+ Lock for the process table
+ Use wait-lock to glue waiting and the process object together + Delete the pid/weak-pointer pair in the process table if the process object gets finalized
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@ -42,11 +42,16 @@
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(make-reinitializer (lambda ()
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(set! process-table (make-integer-table))))
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(define process-table-lock (make-lock))
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(define (process-table-ref n)
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(weak-table-ref process-table n))
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(with-lock process-table-lock
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(lambda ()
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(weak-table-ref process-table n))))
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(define (process-table-set! n val)
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(weak-table-set! process-table n val))
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(with-lock process-table-lock
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(lambda ()
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(weak-table-set! process-table n val))))
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(define (maybe-pid->proc pid)
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(process-table-ref pid))
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@ -195,10 +200,13 @@
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;;; reap this special pid
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;;; return status or #f
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(define (reap-pid pid)
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(with-lock
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wait-lock
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(lambda ()
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(let ((status (atomic-wait pid wait/poll)))
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(if status
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(waited-by-reap pid status))
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status))
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status))))
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;;; Handler for SIGCHLD according policy
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(define (late-sigchld-handler) #f)
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@ -212,6 +220,7 @@
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;;; Finalizer for procobjs
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;;;
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(define (procobj-finalizer procobj)
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(process-table-set! (proc:pid procobj) #f)
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(if (not (proc:finished? procobj))
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(need-reaping-add! (proc:pid procobj))))
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@ -222,14 +231,18 @@
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(define (reap-zombies)
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(let lp ()
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(obtain-lock wait-lock)
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(receive (pid status)
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(%wait-any (bitwise-ior wait/poll wait/stopped-children))
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(if pid
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(begin (waited-by-reap pid status)
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(release-lock wait-lock)
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; (format (current-error-port)
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; "Reaping ~d[~d]~%" pid status)
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(lp))
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status))))
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(begin
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(release-lock wait-lock)
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status)))))
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@ -260,7 +273,7 @@
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;;; With this lock, we ensure that only one thread may call
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;;; really-wait for a given pid
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;;; really-wait for a given pid and manipulates the associated process object
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(define wait-lock (make-lock))
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@ -272,6 +285,9 @@
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status)))
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;; save the event before we check for finished
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(let ((pre-event (most-recent-sigevent)))
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(with-lock
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wait-lock
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(lambda ()
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(cond ((atomic-wait proc (bitwise-ior flags wait/poll)) => win)
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((zero? (bitwise-and flags wait/poll))
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@ -280,18 +296,18 @@
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(cond ((atomic-wait proc (bitwise-ior flags wait/poll))
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=> win)
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(else
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(lp (next-sigevent pre-event interrupt/chld))))))
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(else #f)))))
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(release-lock wait-lock)
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(let ((next-event (next-sigevent pre-event interrupt/chld)))
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(obtain-lock wait-lock)
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(lp next-event))))))
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(else #f)))))))
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;;; -> process-object proc status/#f
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(define (atomic-wait proc flags)
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(with-lock
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wait-lock
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(lambda ()
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(cond ((proc:finished? proc)
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(placeholder-value (proc:status proc)))
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(else (really-wait (proc:pid proc) (bitwise-ior flags wait/poll)))))))
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(else (really-wait (proc:pid proc) (bitwise-ior flags wait/poll)))))
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;;; This one is used, to wait on a positive pid
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;;; We NEVER do a blocking wait syscall
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@ -315,7 +331,8 @@
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(cond ((maybe-pid->proc pid) =>
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(lambda (proc)
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(obituary proc status)
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(push-reaped-proc proc)))))
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(push-reaped-proc proc)
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))))
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;;; All you have to do, if a wait on proc was successful
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@ -373,13 +390,16 @@
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(define (really-wait-any flags)
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(if (zero? (bitwise-and flags wait/poll))
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(error "real-wait-any without wait/poll" flags))
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(with-lock
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wait-lock
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(lambda ()
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(receive (pid status)
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(%wait-any flags)
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(if pid
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(let ((proc (new-child-proc pid)))
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(waited-by-wait proc status)
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(values proc status))
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(values #f #f))))
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(values #f #f))))))
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;;; (wait-process-group [proc-group flags]) => [proc status]
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@ -424,7 +444,10 @@
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;;; (%wait-any flags) (%wait-pid pid flags) (%wait-process-group pgrp flags)
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;;; Direct interfaces to waitpid(2) call.
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;;; Direct interfaces to waitpid(2) call. As opposed to %wait-pid this
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;;; waits on any child (using -1) and gets along if no child is alive
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;;; at all (i.e. catches errno/child).
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;;; [#f #f] means no processes ready on a non-blocking wait.
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;;; [#f #t] means no waitable process on wait-any.
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