[shepherd] 01/01: services: 'read-pid-file' always exits its busy loop.

[Ludovic Courtès]

civodul pushed a commit to branch master
in repository shepherd.

commit 83a83697c870a6ccb195662d7ad54e67f14f9443
Author: Ludovic Courtès <address@hidden>
Date:   Mon May 6 11:45:07 2019 +0200

    services: 'read-pid-file' always exits its busy loop.
    
    * modules/shepherd/service.scm (read-pid-file): Factorize retrial in
    'try-again'.  This avoids the direct and unconditional call to 'loop'
    introduced in 72631752149d000c8c98ae0cc66e0b0c2eda94ef.
---
 modules/shepherd/service.scm | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/modules/shepherd/service.scm b/modules/shepherd/service.scm
index 3aea7b8..b937609 100644
--- a/modules/shepherd/service.scm
+++ b/modules/shepherd/service.scm
@@ -714,7 +714,17 @@ set when starting a service."
 number.  Return #f if FILE was not created or does not contain a number;
 otherwise return the number that was read (a PID)."
   (define start (current-time))
+
   (let loop ()
+    (define (try-again)
+      (and (< (current-time) (+ start max-delay))
+           (begin
+             ;; FILE does not exist yet, so wait and try again.
+             ;; XXX: Ideally we would yield to the main event loop
+             ;; and/or use inotify.
+             (sleep 1)
+             (loop))))
+
     (catch 'system-error
       (lambda ()
         (match (string->number
@@ -723,7 +733,7 @@ otherwise return the number that was read (a PID)."
           (#f
            ;; If we didn't get an integer, it may be because the daemon didn't
            ;; create FILE atomically and isn't done writing to it.  Try again.
-           (loop))
+           (try-again))
           ((? integer? pid)
            ;; It's possible, though unlikely, that PID is not a valid PID, for
            ;; instance because writes to FILE did not complete.  However, we
@@ -734,13 +744,7 @@ otherwise return the number that was read (a PID)."
       (lambda args
         (let ((errno (system-error-errno args)))
           (if (= ENOENT errno)
-              (and (< (current-time) (+ start max-delay))
-                   (begin
-                     ;; FILE does not exist yet, so wait and try again.
-                     ;; XXX: Ideally we would yield to the main event loop
-                     ;; and/or use inotify.
-                     (sleep 1)
-                     (loop)))
+              (try-again)
               (apply throw args)))))))
 
 (define* (exec-command command