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slave_health_checker.go
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/
slave_health_checker.go
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/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package healthchecker
import (
"fmt"
"net/http"
"sync"
"time"
log "github.com/golang/glog"
"github.com/mesos/mesos-go/upid"
)
const (
defaultTimeout = time.Second
defaultCheckDuration = time.Second
defaultThreshold = 5
)
// SlaveHealthChecker is for checking the slave's health.
type SlaveHealthChecker struct {
sync.RWMutex
slaveUPID *upid.UPID
client *http.Client
threshold int
checkDuration time.Duration
continuousUnhealthyCount int
stop chan struct{}
ch chan time.Time
paused bool
}
// NewSlaveHealthChecker creates a slave health checker and return a notification channel.
// Each time the checker thinks the slave is unhealthy, it will send a notification through the channel.
func NewSlaveHealthChecker(slaveUPID *upid.UPID, threshold int, checkDuration time.Duration, timeout time.Duration) *SlaveHealthChecker {
checker := &SlaveHealthChecker{
slaveUPID: slaveUPID,
client: &http.Client{Timeout: timeout},
threshold: threshold,
checkDuration: checkDuration,
stop: make(chan struct{}),
ch: make(chan time.Time, 1),
}
if timeout == 0 {
checker.client.Timeout = defaultTimeout
}
if checkDuration == 0 {
checker.checkDuration = defaultCheckDuration
}
if threshold <= 0 {
checker.threshold = defaultThreshold
}
return checker
}
// Start will start the health checker and returns the notification channel.
func (s *SlaveHealthChecker) Start() <-chan time.Time {
go func() {
ticker := time.Tick(s.checkDuration)
for {
select {
case <-ticker:
s.RLock()
if !s.paused {
s.doCheck()
}
s.RUnlock()
case <-s.stop:
return
}
}
}()
return s.ch
}
// Pause will pause the slave health checker.
func (s *SlaveHealthChecker) Pause() {
s.Lock()
defer s.Unlock()
s.paused = true
}
// Continue will continue the slave health checker with a new slave upid.
func (s *SlaveHealthChecker) Continue(slaveUPID *upid.UPID) {
s.Lock()
defer s.Unlock()
s.paused = false
s.slaveUPID = slaveUPID
}
// Stop will stop the slave health checker.
// It should be called only once during the life span of the checker.
func (s *SlaveHealthChecker) Stop() {
close(s.stop)
}
func (s *SlaveHealthChecker) doCheck() {
path := fmt.Sprintf("http://%s:%s/%s/health", s.slaveUPID.Host, s.slaveUPID.Port, s.slaveUPID.ID)
resp, err := s.client.Head(path)
unhealthy := false
if err != nil {
log.Errorf("Failed to request the health path: %v\n", err)
unhealthy = true
} else if resp.StatusCode != http.StatusOK {
log.Errorf("Failed to request the health path: status: %v\n", resp.StatusCode)
unhealthy = true
}
if unhealthy {
s.continuousUnhealthyCount++
if s.continuousUnhealthyCount >= s.threshold {
select {
case s.ch <- time.Now(): // If no one is receiving the channel, then just skip it.
default:
}
s.continuousUnhealthyCount = 0
}
return
}
s.continuousUnhealthyCount = 0
resp.Body.Close()
}