104 lines
3.0 KiB
Go
104 lines
3.0 KiB
Go
// Copyright 2015 Light Code Labs, LLC
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//
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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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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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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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package caddy
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import (
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"log"
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"os"
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"os/signal"
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"sync"
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)
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// TrapSignals create signal handlers for all applicable signals for this
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// system. If your Go program uses signals, this is a rather invasive
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// function; best to implement them yourself in that case. Signals are not
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// required for the caddy package to function properly, but this is a
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// convenient way to allow the user to control this part of your program.
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func TrapSignals() {
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trapSignalsCrossPlatform()
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trapSignalsPosix()
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}
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// trapSignalsCrossPlatform captures SIGINT, which triggers forceful
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// shutdown that executes shutdown callbacks first. A second interrupt
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// signal will exit the process immediately.
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func trapSignalsCrossPlatform() {
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go func() {
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shutdown := make(chan os.Signal, 1)
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signal.Notify(shutdown, os.Interrupt)
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for i := 0; true; i++ {
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<-shutdown
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if i > 0 {
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log.Println("[INFO] SIGINT: Force quit")
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for _, f := range OnProcessExit {
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f() // important cleanup actions only
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}
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os.Exit(2)
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}
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log.Println("[INFO] SIGINT: Shutting down")
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// important cleanup actions before shutdown callbacks
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for _, f := range OnProcessExit {
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f()
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}
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go func() {
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os.Exit(executeShutdownCallbacks("SIGINT"))
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}()
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}
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}()
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}
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// executeShutdownCallbacks executes the shutdown callbacks as initiated
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// by signame. It logs any errors and returns the recommended exit status.
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// This function is idempotent; subsequent invocations always return 0.
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func executeShutdownCallbacks(signame string) (exitCode int) {
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shutdownCallbacksOnce.Do(func() {
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// execute third-party shutdown hooks
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EmitEvent(ShutdownEvent, signame)
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errs := allShutdownCallbacks()
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if len(errs) > 0 {
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for _, err := range errs {
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log.Printf("[ERROR] %s shutdown: %v", signame, err)
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}
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exitCode = 4
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}
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})
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return
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}
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// allShutdownCallbacks executes all the shutdown callbacks
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// for all the instances, and returns all the errors generated
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// during their execution. An error executing one shutdown
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// callback does not stop execution of others. Only one shutdown
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// callback is executed at a time.
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func allShutdownCallbacks() []error {
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var errs []error
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instancesMu.Lock()
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for _, inst := range instances {
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errs = append(errs, inst.ShutdownCallbacks()...)
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}
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instancesMu.Unlock()
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return errs
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}
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// shutdownCallbacksOnce ensures that shutdown callbacks
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// for all instances are only executed once.
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var shutdownCallbacksOnce sync.Once
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