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#pragma once
#if defined(OS_LINUX) || defined(OS_FREEBSD)
#include <cstdint>
#if defined(OS_FREEBSD)
#include <unistd.h>
#endif
namespace DB
{
/** Opens a file /proc/self/statm. Keeps it open and reads memory statistics via 'pread'.
* This is Linux specific.
* See: man procfs
*
* Note: a class is used instead of a single function to avoid excessive file open/close on every use.
* pread is used to avoid lseek.
*
* Actual performance is from 1 to 5 million iterations per second.
*/
class MemoryStatisticsOS
{
public:
/// In number of bytes.
struct Data
{
uint64_t virt;
uint64_t resident;
#if defined(OS_LINUX)
uint64_t shared;
#endif
uint64_t code;
uint64_t data_and_stack;
};
MemoryStatisticsOS();
~MemoryStatisticsOS();
/// Thread-safe.
Data get() const;
private:
#if defined(OS_LINUX)
int fd;
#endif
#if defined(OS_FREEBSD)
size_t pagesize;
pid_t self;
#endif
};
}
#endif
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