[zz]libvirt Progress monitoring & cancellation of jobs

This series introduces 2 new APIs to allow long running jobs to
be monitored and cancelled. This applies to virDomainMigrate,
virDomainSave, virDomainRestore and virDomainCoreDump at least.
The implementation is provided for QEMU only, any others that
are able to implementation can do so as desired.

Usefulness of these new APIs requires use of multiple threads on
a single connection, or multiple connections, since the main
API calls are still all fully blocking. Instead a parallel thread
or process can monitor. This can be seen with virsh

In termainl 1

 $ virsh save demo demo.img

In terminal 2

 $ ./virsh domjobinfo demo
  Job type:         Unbounded   
  Time elapsed:     795          ms
  Data processed:   22446080     bytes
  Data remaining:   219119616    bytes
  Data total:       241565696    bytes
  Memory processed: 22446080     bytes
  Memory remaining: 219119616    bytes
  Memory total:     241565696    bytes

 $ ./virsh domjobinfo demo
  Job type:         Unbounded   
  Time elapsed:     1669         ms
  Data processed:   139784192    bytes
  Data remaining:   101781504    bytes
  Data total:       241565696    bytes
  Memory processed: 139784192    bytes
  Memory remaining: 101781504    bytes
  Memory total:     241565696    bytes

 $ ./virsh domjobabort demo


Back in terminal 1

  error: Failed to save domain demo to demo.img
  error: operation failed: Migration was cancelled by client

Daniel P. Berrange — 2010年02月05日星期五 01时25分07秒

The new virDomainAbortJob() method provides a way for a second
thread to abort an ongoing job run by another thread. This
extends to any API with  which the virDomainGetJobInfo() API
is intended to work. Cancellation is not guarenteed, rather best
effort on part of the hypervisor and not required to be implmented.

* include/libvirt/libvirt.h.in: Define virDomainAbortJob()
---
 include/libvirt/libvirt.h.in |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/include/libvirt/libvirt.h.in b/include/libvirt/libvirt.h.in
index 5058bc0..0ffcf11 100644
--- a/include/libvirt/libvirt.h.in
+++ b/include/libvirt/libvirt.h.in
@@ -1804,6 +1804,8 @@ struct _virDomainJobInfo {
 int virDomainGetJobInfo(virDomainPtr dom,
                         virDomainJobInfoPtr info);+int virDomainAbortJob(virDomainPtr dom);
+
 #ifdef __cplusplus
 }
 #endif

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Daniel P. Berrange — 2010年02月05日星期五 01时25分09秒

Introduce support for  virDomainGetJobInfo in the QEMU driver. This
allows for monitoring of any API that uses the 'info migrate' monitor
command. ie virDomainMigrate, virDomainSave and virDomainCoreDump

Unfortunately QEMU does not provide a way to monitor incoming migration
so we can't wire up virDomainRestore yet.

The virsh tool gets a new command 'domjobinfo' to query status