RCPP_PARALLEL_COMMON__
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