Merge pull request #4228 from thaJeztah/refactor_reaper

Refactor reaper-related functionality to be in the sys/reaper package

cmd/containerd-shim/shim_linux.go

@@ -20,7 +20,6 @@ import (
 	"os"
 	"os/signal"
 
-	"github.com/containerd/containerd/sys"
 	"github.com/containerd/containerd/sys/reaper"
 	runc "github.com/containerd/go-runc"
 	"github.com/containerd/ttrpc"
@@ -36,7 +35,7 @@ func setupSignals() (chan os.Signal, error) {
 	// for waiting on processes
 	runc.Monitor = reaper.Default
 	// set the shim as the subreaper for all orphaned processes created by the container
-	if err := sys.SetSubreaper(1); err != nil {
+	if err := reaper.SetSubreaper(1); err != nil {
 		return nil, err
 	}
 	return signals, nil

runtime/v2/shim/shim_linux.go

@@ -17,7 +17,7 @@
 package shim
 
 import (
-	"github.com/containerd/containerd/sys"
+	"github.com/containerd/containerd/sys/reaper"
 	"github.com/containerd/ttrpc"
 )
 
@@ -26,5 +26,5 @@ func newServer() (*ttrpc.Server, error) {
 }
 
 func subreaper() error {
-	return sys.SetSubreaper(1)
+	return reaper.SetSubreaper(1)
 }

sys/reaper.go

@@ -1,69 +0,0 @@
-// +build !windows
-
-/*
-   Copyright The containerd Authors.
-
-   Licensed under the Apache License, Version 2.0 (the "License");
-   you may not use this file except in compliance with the License.
-   You may obtain a copy of the License at
-
-       http://www.apache.org/licenses/LICENSE-2.0
-
-   Unless required by applicable law or agreed to in writing, software
-   distributed under the License is distributed on an "AS IS" BASIS,
-   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-   See the License for the specific language governing permissions and
-   limitations under the License.
-*/
-
-package sys
-
-import (
-	"golang.org/x/sys/unix"
-)
-
-// Exit is the wait4 information from an exited process
-type Exit struct {
-	Pid    int
-	Status int
-}
-
-// Reap reaps all child processes for the calling process and returns their
-// exit information
-func Reap(wait bool) (exits []Exit, err error) {
-	var (
-		ws  unix.WaitStatus
-		rus unix.Rusage
-	)
-	flag := unix.WNOHANG
-	if wait {
-		flag = 0
-	}
-	for {
-		pid, err := unix.Wait4(-1, &ws, flag, &rus)
-		if err != nil {
-			if err == unix.ECHILD {
-				return exits, nil
-			}
-			return exits, err
-		}
-		if pid <= 0 {
-			return exits, nil
-		}
-		exits = append(exits, Exit{
-			Pid:    pid,
-			Status: exitStatus(ws),
-		})
-	}
-}
-
-const exitSignalOffset = 128
-
-// exitStatus returns the correct exit status for a process based on if it
-// was signaled or exited cleanly
-func exitStatus(status unix.WaitStatus) int {
-	if status.Signaled() {
-		return exitSignalOffset + int(status.Signal())
-	}
-	return status.ExitStatus()
-}

sys/reaper/reaper_unix.go

@@ -23,9 +23,9 @@ import (
 	"sync"
 	"time"
 
-	"github.com/containerd/containerd/sys"
 	runc "github.com/containerd/go-runc"
 	"github.com/pkg/errors"
+	"golang.org/x/sys/unix"
 )
 
 // ErrNoSuchProcess is returned when the process no longer exists
@@ -60,7 +60,7 @@ func (s *subscriber) do(fn func()) {
 // all exited processes and close their wait channels
 func Reap() error {
 	now := time.Now()
-	exits, err := sys.Reap(false)
+	exits, err := reap(false)
 	for _, e := range exits {
 		done := Default.notify(runc.Exit{
 			Timestamp: now,
@@ -200,3 +200,49 @@ func stop(timer *time.Timer, recv bool) {
 		<-timer.C
 	}
 }
+
+// exit is the wait4 information from an exited process
+type exit struct {
+	Pid    int
+	Status int
+}
+
+// reap reaps all child processes for the calling process and returns their
+// exit information
+func reap(wait bool) (exits []exit, err error) {
+	var (
+		ws  unix.WaitStatus
+		rus unix.Rusage
+	)
+	flag := unix.WNOHANG
+	if wait {
+		flag = 0
+	}
+	for {
+		pid, err := unix.Wait4(-1, &ws, flag, &rus)
+		if err != nil {
+			if err == unix.ECHILD {
+				return exits, nil
+			}
+			return exits, err
+		}
+		if pid <= 0 {
+			return exits, nil
+		}
+		exits = append(exits, exit{
+			Pid:    pid,
+			Status: exitStatus(ws),
+		})
+	}
+}
+
+const exitSignalOffset = 128
+
+// exitStatus returns the correct exit status for a process based on if it
+// was signaled or exited cleanly
+func exitStatus(status unix.WaitStatus) int {
+	if status.Signaled() {
+		return exitSignalOffset + int(status.Signal())
+	}
+	return status.ExitStatus()
+}

sys/reaper/reaper_utils_linux.go

@@ -14,7 +14,7 @@
    limitations under the License.
 */
 
-package sys
+package reaper
 
 import (
 	"unsafe"
@@ -22,22 +22,9 @@ import (
 	"golang.org/x/sys/unix"
 )
 
-// If arg2 is nonzero, set the "child subreaper" attribute of the
-// calling process; if arg2 is zero, unset the attribute.  When a
-// process is marked as a child subreaper, all of the children
-// that it creates, and their descendants, will be marked as
-// having a subreaper.  In effect, a subreaper fulfills the role
-// of init(1) for its descendant processes.  Upon termination of
-// a process that is orphaned (i.e., its immediate parent has
-// already terminated) and marked as having a subreaper, the
-// nearest still living ancestor subreaper will receive a SIGCHLD
-// signal and be able to wait(2) on the process to discover its
-// termination status.
-const setChildSubreaper = 36
-
 // SetSubreaper sets the value i as the subreaper setting for the calling process
 func SetSubreaper(i int) error {
-	return unix.Prctl(setChildSubreaper, uintptr(i), 0, 0, 0)
+	return unix.Prctl(unix.PR_SET_CHILD_SUBREAPER, uintptr(i), 0, 0, 0)
 }
 
 // GetSubreaper returns the subreaper setting for the calling process