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offload: Generalize the machine lock mechanism. 

* guix/scripts/offload.scm (lock-machine): Add 'hint' parameter.
  (unlock-machine): Remove 'machine' parameter.
  (with-machine-lock): Add 'hint' parameter, and pass it down.
  (process-request): Adjust uses of 'with-machine-lock' to pass the
  'bandwidth hint.
master
Ludovic Courtès 2014-03-08 11:29:52 +01:00
parent c7445833eb
commit 178f5828eb
1 changed files with 16 additions and 15 deletions
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31
guix/scripts/offload.scm
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@ -303,37 +303,38 @@ allowed on MACHINE."
(or (machine-less-loaded? m1 m2)
(machine-faster? m1 m2)))
(define (machine-lock-file machine)
"Return the name of MACHINE's lock file."
(define (machine-lock-file machine hint)
"Return the name of MACHINE's lock file for HINT."
(string-append %state-directory "/offload/"
(build-machine-name machine) ".lock"))
(build-machine-name machine)
"." (symbol->string hint) ".lock"))
(define (lock-machine machine)
"Wait to acquire MACHINE's lock, and return the lock."
(let ((file (machine-lock-file machine)))
(define (lock-machine machine hint)
"Wait to acquire MACHINE's lock for HINT, and return the lock."
(let ((file (machine-lock-file machine hint)))
(mkdir-p (dirname file))
(let ((port (open-file file "w0")))
(fcntl-flock port 'write-lock)
port)))
(define (unlock-machine machine lock)
"Unlock LOCK, MACHINE's lock."
(define (unlock-machine lock)
"Unlock LOCK."
(fcntl-flock lock 'unlock)
(close-port lock)
#t)
(define-syntax-rule (with-machine-lock machine exp ...)
"Wait to acquire MACHINE's exclusive lock, and evaluate EXP in that
(define-syntax-rule (with-machine-lock machine hint exp ...)
"Wait to acquire MACHINE's exclusive lock for HINT, and evaluate EXP in that
context."
(let* ((m machine)
(lock (lock-machine m)))
(lock (lock-machine m hint)))
(dynamic-wind
(lambda ()
#t)
(lambda ()
exp ...)
(lambda ()
(unlock-machine m lock)))))
(unlock-machine lock)))))
(define (choose-build-machine requirements machines)
"Return the best machine among MACHINES fulfilling REQUIREMENTS, or #f."
@ -365,7 +366,7 @@ context."
;; Acquire MACHINE's exclusive lock to serialize file transfers
;; to/from MACHINE in the presence of several 'offload' hook
;; instance.
(when (with-machine-lock machine
(when (with-machine-lock machine 'bandwidth
(send-files (cons (derivation-file-name drv) inputs)
machine))
(let ((status (offload drv machine
@ -375,7 +376,7 @@ context."
(if (zero? status)
(begin
;; Likewise (see above.)
(with-machine-lock machine
(with-machine-lock machine 'bandwidth
(retrieve-files outputs machine))
(format (current-error-port)
"done with offloaded '~a'~%"
@ -459,7 +460,7 @@ This tool is meant to be used internally by 'guix-daemon'.\n"))
(leave (_ "invalid arguments: ~{~s ~}~%") x))))
;;; Local Variables:
;;; eval: (put 'with-machine-lock 'scheme-indent-function 1)
;;; eval: (put 'with-machine-lock 'scheme-indent-function 2)
;;; End:
;;; offload.scm ends here