var once … var logger … func log() { … } // GetCPUTime returns the how much CPU time has passed since the start of this // process. It always returns 0 under non-linux environments. func GetCPUTime() int64 { … } type Rusage … // GetRusage is a no-op function under non-linux environments. func GetRusage() *Rusage { … } // CPUTimeDiff returns the differences of user CPU time and system CPU time used // between two Rusage structs. It a no-op function for non-linux environments. func CPUTimeDiff(first *Rusage, latest *Rusage) (float64, float64) { … } // SetTCPUserTimeout is a no-op function under non-linux environments. func SetTCPUserTimeout(conn net.Conn, timeout time.Duration) error { … } // GetTCPUserTimeout is a no-op function under non-linux environments. // A negative return value indicates the operation is not supported func GetTCPUserTimeout(conn net.Conn) (int, error) { … }