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minio/cmd/service.go

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3.5 KiB

/*
* Minio Cloud Storage, (C) 2016 Minio, Inc.
*
* Licensed 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 cmd
import (
"os"
"os/exec"
"syscall"
)
// Represents a type of an exit func which will be invoked upon service signal.
type onExitFunc func(err error)
// Represents a type for all the the callback functions invoked upon service signal.
type cleanupOnExitFunc func() error
// Type of service signals currently supported.
type serviceSignal int
const (
serviceStatus = iota // Gets status about the service.
serviceRestart // Restarts the service.
serviceStop // Stops the server.
// Add new service requests here.
)
// Global service signal channel.
var globalServiceSignalCh chan serviceSignal
// Global service done channel.
var globalServiceDoneCh chan struct{}
// Initialize service mutex once.
func init() {
globalServiceDoneCh = make(chan struct{}, 1)
globalServiceSignalCh = make(chan serviceSignal, 1)
}
// restartProcess starts a new process passing it the active fd's. It
// doesn't fork, but starts a new process using the same environment and
// arguments as when it was originally started. This allows for a newly
// deployed binary to be started. It returns the pid of the newly started
// process when successful.
func restartProcess() error {
// Use the original binary location. This works with symlinks such that if
// the file it points to has been changed we will use the updated symlink.
argv0, err := exec.LookPath(os.Args[0])
if err != nil {
return err
}
// Pass on the environment and replace the old count key with the new one.
cmd := exec.Command(argv0, os.Args[1:]...)
cmd.Stdout = os.Stdout
cmd.Stderr = os.Stderr
return cmd.Start()
}
// Handles all serviceSignal and execute service functions.
func (m *ServerMux) handleServiceSignals() error {
// Custom exit function
runExitFn := func(err error) {
// If global profiler is set stop before we exit.
if globalProfiler != nil {
globalProfiler.Stop()
}
// Call user supplied user exit function
fatalIf(err, "Unable to gracefully complete service operation.")
// We are usually done here, close global service done channel.
globalServiceDoneCh <- struct{}{}
}
// Start listening on service signal. Monitor signals.
trapCh := signalTrap(os.Interrupt, syscall.SIGTERM)
for {
select {
case <-trapCh:
// Initiate graceful stop.
globalServiceSignalCh <- serviceStop
case signal := <-globalServiceSignalCh:
switch signal {
case serviceStatus:
/// We don't do anything for this.
case serviceRestart:
if err := m.Close(); err != nil {
errorIf(err, "Unable to close server gracefully")
}
if err := restartProcess(); err != nil {
errorIf(err, "Unable to restart the server.")
}
runExitFn(nil)
case serviceStop:
if err := m.Close(); err != nil {
errorIf(err, "Unable to close server gracefully")
}
objAPI := newObjectLayerFn()
if objAPI == nil {
// Server not initialized yet, exit happily.
runExitFn(nil)
} else {
runExitFn(objAPI.Shutdown())
}
}
}
}
}