github.com/psiphon-Labs/psiphon-tunnel-core@v2.0.28+incompatible/psiphon/common/monotime/nanotime.go (about)

     1  // Copyright (C) 2016  Arista Networks, Inc.
     2  // Use of this source code is governed by the Apache License 2.0
     3  // that can be found in the COPYING file.
     4  
     5  // Package monotime provides a fast monotonic clock source.
     6  package monotime
     7  
     8  import (
     9  	"time"
    10  	_ "unsafe" // required to use //go:linkname
    11  )
    12  
    13  //go:noescape
    14  //go:linkname nanotime runtime.nanotime
    15  func nanotime() int64
    16  
    17  // Time is a point in time represented in nanoseconds.
    18  type Time int64
    19  
    20  // Now returns the current time in nanoseconds from a monotonic clock.
    21  // The time returned is based on some arbitrary platform-specific point in the
    22  // past.  The time returned is guaranteed to increase monotonically at a
    23  // constant rate, unlike time.Now() from the Go standard library, which may
    24  // slow down, speed up, jump forward or backward, due to NTP activity or leap
    25  // seconds.
    26  func Now() Time {
    27  	return Time(nanotime())
    28  }
    29  
    30  // Since is analogous to https://golang.org/pkg/time/#Since
    31  func Since(t Time) time.Duration {
    32  	return time.Duration(Now() - t)
    33  }
    34  
    35  // Add is analogous to https://golang.org/pkg/time/#Time.Add
    36  func (t Time) Add(d time.Duration) Time {
    37  	return t + Time(d)
    38  }
    39  
    40  // Sub is analogous to https://golang.org/pkg/time/#Time.Sub
    41  func (t Time) Sub(s Time) time.Duration {
    42  	return time.Duration(t - s)
    43  }
    44  
    45  // Before is analogous to https://golang.org/pkg/time/#Time.Before
    46  func (t Time) Before(u Time) bool {
    47  	return t < u
    48  }
    49  
    50  // After is analogous to https://golang.org/pkg/time/#Time.After
    51  func (t Time) After(u Time) bool {
    52  	return t > u
    53  }
    54  
    55  // Equal is analogous to https://golang.org/pkg/time/#Time.Equal
    56  func (t Time) Equal(u Time) bool {
    57  	return t == u
    58  }