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authorLudovic Courtès <ludo@gnu.org>2014-03-08 12:07:57 +0100
committerLudovic Courtès <ludo@gnu.org>2014-03-08 12:07:57 +0100
commit4bf1eb4f88f2d2b0596fe8a4b98490fc277f323b (patch)
tree1a4152102d8265e8d00095c3779e5cedf4b9d1b3 /guix
parent178f5828ebcb5a5c7019b5463e4ecee5df48870b (diff)
offload: Further generalize lock files.
* guix/scripts/offload.scm (lock-machine, unlock-machine): Remove. (lock-file, unlock-file): New procedures. (with-file-lock): New macro. (with-machine-lock): Rewrite in terms of 'with-file-lock'.
Diffstat (limited to 'guix')
-rw-r--r--guix/scripts/offload.scm34
1 files changed, 19 insertions, 15 deletions
diff --git a/guix/scripts/offload.scm b/guix/scripts/offload.scm
index 9b2ea72dc3..fb5d178109 100644
--- a/guix/scripts/offload.scm
+++ b/guix/scripts/offload.scm
@@ -309,32 +309,35 @@ allowed on MACHINE."
(build-machine-name machine)
"." (symbol->string hint) ".lock"))
-(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 lock)
+(define (lock-file file)
+ "Wait and acquire an exclusive lock on FILE. Return an open port."
+ (mkdir-p (dirname file))
+ (let ((port (open-file file "w0")))
+ (fcntl-flock port 'write-lock)
+ port))
+
+(define (unlock-file lock)
"Unlock LOCK."
(fcntl-flock lock 'unlock)
(close-port lock)
#t)
-(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 hint)))
+(define-syntax-rule (with-file-lock file exp ...)
+ "Wait to acquire a lock on FILE and evaluate EXP in that context."
+ (let ((port (lock-file file)))
(dynamic-wind
(lambda ()
#t)
(lambda ()
exp ...)
(lambda ()
- (unlock-machine lock)))))
+ (unlock-file port)))))
+
+(define-syntax-rule (with-machine-lock machine hint exp ...)
+ "Wait to acquire MACHINE's exclusive lock for HINT, and evaluate EXP in that
+context."
+ (with-file-lock (machine-lock-file machine hint)
+ exp ...))
(define (choose-build-machine requirements machines)
"Return the best machine among MACHINES fulfilling REQUIREMENTS, or #f."
@@ -461,6 +464,7 @@ This tool is meant to be used internally by 'guix-daemon'.\n"))
;;; Local Variables:
;;; eval: (put 'with-machine-lock 'scheme-indent-function 2)
+;;; eval: (put 'with-file-lock 'scheme-indent-function 1)
;;; End:
;;; offload.scm ends here