go.temporal.io/server@v1.23.0/common/timer/local_gate.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 timer
    26  
    27  import (
    28  	"time"
    29  
    30  	"go.temporal.io/server/common/clock"
    31  )
    32  
    33  type (
    34  	LocalGate interface {
    35  		Gate
    36  	}
    37  
    38  	LocalGateImpl struct {
    39  		// the channel which will be used to proxy the fired timer
    40  		fireCh  chan struct{}
    41  		closeCh chan struct{}
    42  
    43  		timeSource clock.TimeSource
    44  
    45  		// the actual timer which will fire
    46  		timer *time.Timer
    47  		// variable indicating when the above timer will fire
    48  		nextWakeupTime time.Time
    49  	}
    50  )
    51  
    52  // NewLocalGate create a new timer gate instance
    53  func NewLocalGate(timeSource clock.TimeSource) LocalGate {
    54  	lg := &LocalGateImpl{
    55  		timer:          time.NewTimer(0),
    56  		nextWakeupTime: time.Time{},
    57  		fireCh:         make(chan struct{}, 1),
    58  		closeCh:        make(chan struct{}),
    59  		timeSource:     timeSource,
    60  	}
    61  	// the timer should be stopped when initialized
    62  	if !lg.timer.Stop() {
    63  		// drain the existing signal if exist
    64  		<-lg.timer.C
    65  	}
    66  
    67  	go func() {
    68  		defer close(lg.fireCh)
    69  		defer lg.timer.Stop()
    70  	loop:
    71  		for {
    72  			select {
    73  			case <-lg.timer.C:
    74  				select {
    75  				// re-transmit on gateC
    76  				case lg.fireCh <- struct{}{}:
    77  				default:
    78  				}
    79  
    80  			case <-lg.closeCh:
    81  				// closed; cleanup and quit
    82  				break loop
    83  			}
    84  		}
    85  	}()
    86  
    87  	return lg
    88  }
    89  
    90  // FireCh return the channel which will be fired when time is up
    91  func (lg *LocalGateImpl) FireCh() <-chan struct{} {
    92  	return lg.fireCh
    93  }
    94  
    95  // FireAfter check will the timer get fired after a certain time
    96  func (lg *LocalGateImpl) FireAfter(now time.Time) bool {
    97  	return lg.nextWakeupTime.After(now)
    98  }
    99  
   100  // Update the timer gate, return true if update is a success.
   101  // Success means timer is idle or timer is set with a sooner time to fire
   102  func (lg *LocalGateImpl) Update(nextTime time.Time) bool {
   103  	// NOTE: negative duration will make the timer fire immediately
   104  	now := lg.timeSource.Now()
   105  
   106  	if lg.timer.Stop() && lg.nextWakeupTime.Before(nextTime) {
   107  		// this means the timer, before stopped, is active && next wake-up time do not have to be updated
   108  		lg.timer.Reset(lg.nextWakeupTime.Sub(now))
   109  		return false
   110  	}
   111  
   112  	// this means the timer, before stopped, is active && next wake-up time has to be updated
   113  	// or this means the timer, before stopped, is already fired / never active
   114  	lg.nextWakeupTime = nextTime
   115  	lg.timer.Reset(nextTime.Sub(now))
   116  	// Notifies caller that next notification is reset to fire at passed in 'next' visibility time
   117  	return true
   118  }
   119  
   120  // Close shutdown the timer
   121  func (lg *LocalGateImpl) Close() {
   122  	close(lg.closeCh)
   123  }