From 4b00f3434e47fc2ddbfda887f36ddbba6a742b82 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ludovic=20Court=C3=A8s?= Date: Thu, 3 Apr 2014 23:41:16 +0200 Subject: [PATCH] offload: Prevent the '.drv' and build result from being GC'd. Before that, there was a small time window during which the GC could wipe the .drv (before 'guix build' has been called), or the build result (before 'retrieve-files' has started.) * guix/scripts/offload.scm (remote-pipe): Add #:quote? parameter and honor it. (%gc-root-file): New variable. (register-gc-root, remove-gc-root): New procedures. (offload): Adjust comment. Run 'guix build' with '-r %GC-ROOT-FILE'. (transfer-and-offload): Call 'register-gc-root' before sending (derivation-file-name DRV). Call 'remove-gc-root' after the call to 'offload' or 'retrieve-files'. (send-files): Call 'remote-pipe' with #:quote? #f. (retrieve-files): Likewise. --- guix/scripts/offload.scm | 76 ++++++++++++++++++++++++++++++++++++---- 1 file changed, 70 insertions(+), 6 deletions(-) diff --git a/guix/scripts/offload.scm b/guix/scripts/offload.scm index 187f1d44c1..1d86f99ca8 100644 --- a/guix/scripts/offload.scm +++ b/guix/scripts/offload.scm @@ -174,8 +174,17 @@ determined." (set-current-error-port old))))))) (define* (remote-pipe machine mode command - #:key (error-port (current-error-port))) - "Run COMMAND on MACHINE, assuming an lsh gateway has been set up." + #:key (error-port (current-error-port)) (quote? #t)) + "Run COMMAND (a string list) on MACHINE, assuming an lsh gateway has been +set up. When QUOTE? is true, perform shell-quotation of all the elements of +COMMAND." + (define (shell-quote str) + ;; Sort-of shell-quote STR so it can be passed as an argument to the + ;; shell. + (with-output-to-string + (lambda () + (write str)))) + (catch 'system-error (lambda () ;; Let the child inherit ERROR-PORT. @@ -188,7 +197,9 @@ determined." "-i" (build-machine-private-key machine) (build-machine-name machine) - command))) + (if quote? + (map shell-quote command) + command)))) (lambda args (warning (_ "failed to execute '~a': ~a~%") %lshg-command (strerror (system-error-errno args))) @@ -283,6 +294,52 @@ hook." (set-port-revealed! port 1) port)) +(define %gc-root-file + ;; File name of the temporary GC root we install. + (format #f "offload-~a-~a" (gethostname) (getpid))) + +(define (register-gc-root file machine) + "Mark FILE, a store item, as a garbage collector root on MACHINE." + (define script + `(begin + (use-modules (guix config)) + + ;; Note: we can't use 'add-indirect-root' because dangling links under + ;; gcroots/auto are automatically deleted by the GC. This strategy + ;; doesn't have this problem, but it requires write access to that + ;; directory. + (let ((root-directory (string-append %state-directory + "/gcroots/tmp"))) + (false-if-exception (mkdir root-directory)) + (symlink ,file + (string-append root-directory "/" ,%gc-root-file))))) + + (let ((pipe (remote-pipe machine OPEN_READ + `("guile" "-c" ,(object->string script))))) + (get-string-all pipe) + (close-pipe pipe))) + +(define (remove-gc-root machine) + "Remove from MACHINE the GC root previously installed with +'register-gc-root'." + (define script + `(begin + (use-modules (guix config)) + + (let ((root-directory (string-append %state-directory + "/gcroots/tmp"))) + (false-if-exception + (delete-file + (string-append root-directory "/" ,%gc-root-file))) + + ;; This one is created with 'guix build -r'. + (false-if-exception (delete-file ,%gc-root-file))))) + + (let ((pipe (remote-pipe machine OPEN_READ + `("guile" "-c" ,(object->string script))))) + (get-string-all pipe) + (close-pipe pipe))) + (define* (offload drv machine #:key print-build-trace? (max-silent-time 3600) build-timeout (log-port (build-log-port))) @@ -293,9 +350,11 @@ there, and write the build log to LOG-PORT. Return the exit status." (format (current-error-port) "@ build-remote ~a ~a~%" (derivation-file-name drv) (build-machine-name machine)) - ;; FIXME: Protect DRV from garbage collection on MACHINE. + ;; Normally DRV has already been protected from GC when it was transferred. + ;; The '-r' flag below prevents the build result from being GC'd. (let ((pipe (remote-pipe machine OPEN_READ `("guix" "build" + "-r" ,%gc-root-file ,(format #f "--max-silent-time=~a" max-silent-time) ,@(if build-timeout @@ -329,6 +388,7 @@ MACHINE." ;; a given direction to/from MACHINE in the presence of several 'offload' ;; hook instance. (when (with-machine-lock machine 'upload + (register-gc-root (derivation-file-name drv) machine) (send-files (cons (derivation-file-name drv) inputs) machine)) (let ((status (offload drv machine @@ -340,10 +400,12 @@ MACHINE." ;; Likewise (see above.) (with-machine-lock machine 'download (retrieve-files outputs machine)) + (false-if-exception (remove-gc-root machine)) (format (current-error-port) "done with offloaded '~a'~%" (derivation-file-name drv))) (begin + (false-if-exception (remove-gc-root machine)) (format (current-error-port) "derivation '~a' offloaded to '~a' failed \ with exit code ~a~%" @@ -386,7 +448,8 @@ success, #f otherwise." (let* ((files (missing-files (topologically-sorted store files))) (pipe (remote-pipe machine OPEN_WRITE '("xz" "-dc" "|" - "guix" "archive" "--import")))) + "guix" "archive" "--import") + #:quote? #f))) (format #t (_ "sending ~a store files to '~a'...~%") (length files) (build-machine-name machine)) (call-with-compressed-output-port 'xz pipe @@ -407,7 +470,8 @@ success, #f otherwise." (let ((pipe (remote-pipe machine OPEN_READ `("guix" "archive" "--export" ,@files - "|" "xz" "-c")))) + "|" "xz" "-c") + #:quote? #f))) (and pipe (with-store store (guard (c ((nix-protocol-error? c)