[Xen-devel] [PATCH v3] xenstat: handle more than 1024 domains

[Juergen Gross <jgross@xxxxxxxx>]

get_domain_ids() in libxenstat used by read_attributes_qdisk() is
limited to 1024 domains. Remove that limit.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
V3: Obey 80 character line length limit as requested by Ian Campbell.
    In order to not have to wrap so many lines just carve out the loop
    body into a sub-function. As this changes the patch structure, drop
    the Reviewed-by tag of Wei.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
 tools/xenstat/libxenstat/src/xenstat_qmp.c | 79 ++++++++++++++----------------
 1 file changed, 38 insertions(+), 41 deletions(-)

diff --git a/tools/xenstat/libxenstat/src/xenstat_qmp.c 
b/tools/xenstat/libxenstat/src/xenstat_qmp.c
index 5e261af..c12929a 100644
--- a/tools/xenstat/libxenstat/src/xenstat_qmp.c
+++ b/tools/xenstat/libxenstat/src/xenstat_qmp.c
@@ -356,18 +356,6 @@ static int qmp_connect(char *path)
        return s;
 }
 
-/* Get up to 1024 active domains */
-static xc_domaininfo_t *get_domain_ids(xc_interface *xc_handle, int *num_doms)
-{
-       xc_domaininfo_t *dominfo;
-
-       dominfo = calloc(1024, sizeof(xc_domaininfo_t));
-       if (dominfo == NULL)
-               return NULL;
-       *num_doms = xc_domain_getinfolist(xc_handle, 0, 1024, dominfo);
-       return dominfo;
-}
-
 /* Gather the qdisk statistics by querying QMP
    Resources: http://wiki.qemu.org/QMP and qmp-commands.hx from the qemu code
    QMP Syntax for entering command mode. This command must be issued before
@@ -394,48 +382,57 @@ static xc_domaininfo_t *get_domain_ids(xc_interface 
*xc_handle, int *num_doms)
             }
           }]}
 */
-void read_attributes_qdisk(xenstat_node * node)
+static void read_attributes_qdisk_dom(xenstat_node *node, domid_t domain)
 {
        char *cmd_mode = "{ \"execute\": \"qmp_capabilities\" }";
        char *query_blockstats_cmd = "{ \"execute\": \"query-blockstats\" }";
-       xc_domaininfo_t *dominfo = NULL;
        unsigned char *qmp_stats, *val;
        char path[80];
-       int i, qfd, num_doms;
+       int qfd;
 
-       dominfo = get_domain_ids(node->handle->xc_handle, &num_doms);
-       if (dominfo == NULL)
+       /* Verify that qdisk disks are used with this VM */
+       snprintf(path, sizeof(path),"/local/domain/0/backend/qdisk/%i", domain);
+       val = xs_read(node->handle->xshandle, XBT_NULL, path, NULL);
+       if (val == NULL)
                return;
+       free(val);
 
-       for (i=0; i<num_doms; i++) {
-               if (dominfo[i].domain <= 0)
-                       continue;
-
-               /* Verify that qdisk disks are used with this VM */
-               snprintf(path, sizeof(path),"/local/domain/0/backend/qdisk/%i", 
dominfo[i].domain);
-               if ((val = xs_read(node->handle->xshandle, XBT_NULL, path, 
NULL)) == NULL)
-                       continue;
-               free(val);
-
-               /* Connect to this VMs QMP socket */
-               snprintf(path, sizeof(path), "/var/run/xen/qmp-libxenstat-%i", 
dominfo[i].domain);
-               if ((qfd = qmp_connect(path)) < 0) {
-                       continue;
-               }
+       /* Connect to this VMs QMP socket */
+       snprintf(path, sizeof(path), "/var/run/xen/qmp-libxenstat-%i", domain);
+       if ((qfd = qmp_connect(path)) < 0)
+               return;
 
-               /* First enable QMP capabilities so that we can query for data 
*/
-               if ((qmp_stats = qmp_query(qfd, cmd_mode)) != NULL) {
+       /* First enable QMP capabilities so that we can query for data */
+       if ((qmp_stats = qmp_query(qfd, cmd_mode)) != NULL) {
+               free(qmp_stats);
+               /* Query QMP for this VMs blockstats */
+               qmp_stats = qmp_query(qfd, query_blockstats_cmd);
+               if (qmp_stats != NULL) {
+                       qmp_parse_stats(node, domain, qmp_stats, qfd);
                        free(qmp_stats);
-                       /* Query QMP for this VMs blockstats */
-                       if ((qmp_stats = qmp_query(qfd, query_blockstats_cmd)) 
!= NULL) {
-                               qmp_parse_stats(node, dominfo[i].domain, 
qmp_stats, qfd);
-                               free(qmp_stats);
-                       }
                }
-               close(qfd);
        }
+       close(qfd);
+}
+
+void read_attributes_qdisk(xenstat_node * node)
+{
+       xc_domaininfo_t dominfo[1024];
+       int i, num_doms;
+       domid_t next_domid = 0;
+
+       for (;;) {
+               num_doms = xc_domain_getinfolist(node->handle->xc_handle,
+                                                next_domid, 1024, dominfo);
+               if (num_doms <= 0)
+                       return;
 
-       free(dominfo);
+               for (i = 0; i < num_doms; i++)
+                       if (dominfo[i].domain > 0)
+                               read_attributes_qdisk_dom(node, 
dominfo[i].domain);
+
+               next_domid = dominfo[num_doms - 1].domain + 1;
+       }
 }
 
 #else /* !HAVE_YAJL_V2 */
-- 
2.6.2


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