go.temporal.io/server@v1.23.0/common/clock/hybrid_logical_clock/hybrid_logical_clock.go (about)

     1  // The MIT License
     2  //
     3  // Copyright (c) 2020 Temporal Technologies Inc.  All rights reserved.
     4  //
     5  // Copyright (c) 2020 Uber Technologies, Inc.
     6  //
     7  // Permission is hereby granted, free of charge, to any person obtaining a copy
     8  // of this software and associated documentation files (the "Software"), to deal
     9  // in the Software without restriction, including without limitation the rights
    10  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
    11  // copies of the Software, and to permit persons to whom the Software is
    12  // furnished to do so, subject to the following conditions:
    13  //
    14  // The above copyright notice and this permission notice shall be included in
    15  // all copies or substantial portions of the Software.
    16  //
    17  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    18  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    19  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    20  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    21  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    22  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    23  // THE SOFTWARE.
    24  
    25  package hybrid_logical_clock
    26  
    27  import (
    28  	"time"
    29  
    30  	clockpb "go.temporal.io/server/api/clock/v1"
    31  	commonclock "go.temporal.io/server/common/clock"
    32  )
    33  
    34  type Clock = clockpb.HybridLogicalClock
    35  
    36  // Next generates the next clock timestamp given the current clock.
    37  // HybridLogicalClock requires the previous clock to ensure that time doesn't move backwards and the next clock is
    38  // monotonically increasing.
    39  func Next(prior *Clock, source commonclock.TimeSource) *Clock {
    40  	wallclock := source.Now().UnixMilli()
    41  	// Ensure time does not move backwards
    42  	if wallclock < prior.GetWallClock() {
    43  		wallclock = prior.GetWallClock()
    44  	}
    45  	// Ensure timestamp is monotonically increasing
    46  	var version int32
    47  	if wallclock == prior.GetWallClock() {
    48  		version = prior.GetVersion() + 1
    49  	}
    50  
    51  	return &Clock{WallClock: wallclock, Version: version, ClusterId: prior.ClusterId}
    52  }
    53  
    54  // Zero generates a zeroed logical clock for the cluster ID.
    55  func Zero(clusterID int64) *Clock {
    56  	return &Clock{WallClock: 0, Version: 0, ClusterId: clusterID}
    57  }
    58  
    59  func sign[T int64 | int32](x T) int {
    60  	if x > 0 {
    61  		return 1
    62  	}
    63  	if x < 0 {
    64  		return -1
    65  	}
    66  	return 0
    67  }
    68  
    69  // Compare 2 Clocks, returns 0 if a == b, -1 if a > b, 1 if a < b
    70  func Compare(a *Clock, b *Clock) int {
    71  	if a.WallClock == b.WallClock {
    72  		if a.Version == b.Version {
    73  			return sign(b.ClusterId - a.ClusterId)
    74  		}
    75  		return sign(b.Version - a.Version)
    76  	}
    77  	return sign(b.WallClock - a.WallClock)
    78  }
    79  
    80  // Greater returns true if a is greater than b
    81  func Greater(a *Clock, b *Clock) bool {
    82  	return Compare(b, a) > 0
    83  }
    84  
    85  // Greater returns true if a is greater than b
    86  func Less(a *Clock, b *Clock) bool {
    87  	return Compare(a, b) > 0
    88  }
    89  
    90  // Max returns the maximum of two Clocks
    91  func Max(a *Clock, b *Clock) *Clock {
    92  	if Compare(a, b) > 0 {
    93  		return b
    94  	}
    95  	return a
    96  }
    97  
    98  // Min returns the minimum of two Clocks
    99  func Min(a *Clock, b *Clock) *Clock {
   100  	if Compare(a, b) > 0 {
   101  		return a
   102  	}
   103  	return b
   104  }
   105  
   106  // Equal returns whether two Clocks are equal
   107  func Equal(a *Clock, b *Clock) bool {
   108  	return Compare(a, b) == 0
   109  }
   110  
   111  // UTC returns a Time from a Clock in millisecond resolution. The Time's Location is set to UTC.
   112  func UTC(c *Clock) time.Time {
   113  	if c == nil {
   114  		return time.Unix(0, 0).UTC()
   115  	}
   116  	return time.Unix(c.WallClock/1000, c.WallClock%1000*1000000).UTC()
   117  }
   118  
   119  // Since returns time.Since(UTC(c))
   120  func Since(c *Clock) time.Duration {
   121  	return time.Since(UTC(c))
   122  }