offload: Move macro definitions before use.
* guix/scripts/offload.scm (lock-file, unlock-file, with-file-lock, with-machine-lock, machine-slot-file, acquire-build-slot, release-build-slot): Move definitions above their first use.master
Ludovic Courtès
parent
2a51db7d8d
commit
59f704dff6
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@ -174,6 +174,86 @@ determined."
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%lshg-command (strerror (system-error-errno args)))
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#f)))
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;;;
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;;; Synchronization.
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;;;
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(define (lock-file file)
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"Wait and acquire an exclusive lock on FILE. Return an open port."
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(mkdir-p (dirname file))
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(let ((port (open-file file "w0")))
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(fcntl-flock port 'write-lock)
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port))
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(define (unlock-file lock)
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"Unlock LOCK."
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(fcntl-flock lock 'unlock)
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(close-port lock)
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#t)
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(define-syntax-rule (with-file-lock file exp ...)
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"Wait to acquire a lock on FILE and evaluate EXP in that context."
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(let ((port (lock-file file)))
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(dynamic-wind
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(lambda ()
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#t)
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(lambda ()
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exp ...)
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(lambda ()
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(unlock-file port)))))
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(define-syntax-rule (with-machine-lock machine hint exp ...)
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"Wait to acquire MACHINE's exclusive lock for HINT, and evaluate EXP in that
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context."
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(with-file-lock (machine-lock-file machine hint)
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exp ...))
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(define (machine-slot-file machine slot)
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"Return the file name of MACHINE's file for SLOT."
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;; For each machine we have a bunch of files representing each build slot.
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;; When choosing a build machine, we attempt to get an exclusive lock on one
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;; of these; if we fail, that means all the build slots are already taken.
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;; Inspired by Nix's build-remote.pl.
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(string-append (string-append %state-directory "/offload/"
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(build-machine-name machine)
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"/" (number->string slot))))
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(define (acquire-build-slot machine)
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"Attempt to acquire a build slot on MACHINE. Return the port representing
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the slot, or #f if none is available.
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This mechanism allows us to set a hard limit on the number of simultaneous
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connections allowed to MACHINE."
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(mkdir-p (dirname (machine-slot-file machine 0)))
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(with-machine-lock machine 'slots
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(any (lambda (slot)
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(let ((port (open-file (machine-slot-file machine slot)
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"w0")))
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(catch 'flock-error
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(lambda ()
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(fcntl-flock port 'write-lock #:wait? #f)
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;; Got it!
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(format (current-error-port)
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"process ~a acquired build slot '~a'~%"
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(getpid) (port-filename port))
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port)
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(lambda args
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;; PORT is already locked by another process.
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(close-port port)
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#f))))
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(iota (build-machine-parallel-builds machine)))))
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(define (release-build-slot slot)
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"Release SLOT, a build slot as returned as by 'acquire-build-slot'."
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(close-port slot))
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;;;
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;;; Offloading.
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;;;
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(define* (offload drv machine
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#:key print-build-trace? (max-silent-time 3600)
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(build-timeout 7200) (log-port (current-output-port)))
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@ -299,6 +379,11 @@ success, #f otherwise."
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(zero? (close-pipe pipe)))))))
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;;;
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;;; Scheduling.
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;;;
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(define (machine-matches? machine requirements)
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"Return #t if MACHINE matches REQUIREMENTS."
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(and (string=? (build-requirements-system requirements)
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@ -350,75 +435,6 @@ allowed on MACHINE."
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"Return the name of the file used as a lock when choosing a build machine."
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(string-append %state-directory "/offload/machine-choice.lock"))
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(define (lock-file file)
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"Wait and acquire an exclusive lock on FILE. Return an open port."
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(mkdir-p (dirname file))
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(let ((port (open-file file "w0")))
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(fcntl-flock port 'write-lock)
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port))
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(define (unlock-file lock)
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"Unlock LOCK."
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(fcntl-flock lock 'unlock)
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(close-port lock)
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#t)
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(define-syntax-rule (with-file-lock file exp ...)
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"Wait to acquire a lock on FILE and evaluate EXP in that context."
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(let ((port (lock-file file)))
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(dynamic-wind
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(lambda ()
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#t)
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(lambda ()
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exp ...)
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(lambda ()
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(unlock-file port)))))
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(define-syntax-rule (with-machine-lock machine hint exp ...)
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"Wait to acquire MACHINE's exclusive lock for HINT, and evaluate EXP in that
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context."
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(with-file-lock (machine-lock-file machine hint)
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exp ...))
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(define (machine-slot-file machine slot)
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"Return the file name of MACHINE's file for SLOT."
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;; For each machine we have a bunch of files representing each build slot.
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;; When choosing a build machine, we attempt to get an exclusive lock on one
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;; of these; if we fail, that means all the build slots are already taken.
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;; Inspired by Nix's build-remote.pl.
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(string-append (string-append %state-directory "/offload/"
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(build-machine-name machine)
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"/" (number->string slot))))
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(define (acquire-build-slot machine)
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"Attempt to acquire a build slot on MACHINE. Return the port representing
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the slot, or #f if none is available.
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This mechanism allows us to set a hard limit on the number of simultaneous
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connections allowed to MACHINE."
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(mkdir-p (dirname (machine-slot-file machine 0)))
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(with-machine-lock machine 'slots
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(any (lambda (slot)
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(let ((port (open-file (machine-slot-file machine slot)
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"w0")))
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(catch 'flock-error
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(lambda ()
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(fcntl-flock port 'write-lock #:wait? #f)
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;; Got it!
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(format (current-error-port)
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"process ~a acquired build slot '~a'~%"
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(getpid) (port-filename port))
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port)
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(lambda args
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;; PORT is already locked by another process.
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(close-port port)
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#f))))
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(iota (build-machine-parallel-builds machine)))))
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(define (release-build-slot slot)
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"Release SLOT, a build slot as returned as by 'acquire-build-slot'."
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(close-port slot))
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(define %slots
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;; List of acquired build slots (open ports).
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