volcano.sh/volcano@v1.9.0/pkg/signals/signal.go (about)

     1  /*
     2  Copyright 2021 The Volcano Authors.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8      http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package signals
    18  
    19  import (
    20  	"context"
    21  	"os"
    22  	"os/signal"
    23  )
    24  
    25  var onlyOneSignalHandler = make(chan struct{})
    26  var shutdownHandler chan os.Signal
    27  
    28  // SetupSignalHandler registered for SIGTERM and SIGINT. A stop channel is returned
    29  // which is closed on one of these signals. If a second signal is caught, the program
    30  // is terminated with exit code 1.
    31  func SetupSignalHandler() (stopCh <-chan struct{}) {
    32  	close(onlyOneSignalHandler) // panics when called twice
    33  
    34  	stop := make(chan struct{})
    35  	shutdownHandler = make(chan os.Signal, 2)
    36  	signal.Notify(shutdownHandler, shutdownSignals...)
    37  	go func() {
    38  		<-shutdownHandler
    39  		close(stop)
    40  		<-shutdownHandler
    41  		os.Exit(1) // second signal. Exit directly.
    42  	}()
    43  
    44  	return stop
    45  }
    46  
    47  // SetupSignalContext is same as SetupSignalHandler, but a context.Context is returned.
    48  // Only one of SetupSignalContext and SetupSignalHandler should be called, and only can
    49  // be called once.
    50  func SetupSignalContext() context.Context {
    51  	close(onlyOneSignalHandler) // panics when called twice
    52  
    53  	shutdownHandler = make(chan os.Signal, 2)
    54  
    55  	ctx, cancel := context.WithCancel(context.Background())
    56  	signal.Notify(shutdownHandler, shutdownSignals...)
    57  	go func() {
    58  		<-shutdownHandler
    59  		cancel()
    60  		<-shutdownHandler
    61  		os.Exit(1) // second signal. Exit directly.
    62  	}()
    63  
    64  	return ctx
    65  }
    66  
    67  // RequestShutdown emulates a received event that is considered as shutdown signal (SIGTERM/SIGINT)
    68  // This returns whether a handler was notified
    69  func RequestShutdown() bool {
    70  	if shutdownHandler != nil {
    71  		select {
    72  		case shutdownHandler <- shutdownSignals[0]:
    73  			return true
    74  		default:
    75  		}
    76  	}
    77  
    78  	return false
    79  }