[libvirt] [PATCH v2 2/2] libxl: implement virDomainInterfaceStats

[Joao Martins]

Introduce support for domainInterfaceStats API call for querying
network interface statistics. Consequently it also enables the
use of `virsh domifstat <dom> <interface name>` command plus
seeing the interfaces names instead of "-" when doing
`virsh domiflist <dom>`.

After successful guest creation we fill the network
interfaces names based on domain, device id and append suffix
if it's emulated in the following form: vif<domid>.<devid>[-emu].
We extract the network interfaces info from libxl in
libxlDomainStartCallback() and make ifname . On domain
cleanup we also clear ifname, in case it was set by libvirt (i.e.
being prefixed with "vif"). We also skip these two steps in case the name
of the interface was manually inserted by the adminstrator.

For getting the interface statistics we resort to virNetInterfaceStats
and let libvirt handle the platform specific nits. Note that the latter
is not yet supported in FreeBSD.

Signed-off-by: Joao Martins <joao.m.martins at oracle.com>
---
Changes since v3:
 - Use libxl_device_nic_list() for getting each network interface
 devid in DomainStartCallback.
 - Improve error reporting by appropriately setting the right error
 when no interface is known.
 - Do not unlock vm if libxlDomainObjEndJob() returns false
 - Set vm->def->net[i]->ifname on DomainStartCallback instead of
 DomainStart.
 - Change commit message reflecting the changes on the previous
 item and mention correct interface names when doing domiflist.

Changes since v2:
 - Clear ifname if it's autogenerated, since otherwise will persist
 on successive domain starts. Change commit message reflecting this
 change.

Changes since v1:
 - Fill <virDomainNetDef>.ifname after domain start with generated
 name from libxl  based on domain id and devid returned by libxl.
 After that path validation don interfaceStats is enterily based
 on ifname pretty much like the other drivers.
 - Modify commit message reflecting the changes mentioned in
 the previous item.
 - Bump version to 1.2.22
---
 src/libxl/libxl_domain.c | 29 +++++++++++++++++++++++++++
 src/libxl/libxl_driver.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 81 insertions(+)

diff --git a/src/libxl/libxl_domain.c b/src/libxl/libxl_domain.c
index a7267b0..141f241 100644
--- a/src/libxl/libxl_domain.c
+++ b/src/libxl/libxl_domain.c
@@ -728,6 +728,17 @@ libxlDomainCleanup(libxlDriverPrivatePtr driver,
         }
     }
 
+    if ((vm->def->nnets)) {
+        ssize_t i;
+
+        for (i = 0; i < vm->def->nnets; i++) {
+            virDomainNetDefPtr net = vm->def->nets[i];
+
+            if (STRPREFIX(net->ifname, "vif"))
+                VIR_FREE(net->ifname);
+        }
+    }
+
     if (virAsprintf(&file, "%s/%s.xml", cfg->stateDir, vm->def->name) > 0) {
         if (unlink(file) < 0 && errno != ENOENT && errno != ENOTDIR)
             VIR_DEBUG("Failed to remove domain XML for %s", vm->def->name);
@@ -857,6 +868,8 @@ static void
 libxlDomainStartCallback(libxl_ctx *ctx, libxl_event *ev, void *for_callback)
 {
     virDomainObjPtr vm = for_callback;
+    libxl_device_nic *nics;
+    int nnics;
     size_t i;
 
     virObjectLock(vm);
@@ -883,6 +896,22 @@ libxlDomainStartCallback(libxl_ctx *ctx, libxl_event *ev, void *for_callback)
             VIR_FREE(console);
         }
     }
+
+    if ((nics = libxl_device_nic_list(ctx, ev->domid, &nnics)) != NULL) {
+        for (i = 0; i < vm->def->nnets && i < nnics; i++) {
+            virDomainNetDefPtr net = vm->def->nets[i];
+            libxl_device_nic *x_nic = &nics[i];
+            const char *suffix =
+                x_nic->nictype != LIBXL_NIC_TYPE_VIF ? "-emu" : "";
+
+            if (net->ifname)
+                continue;
+
+            if (virAsprintf(&net->ifname, "vif%d.%d%s",
+                            ev->domid, x_nic->devid, suffix) < 0)
+                continue;
+        }
+    }
     virObjectUnlock(vm);
     libxl_event_free(ctx, ev);
 }
diff --git a/src/libxl/libxl_driver.c b/src/libxl/libxl_driver.c
index d77a0e4..55d991b 100644
--- a/src/libxl/libxl_driver.c
+++ b/src/libxl/libxl_driver.c
@@ -58,6 +58,7 @@
 #include "virhostdev.h"
 #include "network/bridge_driver.h"
 #include "locking/domain_lock.h"
+#include "virstats.h"
 
 #define VIR_FROM_THIS VIR_FROM_LIBXL
 
@@ -4643,6 +4644,56 @@ libxlDomainIsUpdated(virDomainPtr dom)
 }
 
 static int
+libxlDomainInterfaceStats(virDomainPtr dom,
+                          const char *path,
+                          virDomainInterfaceStatsPtr stats)
+{
+    libxlDriverPrivatePtr driver = dom->conn->privateData;
+    virDomainObjPtr vm;
+    ssize_t i;
+    int ret = -1;
+
+    if (!(vm = libxlDomObjFromDomain(dom)))
+        goto cleanup;
+
+    if (virDomainInterfaceStatsEnsureACL(dom->conn, vm->def) < 0)
+        goto cleanup;
+
+    if (libxlDomainObjBeginJob(driver, vm, LIBXL_JOB_QUERY) < 0)
+        goto cleanup;
+
+    if (!virDomainObjIsActive(vm)) {
+        virReportError(VIR_ERR_OPERATION_INVALID,
+                       "%s", _("domain is not running"));
+        goto endjob;
+    }
+
+    /* Check the path is one of the domain's network interfaces. */
+    for (i = 0; i < vm->def->nnets; i++) {
+        if (vm->def->nets[i]->ifname &&
+            STREQ(vm->def->nets[i]->ifname, path)) {
+            ret = 0;
+            break;
+        }
+    }
+
+    if (ret == 0)
+        ret = virNetInterfaceStats(path, stats);
+    else
+        virReportError(VIR_ERR_INVALID_ARG,
+                       _("'%s' is not a known interface"), path);
+
+ endjob:
+    if (!libxlDomainObjEndJob(driver, vm))
+        vm = NULL;
+
+ cleanup:
+    if (vm)
+        virObjectUnlock(vm);
+    return ret;
+}
+
+static int
 libxlDomainGetTotalCPUStats(libxlDriverPrivatePtr driver,
                             virDomainObjPtr vm,
                             virTypedParameterPtr params,
@@ -5421,6 +5472,7 @@ static virHypervisorDriver libxlHypervisorDriver = {
 #endif
     .nodeGetFreeMemory = libxlNodeGetFreeMemory, /* 0.9.0 */
     .nodeGetCellsFreeMemory = libxlNodeGetCellsFreeMemory, /* 1.1.1 */
+    .domainInterfaceStats = libxlDomainInterfaceStats, /* 1.2.22 */
     .domainMemoryStats = libxlDomainMemoryStats, /* 1.2.22 */
     .domainGetCPUStats = libxlDomainGetCPUStats, /* 1.2.22 */
     .connectDomainEventRegister = libxlConnectDomainEventRegister, /* 0.9.0 */
-- 
2.1.4