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02ba67937c55331fe99f972caab2fafe72838a3f
xen/tools/python/xen/xend/server/DevController.py
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Alastair Tse 02ba67937c [XEND] Massive XendDomain XendDomainInfo reorganisation to use XendConfig. 
* Added some constants to do with lifecycle management in XendDomain
* Added docstrings
* Made all private functions prefixed with an underscore (_)
* Added lifecycle management in XendDomain which stores configs in SXP
  format.
* Added bits of XenAPI support.
* Moved all XendDomainInfo constants to a separate file
* Moved most of the domain creation login into XendDomainInfo rather
  than in module level functions.
* Moved to use Xen API compatible reporting of state.
* Reorganised methods into logical groups in XendDomain and XendDomainInfo
* Moved all domain configuration validation into XendConfig
* Removed DevController cruft from the bottom of XendDomainInfo to
  XendDevices.

Signed-off-by: Alastair Tse <atse@xensource.com>
2006-10-05 17:29:19 +01:00

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#============================================================================
# This library is free software; you can redistribute it and/or
# modify it under the terms of version 2.1 of the GNU Lesser General Public
# License as published by the Free Software Foundation.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
#============================================================================
# Copyright (C) 2004, 2005 Mike Wray <mike.wray@hp.com>
# Copyright (C) 2005 XenSource Ltd
#============================================================================
from threading import Event
from xen.xend import sxp
from xen.xend.XendError import VmError
from xen.xend.XendLogging import log
from xen.xend.xenstore.xstransact import xstransact, complete
from xen.xend.xenstore.xswatch import xswatch
DEVICE_CREATE_TIMEOUT = 100
HOTPLUG_STATUS_NODE = "hotplug-status"
HOTPLUG_ERROR_NODE = "hotplug-error"
HOTPLUG_STATUS_ERROR = "error"
HOTPLUG_STATUS_BUSY = "busy"
Connected = 1
Error = 2
Missing = 3
Timeout = 4
Busy = 5
xenbusState = {
'Unknown' : 0,
'Initialising' : 1,
'InitWait' : 2,
'Initialised' : 3,
'Connected' : 4,
'Closing' : 5,
'Closed' : 6,
}
xenbusState.update(dict(zip(xenbusState.values(), xenbusState.keys())))
class DevController:
"""Abstract base class for a device controller. Device controllers create
appropriate entries in the store to trigger the creation, reconfiguration,
and destruction of devices in guest domains. Each subclass of
DevController is responsible for a particular device-class, and
understands the details of configuration specific to that device-class.
DevController itself provides the functionality common to all device
creation tasks, as well as providing an interface to XendDomainInfo for
triggering those events themselves.
"""
# Set when registered.
deviceClass = None
## public:
def __init__(self, vm):
self.vm = vm
def createDevice(self, config):
"""Trigger the creation of a device with the given configuration.
@return The ID for the newly created device.
"""
(devid, back, front) = self.getDeviceDetails(config)
if devid is None:
return 0
(backpath, frontpath) = self.addStoreEntries(config, devid, back,
front)
import xen.xend.XendDomain
xd = xen.xend.XendDomain.instance()
backdom_name = sxp.child_value(config, 'backend')
if backdom_name is None:
backdom = xen.xend.XendDomain.DOM0_ID
else:
bd = xd.domain_lookup_nr(backdom_name)
backdom = bd.getDomid()
count = 0
while True:
t = xstransact()
try:
if devid in self.deviceIDs(t):
if 'dev' in back:
dev_str = '%s (%d, %s)' % (back['dev'], devid,
self.deviceClass)
else:
dev_str = '%s (%s)' % (devid, self.deviceClass)
raise VmError("Device %s is already connected." % dev_str)
if count == 0:
log.debug('DevController: writing %s to %s.', str(front),
frontpath)
log.debug('DevController: writing %s to %s.', str(back),
backpath)
elif count % 50 == 0:
log.debug(
'DevController: still waiting to write device entries.')
t.remove(frontpath)
t.remove(backpath)
t.mkdir(backpath)
t.set_permissions(backpath,
{'dom': backdom },
{'dom' : self.vm.getDomid(),
'read' : True })
t.mkdir(frontpath)
t.set_permissions(frontpath,
{'dom': self.vm.getDomid()},
{'dom': backdom, 'read': True})
t.write2(frontpath, front)
t.write2(backpath, back)
if t.commit():
return devid
count += 1
except:
t.abort()
raise
def waitForDevices(self):
log.debug("Waiting for devices %s.", self.deviceClass)
return map(self.waitForDevice, self.deviceIDs())
def waitForDevice(self, devid):
log.debug("Waiting for %s.", devid)
status = self.waitForBackend(devid)
if status == Timeout:
self.destroyDevice(devid)
raise VmError("Device %s (%s) could not be connected. "
"Hotplug scripts not working." %
(devid, self.deviceClass))
elif status == Error:
self.destroyDevice(devid)
raise VmError("Device %s (%s) could not be connected. "
"Backend device not found." %
(devid, self.deviceClass))
elif status == Missing:
# Don't try to destroy the device; it's already gone away.
raise VmError("Device %s (%s) could not be connected. "
"Device not found." % (devid, self.deviceClass))
elif status == Busy:
err = None
frontpath = self.frontendPath(devid)
backpath = xstransact.Read(frontpath, "backend")
if backpath:
err = xstransact.Read(backpath, HOTPLUG_ERROR_NODE)
if not err:
err = "Busy."
self.destroyDevice(devid)
raise VmError("Device %s (%s) could not be connected.\n%s" %
(devid, self.deviceClass, err))
def reconfigureDevice(self, devid, config):
"""Reconfigure the specified device.
The implementation here just raises VmError. This may be overridden
by those subclasses that can reconfigure their devices.
"""
raise VmError('%s devices may not be reconfigured' % self.deviceClass)
def destroyDevice(self, devid):
"""Destroy the specified device.
@param devid The device ID, or something device-specific from which
the device ID can be determined (such as a guest-side device name).
The implementation here simply deletes the appropriate paths from the
store. This may be overridden by subclasses who need to perform other
tasks on destruction. Further, the implementation here can only
accept integer device IDs, or values that can be converted to
integers. Subclasses may accept other values and convert them to
integers before passing them here.
"""
devid = int(devid)
# Modify online status /before/ updating state (latter is watched by
# drivers, so this ordering avoids a race).
self.writeBackend(devid, 'online', "0")
self.writeBackend(devid, 'state', str(xenbusState['Closing']))
def configurations(self):
return map(self.configuration, self.deviceIDs())
def configuration(self, devid):
"""@return an s-expression giving the current configuration of the
specified device. This would be suitable for giving to {@link
#createDevice} in order to recreate that device."""
configDict = self.getDeviceConfiguration(devid)
sxpr = [self.deviceClass]
for key, val in configDict.items():
if type(val) == type(list()):
for v in val:
sxpr.append([key, v])
else:
sxpr.append([key, val])
return sxpr
def sxprs(self):
"""@return an s-expression describing all the devices of this
controller's device-class.
"""
return xstransact.ListRecursive(self.frontendRoot())
def sxpr(self, devid):
"""@return an s-expression describing the specified device.
"""
return [self.deviceClass, ['dom', self.vm.getDomid(),
'id', devid]]
def getDeviceConfiguration(self, devid):
"""Returns the configuration of a device.
@note: Similar to L{configuration} except it returns a dict.
@return: dict
"""
backdomid = xstransact.Read(self.frontendPath(devid), "backend-id")
if backdomid is None:
raise VmError("Device %s not connected" % devid)
return {'backend': int(backdomid)}
## protected:
def getDeviceDetails(self, config):
"""Compute the details for creation of a device corresponding to the
given configuration. These details consist of a tuple of (devID,
backDetails, frontDetails), where devID is the ID for the new device,
and backDetails and frontDetails are the device configuration
specifics for the backend and frontend respectively.
backDetails and frontDetails should be dictionaries, the keys and
values of which will be used as paths in the store. There is no need
for these dictionaries to include the references from frontend to
backend, nor vice versa, as these will be handled by DevController.
Abstract; must be implemented by every subclass.
@return (devID, backDetails, frontDetails), as specified above.
"""
raise NotImplementedError()
def migrate(self, deviceConfig, network, dst, step, domName):
""" Migration of a device. The 'network' parameter indicates
whether the device is network-migrated (True). 'dst' then gives
the hostname of the machine to migrate to.
This function is called for 4 steps:
If step == 0: Check whether the device is ready to be migrated
or can at all be migrated; return a '-1' if
the device is NOT ready, a '0' otherwise. If it is
not ready ( = not possible to migrate this device),
migration will not take place.
step == 1: Called immediately after step 0; migration
of the kernel has started;
step == 2: Called after the suspend has been issued
to the domain and the domain is not scheduled anymore.
Synchronize with what was started in step 1, if necessary.
Now the device should initiate its transfer to the
given target. Since there might be more than just
one device initiating a migration, this step should
put the process performing the transfer into the
background and return immediately to achieve as much
concurrency as possible.
step == 3: Synchronize with the migration of the device that
was initiated in step 2.
Make sure that the migration has finished and only
then return from the call.
"""
return 0
def recover_migrate(self, deviceConfig, network, dst, step, domName):
""" Recover from device migration. The given step was the
last one that was successfully executed.
"""
return 0
def getDomid(self):
"""Stub to {@link XendDomainInfo.getDomid}, for use by our
subclasses.
"""
return self.vm.getDomid()
def allocateDeviceID(self):
"""Allocate a device ID, allocating them consecutively on a
per-domain, per-device-class basis, and using the store to record the
next available ID.
This method is available to our subclasses, though it is not
compulsory to use it; subclasses may prefer to allocate IDs based upon
the device configuration instead.
"""
path = self.frontendMiscPath()
return complete(path, self._allocateDeviceID)
def _allocateDeviceID(self, t):
result = t.read("nextDeviceID")
if result:
result = int(result)
else:
result = 0
t.write("nextDeviceID", str(result + 1))
return result
def readBackend(self, devid, *args):
frontpath = self.frontendPath(devid)
backpath = xstransact.Read(frontpath, "backend")
if backpath:
return xstransact.Read(backpath, *args)
else:
raise VmError("Device %s not connected" % devid)
def readFrontend(self, devid, *args):
return xstransact.Read(self.frontendPath(devid), *args)
def deviceIDs(self, transaction = None):
"""@return The IDs of each of the devices currently configured for
this instance's deviceClass.
"""
fe = self.backendRoot()
if transaction:
return map(lambda x: int(x.split('/')[-1]), transaction.list(fe))
else:
return map(int, xstransact.List(fe))
def writeBackend(self, devid, *args):
frontpath = self.frontendPath(devid)
backpath = xstransact.Read(frontpath, "backend")
if backpath:
xstransact.Write(backpath, *args)
else:
raise VmError("Device %s not connected" % devid)
## private:
def addStoreEntries(self, config, devid, backDetails, frontDetails):
"""Add to backDetails and frontDetails the entries to be written in
the store to trigger creation of a device. The backend domain ID is
taken from the given config, paths for frontend and backend are
computed, and these are added to the backDetails and frontDetails
dictionaries for writing to the store, including references from
frontend to backend and vice versa.
@return A pair of (backpath, frontpath). backDetails and frontDetails
will have been updated appropriately, also.
@param config The configuration of the device, as given to
{@link #createDevice}.
@param devid As returned by {@link #getDeviceDetails}.
@param backDetails As returned by {@link #getDeviceDetails}.
@param frontDetails As returned by {@link #getDeviceDetails}.
"""
import xen.xend.XendDomain
xd = xen.xend.XendDomain.instance()
backdom_name = sxp.child_value(config, 'backend')
if backdom_name:
backdom = xd.domain_lookup_nr(backdom_name)
else:
backdom = xd.privilegedDomain()
if not backdom:
raise VmError("Cannot configure device for unknown backend %s" %
backdom_name)
frontpath = self.frontendPath(devid)
backpath = self.backendPath(backdom, devid)
frontDetails.update({
'backend' : backpath,
'backend-id' : "%i" % backdom.getDomid(),
'state' : str(xenbusState['Initialising'])
})
backDetails.update({
'domain' : self.vm.getName(),
'frontend' : frontpath,
'frontend-id' : "%i" % self.vm.getDomid(),
'state' : str(xenbusState['Initialising']),
'online' : "1"
})
return (backpath, frontpath)
def waitForBackend(self, devid):
frontpath = self.frontendPath(devid)
backpath = xstransact.Read(frontpath, "backend")
if backpath:
statusPath = backpath + '/' + HOTPLUG_STATUS_NODE
ev = Event()
result = { 'status': Timeout }
xswatch(statusPath, hotplugStatusCallback, ev, result)
ev.wait(DEVICE_CREATE_TIMEOUT)
return result['status']
else:
return Missing
def backendPath(self, backdom, devid):
"""@param backdom [XendDomainInfo] The backend domain info."""
return "%s/backend/%s/%s/%d" % (backdom.getDomainPath(),
self.deviceClass,
self.vm.getDomid(), devid)
def frontendPath(self, devid):
return "%s/%d" % (self.frontendRoot(), devid)
def frontendRoot(self):
return "%s/device/%s" % (self.vm.getDomainPath(), self.deviceClass)
def backendRoot(self):
import xen.xend.XendDomain
from xen.xend.xenstore.xsutil import GetDomainPath
backdom = xen.xend.XendDomain.DOM0_ID
return "%s/backend/%s/%s" % (GetDomainPath(backdom),
self.deviceClass, self.vm.getDomid())
def frontendMiscPath(self):
return "%s/device-misc/%s" % (self.vm.getDomainPath(),
self.deviceClass)
def hotplugStatusCallback(statusPath, ev, result):
log.debug("hotplugStatusCallback %s.", statusPath)
status = xstransact.Read(statusPath)
if status is not None:
if status == HOTPLUG_STATUS_ERROR:
result['status'] = Error
elif status == HOTPLUG_STATUS_BUSY:
result['status'] = Busy
else:
result['status'] = Connected
else:
return 1
log.debug("hotplugStatusCallback %d.", result['status'])
ev.set()
return 0
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