[libvirt] [PATCH 2/2] qemu: Add libvirt version check to refresh capabilities algorithm

[Martin Kletzander]

On Sat, May 23, 2015 at 10:33:31AM -0400, John Ferlan wrote:
>Rather than an algorithm based solely on libvirtd ctime to refresh the
>capabilities add the element of the libvirt build version into the equation.
>Since that version wouldn't be there prior to this code being run - don't
>fail on reading the capabilities if not found. In this case, the cache
>will always be read when a new libvirt version is installed.
>

You meant 'rebuilt' not 'read', right?  Anyway, this makes complete
sense, ACK.

>Signed-off-by: John Ferlan <jferlan at redhat.com>
>---
> src/qemu/qemu_capabilities.c | 23 ++++++++++++++++++-----
> 1 file changed, 18 insertions(+), 5 deletions(-)
>
>diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
>index a6fae38..960afa4 100644
>--- a/src/qemu/qemu_capabilities.c
>+++ b/src/qemu/qemu_capabilities.c
>@@ -2605,6 +2605,7 @@ int virQEMUCapsProbeQMP(virQEMUCapsPtr qemuCaps,
>  * <qemuCaps>
>  *   <qemuctime>234235253</qemuctime>
>  *   <selfctime>234235253</selfctime>
>+ *   <selfvers>1002016</selfvers>
>  *   <usedQMP/>
>  *   <flag name='foo'/>
>  *   <flag name='bar'/>
>@@ -2617,7 +2618,8 @@ int virQEMUCapsProbeQMP(virQEMUCapsPtr qemuCaps,
>  */
> static int
> virQEMUCapsLoadCache(virQEMUCapsPtr qemuCaps, const char *filename,
>-                     time_t *qemuctime, time_t *selfctime)
>+                     time_t *qemuctime, time_t *selfctime,
>+                     unsigned long *selfvers)
> {
>     xmlDocPtr doc = NULL;
>     int ret = -1;
>@@ -2627,6 +2629,7 @@ virQEMUCapsLoadCache(virQEMUCapsPtr qemuCaps, const char *filename,
>     xmlXPathContextPtr ctxt = NULL;
>     char *str = NULL;
>     long long int l;
>+    unsigned long lu;
>
>     if (!(doc = virXMLParseFile(filename)))
>         goto cleanup;
>@@ -2660,6 +2663,10 @@ virQEMUCapsLoadCache(virQEMUCapsPtr qemuCaps, const char *filename,
>     }
>     *selfctime = (time_t)l;
>
>+    *selfvers = 0;
>+    if (virXPathULong("string(./selfvers)", ctxt, &lu) == 0)
>+        *selfvers = lu;
>+
>     qemuCaps->usedQMP = virXPathBoolean("count(./usedQMP) > 0",
>                                         ctxt) > 0;
>
>@@ -2798,6 +2805,8 @@ virQEMUCapsSaveCache(virQEMUCapsPtr qemuCaps, const char *filename)
>                       (long long)qemuCaps->ctime);
>     virBufferAsprintf(&buf, "<selfctime>%llu</selfctime>\n",
>                       (long long)virGetSelfLastChanged());
>+    virBufferAsprintf(&buf, "<selfvers>%lu</selfvers>\n",
>+                      (unsigned long)LIBVIR_VERSION_NUMBER);
>
>     if (qemuCaps->usedQMP)
>         virBufferAddLit(&buf, "<usedQMP/>\n");
>@@ -2938,6 +2947,7 @@ virQEMUCapsInitCached(virQEMUCapsPtr qemuCaps, const char *cacheDir)
>     struct stat sb;
>     time_t qemuctime;
>     time_t selfctime;
>+    unsigned long selfvers;
>
>     if (virAsprintf(&capsdir, "%s/capabilities", cacheDir) < 0)
>         goto cleanup;
>@@ -2970,7 +2980,8 @@ virQEMUCapsInitCached(virQEMUCapsPtr qemuCaps, const char *cacheDir)
>         goto cleanup;
>     }
>
>-    if (virQEMUCapsLoadCache(qemuCaps, capsfile, &qemuctime, &selfctime) < 0) {
>+    if (virQEMUCapsLoadCache(qemuCaps, capsfile, &qemuctime, &selfctime,
>+                             &selfvers) < 0) {
>         virErrorPtr err = virGetLastError();
>         VIR_WARN("Failed to load cached caps from '%s' for '%s': %s",
>                  capsfile, qemuCaps->binary, err ? NULLSTR(err->message) :
>@@ -2983,12 +2994,14 @@ virQEMUCapsInitCached(virQEMUCapsPtr qemuCaps, const char *cacheDir)
>
>     /* Discard cache if QEMU binary or libvirtd changed */
>     if (qemuctime != qemuCaps->ctime ||
>-        selfctime != virGetSelfLastChanged()) {
>+        selfctime != virGetSelfLastChanged() ||
>+        selfvers != LIBVIR_VERSION_NUMBER) {
>         VIR_DEBUG("Outdated cached capabilities '%s' for '%s' "
>-                  "(%lld vs %lld, %lld vs %lld)",
>+                  "(%lld vs %lld, %lld vs %lld, %lu vs %lu)",
>                   capsfile, qemuCaps->binary,
>                   (long long)qemuctime, (long long)qemuCaps->ctime,
>-                  (long long)selfctime, (long long)virGetSelfLastChanged());
>+                  (long long)selfctime, (long long)virGetSelfLastChanged(),
>+                  selfvers, (unsigned long)LIBVIR_VERSION_NUMBER);
>         ignore_value(unlink(capsfile));
>         virQEMUCapsReset(qemuCaps);
>         ret = 0;
>--
>2.1.0
>
>--
>libvir-list mailing list
>libvir-list at redhat.com
>https://www.redhat.com/mailman/listinfo/libvir-list
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