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services: Move 'user-processes' to (gnu services shepherd).

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* gnu/services/base.scm (%do-not-kill-file)
(user-processes-shepherd-service, user-processes-service-type): Move
to...
* gnu/services/shepherd.scm: ... here.
This commit is contained in:
Ludovic Courtès 2020-04-17 12:45:54 +02:00
parent 9d0b9c7c6c
commit 10c413685f
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GPG key ID: 090B11993D9AEBB5
2 changed files with 126 additions and 124 deletions
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124
gnu/services/base.scm
View file

@ -61,11 +61,11 @@ (define-module (gnu services base)
#:use-module (srfi srfi-26)
#:use-module (ice-9 match)
#:use-module (ice-9 format)
#:re-export (user-processes-service-type) ;backwards compatibility
#:export (fstab-service-type
root-file-system-service
file-system-service-type
swap-service
user-processes-service-type
host-name-service
console-keymap-service
%default-console-font
@ -185,128 +185,6 @@ (define-module (gnu services base)
;;; Code:
;;;
;;; User processes.
;;;
(define %do-not-kill-file
;; Name of the file listing PIDs of processes that must survive when halting
;; the system. Typical example is user-space file systems.
"/etc/shepherd/do-not-kill")
(define (user-processes-shepherd-service requirements)
"Return the 'user-processes' Shepherd service with dependencies on
REQUIREMENTS (a list of service names).
This is a synchronization point used to make sure user processes and daemons
get started only after crucial initial services have been started---file
system mounts, etc. This is similar to the 'sysvinit' target in systemd."
(define grace-delay
;; Delay after sending SIGTERM and before sending SIGKILL.
4)
(list (shepherd-service
(documentation "When stopped, terminate all user processes.")
(provision '(user-processes))
(requirement requirements)
(start #~(const #t))
(stop #~(lambda _
(define (kill-except omit signal)
;; Kill all the processes with SIGNAL except those listed
;; in OMIT and the current process.
(let ((omit (cons (getpid) omit)))
(for-each (lambda (pid)
(unless (memv pid omit)
(false-if-exception
(kill pid signal))))
(processes))))
(define omitted-pids
;; List of PIDs that must not be killed.
(if (file-exists? #$%do-not-kill-file)
(map string->number
(call-with-input-file #$%do-not-kill-file
(compose string-tokenize
(@ (ice-9 rdelim) read-string))))
'()))
(define (now)
(car (gettimeofday)))
(define (sleep* n)
;; Really sleep N seconds.
;; Work around <http://bugs.gnu.org/19581>.
(define start (now))
(let loop ((elapsed 0))
(when (> n elapsed)
(sleep (- n elapsed))
(loop (- (now) start)))))
(define lset= (@ (srfi srfi-1) lset=))
(display "sending all processes the TERM signal\n")
(if (null? omitted-pids)
(begin
;; Easy: terminate all of them.
(kill -1 SIGTERM)
(sleep* #$grace-delay)
(kill -1 SIGKILL))
(begin
;; Kill them all except OMITTED-PIDS. XXX: We would
;; like to (kill -1 SIGSTOP) to get a fixed list of
;; processes, like 'killall5' does, but that seems
;; unreliable.
(kill-except omitted-pids SIGTERM)
(sleep* #$grace-delay)
(kill-except omitted-pids SIGKILL)
(delete-file #$%do-not-kill-file)))
(let wait ()
;; Reap children, if any, so that we don't end up with
;; zombies and enter an infinite loop.
(let reap-children ()
(define result
(false-if-exception
(waitpid WAIT_ANY (if (null? omitted-pids)
0
WNOHANG))))
(when (and (pair? result)
(not (zero? (car result))))
(reap-children)))
(let ((pids (processes)))
(unless (lset= = pids (cons 1 omitted-pids))
(format #t "waiting for process termination\
(processes left: ~s)~%"
pids)
(sleep* 2)
(wait))))
(display "all processes have been terminated\n")
#f))
(respawn? #f))))
(define user-processes-service-type
(service-type
(name 'user-processes)
(extensions (list (service-extension shepherd-root-service-type
user-processes-shepherd-service)))
(compose concatenate)
(extend append)
;; The value is the list of Shepherd services 'user-processes' depends on.
;; Extensions can add new services to this list.
(default-value '())
(description "The @code{user-processes} service is responsible for
terminating all the processes so that the root file system can be re-mounted
read-only, just before rebooting/halting. Processes still running after a few
seconds after @code{SIGTERM} has been sent are terminated with
@code{SIGKILL}.")))
;;;
;;; File systems.

126
gnu/services/shepherd.scm
View file

@ -63,7 +63,9 @@ (define-module (gnu services shepherd)
shepherd-service-lookup-procedure
shepherd-service-back-edges
shepherd-service-upgrade))
shepherd-service-upgrade
user-processes-service-type))
;;; Commentary:
;;;
@ -415,4 +417,126 @@ (define to-unload
(values to-unload to-restart))
;;;
;;; User processes.
;;;
(define %do-not-kill-file
;; Name of the file listing PIDs of processes that must survive when halting
;; the system. Typical example is user-space file systems.
"/etc/shepherd/do-not-kill")
(define (user-processes-shepherd-service requirements)
"Return the 'user-processes' Shepherd service with dependencies on
REQUIREMENTS (a list of service names).
This is a synchronization point used to make sure user processes and daemons
get started only after crucial initial services have been started---file
system mounts, etc. This is similar to the 'sysvinit' target in systemd."
(define grace-delay
;; Delay after sending SIGTERM and before sending SIGKILL.
4)
(list (shepherd-service
(documentation "When stopped, terminate all user processes.")
(provision '(user-processes))
(requirement requirements)
(start #~(const #t))
(stop #~(lambda _
(define (kill-except omit signal)
;; Kill all the processes with SIGNAL except those listed
;; in OMIT and the current process.
(let ((omit (cons (getpid) omit)))
(for-each (lambda (pid)
(unless (memv pid omit)
(false-if-exception
(kill pid signal))))
(processes))))
(define omitted-pids
;; List of PIDs that must not be killed.
(if (file-exists? #$%do-not-kill-file)
(map string->number
(call-with-input-file #$%do-not-kill-file
(compose string-tokenize
(@ (ice-9 rdelim) read-string))))
'()))
(define (now)
(car (gettimeofday)))
(define (sleep* n)
;; Really sleep N seconds.
;; Work around <http://bugs.gnu.org/19581>.
(define start (now))
(let loop ((elapsed 0))
(when (> n elapsed)
(sleep (- n elapsed))
(loop (- (now) start)))))
(define lset= (@ (srfi srfi-1) lset=))
(display "sending all processes the TERM signal\n")
(if (null? omitted-pids)
(begin
;; Easy: terminate all of them.
(kill -1 SIGTERM)
(sleep* #$grace-delay)
(kill -1 SIGKILL))
(begin
;; Kill them all except OMITTED-PIDS. XXX: We would
;; like to (kill -1 SIGSTOP) to get a fixed list of
;; processes, like 'killall5' does, but that seems
;; unreliable.
(kill-except omitted-pids SIGTERM)
(sleep* #$grace-delay)
(kill-except omitted-pids SIGKILL)
(delete-file #$%do-not-kill-file)))
(let wait ()
;; Reap children, if any, so that we don't end up with
;; zombies and enter an infinite loop.
(let reap-children ()
(define result
(false-if-exception
(waitpid WAIT_ANY (if (null? omitted-pids)
0
WNOHANG))))
(when (and (pair? result)
(not (zero? (car result))))
(reap-children)))
(let ((pids (processes)))
(unless (lset= = pids (cons 1 omitted-pids))
(format #t "waiting for process termination\
(processes left: ~s)~%"
pids)
(sleep* 2)
(wait))))
(display "all processes have been terminated\n")
#f))
(respawn? #f))))
(define user-processes-service-type
(service-type
(name 'user-processes)
(extensions (list (service-extension shepherd-root-service-type
user-processes-shepherd-service)))
(compose concatenate)
(extend append)
;; The value is the list of Shepherd services 'user-processes' depends on.
;; Extensions can add new services to this list.
(default-value '())
(description "The @code{user-processes} service is responsible for
terminating all the processes so that the root file system can be re-mounted
read-only, just before rebooting/halting. Processes still running after a few
seconds after @code{SIGTERM} has been sent are terminated with
@code{SIGKILL}.")))
;;; shepherd.scm ends here