go.etcd.io/etcd@v3.3.27+incompatible/pkg/contention/contention.go (about)

     1  // Copyright 2016 The etcd Authors
     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 contention
    16  
    17  import (
    18  	"sync"
    19  	"time"
    20  )
    21  
    22  // TimeoutDetector detects routine starvations by
    23  // observing the actual time duration to finish an action
    24  // or between two events that should happen in a fixed
    25  // interval. If the observed duration is longer than
    26  // the expectation, the detector will report the result.
    27  type TimeoutDetector struct {
    28  	mu          sync.Mutex // protects all
    29  	maxDuration time.Duration
    30  	// map from event to time
    31  	// time is the last seen time of the event.
    32  	records map[uint64]time.Time
    33  }
    34  
    35  // NewTimeoutDetector creates the TimeoutDetector.
    36  func NewTimeoutDetector(maxDuration time.Duration) *TimeoutDetector {
    37  	return &TimeoutDetector{
    38  		maxDuration: maxDuration,
    39  		records:     make(map[uint64]time.Time),
    40  	}
    41  }
    42  
    43  // Reset resets the NewTimeoutDetector.
    44  func (td *TimeoutDetector) Reset() {
    45  	td.mu.Lock()
    46  	defer td.mu.Unlock()
    47  
    48  	td.records = make(map[uint64]time.Time)
    49  }
    50  
    51  // Observe observes an event for given id. It returns false and exceeded duration
    52  // if the interval is longer than the expectation.
    53  func (td *TimeoutDetector) Observe(which uint64) (bool, time.Duration) {
    54  	td.mu.Lock()
    55  	defer td.mu.Unlock()
    56  
    57  	ok := true
    58  	now := time.Now()
    59  	exceed := time.Duration(0)
    60  
    61  	if pt, found := td.records[which]; found {
    62  		exceed = now.Sub(pt) - td.maxDuration
    63  		if exceed > 0 {
    64  			ok = false
    65  		}
    66  	}
    67  	td.records[which] = now
    68  	return ok, exceed
    69  }