mirror of https://github.com/minio/minio.git
105 lines
3.6 KiB
Go
105 lines
3.6 KiB
Go
// Copyright (c) 2015-2021 MinIO, Inc.
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//
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// This file is part of MinIO Object Storage stack
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Affero General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Affero General Public License for more details.
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//
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// You should have received a copy of the GNU Affero General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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package cmd
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import (
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"context"
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"os"
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"os/exec"
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"syscall"
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)
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// Type of service signals currently supported.
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type serviceSignal int
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const (
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serviceRestart serviceSignal = iota // Restarts the server.
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serviceStop // Stops the server.
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serviceReloadDynamic // Reload dynamic config values.
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serviceFreeze // Freeze all S3 API calls.
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serviceUnFreeze // Un-Freeze previously frozen S3 API calls.
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// Add new service requests here.
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)
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// Global service signal channel.
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var globalServiceSignalCh chan serviceSignal
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// GlobalContext context that is canceled when server is requested to shut down.
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var GlobalContext context.Context
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// cancelGlobalContext can be used to indicate server shutdown.
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var cancelGlobalContext context.CancelFunc
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func initGlobalContext() {
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GlobalContext, cancelGlobalContext = context.WithCancel(context.Background())
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globalServiceSignalCh = make(chan serviceSignal)
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}
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// restartProcess starts a new process passing it the active fd's. It
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// doesn't fork, but starts a new process using the same environment and
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// arguments as when it was originally started. This allows for a newly
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// deployed binary to be started. It returns the pid of the newly started
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// process when successful.
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func restartProcess() error {
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// Use the original binary location. This works with symlinks such that if
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// the file it points to has been changed we will use the updated symlink.
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argv0, err := exec.LookPath(os.Args[0])
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if err != nil {
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return err
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}
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// Invokes the execve system call.
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// Re-uses the same pid. This preserves the pid over multiple server-respawns.
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return syscall.Exec(argv0, os.Args, os.Environ())
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}
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// freezeServices will freeze all incoming S3 API calls.
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// For each call, unfreezeServices must be called once.
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func freezeServices() {
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// Use atomics for globalServiceFreeze, so we can read without locking.
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// We need a lock since we are need the 2 atomic values to remain in sync.
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globalServiceFreezeMu.Lock()
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// If multiple calls, first one creates channel.
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globalServiceFreezeCnt++
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if globalServiceFreezeCnt == 1 {
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globalServiceFreeze.Store(make(chan struct{}))
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}
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globalServiceFreezeMu.Unlock()
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}
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// unfreezeServices will unfreeze all incoming S3 API calls.
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// For each call, unfreezeServices must be called once.
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func unfreezeServices() {
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// We need a lock since we need the 2 atomic values to remain in sync.
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globalServiceFreezeMu.Lock()
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// Close when we reach 0
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globalServiceFreezeCnt--
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if globalServiceFreezeCnt <= 0 {
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// Ensure we only close once.
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if val := globalServiceFreeze.Load(); val != nil {
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var _ch chan struct{}
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if ch, ok := val.(chan struct{}); ok {
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globalServiceFreeze.Store(_ch)
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close(ch)
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}
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}
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globalServiceFreezeCnt = 0 // Don't risk going negative.
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}
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globalServiceFreezeMu.Unlock()
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}
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