From 9b5f4eb57af28a604cd7ac8b2c1be9e49f0b517d Mon Sep 17 00:00:00 2001

From: Laine Stump <laine@laine.org>

Date: Mon, 28 Sep 2015 17:11:11 -0400

Subject: [PATCH] call aug_load() at most once per second

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1268384

Previously, netcf would call aug_load() at the start of each public

API call, and rely on augeas quickly determining if the files needed

to be reread based on checking the mtime of all files. With a large

number of files (i.e. several hundred ifcfg files) just checking the

mtime of all files ends up taking quite a long time; enough to turn a

simple "virsh iface-list" of 300 bridges + 300 vlans into a 22 second

ordeal.

With this patch applied, netcf will only call aug_load() at most once

every second, resulting in runtime for virsh iface-list going down to

< 1 second.

The trade-off is that the results of a netcf API call could be up to 1

second out of date (but only due to changes in the config external to

netcf). Since ifcfg files change very infrequently, this is likely

acceptable.

---

 src/dutil_linux.c | 8 +++++++-

 src/dutil_linux.h | 1 +

 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/dutil_linux.c b/src/dutil_linux.c

index 0850593..24f4d95 100644

--- a/src/dutil_linux.c

+++ b/src/dutil_linux.c

@@ -32,6 +32,7 @@

 #include <unistd.h>

 #include <ctype.h>

 #include <errno.h>

+#include <time.h>

 #include <dirent.h>

 #include <sys/wait.h>

@@ -151,6 +152,7 @@ int remove_augeas_xfm_table(struct netcf *ncf,

  */

 augeas *get_augeas(struct netcf *ncf) {

     int r;

+    time_t current_time;

     if (ncf->driver->augeas == NULL) {

         augeas *aug;

@@ -186,9 +188,12 @@ augeas *get_augeas(struct netcf *ncf) {

         }

         ncf->driver->copy_augeas_xfm = 0;

         ncf->driver->load_augeas = 1;

+        ncf->driver->load_augeas_time = 0;

     }

-    if (ncf->driver->load_augeas) {

+    current_time = time(NULL);

+    if (ncf->driver->load_augeas &&

+        ncf->driver->load_augeas_time != current_time) {

         augeas *aug = ncf->driver->augeas;

         r = aug_load(aug);

@@ -207,6 +212,7 @@ augeas *get_augeas(struct netcf *ncf) {

         }

         ERR_THROW(r > 0, ncf, EOTHER, "errors in loading some config files");

         ncf->driver->load_augeas = 0;

+        ncf->driver->load_augeas_time = current_time;

     }

     return ncf->driver->augeas;

  error:

diff --git a/src/dutil_linux.h b/src/dutil_linux.h

index a06a15c..75ac631 100644

--- a/src/dutil_linux.h

+++ b/src/dutil_linux.h

@@ -41,6 +41,7 @@ struct driver {

     struct nl_sock     *nl_sock;

     struct nl_cache   *link_cache;

     struct nl_cache   *addr_cache;

+    time_t             load_augeas_time;

     unsigned int       load_augeas : 1;

     unsigned int       copy_augeas_xfm : 1;

     unsigned int       augeas_xfm_num_tables;

-- 

2.4.3