Introduce VIR_CONNECT_GET_ALL_DOMAINS_STATS_NOWAIT

https://bugzilla.redhat.com/show_bug.cgi?id=1552092

If there's a long running job it might cause us to wait 30
seconds before we give up acquiring the job. This is problematic
to interactive applications that fetch stats repeatedly every few
seconds.

The solution is to introduce
VIR_CONNECT_GET_ALL_DOMAINS_STATS_NOWAIT flag which tries to
acquire job but does not wait if acquiring failed.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: John Ferlan <jferlan@redhat.com>

diff --git a/include/libvirt/libvirt-domain.h b/include/libvirt/libvirt-domain.h
index 3ef7c2452843b8a6a78e14482ece7bb5ae51ce3d..796f2e140883abb1582ee07f4a1f73e1954a1b83 100644 (file)
--- a/include/libvirt/libvirt-domain.h
+++ b/include/libvirt/libvirt-domain.h
@@ -2055,6 +2055,8 @@ typedef enum {
     VIR_CONNECT_GET_ALL_DOMAINS_STATS_SHUTOFF = VIR_CONNECT_LIST_DOMAINS_SHUTOFF,
     VIR_CONNECT_GET_ALL_DOMAINS_STATS_OTHER = VIR_CONNECT_LIST_DOMAINS_OTHER,
 
+    VIR_CONNECT_GET_ALL_DOMAINS_STATS_NOWAIT = 1 << 29, /* report statistics that can be obtained
+                                                           immediately without any blocking */
     VIR_CONNECT_GET_ALL_DOMAINS_STATS_BACKING = 1 << 30, /* include backing chain for block stats */
     VIR_CONNECT_GET_ALL_DOMAINS_STATS_ENFORCE_STATS = 1U << 31, /* enforce requested stats */
 } virConnectGetAllDomainStatsFlags;

diff --git a/src/libvirt-domain.c b/src/libvirt-domain.c
index 4a899f31c80509fe71d39054c124d0e058b47e3a..c71f2e68773b56e388aaf3a05c015bcaf7b4f7a7 100644 (file)
--- a/src/libvirt-domain.c
+++ b/src/libvirt-domain.c
@@ -11502,6 +11502,12 @@ virConnectGetDomainCapabilities(virConnectPtr conn,
  * fields for offline domains if the statistics are meaningful only for a
  * running domain.
  *
+ * Passing VIR_CONNECT_GET_ALL_DOMAINS_STATS_NOWAIT in
+ * @flags means when libvirt is unable to fetch stats for any of
+ * the domains (for whatever reason) only a subset of statistics
+ * is returned for the domain.  That subset being statistics that
+ * don't involve querying the underlying hypervisor.
+ *
  * Similarly to virConnectListAllDomains, @flags can contain various flags to
  * filter the list of domains to provide stats for.
  *
@@ -11586,6 +11592,12 @@ virConnectGetAllDomainStats(virConnectPtr conn,
  * fields for offline domains if the statistics are meaningful only for a
  * running domain.
  *
+ * Passing VIR_CONNECT_GET_ALL_DOMAINS_STATS_NOWAIT in
+ * @flags means when libvirt is unable to fetch stats for any of
+ * the domains (for whatever reason) only a subset of statistics
+ * is returned for the domain.  That subset being statistics that
+ * don't involve querying the underlying hypervisor.
+ *
  * Note that any of the domain list filtering flags in @flags may be rejected
  * by this function.
  *

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 7fe86d4d2edd64f8de686e30b514497a42605864..3abbe418955b7857e143eb0abfa9541a2e6b5edc 100644 (file)
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -20426,6 +20426,7 @@ qemuConnectGetAllDomainStats(virConnectPtr conn,
     virCheckFlags(VIR_CONNECT_LIST_DOMAINS_FILTERS_ACTIVE |
                   VIR_CONNECT_LIST_DOMAINS_FILTERS_PERSISTENT |
                   VIR_CONNECT_LIST_DOMAINS_FILTERS_STATE |
+                  VIR_CONNECT_GET_ALL_DOMAINS_STATS_NOWAIT |
                   VIR_CONNECT_GET_ALL_DOMAINS_STATS_BACKING |
                   VIR_CONNECT_GET_ALL_DOMAINS_STATS_ENFORCE_STATS, -1);
 
@@ -20460,9 +20461,17 @@ qemuConnectGetAllDomainStats(virConnectPtr conn,
 
         virObjectLock(vm);
 
-        if (HAVE_JOB(privflags) &&
-            qemuDomainObjBeginJob(driver, vm, QEMU_JOB_QUERY) == 0)
-            domflags |= QEMU_DOMAIN_STATS_HAVE_JOB;
+        if (HAVE_JOB(privflags)) {
+            int rv;
+
+            if (flags & VIR_CONNECT_GET_ALL_DOMAINS_STATS_NOWAIT)
+                rv = qemuDomainObjBeginJobNowait(driver, vm, QEMU_JOB_QUERY);
+            else
+                rv = qemuDomainObjBeginJob(driver, vm, QEMU_JOB_QUERY);
+
+            if (rv == 0)
+                domflags |= QEMU_DOMAIN_STATS_HAVE_JOB;
+        }
         /* else: without a job it's still possible to gather some data */
 
         if (flags & VIR_CONNECT_GET_ALL_DOMAINS_STATS_BACKING)