github.com/livekit/protocol@v1.16.1-0.20240517185851-47e4c6bba773/utils/timed_version.go (about)

     1  // Copyright 2023 LiveKit, Inc.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package utils
    16  
    17  import (
    18  	"database/sql/driver"
    19  	"encoding/binary"
    20  	"errors"
    21  	"fmt"
    22  	"sync"
    23  	"time"
    24  
    25  	"github.com/livekit/protocol/livekit"
    26  )
    27  
    28  const tickBits uint64 = 13
    29  const tickMask uint64 = (1 << tickBits) - 1
    30  
    31  var epoch = time.Date(2000, 0, 0, 0, 0, 0, 0, time.UTC).UnixMicro()
    32  
    33  type TimedVersionGenerator interface {
    34  	Next() TimedVersion
    35  }
    36  
    37  func timedVersionComponents(v TimedVersion) (ts int64, ticks int32) {
    38  	return int64(v>>tickBits) + epoch, int32(uint64(v) & tickMask)
    39  }
    40  
    41  func timedVersionFromComponents(ts int64, ticks int32) TimedVersion {
    42  	if ts < epoch {
    43  		ts = epoch
    44  	}
    45  	return TimedVersion((uint64(ts-epoch) << tickBits) | uint64(ticks))
    46  }
    47  
    48  type timedVersionGenerator struct {
    49  	mu    sync.Mutex
    50  	ts    int64
    51  	ticks uint64
    52  }
    53  
    54  func NewDefaultTimedVersionGenerator() TimedVersionGenerator {
    55  	return new(timedVersionGenerator)
    56  }
    57  
    58  func (g *timedVersionGenerator) New() *TimedVersion {
    59  	v := g.Next()
    60  	return &v
    61  }
    62  
    63  func (g *timedVersionGenerator) Next() TimedVersion {
    64  	ts := time.Now().UnixMicro()
    65  
    66  	g.mu.Lock()
    67  	defer g.mu.Unlock()
    68  
    69  	for {
    70  		if ts < g.ts {
    71  			ts = g.ts
    72  		}
    73  		if g.ts == ts {
    74  			// if incrementing the ticks would overflow the version sleep for a
    75  			// microsecond then try again.
    76  			if g.ticks == tickMask {
    77  				time.Sleep(time.Microsecond)
    78  				ts = time.Now().UnixMicro()
    79  				continue
    80  			}
    81  			g.ticks++
    82  		} else {
    83  			g.ts = ts
    84  			g.ticks = 0
    85  		}
    86  		return timedVersionFromComponents(g.ts, int32(g.ticks))
    87  	}
    88  }
    89  
    90  type TimedVersion uint64
    91  
    92  func TimedVersionFromProto(proto *livekit.TimedVersion) TimedVersion {
    93  	return timedVersionFromComponents(proto.GetUnixMicro(), proto.GetTicks())
    94  }
    95  
    96  func TimedVersionFromTime(t time.Time) TimedVersion {
    97  	return timedVersionFromComponents(t.UnixMicro(), 0)
    98  }
    99  
   100  func (t *TimedVersion) Update(other TimedVersion) bool {
   101  	return t.Upgrade(other)
   102  }
   103  
   104  func (t *TimedVersion) Upgrade(other TimedVersion) bool {
   105  	if *t < other {
   106  		*t = other
   107  		return true
   108  	}
   109  	return false
   110  }
   111  
   112  func (t *TimedVersion) Downgrade(other TimedVersion) bool {
   113  	if *t > other {
   114  		*t = other
   115  		return true
   116  	}
   117  	return false
   118  }
   119  
   120  func (t *TimedVersion) Store(other TimedVersion) {
   121  	*t = other
   122  }
   123  
   124  func (t TimedVersion) Load() TimedVersion {
   125  	return t
   126  }
   127  
   128  func (t TimedVersion) After(other TimedVersion) bool {
   129  	return t > other
   130  }
   131  
   132  func (t TimedVersion) Compare(other TimedVersion) int {
   133  	if t < other {
   134  		return -1
   135  	}
   136  	if t == other {
   137  		return 0
   138  	}
   139  	return 1
   140  }
   141  
   142  func (t TimedVersion) IsZero() bool {
   143  	return t == 0
   144  }
   145  
   146  func (t TimedVersion) ToProto() *livekit.TimedVersion {
   147  	ts, ticks := timedVersionComponents(t)
   148  	return &livekit.TimedVersion{
   149  		UnixMicro: ts,
   150  		Ticks:     ticks,
   151  	}
   152  }
   153  
   154  func (t TimedVersion) Time() time.Time {
   155  	ts, _ := timedVersionComponents(t)
   156  	return time.UnixMicro(ts)
   157  }
   158  
   159  func (t TimedVersion) String() string {
   160  	ts, ticks := timedVersionComponents(t)
   161  	return fmt.Sprintf("%d.%d", ts, ticks)
   162  }
   163  
   164  func (t TimedVersion) Value() (driver.Value, error) {
   165  	if t.IsZero() {
   166  		return nil, nil
   167  	}
   168  
   169  	ts, ticks := timedVersionComponents(t)
   170  	b := make([]byte, 0, 12)
   171  	b = binary.BigEndian.AppendUint64(b, uint64(ts))
   172  	b = binary.BigEndian.AppendUint32(b, uint32(ticks))
   173  	return b, nil
   174  }
   175  
   176  func (t *TimedVersion) Scan(src interface{}) (err error) {
   177  	switch b := src.(type) {
   178  	case []byte:
   179  		switch len(b) {
   180  		case 0:
   181  			*t = 0
   182  		case 12:
   183  			ts := int64(binary.BigEndian.Uint64(b))
   184  			ticks := int32(binary.BigEndian.Uint32(b[8:]))
   185  			*t = timedVersionFromComponents(ts, ticks)
   186  		default:
   187  			return errors.New("(*TimedVersion).Scan: unsupported format")
   188  		}
   189  	case nil:
   190  		*t = 0
   191  	default:
   192  		return errors.New("(*TimedVersion).Scan: unsupported data type")
   193  	}
   194  	return nil
   195  }
   196  
   197  func (t TimedVersion) GormDataType() string {
   198  	return "bytes"
   199  }