From ac246d3d6aa9201ae93c112c29b07ebf5db39544 Mon Sep 17 00:00:00 2001
From: Marek Marczykowski <marmarek@invisiblethingslab.com>
Date: Fri, 9 Mar 2012 17:23:41 +0100
Subject: [PATCH] dom0/qvm-ls: improve performance

Do not evaluate each field twice - some of them (eg. disk usage) are expensive.
---
 dom0/qvm-tools/qvm-ls | 29 ++++++++++++++++++-----------
 1 file changed, 18 insertions(+), 11 deletions(-)

diff --git a/dom0/qvm-tools/qvm-ls b/dom0/qvm-tools/qvm-ls
index 48d4217b..2d2c750b 100755
--- a/dom0/qvm-tools/qvm-ls
+++ b/dom0/qvm-tools/qvm-ls
@@ -167,16 +167,28 @@ def main():
     assert len(vms_to_display) == no_vms
 
     # First calculate the maximum width of each field we want to display
-    total_width = 0;
+    #  also collect data to display
     for f in fields_to_display:
         fields[f]["max_width"] = len(f)
-        for vm in vms_to_display:
-            l = len(str(eval(fields[f]["func"])))
+    data_to_display = []
+    for vm in vms_to_display:
+        data_row = {}
+        for f in fields_to_display:
+            data_row[f] = str(eval(fields[f]["func"]))
+            l = len(data_row[f])
             if l > fields[f]["max_width"]:
                 fields[f]["max_width"] = l
+        data_to_display.append(data_row)
+        try:
+            vm.verify_files()
+        except QubesException as err:
+            print >> sys.stderr, "WARNING: VM '{0}' has corrupted files!".format(vm.name)
+                
+    # XXX: For what?
+    total_width = 0;
+    for f in fields_to_display:
         total_width += fields[f]["max_width"]
 
-
     # Display the header
     s = ""
     for f in fields_to_display:
@@ -195,16 +207,11 @@ def main():
     print s
 
     # ... and the actual data
-    for vm in vms_to_display:
+    for row in data_to_display:
         s = ""
         for f in fields_to_display:
             fmt="{{0:>{0}}} |".format(fields[f]["max_width"] + 1)
-            s += fmt.format(eval(fields[f]["func"])) 
+            s += fmt.format(row[f]) 
         print s
 
-        try:
-            vm.verify_files()
-        except QubesException as err:
-            print >> sys.stderr, "WARNING: VM '{0}' has corrupted files!".format(vm.name)
-
 main()