/usr/share/gocode/src/github.com/mesos/mesos-go/healthchecker/slave_health_checker.go is in golang-github-mesos-mesos-go-dev 0.0.2+dfsg-3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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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 (
"errors"
"fmt"
"net/http"
"sync"
"sync/atomic"
"time"
log "github.com/golang/glog"
"github.com/mesos/mesos-go/upid"
)
const (
defaultTimeout = time.Second
defaultCheckDuration = time.Second
defaultThreshold = 5
)
var errCheckerStopped = errors.New("aborted HTTP request because checker was asked to stop")
// SlaveHealthChecker is for checking the slave's health.
type SlaveHealthChecker struct {
sync.RWMutex
slaveUPID *upid.UPID
tr *http.Transport
client *http.Client
threshold int32
checkDuration time.Duration
continuousUnhealthyCount int32
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 {
tr := &http.Transport{}
checker := &SlaveHealthChecker{
slaveUPID: slaveUPID,
client: &http.Client{Timeout: timeout, Transport: tr},
threshold: int32(threshold),
checkDuration: checkDuration,
stop: make(chan struct{}),
ch: make(chan time.Time, 1),
tr: tr,
}
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() {
t := time.NewTicker(s.checkDuration)
defer t.Stop()
for {
select {
case <-t.C:
select {
case <-s.stop:
return
default:
// continue
}
if paused, slavepid := func() (x bool, y upid.UPID) {
s.RLock()
defer s.RUnlock()
x = s.paused
if s.slaveUPID != nil {
y = *s.slaveUPID
}
return
}(); !paused {
s.doCheck(slavepid)
}
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(pid upid.UPID) {
unhealthy := false
path := fmt.Sprintf("http://%s:%s/%s/health", pid.Host, pid.Port, pid.ID)
req, err := http.NewRequest("HEAD", path, nil)
req.Close = true
err = s.httpDo(req, func(resp *http.Response, err error) error {
if err != nil {
return err
}
defer resp.Body.Close()
if resp.StatusCode != http.StatusOK {
return fmt.Errorf("http status error: %v\n", resp.StatusCode)
}
return nil
})
select {
case <-s.stop:
return
default:
}
if err != nil {
log.Errorf("Failed to request the health path: %v\n", err)
unhealthy = true
}
if unhealthy {
x := atomic.AddInt32(&s.continuousUnhealthyCount, 1)
if x >= s.threshold {
select {
case s.ch <- time.Now(): // If no one is receiving the channel, then just skip it.
default:
}
atomic.StoreInt32(&s.continuousUnhealthyCount, 0)
}
return
}
atomic.StoreInt32(&s.continuousUnhealthyCount, 0)
}
func (s *SlaveHealthChecker) httpDo(req *http.Request, f func(*http.Response, error) error) error {
// Run the HTTP request in a goroutine and pass the response to f.
c := make(chan error, 1)
go func() { c <- f(s.client.Do(req)) }()
select {
case <-s.stop:
s.tr.CancelRequest(req)
<-c // Wait for f to return.
return errCheckerStopped
case err := <-c:
return err
}
}
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