[PATCH 1/3] qemu_monitor: add qemuMonitorQueryStats
Kristina Hanicova
khanicov at redhat.com
Fri Jul 22 12:44:30 UTC 2022
On Thu, Jul 14, 2022 at 7:54 AM Amneesh Singh <natto at weirdnatto.in> wrote:
> Related: https://gitlab.com/libvirt/libvirt/-/issues/276
>
> This patch adds an API for the "query-stats" QMP command.
>
> The query returns a JSON containing the statistics based on the target,
> which can either be vCPU or VM, and the providers. The API deserializes
> the query result into an array of GHashMaps, which can later be used to
> extract all the query statistics. GHashMaps are used to avoid traversing
> the entire array to find the statistics you are looking for. This would
> be a singleton array if the target is a VM since the returned JSON is
> also a singleton array in that case.
>
> Signed-off-by: Amneesh Singh <natto at weirdnatto.in>
> ---
> src/qemu/qemu_monitor.c | 70 +++++++++++++++++++
> src/qemu/qemu_monitor.h | 45 ++++++++++++
> src/qemu/qemu_monitor_json.c | 130 +++++++++++++++++++++++++++++++++++
> src/qemu/qemu_monitor_json.h | 6 ++
> 4 files changed, 251 insertions(+)
>
> diff --git a/src/qemu/qemu_monitor.c b/src/qemu/qemu_monitor.c
> index fda5d2f3..a07e6017 100644
> --- a/src/qemu/qemu_monitor.c
> +++ b/src/qemu/qemu_monitor.c
> @@ -4541,3 +4541,73 @@ qemuMonitorMigrateRecover(qemuMonitor *mon,
>
> return qemuMonitorJSONMigrateRecover(mon, uri);
> }
> +
> +VIR_ENUM_IMPL(qemuMonitorQueryStatsTarget,
> + QEMU_MONITOR_QUERY_STATS_TARGET_LAST,
> + "vm",
> + "vcpu",
> +);
> +
> +VIR_ENUM_IMPL(qemuMonitorQueryStatsName,
> + QEMU_MONITOR_QUERY_STATS_NAME_LAST,
> + "halt_poll_success_ns",
> + "halt_poll_fail_ns"
> +);
> +
> +VIR_ENUM_IMPL(qemuMonitorQueryStatsProvider,
> + QEMU_MONITOR_QUERY_STATS_PROVIDER_LAST,
> + "kvm",
> +);
> +
> +void
> +qemuMonitorQueryStatsProviderFree(qemuMonitorQueryStatsProvider *provider)
> +{
> + virBitmapFree(provider->names);
> + g_free(provider);
> +}
> +
> +qemuMonitorQueryStatsProvider *
> +qemuMonitorQueryStatsProviderNew(qemuMonitorQueryStatsProviderType
> provider_type,
> + ...)
> +{
> + g_autoptr(qemuMonitorQueryStatsProvider) provider = NULL;
> + qemuMonitorQueryStatsNameType stat;
> + va_list name_list;
> + size_t sentinel = QEMU_MONITOR_QUERY_STATS_NAME_LAST;
> +
> + provider = g_new0(qemuMonitorQueryStatsProvider, 1);
> + provider->provider = provider_type;
> + provider->names = NULL;
> +
> + va_start(name_list, provider_type);
> + stat = va_arg(name_list, qemuMonitorQueryStatsNameType);
> +
> + if (stat != sentinel) {
>
It would be better to compare 'stat' with QEMU_MONITOR_QUERY_STATS_NAME_LAST
directly without the additional variable 'sentinel'.
> + provider->names =
> virBitmapNew(QEMU_MONITOR_QUERY_STATS_NAME_LAST);
> +
> + while (stat != sentinel) {
>
Same here.
This while cycle would be better outside the if case, such as:
if (stat != sentinel)
provider->names = virBitmapNew(QEMU_MONITOR_QUERY_STATS_NAME_LAST);
while (stat != sentinel) {
....
}
Because the 'while' cycle has the same condition as the 'if' case.
> + if (virBitmapSetBit(provider->names, stat) < 0)
> + return NULL;
> + stat = va_arg(name_list, qemuMonitorQueryStatsNameType);
> + }
> + }
> + va_end(name_list);
> +
> + return g_steal_pointer(&provider);
> +}
> +
> +GPtrArray *
> +qemuMonitorQueryStats(qemuMonitor *mon,
> + qemuMonitorQueryStatsTargetType target,
> + char **vcpus,
> + GPtrArray *providers)
> +{
> + VIR_DEBUG("target=%u vcpus=%p providers=%p", target, vcpus,
> providers);
> +
> + QEMU_CHECK_MONITOR_NULL(mon);
> +
> + if (target != QEMU_MONITOR_QUERY_STATS_TARGET_VCPU && vcpus)
> + return NULL;
> +
> + return qemuMonitorJSONQueryStats(mon, target, vcpus, providers);
> +}
> diff --git a/src/qemu/qemu_monitor.h b/src/qemu/qemu_monitor.h
> index 95267ec6..344636e1 100644
> --- a/src/qemu/qemu_monitor.h
> +++ b/src/qemu/qemu_monitor.h
> @@ -1554,3 +1554,48 @@ qemuMonitorChangeMemoryRequestedSize(qemuMonitor
> *mon,
> int
> qemuMonitorMigrateRecover(qemuMonitor *mon,
> const char *uri);
> +
> +typedef enum {
> + QEMU_MONITOR_QUERY_STATS_TARGET_VM,
> + QEMU_MONITOR_QUERY_STATS_TARGET_VCPU,
> + QEMU_MONITOR_QUERY_STATS_TARGET_LAST,
> +} qemuMonitorQueryStatsTargetType;
> +
> +VIR_ENUM_DECL(qemuMonitorQueryStatsTarget);
> +
> +typedef enum {
> + QEMU_MONITOR_QUERY_STATS_NAME_HALT_POLL_SUCCESS_NS,
> + QEMU_MONITOR_QUERY_STATS_NAME_HALT_POLL_FAIL_NS,
> + QEMU_MONITOR_QUERY_STATS_NAME_LAST,
> +} qemuMonitorQueryStatsNameType;
> +
> +VIR_ENUM_DECL(qemuMonitorQueryStatsName);
> +
> +typedef enum {
> + QEMU_MONITOR_QUERY_STATS_PROVIDER_KVM,
> + QEMU_MONITOR_QUERY_STATS_PROVIDER_LAST,
> +} qemuMonitorQueryStatsProviderType;
> +
> +VIR_ENUM_DECL(qemuMonitorQueryStatsProvider);
> +
> +typedef struct _qemuMonitorQueryStatsProvider
> qemuMonitorQueryStatsProvider;
> +struct _qemuMonitorQueryStatsProvider {
> + qemuMonitorQueryStatsProviderType provider;
>
It is a bit confusing for me to have a variable 'provider' in the
'provider' structure.
Later you use provider->provider which is not very readable.
I would prefer 'type' (maybe even 'providerType') instead.
> + virBitmap *names;
> +};
> +
> +void
> +qemuMonitorQueryStatsProviderFree(qemuMonitorQueryStatsProvider
> *provider);
> +
> +qemuMonitorQueryStatsProvider *
> +qemuMonitorQueryStatsProviderNew(qemuMonitorQueryStatsProviderType
> provider_type,
> + ...);
> +
> +G_DEFINE_AUTOPTR_CLEANUP_FUNC(qemuMonitorQueryStatsProvider,
> + qemuMonitorQueryStatsProviderFree);
> +
> +GPtrArray *
> +qemuMonitorQueryStats(qemuMonitor *mon,
> + qemuMonitorQueryStatsTargetType target,
> + char **vcpus,
> + GPtrArray *providers);
> diff --git a/src/qemu/qemu_monitor_json.c b/src/qemu/qemu_monitor_json.c
> index 80696de7..4e228bfb 100644
> --- a/src/qemu/qemu_monitor_json.c
> +++ b/src/qemu/qemu_monitor_json.c
> @@ -9031,3 +9031,133 @@ qemuMonitorJSONMigrateRecover(qemuMonitor *mon,
>
> return qemuMonitorJSONCheckError(cmd, reply);
> }
> +
> +static GPtrArray *
> +qemuMonitorJSONExtractQueryStats(virJSONValue *arr)
> +{
> + g_autoptr(GPtrArray) queried_stats = NULL;
> + size_t nstats = virJSONValueArraySize(arr);
> + size_t i;
> +
> + /* Create a GPtrArray for GHashTables */
> + queried_stats = g_ptr_array_new_full(nstats, (GDestroyNotify)
> g_hash_table_destroy);
> +
> + for (i = 0; i < nstats; i++) {
> + virJSONValue *obj = virJSONValueArrayGet(arr, i);
> + virJSONValue *stats = virJSONValueObjectGetArray(obj, "stats");
> + size_t j;
> +
> + /* Create a GHashTable for virJSONValues */
> + GHashTable *hash_table = virHashNew((GDestroyNotify)
> virJSONValueFree);
> +
> + for (j = 0; j < virJSONValueArraySize(stats); j++) {
> + virJSONValue *stat = virJSONValueArrayGet(stats, j);
> +
> + g_hash_table_insert(hash_table,
> +
> g_strdup(virJSONValueObjectGetString(stat, "name")),
> + virJSONValueObjectGet(stat, "value"));
> + }
> +
> + g_ptr_array_add(queried_stats, hash_table);
> + }
> +
> + return g_steal_pointer(&queried_stats);
> +}
> +
> +
> +/**
> + * qemuMonitorJSONQueryStats:
> + * @mon: monitor object
> + * @target: the target type for the query
> + * @vcpus: a list of vCPU QOM paths for filtering the statistics
> + * @providers: an array of providers to filter statistics
> + *
> + * @vcpus is a NULL terminated array of strings. @providers is a GPtrArray
> + * for qemuMonitorQueryStatsProvider.
> + * @vcpus and @providers are optional and can be NULL.
> + *
> + * Queries for the @target based statistics.
> + * Returns a GPtrArray of GHashTables containing the statistics on
> success or
> + * NULL on failure.
> + */
> +
> +GPtrArray *
> +qemuMonitorJSONQueryStats(qemuMonitor *mon,
> + qemuMonitorQueryStatsTargetType target,
> + char **vcpus,
> + GPtrArray *providers)
> +{
> + g_autoptr(virJSONValue) cmd = NULL;
> + g_autoptr(virJSONValue) reply = NULL;
> + g_autoptr(virJSONValue) vcpu_list = NULL;
> + g_autoptr(virJSONValue) provider_list = NULL;
> + virJSONValue *rv = NULL;
> +
> + size_t i;
> +
> + if (providers) {
> + provider_list = virJSONValueNewArray();
> +
> + for (i = 0; i < providers->len; i++) {
> + g_autoptr(virJSONValue) provider_obj =
> virJSONValueNewObject();
> + qemuMonitorQueryStatsProvider *provider = providers->pdata[i];
> + const char *type_str =
> qemuMonitorQueryStatsProviderTypeToString(provider->provider);
> + virBitmap *names = provider->names;
> + int rc;
> +
>
We usually use 'rc' (or any variable storing the result) if we need the
value also after the
check of its return code. When we only need to check the result, we usually
compare the
value directly:
if (virJSONValueObjectAppendString(provider_obj, "provider", type_str) < 0)
return NULL;
> + rc = virJSONValueObjectAppendString(provider_obj, "provider",
> type_str);
> +
> + if (rc < 0)
> + return NULL;
> +
> + if (names) {
> + g_autoptr(virJSONValue) provider_names =
> virJSONValueNewArray();
> + int curBit = virBitmapNextSetBit(names, -1);
> +
> + while (curBit >= 0) {
> + const char *name =
> qemuMonitorQueryStatsNameTypeToString(curBit);
> +
> + if (virJSONValueArrayAppendString(provider_names,
> name) < 0)
> + return NULL;
> +
> + curBit = virBitmapNextSetBit(names, curBit);
> + }
> +
> + rc = virJSONValueObjectAppend(provider_obj, "names",
> &provider_names);
> +
>
Same here
> + if (rc < 0)
> + return NULL;
> + }
> +
> + if (virJSONValueArrayAppend(provider_list, &provider_obj) < 0)
> + return NULL;
> + }
> + }
> +
> + if (vcpus) {
> + vcpu_list = virJSONValueNewArray();
> +
> + for (i = 0; vcpus[i]; i++)
> + if (virJSONValueArrayAppendString(vcpu_list, vcpus[i]) < 0)
> + return NULL;
> + }
> +
> + cmd = qemuMonitorJSONMakeCommand("query-stats",
> + "s:target",
> qemuMonitorQueryStatsTargetTypeToString(target),
> + "A:vcpus", &vcpu_list,
> + "A:providers", &provider_list,
> + NULL);
> +
> + if (!cmd)
> + return NULL;
> +
> + if (qemuMonitorJSONCommand(mon, cmd, &reply) < 0)
> + return NULL;
> +
> + if (qemuMonitorJSONCheckError(cmd, reply) < 0)
> + return NULL;
> +
> + rv = virJSONValueObjectStealArray(reply, "return");
> +
> + return qemuMonitorJSONExtractQueryStats(rv);
> +}
> diff --git a/src/qemu/qemu_monitor_json.h b/src/qemu/qemu_monitor_json.h
> index ad3853ae..db8dec80 100644
> --- a/src/qemu/qemu_monitor_json.h
> +++ b/src/qemu/qemu_monitor_json.h
> @@ -878,3 +878,9 @@ qemuMonitorJSONChangeMemoryRequestedSize(qemuMonitor
> *mon,
> int
> qemuMonitorJSONMigrateRecover(qemuMonitor *mon,
> const char *uri);
> +
> +GPtrArray *
> +qemuMonitorJSONQueryStats(qemuMonitor *mon,
> + qemuMonitorQueryStatsTargetType target,
> + char **vcpus,
> + GPtrArray *providers);
> --
> 2.36.1
>
>
Kind regards,
Kristina
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