[PATCH v2 09/12] getstats: prepare for dynamic block.count stat

[Eric Blake <eblake@xxxxxxxxxx>]

A coming patch will make it optionally possible to list backing
chain block stats; in this mode of operation, block.counts is no
longer the number of <disks> in the domain, but the number of
blocks in the array being reported.  We still want block.count
listed first, but rather than iterate the tree twice (once to
count, and once to list stats), it's easier to just touch things
up after the fact.

* src/qemu/qemu_driver.c (qemuDomainGetStatsBlock): Compute count
after the fact.

Signed-off-by: Eric Blake <eblake@xxxxxxxxxx>
---
 src/qemu/qemu_driver.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index ef73502..1127312 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -18542,13 +18542,14 @@ qemuDomainGetStatsBlock(virQEMUDriverPtr driver,
                         int *maxparams,
                         unsigned int privflags)
 {
-    size_t i;
+    size_t i = 0;
     int ret = -1;
     int rc;
     virHashTablePtr stats = NULL;
     qemuDomainObjPrivatePtr priv = dom->privateData;
     bool abbreviated = false;
     virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver);
+    int count_index = -1;

     if (!HAVE_JOB(privflags) || !virDomainObjIsActive(dom)) {
         abbreviated = true; /* it's ok, just go ahead silently */
@@ -18565,9 +18566,13 @@ qemuDomainGetStatsBlock(virQEMUDriverPtr driver,
         }
     }

-    QEMU_ADD_COUNT_PARAM(record, maxparams, "block", dom->def->ndisks);
+    /* When listing backing chains, it's easier to fix up the count
+     * after the iteration than it is to iterate twice; but we still
+     * want count listed first.  */
+    count_index = record->nparams;
+    QEMU_ADD_COUNT_PARAM(record, maxparams, "block", 0);

-    for (i = 0; i < dom->def->ndisks; i++) {
+    for (; i < dom->def->ndisks; i++) {
         qemuBlockStats *entry;
         virDomainDiskDefPtr disk = dom->def->disks[i];

@@ -18627,6 +18632,8 @@ qemuDomainGetStatsBlock(virQEMUDriverPtr driver,
     ret = 0;

  cleanup:
+    if (count_index >= 0)
+        record->params[count_index].value.ui = i;
     virHashFree(stats);
     virObjectUnref(cfg);
     return ret;
-- 
1.9.3

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