[libvirt] [PATCHv2 5/5] network: add connections counter to networks

[Laine Stump]

Just as each physical device used by a network has a connections
counter, now each network has a connections counter which is
incremented once for each guest interface that connects using this
network.

The count is output in the live network XML, like this:

   <network connections='20'>
   ...
   </network>

It is read-only, and for informational purposes only - it isn't used
internally anywhere by libvirt.
---
 src/conf/network_conf.c     |  6 +++++-
 src/conf/network_conf.h     |  1 +
 src/network/bridge_driver.c | 10 ++++++++++
 3 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/src/conf/network_conf.c b/src/conf/network_conf.c
index ca5b759..45f8e69 100644
--- a/src/conf/network_conf.c
+++ b/src/conf/network_conf.c
@@ -1463,7 +1463,11 @@ char *virNetworkDefFormat(const virNetworkDefPtr def, unsigned int flags)
     char uuidstr[VIR_UUID_STRING_BUFLEN];
     int ii;
 
-    virBufferAddLit(&buf, "<network>\n");
+    virBufferAddLit(&buf, "<network");
+    if (!(flags & VIR_NETWORK_XML_INACTIVE) && (def->connections > 0)) {
+        virBufferAsprintf(&buf, " connections='%d'", def->connections);
+    }
+    virBufferAddLit(&buf, ">\n");
     virBufferEscapeString(&buf, "  <name>%s</name>\n", def->name);
 
     uuid = def->uuid;
diff --git a/src/conf/network_conf.h b/src/conf/network_conf.h
index 23f1632..32fc765 100644
--- a/src/conf/network_conf.h
+++ b/src/conf/network_conf.h
@@ -156,6 +156,7 @@ struct _virNetworkDef {
     unsigned char uuid[VIR_UUID_BUFLEN];
     bool uuid_specified;
     char *name;
+    int   connections; /* # of guest interfaces connected to this network */
 
     char *bridge;       /* Name of bridge device */
     char *domain;
diff --git a/src/network/bridge_driver.c b/src/network/bridge_driver.c
index 680b3f3..b784eb4 100644
--- a/src/network/bridge_driver.c
+++ b/src/network/bridge_driver.c
@@ -3005,6 +3005,10 @@ networkAllocateActualDevice(virDomainNetDefPtr iface)
         VIR_DEBUG("Using physical device %s, %d connections",
                   dev->dev, dev->connections);
     }
+
+    netdef->connections++;
+    VIR_DEBUG("Using network %s, %d connections",
+              netdef->name, netdef->connections);
     ret = 0;
 error:
     for (ii = 0; ii < num_virt_fns; ii++)
@@ -3114,6 +3118,9 @@ networkNotifyActualDevice(virDomainNetDefPtr iface)
     }
 
 cleanup:
+    netdef->connections++;
+    VIR_DEBUG("Using network %s, %d connections",
+              netdef->name, netdef->connections);
     ret = 0;
 error:
     if (network)
@@ -3199,6 +3206,9 @@ networkReleaseActualDevice(virDomainNetDefPtr iface)
     }
 
 cleanup:
+    netdef->connections--;
+    VIR_DEBUG("Releasing network %s, %d connections",
+              netdef->name, netdef->connections);
     ret = 0;
 error:
     if (network)
-- 
1.7.11.2