85 lines
2.1 KiB
Go
85 lines
2.1 KiB
Go
/*
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© Copyright IBM Corporation 2017, 2019
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package main
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import (
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"os"
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"os/signal"
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"syscall"
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"github.com/ibm-messaging/mq-container/internal/metrics"
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"golang.org/x/sys/unix"
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)
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const (
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startReaping = iota
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reapNow = iota
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)
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func signalHandler(qmgr string) chan int {
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control := make(chan int)
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// Use separate channels for the signals, to avoid SIGCHLD signals swamping
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// the buffer, and preventing other signals.
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stopSignals := make(chan os.Signal)
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reapSignals := make(chan os.Signal)
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signal.Notify(stopSignals, syscall.SIGTERM, syscall.SIGINT)
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go func() {
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for {
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select {
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case sig := <-stopSignals:
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log.Printf("Signal received: %v", sig)
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signal.Stop(reapSignals)
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signal.Stop(stopSignals)
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metrics.StopMetricsGathering(log)
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// #nosec G104
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stopQueueManager(qmgr)
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// One final reap
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reapZombies()
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close(control)
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// End the goroutine
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return
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case <-reapSignals:
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log.Debug("Received SIGCHLD signal")
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reapZombies()
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case job := <-control:
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switch {
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case job == startReaping:
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// Add SIGCHLD to the list of signals we're listening to
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log.Debug("Listening for SIGCHLD signals")
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signal.Notify(reapSignals, syscall.SIGCHLD)
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case job == reapNow:
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reapZombies()
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}
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}
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}
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}()
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return control
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}
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// reapZombies reaps any zombie (terminated) processes now.
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// This function should be called before exiting.
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func reapZombies() {
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for {
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var ws unix.WaitStatus
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pid, err := unix.Wait4(-1, &ws, unix.WNOHANG, nil)
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// If err or pid indicate "no child processes"
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if pid == 0 || err == unix.ECHILD {
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return
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}
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log.Debugf("Reaped PID %v", pid)
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}
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}
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