Hi Peter, On 08/21/2014 09:20 PM, Peter Krempa wrote:

I'd like to propose a (hopefully) fairly future-proof API to retrieve various statistics for domains.

The motivation is that management layers that use libvirt usually poll libvirt for statistics using various split up APIs we currently provide. To get all the necessary stuff, the mgmt app need to issue Ndomains * Napis calls and cope with the various returned formats. The APIs I'm wanting to introduce here will:

1) Return data in a format that we can expand in the future and is hierarchical. This version returns the data as typed parameters where the fields are constructed as dot-separated strings containing names and other stuff in a list of typed params.

2) Stats for multiple (all) domains can be queried at once and are returned in one call. This will allow to decrease the overhead necessary to issue multiple calls per domain multiplied by the count of domains.

3) Selectable (bit mask) fields in the returned format. This will allow to retrieve only specific stats according to the APPs need.

Initially the implementation will introduce the option to retrieve block, interface and cpu stats with the possibility to add more in the future.

The stats groups will be enabled using a bit field @stats passed as the function argument. A few groups for inspiration:

VIR_DOMAIN_STATS_STATE VIR_DOMAIN_STATS_CPU VIR_DOMAIN_STATS_BLOCK VIR_DOMAIN_STATS_INTERFACE

I'm working on an API to retrieve bulk domain block stats[1], after noticed your "all-in-one" API for bulk stats retrieving I think your API would be better for bulk stats retrieving. I wonder if I could take the block part(VIR_DOMAIN_STATS_BLOCK) of this API? If so, please cc me when you post the formal patchset so I can review it and make the block part base on you patch.

the returned typed params will use the following scheme

state.state = running state.reason = started cpu.count = 8 cpu.0.state = running cpu.0.time = 1234

...

I'm also thinking of doing an async version of this, where the user would provide a callback that would be called for each returned domain but I'm not quite sure if that would play nicely with our RPC so that requires a bit more investigation first.

An async version would be useful to overcome the RPC message size limit for the bulk stats. [1]: https://www.redhat.com/archives/libvir-list/2014-August/msg00080.html Thanks, Li Wei

Peter --- include/libvirt/libvirt.h.in | 26 +++++++ src/driver.h | 9 +++ src/libvirt.c | 178 +++++++++++++++++++++++++++++++++++++++++++ src/libvirt_public.syms | 7 ++ 4 files changed, 220 insertions(+)

diff --git a/include/libvirt/libvirt.h.in b/include/libvirt/libvirt.h.in index 47ea695..962f740 100644 --- a/include/libvirt/libvirt.h.in +++ b/include/libvirt/libvirt.h.in @@ -2501,6 +2501,32 @@ int virDomainDetachDeviceFlags(virDomainPtr domain, int virDomainUpdateDeviceFlags(virDomainPtr domain, const char *xml, unsigned int flags);

+typedef struct _virDomainStatsRecord virDomainStatsRecord; +typedef virDomainStatsRecord *virDomainStatsRecordPtr; +struct _virDomainStatsRecord { + virDomainPtr dom; + unsigned int nparams; + virTypedParameterPtr params; +}; + +typedef enum { + VIR_DOMAIN_STATS_ALL = (1 << 0), /* return all stats fields + implemented in the daemon */ + VIR_DOMAIN_STATS_STATE = (1 << 1), /* return domain state */ +} virDomainStatsTypes; + +int virConnectGetAllDomainStats(virConnectPtr conn, + unsigned int stats, + virDomainStatsRecordPtr **retStats, + unsigned int flags); + +int virDomainListGetStats(virDomainPtr *doms, + unsigned int stats, + virDomainStatsRecordPtr **retStats, + unsigned int flags); + +void virDomainStatsRecordListFree(virDomainStatsRecordPtr *stats); + /* * BlockJob API */ diff --git a/src/driver.h b/src/driver.h index 158df79..eab794d 100644 --- a/src/driver.h +++ b/src/driver.h @@ -1191,6 +1191,14 @@ typedef int unsigned int flags);

+typedef int +(*virDrvDomainListGetStats)(virConnectPtr conn, + virDomainPtr *doms, + unsigned int ndoms, + unsigned int stats, + virDomainStatsRecordPtr **retStats, + unsigned int flags); + typedef struct _virDriver virDriver; typedef virDriver *virDriverPtr;

@@ -1411,6 +1419,7 @@ struct _virDriver { virDrvDomainSetTime domainSetTime; virDrvNodeGetFreePages nodeGetFreePages; virDrvConnectGetDomainCapabilities connectGetDomainCapabilities; + virDrvDomainListGetStats domainListGetStats; };

diff --git a/src/libvirt.c b/src/libvirt.c index 8349261..c2244d0 100644 --- a/src/libvirt.c +++ b/src/libvirt.c @@ -21341,3 +21341,181 @@ virConnectGetDomainCapabilities(virConnectPtr conn, virDispatchError(conn); return NULL; } + + +/** + * virConnectGetAllDomainStats: + * @conn: pointer to the hypervisor connection + * @stats: stats to return, binary-OR of virDomainStatsTypes + * @retStats: Pointer that will be filled with the array of returned stats. + * @flags: extra flags; not used yet, so callers should always pass 0 + * + * Query statistics for all domains on a given connection. + * + * Report statistics of various parameters for a running VM according to @stats + * field. The statistics are returned as an array of structures for each queried + * domain. The structure contains an array of typed parameters containing the + * individual statistics. The typed parameter name for each statistic field + * consists of a dot-separated string containing name of the requested group + * followed by a group specific description of the statistic value. + * + * The statistic groups are enabled using the @stats parameter which is a + * binary-OR of enum virDomainStatsTypes. The following groups are available + * (although not necessarily implemented for each storage driver): + * + * VIR_DOMAIN_STATS_ALL: Return all statistics supported by the hypervisor + * driver. This allows to query everything the driver supports without getting + * an error. + * + * VIR_DOMAIN_STATS_STATE: Return domain state and reason for entering that + * state. The typed parameter keys are in format: + * "state.state" - state of the VM, returned as int from virDomainState enum + * "state.reason" - reason for entering given state, returned as in from + * virDomain*Reason enmum corresponding to given state. + * + * Returns the count of returned statistics strucutres on success, -1 on error. + * The requested data are returned in the @retStats parameter. The returned + * array should be freed by the caller. See virDomainStatsRecordListFree. + */ +int +virConnectGetAllDomainStats(virConnectPtr conn, + unsigned int stats, + virDomainStatsRecordPtr **retStats, + unsigned int flags) +{ + int ret = -1; + + VIR_DEBUG("conn=%p, stats=0x%x, retStats=%p, flags=0x%x", + conn, stats, retStats, flags); + + virResetLastError(); + + virCheckConnectReturn(conn, -1); + + if (!conn->driver->domainListGetStats) { + virReportUnsupportedError(); + goto cleanup; + } + + ret = conn->driver->domainListGetStats(conn, NULL, 0, stats, + retStats, flags); + + cleanup: + if (ret < 0) + virDispatchError(conn); + + return ret; +} + + +/** + * virDomainListGetStats: + * @doms: NULL terminated array of domains + * @stats: stats to return, binary-OR of virDomainStatsTypes + * @retStats: Pointer that will be filled with the array of returned stats. + * @flags: extra flags; not used yet, so callers should always pass 0 + * + * Query statistics for domains provided by @doms. Note that all domains in + * @doms must share the same connection. + * + * Report statistics of various parameters for a running VM according to @stats + * field. The statistics are returned as an array of structures for each queried + * domain. The structure contains an array of typed parameters containing the + * individual statistics. The typed parameter name for each statistic field + * consists of a dot-separated string containing name of the requested group + * followed by a group specific description of the statistic value. + * + * The statistic groups are enabled using the @stats parameter which is a + * binary-OR of enum virDomainStatsTypes. The following groups are available + * (although not necessarily implemented for each storage driver): + * + * VIR_DOMAIN_STATS_ALL: Return all statistics supported by the hypervisor + * driver. This allows to query everything the driver supports without getting + * an error. + * + * VIR_DOMAIN_STATS_STATE: Return domain state and reason for entering that + * state. The typed parameter keys are in format: + * "state.state" - state of the VM, returned as int from virDomainState enum + * "state.reason" - reason for entering given state, returned as in from + * virDomain*Reason enmum corresponding to given state. + * + * Returns the count of returned statistics strucutres on success, -1 on error. + * The requested data are returned in the @retStats parameter. The returned + * array should be freed by the caller. See virDomainStatsRecordListFree. + */ +int +virDomainListGetStats(virDomainPtr *doms, + unsigned int stats, + virDomainStatsRecordPtr **retStats, + unsigned int flags) +{ + virConnectPtr conn = NULL; + virDomainPtr *nextdom = doms; + unsigned int ndoms = 0; + int ret = -1; + + VIR_DEBUG("doms=%p, stats=0x%x, retStats=%p, flags=0x%x", + doms, stats, retStats, flags); + + virResetLastError(); + + if (!*doms) { + virReportError(VIR_ERR_INVALID_ARG, + _("doms array in %s must contain at leas one domain"), + __FUNCTION__); + goto cleanup; + } + + conn = doms[0]->conn; + + if (!conn->driver->domainListGetStats) { + virReportUnsupportedError(); + goto cleanup; + } + + while (*(++nextdom)) { + virDomainPtr dom = *nextdom; + + virCheckDomainGoto(dom, cleanup); + + if (dom->conn != conn) { + virReportError(VIR_ERR_INVALID_ARG, + _("domains in 'doms' array must belong to a " + "single connection in %s"), __FUNCTION__); + goto cleanup; + } + + ndoms++; + } + + ret = conn->driver->domainListGetStats(conn, doms, ndoms, stats, retStats, + flags); + + cleanup: + if (ret < 0) + virDispatchError(conn); + return ret; +} + + +/** + * virDomainStatsRecordListFree: + * @stats: NULL terminated array of virDomainStatsRecords to free + * + * Convenience function to free a list of domain stats returned by + * virDomainListGetStats and virConnectGetAllDomainStats. + */ +void +virDomainStatsRecordListFree(virDomainStatsRecordPtr *stats) +{ + virDomainStatsRecordPtr *next = stats; + + while (*next) { + virTypedParamsFree((*next)->params, (*next)->nparams); + virDomainFree((*next)->dom); + VIR_FREE((*next)); + next++; + } + + VIR_FREE(stats); +} diff --git a/src/libvirt_public.syms b/src/libvirt_public.syms index 9f4016a..3714159 100644 --- a/src/libvirt_public.syms +++ b/src/libvirt_public.syms @@ -670,4 +670,11 @@ LIBVIRT_1.2.7 { virConnectGetDomainCapabilities; } LIBVIRT_1.2.6;

+LIBVIRT_1.2.8 { + global: + virDomainListGetStats; + virConnectGetAllDomainStats; + virDomainStatsRecordListFree; +} LIBVIRT_1.2.7; + # .... define new API here using predicted next version number ....