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From: zkabelac@sourceware.org To: lvm-devel@redhat.com, lvm2-cvs@sourceware.org Subject: LVM2 ./WHATS_NEW_DM libdm/libdm-string.c Date: Thu, 23 Feb 2012 18:05:00 -0000 [thread overview] Message-ID: <20120223180517.22672.qmail@sourceware.org> (raw) CVSROOT: /cvs/lvm2 Module name: LVM2 Changes by: zkabelac@sourceware.org 2012-02-23 18:05:13 Modified files: . : WHATS_NEW_DM libdm : libdm-string.c Log message: Limit number of mem allocs and copies If we have good enough glibc to return number of needed chars, do not loop try to reach good size, but use this size directly for allocation, saving also last strdup. Since now we start with 16 bytes - skip buffer realloc for shorter string. Patches: http://sourceware.org/cgi-bin/cvsweb.cgi/LVM2/WHATS_NEW_DM.diff?cvsroot=lvm2&r1=1.570&r2=1.571 http://sourceware.org/cgi-bin/cvsweb.cgi/LVM2/libdm/libdm-string.c.diff?cvsroot=lvm2&r1=1.18&r2=1.19 --- LVM2/WHATS_NEW_DM 2012/02/20 21:11:06 1.570 +++ LVM2/WHATS_NEW_DM 2012/02/23 18:05:12 1.571 @@ -1,5 +1,6 @@ Version 1.02.72 - ==================================== + Avoid memory reallocation for dm_asprintf. Version 1.02.71 - 20th February 2012 ==================================== --- LVM2/libdm/libdm-string.c 2012/02/10 13:56:20 1.18 +++ LVM2/libdm/libdm-string.c 2012/02/23 18:05:12 1.19 @@ -1,5 +1,5 @@ /* - * Copyright (C) 2006-2007 Red Hat, Inc. All rights reserved. + * Copyright (C) 2006-2012 Red Hat, Inc. All rights reserved. * * This file is part of the device-mapper userspace tools. * @@ -131,7 +131,7 @@ int dm_asprintf(char **result, const char *format, ...) { - int n, ok = 0, size = 32; + int i, n, size = 16; va_list ap; char *buf = dm_malloc(size); @@ -140,26 +140,30 @@ if (!buf) return -1; - while (!ok) { + for (i = 0;; i++) { va_start(ap, format); n = vsnprintf(buf, size, format, ap); va_end(ap); if (0 <= n && n < size) - ok = 1; - else { - dm_free(buf); - size *= 2; - buf = dm_malloc(size); - if (!buf) - return -1; - } + break; + + dm_free(buf); + /* Up to glibc 2.0.6 returns -1 */ + size = (n < 0) ? size * 2 : n + 1; + if (!(buf = dm_malloc(size))) + return -1; } - if (!(*result = dm_strdup(buf))) - n = -2; /* return -1 */ + if (i > 1) { + /* Reallocating more then once? */ + if (!(*result = dm_strdup(buf))) { + dm_free(buf); + return -1; + } + } else + *result = buf; - dm_free(buf); return n + 1; }
next reply other threads:[~2012-02-23 18:05 UTC|newest] Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top 2012-02-23 18:05 zkabelac [this message] -- strict thread matches above, loose matches on Subject: below -- 2012-02-10 13:56 zkabelac
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