From f51885a9732c84d3b91d049ae5fe995d9296795e Mon Sep 17 00:00:00 2001
From: Cian O'Driscoll <cian@hp.com>
Date: Tue, 31 Jul 2012 10:29:42 +0000
Subject: Implements volume usage metering.

Add volume usage cache tables to record no. of reads, bytes read,
no. of write, bytes written to a volume.
A periodic task runs in compute manager to query each volume mounted
on a compute host and record its usage, this task also send a
volume.usage notification contains volume usage statistics

Part of blueprint volume-usage-metering

Change-Id: I215ce0c94e9ea5a07e18940802c20d1379b8f6d1
---
 nova/virt/driver.py         |  5 +++++
 nova/virt/fake.py           |  7 +++++++
 nova/virt/libvirt/driver.py | 42 ++++++++++++++++++++++++++++++++++++++++--
 3 files changed, 52 insertions(+), 2 deletions(-)

(limited to 'nova/virt')

diff --git a/nova/virt/driver.py b/nova/virt/driver.py
index ee775bc6b..005012c7f 100644
--- a/nova/virt/driver.py
+++ b/nova/virt/driver.py
@@ -251,6 +251,11 @@ class ComputeDriver(object):
            running VM"""
         raise NotImplementedError()
 
+    def get_all_volume_usage(self, context, compute_host_bdms):
+        """Return usage info for volumes attached to vms on
+           a given host"""
+        raise NotImplementedError()
+
     def get_host_ip_addr(self):
         """
         Retrieves the IP address of the dom0
diff --git a/nova/virt/fake.py b/nova/virt/fake.py
index 9f5956b0d..fb1ed5558 100644
--- a/nova/virt/fake.py
+++ b/nova/virt/fake.py
@@ -248,6 +248,13 @@ class FakeDriver(driver.ComputeDriver):
         bw = []
         return bw
 
+    def get_all_volume_usage(self, context, instances, start_time,
+                             stop_time=None):
+        """Return usage info for volumes attached to vms on
+           a given host"""
+        volusage = []
+        return volusage
+
     def block_stats(self, instance_name, disk_id):
         return [0L, 0L, 0L, 0L, None]
 
diff --git a/nova/virt/libvirt/driver.py b/nova/virt/libvirt/driver.py
index b39fd773b..8cc79614e 100644
--- a/nova/virt/libvirt/driver.py
+++ b/nova/virt/libvirt/driver.py
@@ -2190,12 +2190,50 @@ class LibvirtDriver(driver.ComputeDriver):
         # data format needs to be standardized across drivers
         return jsonutils.dumps(cpu_info)
 
+    def get_all_volume_usage(self, context, compute_host_bdms):
+        """Return usage info for volumes attached to vms on
+           a given host"""
+        vol_usage = []
+
+        for instance_bdms in compute_host_bdms:
+            instance = instance_bdms['instance']
+
+            for bdm in instance_bdms['instance_bdms']:
+                vol_stats = []
+                mountpoint = bdm['device_name']
+                if mountpoint.startswith('/dev/'):
+                    mountpoint = mountpoint[5:]
+
+                LOG.debug(_("Trying to get stats for the volume %s"),
+                            bdm['volume_id'])
+                vol_stats = self.block_stats(instance['name'], mountpoint)
+
+                if vol_stats:
+                    rd_req, rd_bytes, wr_req, wr_bytes, flush_ops = vol_stats
+                    vol_usage.append(dict(volume=bdm['volume_id'],
+                                          instance_id=instance['id'],
+                                          rd_req=rd_req,
+                                          rd_bytes=rd_bytes,
+                                          wr_req=wr_req,
+                                          wr_bytes=wr_bytes,
+                                          flush_operations=flush_ops))
+        return vol_usage
+
     def block_stats(self, instance_name, disk):
         """
         Note that this function takes an instance name.
         """
-        domain = self._lookup_by_name(instance_name)
-        return domain.blockStats(disk)
+        try:
+            domain = self._lookup_by_name(instance_name)
+            return domain.blockStats(disk)
+        except libvirt.libvirtError as e:
+            errcode = e.get_error_code()
+            LOG.info(_("Getting block stats failed, device might have "
+                       "been detached. Code=%(errcode)s Error=%(e)s")
+                       % locals())
+        except exception.InstanceNotFound:
+            LOG.info(_("Could not find domain in libvirt for instance %s. "
+                       "Cannot get block stats for device") % instance_name)
 
     def interface_stats(self, instance_name, interface):
         """
-- 
cgit