diff options
Diffstat (limited to 'Godeps/_workspace/src/github.com/pborman/uuid/time.go')
-rw-r--r-- | Godeps/_workspace/src/github.com/pborman/uuid/time.go | 132 |
1 files changed, 132 insertions, 0 deletions
diff --git a/Godeps/_workspace/src/github.com/pborman/uuid/time.go b/Godeps/_workspace/src/github.com/pborman/uuid/time.go new file mode 100644 index 000000000..7ebc9bef1 --- /dev/null +++ b/Godeps/_workspace/src/github.com/pborman/uuid/time.go @@ -0,0 +1,132 @@ +// Copyright 2014 Google Inc. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package uuid + +import ( + "encoding/binary" + "sync" + "time" +) + +// A Time represents a time as the number of 100's of nanoseconds since 15 Oct +// 1582. +type Time int64 + +const ( + lillian = 2299160 // Julian day of 15 Oct 1582 + unix = 2440587 // Julian day of 1 Jan 1970 + epoch = unix - lillian // Days between epochs + g1582 = epoch * 86400 // seconds between epochs + g1582ns100 = g1582 * 10000000 // 100s of a nanoseconds between epochs +) + +var ( + mu sync.Mutex + lasttime uint64 // last time we returned + clock_seq uint16 // clock sequence for this run + + timeNow = time.Now // for testing +) + +// UnixTime converts t the number of seconds and nanoseconds using the Unix +// epoch of 1 Jan 1970. +func (t Time) UnixTime() (sec, nsec int64) { + sec = int64(t - g1582ns100) + nsec = (sec % 10000000) * 100 + sec /= 10000000 + return sec, nsec +} + +// GetTime returns the current Time (100s of nanoseconds since 15 Oct 1582) and +// clock sequence as well as adjusting the clock sequence as needed. An error +// is returned if the current time cannot be determined. +func GetTime() (Time, uint16, error) { + defer mu.Unlock() + mu.Lock() + return getTime() +} + +func getTime() (Time, uint16, error) { + t := timeNow() + + // If we don't have a clock sequence already, set one. + if clock_seq == 0 { + setClockSequence(-1) + } + now := uint64(t.UnixNano()/100) + g1582ns100 + + // If time has gone backwards with this clock sequence then we + // increment the clock sequence + if now <= lasttime { + clock_seq = ((clock_seq + 1) & 0x3fff) | 0x8000 + } + lasttime = now + return Time(now), clock_seq, nil +} + +// ClockSequence returns the current clock sequence, generating one if not +// already set. The clock sequence is only used for Version 1 UUIDs. +// +// The uuid package does not use global static storage for the clock sequence or +// the last time a UUID was generated. Unless SetClockSequence a new random +// clock sequence is generated the first time a clock sequence is requested by +// ClockSequence, GetTime, or NewUUID. (section 4.2.1.1) sequence is generated +// for +func ClockSequence() int { + defer mu.Unlock() + mu.Lock() + return clockSequence() +} + +func clockSequence() int { + if clock_seq == 0 { + setClockSequence(-1) + } + return int(clock_seq & 0x3fff) +} + +// SetClockSeq sets the clock sequence to the lower 14 bits of seq. Setting to +// -1 causes a new sequence to be generated. +func SetClockSequence(seq int) { + defer mu.Unlock() + mu.Lock() + setClockSequence(seq) +} + +func setClockSequence(seq int) { + if seq == -1 { + var b [2]byte + randomBits(b[:]) // clock sequence + seq = int(b[0])<<8 | int(b[1]) + } + old_seq := clock_seq + clock_seq = uint16(seq&0x3fff) | 0x8000 // Set our variant + if old_seq != clock_seq { + lasttime = 0 + } +} + +// Time returns the time in 100s of nanoseconds since 15 Oct 1582 encoded in +// uuid. It returns false if uuid is not valid. The time is only well defined +// for version 1 and 2 UUIDs. +func (uuid UUID) Time() (Time, bool) { + if len(uuid) != 16 { + return 0, false + } + time := int64(binary.BigEndian.Uint32(uuid[0:4])) + time |= int64(binary.BigEndian.Uint16(uuid[4:6])) << 32 + time |= int64(binary.BigEndian.Uint16(uuid[6:8])&0xfff) << 48 + return Time(time), true +} + +// ClockSequence returns the clock sequence encoded in uuid. It returns false +// if uuid is not valid. The clock sequence is only well defined for version 1 +// and 2 UUIDs. +func (uuid UUID) ClockSequence() (int, bool) { + if len(uuid) != 16 { + return 0, false + } + return int(binary.BigEndian.Uint16(uuid[8:10])) & 0x3fff, true +} |