[libvirt] [PATCH 4/5] Introcude VIR_CONNECT_GET_ALL_DOMAINS_STATS_BEST_EFFORT

[Michal Privoznik]

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 job. This may cause trouble
to interactive applications that fetch stats repeatedly every few
seconds.

Solution is to introduce
VIR_CONNECT_GET_ALL_DOMAINS_STATS_BEST_EFFORT flag which tries to
acquire job but does not wait if acquiring failed.

Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
---
 include/libvirt/libvirt-domain.h |  1 +
 src/libvirt-domain.c             | 10 ++++++++++
 src/qemu/qemu_driver.c           | 15 ++++++++++++---
 3 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/include/libvirt/libvirt-domain.h b/include/libvirt/libvirt-domain.h
index da773b76cb..1a1d34620d 100644
--- a/include/libvirt/libvirt-domain.h
+++ b/include/libvirt/libvirt-domain.h
@@ -2055,6 +2055,7 @@ 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_BEST_EFFORT = 1 << 29, /* ignore stalled domains */
     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 d44b553c74..906b097adb 100644
--- a/src/libvirt-domain.c
+++ b/src/libvirt-domain.c
@@ -11502,6 +11502,11 @@ virConnectGetDomainCapabilities(virConnectPtr conn,
  * fields for offline domains if the statistics are meaningful only for a
  * running domain.
  *
+ * Passing VIR_CONNECT_GET_ALL_DOMAINS_STATS_BEST_EFFORT in
+ * @flags means when libvirt is unable to fetch stats for any of
+ * the domains (for whatever reason) such domain is silently
+ * ignored.
+ *
  * Similarly to virConnectListAllDomains, @flags can contain various flags to
  * filter the list of domains to provide stats for.
  *
@@ -11586,6 +11591,11 @@ virConnectGetAllDomainStats(virConnectPtr conn,
  * fields for offline domains if the statistics are meaningful only for a
  * running domain.
  *
+ * Passing VIR_CONNECT_GET_ALL_DOMAINS_STATS_BEST_EFFORT in
+ * @flags means when libvirt is unable to fetch stats for any of
+ * the domains (for whatever reason) such domain is silently
+ * ignored.
+ *
  * 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 38ea865ce3..28338de05f 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -20446,6 +20446,7 @@ 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_BEST_EFFORT |
                   VIR_CONNECT_GET_ALL_DOMAINS_STATS_BACKING |
                   VIR_CONNECT_GET_ALL_DOMAINS_STATS_ENFORCE_STATS, -1);
 
@@ -20480,9 +20481,17 @@ 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_BEST_EFFORT)
+                rv = qemuDomainObjBeginJobInstant(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)
-- 
2.16.4