[lxc-devel] [PATCH] Eliminate duplicate entries from list_active_containers
Serge Hallyn
serge.hallyn at ubuntu.com
Tue Oct 22 00:22:47 UTC 2013
Quoting S.Çağlar Onur (caglar at 10ur.org):
> list_active_containers parses /proc/net/unix which can contain multiple entries for the same container;
>
> 0000000000000000: 00000002 00000000 00010000 0001 01 273672 @/var/lib/lxc/6/command
> 0000000000000000: 00000002 00000000 00010000 0001 01 274395 @/var/lib/lxc/5/command
> 0000000000000000: 00000002 00000000 00010000 0001 01 273890 @/var/lib/lxc/4/command
> 0000000000000000: 00000002 00000000 00010000 0001 01 273141 @/var/lib/lxc/3/command
> 0000000000000000: 00000002 00000000 00010000 0001 01 273915 @/var/lib/lxc/2/command
> 0000000000000000: 00000002 00000000 00010000 0001 01 273683 @/var/lib/lxc/1/command
> 0000000000000000: 00000002 00000000 00010000 0001 01 273074 @/var/lib/lxc/0/command
> 0000000000000000: 00000002 00000000 00010000 0001 01 273931 @/var/lib/lxc/9/command
> 0000000000000000: 00000002 00000000 00010000 0001 01 273110 @/var/lib/lxc/8/command
> 0000000000000000: 00000002 00000000 00010000 0001 01 273390 @/var/lib/lxc/7/command
> 0000000000000000: 00000003 00000000 00000000 0001 03 275903 @/var/lib/lxc/8/command
> 0000000000000000: 00000003 00000000 00000000 0001 03 276043 @/var/lib/lxc/1/command
> 0000000000000000: 00000003 00000000 00000000 0001 03 273301 @/var/lib/lxc/0/command
> 0000000000000000: 00000003 00000000 00000000 0001 03 275650 @/var/lib/lxc/4/command
>
> On this system list_active_containers returns 14 containers while only 10 containers are running.
>
> Following patch;
>
> * Introduces array_contains function to do a binary search on given array,
> * Starts to sort arrays inside the add_to_clist and add_to_names functions,
> * Consumes array_contains in list_active_containers to eliminate duplicates,
> * Replaces the linear search code in lxcapi_get_interfaces with the new function.
Thanks - that patch on the whole is good, except that you move the
adding to *names in list_active_containers() to after the attempt to
load the container. Not loading the container if a container list is
not passed in is deliberately done to avoid a potentially large
amount of work. (The very low potential for differing results when
passing in *cret and not is deemed worthwhile)
> Signed-off-by: S.Çağlar Onur <caglar at 10ur.org>
> ---
> src/lxc/lxccontainer.c | 161 ++++++++++++++++++++++++++-----------------------
> 1 file changed, 86 insertions(+), 75 deletions(-)
>
> diff --git a/src/lxc/lxccontainer.c b/src/lxc/lxccontainer.c
> index c8ecef3..46389ab 100644
> --- a/src/lxc/lxccontainer.c
> +++ b/src/lxc/lxccontainer.c
> @@ -1240,12 +1240,67 @@ out:
> return false;
> }
>
> +// used by qsort and bsearch functions
> +static inline int string_cmp(char **first, char **second)
> +{
> + return strcmp(*first, *second);
> +}
> +
> +static bool add_to_names(char ***names, char *cname, int pos)
> +{
> + char **newnames = realloc(*names, (pos+1) * sizeof(char *));
> + if (!newnames) {
> + ERROR("Out of memory");
> + return false;
> + }
> +
> + *names = newnames;
> + newnames[pos] = strdup(cname);
> + if (!newnames[pos])
> + return false;
> +
> + // sort the arrray as we will use binary search on it
> + qsort(newnames, pos + 1, sizeof(char *), (int (*)(const void *,const void *))string_cmp);
> +
> + return true;
> +}
> +
> +// used by qsort and bsearch functions
> +static inline int container_cmp(struct lxc_container **first, struct lxc_container **second)
> +{
> + return strcmp((*first)->name, (*second)->name);
> +}
> +
> +static bool add_to_clist(struct lxc_container ***list, struct lxc_container *c, int pos)
> +{
> + struct lxc_container **newlist = realloc(*list, (pos+1) * sizeof(struct lxc_container *));
> + if (!newlist) {
> + ERROR("Out of memory");
> + return false;
> + }
> +
> + *list = newlist;
> + newlist[pos] = c;
> +
> + // sort the arrray as we will use binary search on it
> + qsort(newlist, pos + 1, sizeof(struct lxc_container *), (int (*)(const void *,const void *))container_cmp);
> +
> + return true;
> +}
> +
> +static bool array_contains(char **names, char *cname, int size) {
> + char *result = NULL;
> + result = (char *)bsearch((char *)&cname, (char *)names, size, sizeof(char *), (int (*)(const void *,const void *))string_cmp);
> + if (result != NULL)
> + return true;
> + return false;
> +}
> +
> static char** lxcapi_get_interfaces(struct lxc_container *c)
> {
> - int count = 0, i;
> - bool found = false;
> + int count = 0;
> struct ifaddrs *interfaceArray = NULL, *tempIfAddr = NULL;
> - char **interfaces = NULL, **temp;
> + char **interfaces = NULL;
> int old_netns = -1, new_netns = -1;
>
> if (!enter_to_ns(c, &old_netns, &new_netns))
> @@ -1259,30 +1314,10 @@ static char** lxcapi_get_interfaces(struct lxc_container *c)
>
> /* Iterate through the interfaces */
> for (tempIfAddr = interfaceArray; tempIfAddr != NULL; tempIfAddr = tempIfAddr->ifa_next) {
> - /*
> - * WARNING: Following "for" loop does a linear search over the interfaces array
> - * For the containers with lots of interfaces this may be problematic.
> - * I'm not expecting this to be the common usage but if it turns out to be
> - * than using binary search or a hash table could be more elegant solution.
> - */
> - for (i = 0; i < count; i++) {
> - if (strcmp(interfaces[i], tempIfAddr->ifa_name) == 0) {
> - found = true;
> - break;
> - }
> - }
> -
> - if (!found) {
> - count += 1;
> - temp = realloc(interfaces, count * sizeof(*interfaces));
> - if (!temp) {
> - count -= 1;
> - goto out;
> - }
> - interfaces = temp;
> - interfaces[count - 1] = strdup(tempIfAddr->ifa_name);
> + if (!array_contains(interfaces, tempIfAddr->ifa_name, count)) {
> + add_to_names(&interfaces, tempIfAddr->ifa_name, count);
> + count++;
> }
> - found = false;
> }
>
> out:
> @@ -2796,34 +2831,6 @@ int lxc_get_wait_states(const char **states)
> return MAX_STATE;
> }
>
> -
> -static bool add_to_names(char ***names, char *cname, int pos)
> -{
> - char **newnames = realloc(*names, (pos+1) * sizeof(char *));
> - if (!newnames) {
> - ERROR("Out of memory");
> - return false;
> - }
> - *names = newnames;
> - newnames[pos] = strdup(cname);
> - if (!newnames[pos])
> - return false;
> - return true;
> -}
> -
> -static bool add_to_clist(struct lxc_container ***list, struct lxc_container *c, int pos)
> -{
> - struct lxc_container **newlist = realloc(*list, (pos+1) * sizeof(struct lxc_container *));
> - if (!newlist) {
> - ERROR("Out of memory");
> - return false;
> - }
> -
> - *list = newlist;
> - newlist[pos] = c;
> - return true;
> -}
> -
> /*
> * These next two could probably be done smarter with reusing a common function
> * with different iterators and tests...
> @@ -2922,9 +2929,10 @@ free_bad:
>
> int list_active_containers(const char *lxcpath, char ***names, struct lxc_container ***cret)
> {
> - int i, cfound = 0, nfound = 0;
> + int i, found = 0;
> int lxcpath_len;
> char *line = NULL;
> + char **unique_names = NULL;
> size_t len = 0;
> struct lxc_container *c;
>
> @@ -2963,52 +2971,55 @@ int list_active_containers(const char *lxcpath, char ***names, struct lxc_contai
> continue;
> *p2 = '\0';
>
> - if (names) {
> - if (!add_to_names(names, p, nfound))
> - goto free_bad;
> - }
> - cfound++;
> -
> - if (!cret) {
> - nfound++;
> + /*
> + * /proc/net/unix may contain multiple entries for command socket
> + * Check the existence before adding to the list
> + */
> + if (array_contains(unique_names, p, found)) {
> + INFO("Container %s:%s is seen before, skipping", lxcpath, p);
> continue;
> }
>
> + // try loading the container
> c = lxc_container_new(p, lxcpath);
> if (!c) {
> - INFO("Container %s:%s is running but could not be loaded",
> - lxcpath, p);
> - if (names)
> - free((*names)[cfound--]);
> + INFO("Container %s:%s is running but could not be loaded, skipping", lxcpath, p);
> continue;
> }
>
> + // all tests passed, we now can add this to names list
> + if(!add_to_names(&unique_names, p, found))
> + goto free_bad;
> +
> /*
> * If this is an anonymous container, then is_defined *can*
> * return false. So we don't do that check. Count on the
> * fact that the command socket exists.
> */
>
> - if (!add_to_clist(cret, c, nfound)) {
> + if (cret && !add_to_clist(cret, c, found)) {
> lxc_container_put(c);
> goto free_bad;
> }
> - nfound++;
> + found++;
> }
>
> + if (names)
> + *names = unique_names;
> +
> process_lock();
> fclose(f);
> process_unlock();
> - return nfound;
> + return found;
>
> free_bad:
> - if (names && *names) {
> - for (i=0; i<cfound; i++)
> - free((*names)[i]);
> - free(*names);
> + if(unique_names) {
> + for (i=0; i<found; i++)
> + free(unique_names[i]);
> + free(unique_names);
> }
> if (cret && *cret) {
> - for (i=0; i<nfound; i++)
> + for (i=0; i<found; i++)
> lxc_container_put((*cret)[i]);
> free(*cret);
> }
> --
> 1.8.3.2
>
>
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