While running objecteventtest, it was found that valgrind pointed out the
following memory leak:
==125== 538 (56 direct, 482 indirect) bytes in 1 blocks are definitely lost in loss record 216 of 226
==125== at 0x4A06B6F: calloc (vg_replace_malloc.c:593)
==125== by 0x4C65D8D: virAllocVar (viralloc.c:558)
==125== by 0x4C9F055: virObjectNew (virobject.c:190)
==125== by 0x4D2B2E8: virGetDomain (datatypes.c:220)
==125== by 0x4D79180: testDomainDefineXML (test_driver.c:2962)
==125== by 0x4D4977D: virDomainDefineXML (libvirt.c:8512)
==125== by 0x4029C2: testDomainCreateXMLMixed (objecteventtest.c:226)
==125== by 0x403A21: virtTestRun (testutils.c:138)
==125== by 0x4021C2: mymain (objecteventtest.c:549)
==125== by 0x4040C2: virtTestMain (testutils.c:593)
==125== by 0x341F421A04: (below main) (libc-start.c:225)
Signed-off-by: Ján Tomko <jtomko@redhat.com>
If a user registers for a domain event filtered to a particular
domain, but the persistent domain is offline at the time, then
the code silently failed to set up the filter. As a result,
the event fires for all domains, rather than being filtered.
Network events were immune, since they always passed an id
0 argument.
The key to this patch is realizing that
virObjectEventDispatchMatchCallback() only cared about uuid;
so refusing to create a meta for a negative id is pointless,
and in fact, malloc'ing meta at all was overkill; instead,
just directly store a uuid and a flag of whether to filter.
Note that virObjectEventPtr still needs all fields of meta,
because this is how we reconstruct a virDomainPtr inside the
dispatch handler before calling the end user's callback
pointer with the correct object, even though only the uuid
portion of meta is used in deciding whether a callback
matches the given event. So while uuid is optional for
callbacks, it is mandatory for events.
The change to testDomainCreateXMLMixed is merely on the setup
scenario (as you can't register for a domain unless it is either
running or persistent). I actually first wrote that test for
this patch, then rebased it to also cover a prior patch (commit
4221d64), but had to adjust it for that patch to use Create
instead of Define for setting up the domain long enough to
register the event in order to work around this bug. But while
the setup is changed, the main body of the test is still about
whether creation events fire as expected.
* src/conf/object_event_private.h (_virObjectEventCallback):
Replace meta with uuid and flag.
(virObjectEventCallbackListAddID): Update signature.
* src/conf/object_event.h (virObjectEventStateRegisterID):
Likewise.
* src/conf/object_event_private.h (virObjectEventNew): Document
use of name and uuid in events.
* src/conf/object_event.c (virObjectEventCallbackListAddID): Drop
arguments that don't affect filtering.
(virObjectEventCallbackListRemoveID)
(virObjectEventDispatchMatchCallback)
(virObjectEventStateRegisterID): Update clients.
* src/conf/domain_event.c (virDomainEventCallbackListAdd)
(virDomainEventStateRegisterID): Likewise.
* src/conf/network_event.c (virNetworkEventStateRegisterID):
Likewise.
* tests/objecteventtest.c (testDomainCreateXMLMixed): Enhance test.
Signed-off-by: Eric Blake <eblake@redhat.com>
Consider these two calls, in either order:
id1 = virConnectDomainEventRegisterAny(conn, NULL,
VIR_DOMAIN_EVENT_ID_LIFECYCLE,
VIR_DOMAIN_EVENT_CALLBACK(callback), NULL, NULL);
virConnectDomainEventRegister(conn, callback, NULL, NULL);
Right now, the second call fails, because under the hood, the
old-style function registration is tightly coupled to the
new style lifecycle eventID, and the two calls both try
to register the same global eventID callback representation.
We've alreay documented that users should avoid old-style
registration and deregistration, so anyone heeding the advice
won't run into this situation. But it would be even nicer if
we pretend the two interfaces are completely separate, and
disallow any cross-linking. That is, a call to old-style
deregister should never remove a new-style callback even if it
is the same function pointer, and a call to new-style callback
using only callbackIDs obtained legitimately should never
remove an old-style callback (of course, since our callback
IDs are sequential, and there is still coupling under the
hood, you can easily guess the callbackID of an old style
registration and use new-style deregistration to nuke it - but
that starts to be blatantly bad coding on your part rather
than a surprising result on what looks like reasonable
stand-alone API).
With this patch, you can now register a global lifecycle event
handler twice, by using both old and new APIs; if such an event
occurs, your callback will be entered twice. But that is not a
problem in practice, since it is already possible to use the
new API to register both a global and per-domain event handler
using the same function, which will likewise fire your callback
twice for that domain. Duplicates are still prevented when
using the same API with same parameters twice (old-style twice,
new-style global twice, or new-style per-domain with same domain
twice), and things are still bounded (it is not possible to
register a single function pointer more than N+2 times per event
id, where N is the number of domains available on the connection).
Besides, it has always been possible to register as many
separate function pointers on the same event id as desired,
through either old or new style API, where the bound there is
the physical limitation of writing a program with enough
distinct function pointers.
Adding another event registration in the testsuite is sufficient
to cover this, where the test fails without the rest of the patch.
* src/conf/object_event.c (_virObjectEventCallback): Add field.
(virObjectEventCallbackLookup): Add argument.
(virObjectEventCallbackListAddID, virObjectEventStateCallbackID):
Adjust callers.
* tests/objecteventtest.c (testDomainCreateXMLMixed): Enhance test.
Signed-off-by: Eric Blake <eblake@redhat.com>
Right now, the older virConnectDomainEventRegister (takes a
function pointer, returns 0 on success) and the newer
virConnectDomainEventRegisterID (takes an eventID, returns a
callbackID) share the underlying implementation (the older
API ends up consuming a callbackID for eventID 0 under the
hood). We implemented that by a lot of copy and pasted
code between object_event.c and domain_event.c, according to
whether we are dealing with a function pointer or an eventID.
However, our copy and paste is not symmetric. Consider this
sequence:
id1 = virConnectDomainEventRegisterAny(conn, dom,
VIR_DOMAIN_EVENT_ID_LIFECYCLE,
VIR_DOMAIN_EVENT_CALLBACK(callback), NULL, NULL);
virConnectDomainEventRegister(conn, callback, NULL, NULL);
virConnectDomainEventDeregister(conn, callback);
virConnectDomainEventDeregsiterAny(conn, id1);
the first three calls would succeed, but the third call ended
up nuking the id1 callbackID (the per-domain new-style handler),
then the fourth call failed with an error about an unknown
callbackID, leaving us with the global handler (old-style) still
live and receiving events. It required another old-style
deregister to clean up the mess. Root cause was that
virDomainEventCallbackList{Remove,MarkDelete} were only
checking for function pointer match, rather than also checking
for whether the registration was global.
Rather than playing with the guts of object_event ourselves
in domain_event, it is nicer to add a mapping function for the
internal callback id, then share common code for event removal.
For now, the function-to-id mapping is used only internally;
I thought about whether a new public API to let a user learn
the callback would be useful, but decided exposing this to the
user is probably a disservice, since we already publicly
document that they should avoid the old style, and since this
patch already demonstrates that older libvirt versions have
weird behavior when mixing old and new styles.
And like all good bug fix patches, I enhanced the testsuite,
validating that the changes in tests/ expose the failure
without the rest of the patch.
* src/conf/object_event.c (virObjectEventCallbackLookup)
(virObjectEventStateCallbackID): New functions.
(virObjectEventCallbackLookup): Use helper function.
* src/conf/object_event_private.h (virObjectEventStateCallbackID):
Declare new function.
* src/conf/domain_event.c (virDomainEventStateRegister)
(virDomainEventStateDeregister): Let common code handle the
complexity.
(virDomainEventCallbackListRemove)
(virDomainEventCallbackListMarkDelete)
(virDomainEventCallbackListAdd): Drop unused functions.
* tests/objecteventtest.c (testDomainCreateXMLMixed): New test.
Signed-off-by: Eric Blake <eblake@redhat.com>
Prior to this patch, every test:/// URI has its own event manager,
which means that registering for an event can only ever receive
events from the connection where it issued the API that triggered
the event. But the whole idea of events is to be able to learn
about something where an API call did NOT trigger the action.
In order to actually test asynchronous events, I wanted to be able
to tie multiple test connections to the same state. Use of a file
in a test URI is still per-connection state, but now parallel
connections to test:///default (from the same binary, of course)
now share common state and can affect one another.
The updated testsuite fails without the rest of this patch.
Valgrind didn't report any leaks.
* src/test/test_driver.c (testConnectOpen): Move per-connection
state initialization...
(testOpenFromFile): ...here.
(defaultConn, defaultConnections, defaultLock, testOnceInit): New
shared state.
(testOpenDefault): Only initialize on first connection.
(testConnectClose): Don't clobber state if still shared.
* tests/objecteventtest.c (testDomainStartStopEvent): Enhance to
cover this.
(timeout, mymain): Ensure test fails rather than blocks.
Signed-off-by: Eric Blake <eblake@redhat.com>
Ever since their introduction (commit 1509b80 in v0.5.0 for
virConnectDomainEventRegister, commit 4445723 in v0.8.0 for
virConnectDomainEventDeregisterAny), the event deregistration
functions have been documented as returning 0 on success;
likewise for older registration (only the newer RegisterAny
must return a non-zero callbackID). And now that we are
adding virConnectNetworkEventDeregisterAny for v1.2.1, it
should have the same semantics.
Fortunately, all of the stateful drivers have been obeying
the docs and returning 0, thanks to the way the remote_driver
tracks things (in fact, the RPC wire protocol is unable to
send a return value for DomainEventRegisterAny, at least not
without adding a new RPC number). Well, except for vbox,
which was always failing deregistration, due to failure to
set the return value to anything besides its initial -1.
But for local drivers, such as test:///default, we've been
returning non-zero numbers; worse, the non-zero numbers have
differed over time. For example, in Fedora 12 (libvirt 0.8.2),
calling Register twice would return 0 and 1 [the callbackID
generated under the hood]; while in Fedora 20 (libvirt 1.1.3),
it returns 1 and 2 [the number of callbacks registered for
that event type]. Since we have changed the behavior over
time, and since it differs by local vs. remote, we can safely
argue that no one could have been reasonably relying on any
particular behavior, so we might as well obey the docs, as well
as prepare callers that might deal with older clients to not be
surprised if the docs are not strictly followed.
For consistency, this patch fixes the code for all drivers,
even though it only makes an impact for vbox and for local
drivers. By fixing all drivers, future copy and paste from
a remote driver to a local driver is less likely to
reintroduce the bug.
Finally, update the testsuite to gain some coverage of the
issue for local drivers, including the first test of old-style
domain event registration via function pointer instead of
event id.
* src/libvirt.c (virConnectDomainEventRegister)
(virConnectDomainEventDeregister)
(virConnectDomainEventDeregisterAny): Clarify docs.
* src/libxl/libxl_driver.c (libxlConnectDomainEventRegister)
(libxlConnectDomainEventDeregister)
(libxlConnectDomainEventDeregisterAny): Match documentation.
* src/lxc/lxc_driver.c (lxcConnectDomainEventRegister)
(lxcConnectDomainEventDeregister)
(lxcConnectDomainEventDeregisterAny): Likewise.
* src/test/test_driver.c (testConnectDomainEventRegister)
(testConnectDomainEventDeregister)
(testConnectDomainEventDeregisterAny)
(testConnectNetworkEventDeregisterAny): Likewise.
* src/uml/uml_driver.c (umlConnectDomainEventRegister)
(umlConnectDomainEventDeregister)
(umlConnectDomainEventDeregisterAny): Likewise.
* src/vbox/vbox_tmpl.c (vboxConnectDomainEventRegister)
(vboxConnectDomainEventDeregister)
(vboxConnectDomainEventDeregisterAny): Likewise.
* src/xen/xen_driver.c (xenUnifiedConnectDomainEventRegister)
(xenUnifiedConnectDomainEventDeregister)
(xenUnifiedConnectDomainEventDeregisterAny): Likewise.
* src/network/bridge_driver.c
(networkConnectNetworkEventDeregisterAny): Likewise.
* tests/objecteventtest.c (testDomainCreateXMLOld): New test.
(mymain): Run it.
(testDomainCreateXML): Check return values.
Signed-off-by: Eric Blake <eblake@redhat.com>
