be/src/util/os-util.h

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//   http://www.apache.org/licenses/LICENSE-2.0
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#ifndef IMPALA_UTIL_PROC_UTIL_H
#define IMPALA_UTIL_PROC_UTIL_H

#include "common/logging.h"
#include "common/status.h"

namespace impala {

/// Utility methods to read interesting values from /proc.
/// TODO: Get stats for parent process.

/// Container struct for statistics read from the /proc filesystem for a thread.
struct ThreadStats {
  int64_t user_ns;
  int64_t kernel_ns;
  int64_t iowait_ns;

  /// Default constructor zeroes all members in case structure can't be filled by
  /// GetThreadStats.
  ThreadStats() : user_ns(0), kernel_ns(0), iowait_ns(0) { }
};

/// Populates ThreadStats object for a given thread by reading from
/// /proc/<pid>/task/<tid>/stats. Returns OK unless the file cannot be read or is in an
/// unrecognised format, or if the kernel version is not modern enough.
Status GetThreadStats(int64_t tid, ThreadStats* stats);

/// Runs a shell command. Returns false if there was any error (either failure to launch
/// or non-0 exit code), and true otherwise. *msg is set to an error message including the
/// OS error string, if any, and the first 1k of output if there was any error, or just
/// the first 1k of output otherwise.
/// If do_trim is 'true', all trailing whitespace is removed from the output.
/// unset_environment is used to unset a set of environment variables prior to running
/// the cmd.
bool RunShellProcess(const std::string& cmd, std::string* msg, bool do_trim=false,
    const std::set<std::string>& unset_environment=std::set<std::string>());

}
#endif