interrupt_unix.go

Documentation: go.etcd.io/etcd/pkg/v3/osutil

     1  // Copyright 2015 The etcd Authors
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  //go:build !windows && !plan9
    16  // +build !windows,!plan9
    17  
    18  package osutil
    19  
    20  import (
    21  	"os"
    22  	"os/signal"
    23  	"sync"
    24  	"syscall"
    25  
    26  	"go.uber.org/zap"
    27  )
    28  
    29  // InterruptHandler is a function that is called on receiving a
    30  // SIGTERM or SIGINT signal.
    31  type InterruptHandler func()
    32  
    33  var (
    34  	interruptRegisterMu, interruptExitMu sync.Mutex
    35  	// interruptHandlers holds all registered InterruptHandlers in order
    36  	// they will be executed.
    37  	interruptHandlers = []InterruptHandler{}
    38  )
    39  
    40  // RegisterInterruptHandler registers a new InterruptHandler. Handlers registered
    41  // after interrupt handing was initiated will not be executed.
    42  func RegisterInterruptHandler(h InterruptHandler) {
    43  	interruptRegisterMu.Lock()
    44  	defer interruptRegisterMu.Unlock()
    45  	interruptHandlers = append(interruptHandlers, h)
    46  }
    47  
    48  // HandleInterrupts calls the handler functions on receiving a SIGINT or SIGTERM.
    49  func HandleInterrupts(lg *zap.Logger) {
    50  	notifier := make(chan os.Signal, 1)
    51  	signal.Notify(notifier, syscall.SIGINT, syscall.SIGTERM)
    52  
    53  	go func() {
    54  		sig := <-notifier
    55  
    56  		interruptRegisterMu.Lock()
    57  		ihs := make([]InterruptHandler, len(interruptHandlers))
    58  		copy(ihs, interruptHandlers)
    59  		interruptRegisterMu.Unlock()
    60  
    61  		interruptExitMu.Lock()
    62  
    63  		if lg != nil {
    64  			lg.Info("received signal; shutting down", zap.String("signal", sig.String()))
    65  		}
    66  
    67  		for _, h := range ihs {
    68  			h()
    69  		}
    70  		signal.Stop(notifier)
    71  		pid := syscall.Getpid()
    72  		// exit directly if it is the "init" process, since the kernel will not help to kill pid 1.
    73  		if pid == 1 {
    74  			os.Exit(0)
    75  		}
    76  		setDflSignal(sig.(syscall.Signal))
    77  		syscall.Kill(pid, sig.(syscall.Signal))
    78  	}()
    79  }
    80  
    81  // Exit relays to os.Exit if no interrupt handlers are running, blocks otherwise.
    82  func Exit(code int) {
    83  	interruptExitMu.Lock()
    84  	os.Exit(code)
    85  }
    86
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