Ovirt devel - Jan 2009 - [PATCH server] Rake task to generate a dot drawing of the possible VM states

I was curious what all the VM state transitions taken together look like
- below is a rake task that generates a dot drawing of the FSM of VM
states.

Attached is a picture of all that for everybody's amusement.

David
>From 08d72ae336afedcfa0dac9a57e5a79a2b6effac8 Mon Sep 17 00:00:00 2001
From: David Lutterkort <lutter at redhat.com>
Date: Tue, 6 Jan 2009 16:54:31 -0800
Subject: [PATCH server] Rake task to generate a dot drawing of the possible VM
states

---
 src/lib/tasks/vm-states-dot.rake |   40 ++++++++++++++++++++++++++++++++++++++
 1 files changed, 40 insertions(+), 0 deletions(-)
 create mode 100644 src/lib/tasks/vm-states-dot.rake

diff --git a/src/lib/tasks/vm-states-dot.rake b/src/lib/tasks/vm-states-dot.rake
new file mode 100644
index 0000000..74f1f8e
--- /dev/null
+++ b/src/lib/tasks/vm-states-dot.rake
@@ -0,0 +1,40 @@
+# -*- ruby -*-
+require 'permission'
+require 'task'
+require 'vm'
+require 'vm_task'
+
+desc "Generate a dot file for VM state transitions (pass output file
in\nvariable 'output')"
+task "vm:states:dot" do
+    out = $stdout
+    out = File::open(ENV['output'], 'w') if
ENV['output']
+
+    # Classify states
+    states = {}
+    [:start, :running, :success, :failure].each do |tag|
+        VmTask::ACTIONS.values.each { |a|
+            states[a[tag]] ||= []
+            states[a[tag]] << tag
+        }
+    end
+
+    out.puts "digraph \"VM Task Transitions\" {"
+    states.each do |state, tags|
+        out.print "  #{state} ["
+        if tags == [:running]
+            out.print("shape=box color=\"#666666\"
fontcolor=\"#666666\"")
+        end
+        out.puts "];"
+    end
+    VmTask::ACTIONS.values.each do |a|
+        out.puts "#{a[:start]} -> #{a[:running]} [ label =
\"#{a[:label]}\" ];"
+        out.puts "#{a[:running]} -> #{a[:success]} [ color = green
];"
+        out.puts "#{a[:running]} -> #{a[:failure]} [ color= red
];"
+    end
+    out.puts '":running" [shape=box color="#666666"
fontcolor="#666666"];'
+    out.puts '":start" -> ":running" [ label =
"Action" ];'
+    out.puts '":running" -> ":success" [ color =
green ];'
+    out.puts '":running" -> ":failure" [ color= red
];'
+    out.puts "}"
+    out.close
+end
-- 
1.6.0.6


-------------- next part --------------
A non-text attachment was scrubbed...
Name: fsm.png
Type: image/png
Size: 93683 bytes
Desc: not available
URL:
<http://listman.redhat.com/archives/ovirt-devel/attachments/20090106/b28232e5/attachment.png>

On Tue, Jan 06, 2009 at 05:07:20PM -0800, David Lutterkort
wrote:
> I was curious what all the VM state transitions taken together look like
> - below is a rake task that generates a dot drawing of the FSM of VM
> states.
> 
> Attached is a picture of all that for everybody's amusement.
> 
> David
> 
A flying spaghetti monster! Awesome!

--Hugh

On Tue, 06 Jan 2009 17:07:20 -0800
David Lutterkort <lutter at redhat.com> wrote:
> I was curious what all the VM state transitions taken together look like
> - below is a rake task that generates a dot drawing of the FSM of VM
> states.
> 
> Attached is a picture of all that for everybody's amusement.
> 
> David
Wow, that's pretty neat!  Pretty graph.

I must say however that these states don't really reflect the states
provided
by libvirt.  Libvirt has no sense of intermediate states like
'starting', 'migrating'
etc.  There's also no distinction regarding 'saved' state vs
stopped.  'saved' is
merely a stopped vm that has had an image taken of it.

I know the 'starting' etc. is mostly for user feedback and also to
prevent race
conditions where you can try to start a vm multiple times.  However while
testing
the taskomatic changes I was able to queue 5 or so 'start_vm' tasks just
because
the UI was slow to update (I kept pressing the button and it lagged but queued
them all).

So anyway, I'm not sure about these intermediate states, and the
'saved' state is
actually broken..  something we'll have to remember to fix.  The
intermediate states
present a problem in that you can get out of sync with what db-omatic and even
taskomatic know the real libvirt state to be if you are not careful.

	Ian