From d0840e4a2332de4f6eb4959836de569b413723c1 Mon Sep 17 00:00:00 2001 From: Ludovic Courtès Date: Wed, 30 Jan 2013 18:56:20 +0100 Subject: derivations: Memoize `read-derivation'. * guix/derivations.scm (read-derivation): Rename to... (%read-derivation): ... this. (read-derivation): New procedure. This reduces the execution of "guix-build gdb" from 2.5s to 1.7s. --- guix/derivations.scm | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) (limited to 'guix/derivations.scm') diff --git a/guix/derivations.scm b/guix/derivations.scm index 6f73534c3c..60d57afa12 100644 --- a/guix/derivations.scm +++ b/guix/derivations.scm @@ -155,9 +155,8 @@ (define (derivation-built? drv sub-drvs) inputs) (map derivation-input-sub-derivations inputs)))))) -(define (read-derivation drv-port) - "Read the derivation from DRV-PORT and return the corresponding - object." +(define (%read-derivation drv-port) + ;; Actually read derivation from DRV-PORT. (define comma (string->symbol ",")) @@ -222,6 +221,20 @@ (define (make-input-drvs x) (loop (read drv-port) (cons (ununquote exp) result)))))) +(define read-derivation + (let ((cache (make-weak-value-hash-table 200))) + (lambda (drv-port) + "Read the derivation from DRV-PORT and return the corresponding + object." + ;; Memoize that operation because `%read-derivation' is quite expensive, + ;; and because the same argument is read more than 15 times on average + ;; during something like (package-derivation s gdb). + (let ((file (and=> (port-filename drv-port) basename))) + (or (and file (hash-ref cache file)) + (let ((drv (%read-derivation drv-port))) + (hash-set! cache file drv) + drv)))))) + (define (write-derivation drv port) "Write the ATerm-like serialization of DRV to PORT. See Section 2.4 of Eelco Dolstra's PhD dissertation for an overview of a previous version of -- cgit v1.2.3