[node-patches] Change in ovirt-node[master]: installer: Improve storage loading time

[rbarry at redhat.com]

Hello Fabian Deutsch,

I'd like you to do a code review.  Please visit

    http://gerrit.ovirt.org/22355

to review the following change.

Change subject: installer: Improve storage loading time
......................................................................

installer: Improve storage loading time

Previously a time consuming function was called several times. This is
now still the case, but we cache the not-expected-to-change value.

Change-Id: Iee46ffac3586d1e5f998aabddf03f4afde19f4c9
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1041213
Signed-off-by: Fabian Deutsch <fabiand at redhat.com>
---
M src/ovirt/node/installer/core/boot_device_page.py
M src/ovirt/node/utils/storage.py
2 files changed, 8 insertions(+), 1 deletion(-)


  git pull ssh://gerrit.ovirt.org:29418/ovirt-node refs/changes/55/22355/1

diff --git a/src/ovirt/node/installer/core/boot_device_page.py b/src/ovirt/node/installer/core/boot_device_page.py
index 76cde7c..246207d 100644
--- a/src/ovirt/node/installer/core/boot_device_page.py
+++ b/src/ovirt/node/installer/core/boot_device_page.py
@@ -140,7 +140,7 @@
         self.do_fake = do_fake
 
     def run(self):
-        devices = utils.storage.Devices(fake=self.do_fake)
+        self.devices = utils.storage.Devices(fake=self.do_fake)
         self._all_devices = devices.get_all()
 
     def all_devices(self):
diff --git a/src/ovirt/node/utils/storage.py b/src/ovirt/node/utils/storage.py
index 8958b70..51b98d3 100644
--- a/src/ovirt/node/utils/storage.py
+++ b/src/ovirt/node/utils/storage.py
@@ -80,6 +80,7 @@
     """A class to retrieve available storage devices
     """
     _fake_devices = None
+    _cached_live_disk_name = None
 
     def __init__(self, fake=False):
         super(Devices, self).__init__()
@@ -95,12 +96,18 @@
 
     def live_disk_name(self):
         """get the device name of the live-media we are booting from
+        BEWARE: Because querying this is so expensive we cache this result
+                Assumption: Live disk name does not change
         """
+        if self._cached_live_disk_name:
+            return self._cached_live_disk_name
+
         from ovirtnode.ovirtfunctions import get_live_disk
         name = get_live_disk()
         if not "/dev/mapper" in name:
             # FIXME explain ...
             name = "/dev/%s" % name.rstrip('0123456789')
+        self._cached_live_disk_name = name
         return name
 
     def get_all(self):


-- 
To view, visit http://gerrit.ovirt.org/22355
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Gerrit-MessageType: newchange
Gerrit-Change-Id: Iee46ffac3586d1e5f998aabddf03f4afde19f4c9
Gerrit-PatchSet: 1
Gerrit-Project: ovirt-node
Gerrit-Branch: master
Gerrit-Owner: Ryan Barry <rbarry at redhat.com>
Gerrit-Reviewer: Fabian Deutsch <fabiand at fedoraproject.org>